Adding upstream version 115.8.0esr.upstream/115.8.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

222 files changed, 18060 insertions, 0 deletions

diff --git a/devtools/server/tests/xpcshell/.eslintrc.js b/devtools/server/tests/xpcshell/.eslintrc.js
new file mode 100644
index 0000000000..b3d0382a56
--- /dev/null
+++ b/devtools/server/tests/xpcshell/.eslintrc.js
@@ -0,0 +1,9 @@
+"use strict";
+
+module.exports = {
+  // Extend from the common devtools xpcshell eslintrc config.
+  extends: "../../../.eslintrc.xpcshell.js",
+  rules: {
+    "no-debugger": 0,
+  },
+};
diff --git a/devtools/server/tests/xpcshell/addons/web-extension-upgrade/manifest.json b/devtools/server/tests/xpcshell/addons/web-extension-upgrade/manifest.json
new file mode 100644
index 0000000000..cad9442b80
--- /dev/null
+++ b/devtools/server/tests/xpcshell/addons/web-extension-upgrade/manifest.json
@@ -0,0 +1,10 @@
+{
+  "manifest_version": 2,
+  "name": "Test Addons Actor Upgrade",
+  "version": "1.0",
+  "browser_specific_settings": {
+    "gecko": {
+      "id": "test-addons-actor@mozilla.org"
+    }
+  }
+}
diff --git a/devtools/server/tests/xpcshell/addons/web-extension/manifest.json b/devtools/server/tests/xpcshell/addons/web-extension/manifest.json
new file mode 100644
index 0000000000..47f07671e5
--- /dev/null
+++ b/devtools/server/tests/xpcshell/addons/web-extension/manifest.json
@@ -0,0 +1,10 @@
+{
+  "manifest_version": 2,
+  "name": "Test Addons Actor",
+  "version": "1.0",
+  "browser_specific_settings": {
+    "gecko": {
+      "id": "test-addons-actor@mozilla.org"
+    }
+  }
+}
diff --git a/devtools/server/tests/xpcshell/addons/web-extension2/manifest.json b/devtools/server/tests/xpcshell/addons/web-extension2/manifest.json
new file mode 100644
index 0000000000..e1ba91f4fb
--- /dev/null
+++ b/devtools/server/tests/xpcshell/addons/web-extension2/manifest.json
@@ -0,0 +1,10 @@
+{
+  "manifest_version": 2,
+  "name": "Test Addons Actor 2",
+  "version": "1.0",
+  "browser_specific_settings": {
+    "gecko": {
+      "id": "test-addons-actor2@mozilla.org"
+    }
+  }
+}
diff --git a/devtools/server/tests/xpcshell/completions.js b/devtools/server/tests/xpcshell/completions.js
new file mode 100644
index 0000000000..5e77e4e886
--- /dev/null
+++ b/devtools/server/tests/xpcshell/completions.js
@@ -0,0 +1,23 @@
+"use strict";
+/* exported global doRet doThrow */
+
+function ret() {
+  return 2;
+}
+
+function throws() {
+  throw new Error("yo");
+}
+
+function doRet() {
+  debugger;
+  const r = ret();
+  return r;
+}
+
+function doThrow() {
+  debugger;
+  try {
+    throws();
+  } catch (e) {}
+}
diff --git a/devtools/server/tests/xpcshell/head_dbg.js b/devtools/server/tests/xpcshell/head_dbg.js
new file mode 100644
index 0000000000..807fe5965e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/head_dbg.js
@@ -0,0 +1,982 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint no-unused-vars: ["error", {"vars": "local"}] */
+/* eslint-disable no-shadow */
+
+"use strict";
+var CC = Components.Constructor;
+
+// Populate AppInfo before anything (like the shared loader) accesses
+// System.appinfo, which is a lazy getter.
+const appInfo = ChromeUtils.importESModule(
+  "resource://testing-common/AppInfo.sys.mjs"
+);
+appInfo.updateAppInfo({
+  ID: "devtools@tests.mozilla.org",
+  name: "devtools-tests",
+  version: "1",
+  platformVersion: "42",
+  crashReporter: true,
+});
+
+const { require, loader } = ChromeUtils.importESModule(
+  "resource://devtools/shared/loader/Loader.sys.mjs"
+);
+const { worker } = ChromeUtils.import(
+  "resource://devtools/shared/loader/worker-loader.js"
+);
+
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
+
+// Always log packets when running tests. runxpcshelltests.py will throw
+// the output away anyway, unless you give it the --verbose flag.
+Services.prefs.setBoolPref("devtools.debugger.log", false);
+// Enable remote debugging for the relevant tests.
+Services.prefs.setBoolPref("devtools.debugger.remote-enabled", true);
+
+const makeDebugger = require("resource://devtools/server/actors/utils/make-debugger.js");
+const DevToolsUtils = require("resource://devtools/shared/DevToolsUtils.js");
+const {
+  ActorRegistry,
+} = require("resource://devtools/server/actors/utils/actor-registry.js");
+const {
+  DevToolsServer,
+} = require("resource://devtools/server/devtools-server.js");
+const { DevToolsServer: WorkerDevToolsServer } = worker.require(
+  "resource://devtools/server/devtools-server.js"
+);
+const {
+  DevToolsClient,
+} = require("resource://devtools/client/devtools-client.js");
+const { ObjectFront } = require("resource://devtools/client/fronts/object.js");
+const {
+  LongStringFront,
+} = require("resource://devtools/client/fronts/string.js");
+const {
+  createCommandsDictionary,
+} = require("resource://devtools/shared/commands/index.js");
+const {
+  CommandsFactory,
+} = require("resource://devtools/shared/commands/commands-factory.js");
+
+const { addDebuggerToGlobal } = ChromeUtils.importESModule(
+  "resource://gre/modules/jsdebugger.sys.mjs"
+);
+
+const { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+const { getAppInfo } = ChromeUtils.importESModule(
+  "resource://testing-common/AppInfo.sys.mjs"
+);
+
+const systemPrincipal = Cc["@mozilla.org/systemprincipal;1"].createInstance(
+  Ci.nsIPrincipal
+);
+
+var { loadSubScript, loadSubScriptWithOptions } = Services.scriptloader;
+
+/**
+ * The logic here must resemble the logic of --start-debugger-server as closely
+ * as possible. DevToolsStartup.sys.mjs uses a distinct loader that results in
+ * the existence of two isolated module namespaces. In practice, this can cause
+ * bugs such as bug 1837185.
+ */
+function getDistinctDevToolsServer() {
+  const {
+    useDistinctSystemPrincipalLoader,
+    releaseDistinctSystemPrincipalLoader,
+  } = ChromeUtils.importESModule(
+    "resource://devtools/shared/loader/DistinctSystemPrincipalLoader.sys.mjs"
+  );
+  const requester = {};
+  const distinctLoader = useDistinctSystemPrincipalLoader(requester);
+  registerCleanupFunction(() => {
+    releaseDistinctSystemPrincipalLoader(requester);
+  });
+
+  const { DevToolsServer: DistinctDevToolsServer } = distinctLoader.require(
+    "resource://devtools/server/devtools-server.js"
+  );
+  return DistinctDevToolsServer;
+}
+
+/**
+ * Initializes any test that needs to work with add-ons.
+ *
+ * Should be called once per test script that needs to use AddonTestUtils (and
+ * not once per test task!).
+ */
+async function startupAddonsManager() {
+  // Create a directory for extensions.
+  const profileDir = do_get_profile().clone();
+  profileDir.append("extensions");
+
+  AddonTestUtils.init(globalThis);
+  AddonTestUtils.overrideCertDB();
+  AddonTestUtils.appInfo = getAppInfo();
+
+  await AddonTestUtils.promiseStartupManager();
+}
+
+async function createTargetForFakeTab(title) {
+  const client = await startTestDevToolsServer(title);
+
+  const tabs = await listTabs(client);
+  const tabDescriptor = findTab(tabs, title);
+
+  // These xpcshell tests use mocked actors (xpcshell-test/testactors)
+  // which still don't support watcher actor.
+  // Because of that we still can't enable server side targets and target swiching.
+  tabDescriptor.disableTargetSwitching();
+
+  return tabDescriptor.getTarget();
+}
+
+async function createTargetForMainProcess() {
+  const commands = await CommandsFactory.forMainProcess();
+  return commands.descriptorFront.getTarget();
+}
+
+/**
+ * Create a MemoryFront for a fake test tab.
+ */
+async function createTabMemoryFront() {
+  const target = await createTargetForFakeTab("test_memory");
+
+  // MemoryFront requires the HeadSnapshotActor actor to be available
+  // as a global actor. This isn't registered by startTestDevToolsServer which
+  // only register the target actors and not the browser ones.
+  DevToolsServer.registerActors({ browser: true });
+
+  const memoryFront = await target.getFront("memory");
+  await memoryFront.attach();
+
+  registerCleanupFunction(async () => {
+    await memoryFront.detach();
+
+    // On XPCShell, the target isn't for a local tab and so target.destroy
+    // won't close the client. So do it so here. It will automatically destroy the target.
+    await target.client.close();
+  });
+
+  return { target, memoryFront };
+}
+
+/**
+ * Same as createTabMemoryFront but attaches the MemoryFront to the MemoryActor
+ * scoped to the full runtime rather than to a tab.
+ */
+async function createMainProcessMemoryFront() {
+  const target = await createTargetForMainProcess();
+
+  const memoryFront = await target.getFront("memory");
+  await memoryFront.attach();
+
+  registerCleanupFunction(async () => {
+    await memoryFront.detach();
+    // For XPCShell, the main process target actor is ContentProcessTargetActor
+    // which doesn't expose any `detach` method. So that the target actor isn't
+    // destroyed when calling target.destroy.
+    // Close the client to cleanup everything.
+    await target.client.close();
+  });
+
+  return { client: target.client, memoryFront };
+}
+
+function createLongStringFront(conn, form) {
+  // CAUTION -- do not replicate in the codebase. Instead, use marshalling
+  // This code is simulating how the LongStringFront would be created by protocol.js
+  // We should not use it like this in the codebase, this is done only for testing
+  // purposes until we can return a proper LongStringFront from the server.
+  const front = new LongStringFront(conn, form);
+  front.actorID = form.actor;
+  front.manage(front);
+  return front;
+}
+
+function createTestGlobal(name, options) {
+  const principal = Cc["@mozilla.org/systemprincipal;1"].createInstance(
+    Ci.nsIPrincipal
+  );
+  // NOTE: The Sandbox constructor behaves differently based on the argument
+  //       length.
+  const sandbox = options
+    ? Cu.Sandbox(principal, options)
+    : Cu.Sandbox(principal);
+  sandbox.__name = name;
+  // Expose a few mocks to better represent a Window object.
+  // These attributes will be used by DOCUMENT_EVENT resource listener.
+  sandbox.performance = { timing: {} };
+  sandbox.document = {
+    readyState: "complete",
+    defaultView: sandbox,
+  };
+  return sandbox;
+}
+
+function connect(client) {
+  dump("Connecting client.\n");
+  return client.connect();
+}
+
+function close(client) {
+  dump("Closing client.\n");
+  return client.close();
+}
+
+function listTabs(client) {
+  dump("Listing tabs.\n");
+  return client.mainRoot.listTabs();
+}
+
+function findTab(tabs, title) {
+  dump("Finding tab with title '" + title + "'.\n");
+  for (const tab of tabs) {
+    if (tab.title === title) {
+      return tab;
+    }
+  }
+  return null;
+}
+
+function waitForNewSource(threadFront, url) {
+  dump("Waiting for new source with url '" + url + "'.\n");
+  return waitForEvent(threadFront, "newSource", function (packet) {
+    return packet.source.url === url;
+  });
+}
+
+function attachThread(targetFront, options = {}) {
+  dump("Attaching to thread.\n");
+  return targetFront.attachThread(options);
+}
+
+function resume(threadFront) {
+  dump("Resuming thread.\n");
+  return threadFront.resume();
+}
+
+async function addWatchpoint(threadFront, frame, variable, property, type) {
+  const path = `${variable}.${property}`;
+  info(`Add an ${path} ${type} watchpoint`);
+  const environment = await frame.getEnvironment();
+  const obj = environment.bindings.variables[variable];
+  const objFront = threadFront.pauseGrip(obj.value);
+  return objFront.addWatchpoint(property, path, type);
+}
+
+function getSources(threadFront) {
+  dump("Getting sources.\n");
+  return threadFront.getSources();
+}
+
+function findSource(sources, url) {
+  dump("Finding source with url '" + url + "'.\n");
+  for (const source of sources) {
+    if (source.url === url) {
+      return source;
+    }
+  }
+  return null;
+}
+
+function waitForPause(threadFront) {
+  dump("Waiting for pause.\n");
+  return waitForEvent(threadFront, "paused");
+}
+
+function waitForProperty(dbg, property) {
+  return new Promise(resolve => {
+    Object.defineProperty(dbg, property, {
+      set(newValue) {
+        resolve(newValue);
+      },
+    });
+  });
+}
+
+function setBreakpoint(threadFront, location) {
+  dump("Setting breakpoint.\n");
+  return threadFront.setBreakpoint(location, {});
+}
+
+function getPrototypeAndProperties(objClient) {
+  dump("getting prototype and properties.\n");
+
+  return objClient.getPrototypeAndProperties();
+}
+
+function dumpn(msg) {
+  dump("DBG-TEST: " + msg + "\n");
+}
+
+function testExceptionHook(ex) {
+  try {
+    do_report_unexpected_exception(ex);
+  } catch (e) {
+    return { throw: e };
+  }
+  return undefined;
+}
+
+// Convert an nsIScriptError 'logLevel' value into an appropriate string.
+function scriptErrorLogLevel(message) {
+  switch (message.logLevel) {
+    case Ci.nsIConsoleMessage.info:
+      return "info";
+    case Ci.nsIConsoleMessage.warn:
+      return "warning";
+    default:
+      Assert.equal(message.logLevel, Ci.nsIConsoleMessage.error);
+      return "error";
+  }
+}
+
+// Register a console listener, so console messages don't just disappear
+// into the ether.
+var errorCount = 0;
+var listener = {
+  observe(message) {
+    try {
+      let string;
+      errorCount++;
+      try {
+        // If we've been given an nsIScriptError, then we can print out
+        // something nicely formatted, for tools like Emacs to pick up.
+        message.QueryInterface(Ci.nsIScriptError);
+        dumpn(
+          message.sourceName +
+            ":" +
+            message.lineNumber +
+            ": " +
+            scriptErrorLogLevel(message) +
+            ": " +
+            message.errorMessage
+        );
+        string = message.errorMessage;
+      } catch (e1) {
+        // Be a little paranoid with message, as the whole goal here is to lose
+        // no information.
+        try {
+          string = "" + message.message;
+        } catch (e2) {
+          string = "<error converting error message to string>";
+        }
+      }
+
+      // Make sure we exit all nested event loops so that the test can finish.
+      while (
+        DevToolsServer &&
+        DevToolsServer.xpcInspector &&
+        DevToolsServer.xpcInspector.eventLoopNestLevel > 0
+      ) {
+        DevToolsServer.xpcInspector.exitNestedEventLoop();
+      }
+
+      // In the world before bug 997440, exceptions were getting lost because of
+      // the arbitrary JSContext being used in nsXPCWrappedJS::CallMethod.
+      // In the new world, the wanderers have returned. However, because of the,
+      // currently very-broken, exception reporting machinery in
+      // nsXPCWrappedJS these get reported as errors to the console, even if
+      // there's actually JS on the stack above that will catch them.  If we
+      // throw an error here because of them our tests start failing.  So, we'll
+      // just dump the message to the logs instead, to make sure the information
+      // isn't lost.
+      dumpn("head_dbg.js observed a console message: " + string);
+    } catch (_) {
+      // Swallow everything to avoid console reentrancy errors. We did our best
+      // to log above, but apparently that didn't cut it.
+    }
+  },
+};
+
+Services.console.registerListener(listener);
+
+function addTestGlobal(name, server = DevToolsServer) {
+  const global = createTestGlobal(name);
+  server.addTestGlobal(global);
+  return global;
+}
+
+// List the DevToolsClient |client|'s tabs, look for one whose title is
+// |title|.
+async function getTestTab(client, title) {
+  const tabs = await client.mainRoot.listTabs();
+  for (const tab of tabs) {
+    if (tab.title === title) {
+      return tab;
+    }
+  }
+  return null;
+}
+/**
+ *  Attach to the client's tab whose title is specified
+ * @param {Object} client
+ * @param {Object} title
+ * @returns commands
+ */
+async function attachTestTab(client, title) {
+  const descriptorFront = await getTestTab(client, title);
+
+  // These xpcshell tests use mocked actors (xpcshell-test/testactors)
+  // which still don't support watcher actor.
+  // Because of that we still can't enable server side targets and target swiching.
+  descriptorFront.disableTargetSwitching();
+
+  const commands = await createCommandsDictionary(descriptorFront);
+  await commands.targetCommand.startListening();
+  return commands;
+}
+
+/**
+ * Attach to the client's tab whose title is specified, and then attach to
+ * that tab's thread.
+ * @param {Object} client
+ * @param {Object} title
+ * @returns {Object}
+ *         targetFront
+ *         threadFront
+ *         commands
+ */
+async function attachTestThread(client, title) {
+  const commands = await attachTestTab(client, title);
+  const targetFront = commands.targetCommand.targetFront;
+  const threadFront = await targetFront.getFront("thread");
+  await targetFront.attachThread({
+    autoBlackBox: true,
+  });
+  Assert.equal(threadFront.state, "attached", "Thread front is attached");
+  return { targetFront, threadFront, commands };
+}
+
+/**
+ * Initialize the testing devtools server.
+ */
+function initTestDevToolsServer(server = DevToolsServer) {
+  if (server === WorkerDevToolsServer) {
+    const { createRootActor } = worker.require("xpcshell-test/testactors");
+    server.setRootActor(createRootActor);
+  } else {
+    const { createRootActor } = require("xpcshell-test/testactors");
+    server.setRootActor(createRootActor);
+  }
+
+  // Allow incoming connections.
+  server.init(function () {
+    return true;
+  });
+}
+
+/**
+ * Initialize the testing devtools server with a tab whose title is |title|.
+ */
+async function startTestDevToolsServer(title, server = DevToolsServer) {
+  initTestDevToolsServer(server);
+  addTestGlobal(title);
+  DevToolsServer.registerActors({ target: true });
+
+  const transport = DevToolsServer.connectPipe();
+  const client = new DevToolsClient(transport);
+
+  await connect(client);
+  return client;
+}
+
+async function finishClient(client) {
+  await client.close();
+  DevToolsServer.destroy();
+  do_test_finished();
+}
+
+/**
+ * Takes a relative file path and returns the absolute file url for it.
+ */
+function getFileUrl(name, allowMissing = false) {
+  const file = do_get_file(name, allowMissing);
+  return Services.io.newFileURI(file).spec;
+}
+
+/**
+ * Returns the full path of the file with the specified name in a
+ * platform-independent and URL-like form.
+ */
+function getFilePath(
+  name,
+  allowMissing = false,
+  usePlatformPathSeparator = false
+) {
+  const file = do_get_file(name, allowMissing);
+  let path = Services.io.newFileURI(file).spec;
+  let filePrePath = "file://";
+  if ("nsILocalFileWin" in Ci && file instanceof Ci.nsILocalFileWin) {
+    filePrePath += "/";
+  }
+
+  path = path.slice(filePrePath.length);
+
+  if (usePlatformPathSeparator && path.match(/^\w:/)) {
+    path = path.replace(/\//g, "\\");
+  }
+
+  return path;
+}
+
+/**
+ * Returns the full text contents of the given file.
+ */
+function readFile(fileName) {
+  const f = do_get_file(fileName);
+  const s = Cc["@mozilla.org/network/file-input-stream;1"].createInstance(
+    Ci.nsIFileInputStream
+  );
+  s.init(f, -1, -1, false);
+  try {
+    return NetUtil.readInputStreamToString(s, s.available());
+  } finally {
+    s.close();
+  }
+}
+
+function writeFile(fileName, content) {
+  const file = do_get_file(fileName, true);
+  const stream = Cc["@mozilla.org/network/file-output-stream;1"].createInstance(
+    Ci.nsIFileOutputStream
+  );
+  stream.init(file, -1, -1, 0);
+  try {
+    do {
+      const numWritten = stream.write(content, content.length);
+      content = content.slice(numWritten);
+    } while (content.length);
+  } finally {
+    stream.close();
+  }
+}
+
+function StubTransport() {}
+StubTransport.prototype.ready = function () {};
+StubTransport.prototype.send = function () {};
+StubTransport.prototype.close = function () {};
+
+// Create async version of the object where calling each method
+// is equivalent of calling it with asyncall. Mainly useful for
+// destructuring objects with methods that take callbacks.
+const Async = target => new Proxy(target, Async);
+Async.get = (target, name) =>
+  typeof target[name] === "function"
+    ? asyncall.bind(null, target[name], target)
+    : target[name];
+
+// Calls async function that takes callback and errorback and returns
+// returns promise representing result.
+const asyncall = (fn, self, ...args) =>
+  new Promise((...etc) => fn.call(self, ...args, ...etc));
+
+const Test = task => () => {
+  add_task(task);
+  run_next_test();
+};
+
+const assert = Assert.ok.bind(Assert);
+
+/**
+ * Create a promise that is resolved on the next occurence of the given event.
+ *
+ * @param ThreadFront threadFront
+ * @param String event
+ * @param Function predicate
+ * @returns Promise
+ */
+function waitForEvent(front, type, predicate) {
+  if (!predicate) {
+    return front.once(type);
+  }
+
+  return new Promise(function (resolve) {
+    function listener(packet) {
+      if (!predicate(packet)) {
+        return;
+      }
+      front.off(type, listener);
+      resolve(packet);
+    }
+    front.on(type, listener);
+  });
+}
+
+/**
+ * Execute the action on the next tick and return a promise that is resolved on
+ * the next pause.
+ *
+ * When using promises and Task.jsm, we often want to do an action that causes a
+ * pause and continue the task once the pause has ocurred. Unfortunately, if we
+ * do the action that causes the pause within the task's current tick we will
+ * pause before we have a chance to yield the promise that waits for the pause
+ * and we enter a dead lock. The solution is to create the promise that waits
+ * for the pause, schedule the action to run on the next tick of the event loop,
+ * and finally yield the promise.
+ *
+ * @param Function action
+ * @param ThreadFront threadFront
+ * @returns Promise
+ */
+function executeOnNextTickAndWaitForPause(action, threadFront) {
+  const paused = waitForPause(threadFront);
+  executeSoon(action);
+  return paused;
+}
+
+function evalCallback(debuggeeGlobal, func) {
+  Cu.evalInSandbox("(" + func + ")()", debuggeeGlobal, "1.8", "test.js", 1);
+}
+
+/**
+ * Interrupt JS execution for the specified thread.
+ *
+ * @param ThreadFront threadFront
+ * @returns Promise
+ */
+function interrupt(threadFront) {
+  dumpn("Interrupting.");
+  return threadFront.interrupt();
+}
+
+/**
+ * Resume JS execution for the specified thread and then wait for the next pause
+ * event.
+ *
+ * @param DevToolsClient client
+ * @param ThreadFront threadFront
+ * @returns Promise
+ */
+async function resumeAndWaitForPause(threadFront) {
+  const paused = waitForPause(threadFront);
+  await resume(threadFront);
+  return paused;
+}
+
+/**
+ * Resume JS execution for a single step and wait for the pause after the step
+ * has been taken.
+ *
+ * @param ThreadFront threadFront
+ * @returns Promise
+ */
+function stepIn(threadFront) {
+  dumpn("Stepping in.");
+  const paused = waitForPause(threadFront);
+  return threadFront.stepIn().then(() => paused);
+}
+
+/**
+ * Resume JS execution for a step over and wait for the pause after the step
+ * has been taken.
+ *
+ * @param ThreadFront threadFront
+ * @returns Promise
+ */
+async function stepOver(threadFront, frameActor) {
+  dumpn("Stepping over.");
+  await threadFront.stepOver(frameActor);
+  return waitForPause(threadFront);
+}
+
+/**
+ * Resume JS execution for a step out and wait for the pause after the step
+ * has been taken.
+ *
+ * @param DevToolsClient client
+ * @param ThreadFront threadFront
+ * @returns Promise
+ */
+async function stepOut(threadFront, frameActor) {
+  dumpn("Stepping out.");
+  await threadFront.stepOut(frameActor);
+  return waitForPause(threadFront);
+}
+
+/**
+ * Restart specific frame and wait for the pause after the restart
+ * has been taken.
+ *
+ * @param DevToolsClient client
+ * @param ThreadFront threadFront
+ * @returns Promise
+ */
+async function restartFrame(threadFront, frameActor) {
+  dumpn("Restarting frame.");
+  await threadFront.restart(frameActor);
+  return waitForPause(threadFront);
+}
+
+/**
+ * Get the list of `count` frames currently on stack, starting at the index
+ * `first` for the specified thread.
+ *
+ * @param ThreadFront threadFront
+ * @param Number first
+ * @param Number count
+ * @returns Promise
+ */
+function getFrames(threadFront, first, count) {
+  dumpn("Getting frames.");
+  return threadFront.getFrames(first, count);
+}
+
+/**
+ * Black box the specified source.
+ *
+ * @param SourceFront sourceFront
+ * @returns Promise
+ */
+async function blackBox(sourceFront, range = null) {
+  dumpn("Black boxing source: " + sourceFront.actor);
+  const pausedInSource = await sourceFront.blackBox(range);
+  ok(true, "blackBox didn't throw");
+  return pausedInSource;
+}
+
+/**
+ * Stop black boxing the specified source.
+ *
+ * @param SourceFront sourceFront
+ * @returns Promise
+ */
+async function unBlackBox(sourceFront, range = null) {
+  dumpn("Un-black boxing source: " + sourceFront.actor);
+  await sourceFront.unblackBox(range);
+  ok(true, "unblackBox didn't throw");
+}
+
+/**
+ * Get a source at the specified url.
+ *
+ * @param ThreadFront threadFront
+ * @param string url
+ * @returns Promise<SourceFront>
+ */
+async function getSource(threadFront, url) {
+  const source = await getSourceForm(threadFront, url);
+  if (source) {
+    return threadFront.source(source);
+  }
+
+  throw new Error("source not found");
+}
+
+async function getSourceById(threadFront, id) {
+  const form = await getSourceFormById(threadFront, id);
+  return threadFront.source(form);
+}
+
+async function getSourceForm(threadFront, url) {
+  const { sources } = await threadFront.getSources();
+  return sources.find(s => s.url === url);
+}
+
+async function getSourceFormById(threadFront, id) {
+  const { sources } = await threadFront.getSources();
+  return sources.find(source => source.actor == id);
+}
+
+async function checkFramesLength(threadFront, expectedFrames) {
+  const frameResponse = await threadFront.getFrames(0, null);
+  Assert.equal(
+    frameResponse.frames.length,
+    expectedFrames,
+    "Thread front has the expected number of frames"
+  );
+}
+
+/**
+ * Do a reload which clears the thread debugger
+ *
+ * @param TabFront tabFront
+ * @returns Promise<response>
+ */
+function reload(tabFront) {
+  return tabFront.reload({});
+}
+
+/**
+ * Returns an array of stack location strings given a thread and a sample.
+ *
+ * @param object thread
+ * @param object sample
+ * @returns object
+ */
+function getInflatedStackLocations(thread, sample) {
+  const stackTable = thread.stackTable;
+  const frameTable = thread.frameTable;
+  const stringTable = thread.stringTable;
+  const SAMPLE_STACK_SLOT = thread.samples.schema.stack;
+  const STACK_PREFIX_SLOT = stackTable.schema.prefix;
+  const STACK_FRAME_SLOT = stackTable.schema.frame;
+  const FRAME_LOCATION_SLOT = frameTable.schema.location;
+
+  // Build the stack from the raw data and accumulate the locations in
+  // an array.
+  let stackIndex = sample[SAMPLE_STACK_SLOT];
+  const locations = [];
+  while (stackIndex !== null) {
+    const stackEntry = stackTable.data[stackIndex];
+    const frame = frameTable.data[stackEntry[STACK_FRAME_SLOT]];
+    locations.push(stringTable[frame[FRAME_LOCATION_SLOT]]);
+    stackIndex = stackEntry[STACK_PREFIX_SLOT];
+  }
+
+  // The profiler tree is inverted, so reverse the array.
+  return locations.reverse();
+}
+
+async function setupTestFromUrl(url) {
+  do_test_pending();
+
+  const { createRootActor } = require("xpcshell-test/testactors");
+  DevToolsServer.setRootActor(createRootActor);
+  DevToolsServer.init(() => true);
+
+  const global = createTestGlobal("test");
+  DevToolsServer.addTestGlobal(global);
+
+  const devToolsClient = new DevToolsClient(DevToolsServer.connectPipe());
+  await connect(devToolsClient);
+
+  const tabs = await listTabs(devToolsClient);
+  const descriptorFront = findTab(tabs, "test");
+
+  // These xpcshell tests use mocked actors (xpcshell-test/testactors)
+  // which still don't support watcher actor.
+  // Because of that we still can't enable server side targets and target swiching.
+  descriptorFront.disableTargetSwitching();
+
+  const targetFront = await descriptorFront.getTarget();
+
+  const threadFront = await attachThread(targetFront);
+
+  const sourceUrl = getFileUrl(url);
+  const promise = waitForNewSource(threadFront, sourceUrl);
+  loadSubScript(sourceUrl, global);
+  const { source } = await promise;
+
+  const sourceFront = threadFront.source(source);
+  return { global, devToolsClient, threadFront, sourceFront };
+}
+
+/**
+ * Run the given test function twice, one with a regular DevToolsServer,
+ * testing against a fake tab. And another one against a WorkerDevToolsServer,
+ * testing the worker codepath.
+ *
+ * @param Function test
+ *        Test function to run twice.
+ *        This test function is called with a dictionary:
+ *        - Sandbox debuggee
+ *          The custom JS debuggee created for this test. This is a Sandbox using system
+ *           principals by default.
+ *        - ThreadFront threadFront
+ *          A reference to a ThreadFront instance that is attached to the debuggee.
+ *        - DevToolsClient client
+ *          A reference to the DevToolsClient used to communicated with the RDP server.
+ * @param Object options
+ *        Optional arguments to tweak test environment
+ *        - JSPrincipal principal
+ *          Principal to use for the debuggee. Defaults to systemPrincipal.
+ *        - boolean doNotRunWorker
+ *          If true, do not run this tests in worker debugger context. Defaults to false.
+ *        - bool wantXrays
+ *          Whether the debuggee wants Xray vision with respect to same-origin objects
+ *          outside the sandbox. Defaults to true.
+ *        - bool waitForFinish
+ *          Whether to wait for a call to threadFrontTestFinished after the test
+ *          function finishes.
+ */
+function threadFrontTest(test, options = {}) {
+  const {
+    principal = systemPrincipal,
+    doNotRunWorker = false,
+    wantXrays = true,
+    waitForFinish = false,
+  } = options;
+
+  async function runThreadFrontTestWithServer(server, test) {
+    // Setup a server and connect a client to it.
+    initTestDevToolsServer(server);
+
+    // Create a custom debuggee and register it to the server.
+    // We are using a custom Sandbox as debuggee. Create a new zone because
+    // debugger and debuggee must be in different compartments.
+    const debuggee = Cu.Sandbox(principal, { freshZone: true, wantXrays });
+    const scriptName = "debuggee.js";
+    debuggee.__name = scriptName;
+    server.addTestGlobal(debuggee);
+
+    const client = new DevToolsClient(server.connectPipe());
+    await client.connect();
+
+    // Attach to the fake tab target and retrieve the ThreadFront instance.
+    // Automatically resume as the thread is paused by default after attach.
+    const { targetFront, threadFront, commands } = await attachTestThread(
+      client,
+      scriptName
+    );
+
+    // Cross the client/server boundary to retrieve the target actor & thread
+    // actor instances, used by some tests.
+    const rootActor = client.transport._serverConnection.rootActor;
+    const targetActor =
+      rootActor._parameters.tabList.getTargetActorForTab("debuggee.js");
+    const { threadActor } = targetActor;
+
+    // Run the test function
+    const args = {
+      threadActor,
+      threadFront,
+      debuggee,
+      client,
+      server,
+      targetFront,
+      commands,
+      isWorkerServer: server === WorkerDevToolsServer,
+    };
+    if (waitForFinish) {
+      // Use dispatchToMainThread so that the test function does not have to
+      // finish executing before the test itself finishes.
+      const promise = new Promise(
+        resolve => (threadFrontTestFinished = resolve)
+      );
+      Services.tm.dispatchToMainThread(() => test(args));
+      await promise;
+    } else {
+      await test(args);
+    }
+
+    // Cleanup the client after the test ran
+    await client.close();
+
+    server.removeTestGlobal(debuggee);
+
+    // Also cleanup the created server
+    server.destroy();
+  }
+
+  return async () => {
+    dump(">>> Run thread front test against a regular DevToolsServer\n");
+    await runThreadFrontTestWithServer(DevToolsServer, test);
+
+    // Skip tests that fail in the worker context
+    if (!doNotRunWorker) {
+      dump(">>> Run thread front test against a worker DevToolsServer\n");
+      await runThreadFrontTestWithServer(WorkerDevToolsServer, test);
+    }
+  };
+}
+
+// This callback is used in tandem with the waitForFinish option of
+// threadFrontTest to support thread front tests that use promises to
+// asynchronously finish the tests, instead of using async/await.
+// Newly written tests should avoid using this. See bug 1596114 for migrating
+// existing tests to async/await and removing this functionality.
+let threadFrontTestFinished;
diff --git a/devtools/server/tests/xpcshell/hello-actor.js b/devtools/server/tests/xpcshell/hello-actor.js
new file mode 100644
index 0000000000..f4fc63cb86
--- /dev/null
+++ b/devtools/server/tests/xpcshell/hello-actor.js
@@ -0,0 +1,23 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint no-unused-vars: ["error", {"vars": "local"}] */
+
+"use strict";
+
+const protocol = require("resource://devtools/shared/protocol.js");
+
+const helloSpec = protocol.generateActorSpec({
+  typeName: "helloActor",
+
+  methods: {
+    hello: {},
+  },
+});
+
+class HelloActor extends protocol.Actor {
+  constructor(conn) {
+    super(conn, helloSpec);
+  }
+
+  hello() {}
+}
diff --git a/devtools/server/tests/xpcshell/post_init_global_actors.js b/devtools/server/tests/xpcshell/post_init_global_actors.js
new file mode 100644
index 0000000000..4ec5fb8078
--- /dev/null
+++ b/devtools/server/tests/xpcshell/post_init_global_actors.js
@@ -0,0 +1,22 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { Actor } = require("resource://devtools/shared/protocol/Actor.js");
+
+class PostInitGlobalActor extends Actor {
+  constructor(conn) {
+    super(conn, { typeName: "postInitGlobal", methods: [] });
+
+    this.requestTypes = {
+      ping: this.onPing,
+    };
+  }
+
+  onPing() {
+    return { message: "pong" };
+  }
+}
+
+exports.PostInitGlobalActor = PostInitGlobalActor;
diff --git a/devtools/server/tests/xpcshell/post_init_target_scoped_actors.js b/devtools/server/tests/xpcshell/post_init_target_scoped_actors.js
new file mode 100644
index 0000000000..9b0b4c053e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/post_init_target_scoped_actors.js
@@ -0,0 +1,22 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { Actor } = require("resource://devtools/shared/protocol/Actor.js");
+
+class PostInitTargetScopedActor extends Actor {
+  constructor(conn) {
+    super(conn, { typeName: "postInitTargetScoped", methods: [] });
+
+    this.requestTypes = {
+      ping: this.onPing,
+    };
+  }
+
+  onPing() {
+    return { message: "pong" };
+  }
+}
+
+exports.PostInitTargetScopedActor = PostInitTargetScopedActor;
diff --git a/devtools/server/tests/xpcshell/pre_init_global_actors.js b/devtools/server/tests/xpcshell/pre_init_global_actors.js
new file mode 100644
index 0000000000..f5e14aaaa9
--- /dev/null
+++ b/devtools/server/tests/xpcshell/pre_init_global_actors.js
@@ -0,0 +1,22 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { Actor } = require("resource://devtools/shared/protocol/Actor.js");
+
+class PreInitGlobalActor extends Actor {
+  constructor(conn) {
+    super(conn, { typeName: "preInitGlobal", methods: [] });
+
+    this.requestTypes = {
+      ping: this.onPing,
+    };
+  }
+
+  onPing() {
+    return { message: "pong" };
+  }
+}
+
+exports.PreInitGlobalActor = PreInitGlobalActor;
diff --git a/devtools/server/tests/xpcshell/pre_init_target_scoped_actors.js b/devtools/server/tests/xpcshell/pre_init_target_scoped_actors.js
new file mode 100644
index 0000000000..360d4b52a0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/pre_init_target_scoped_actors.js
@@ -0,0 +1,22 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { Actor } = require("resource://devtools/shared/protocol/Actor.js");
+
+class PreInitTargetScopedActor extends Actor {
+  constructor(conn) {
+    super(conn, { typeName: "preInitTargetScoped", methods: [] });
+
+    this.requestTypes = {
+      ping: this.onPing,
+    };
+  }
+
+  onPing() {
+    return { message: "pong" };
+  }
+}
+
+exports.PreInitTargetScopedActor = PreInitTargetScopedActor;
diff --git a/devtools/server/tests/xpcshell/registertestactors-lazy.js b/devtools/server/tests/xpcshell/registertestactors-lazy.js
new file mode 100644
index 0000000000..ef04e7a8d2
--- /dev/null
+++ b/devtools/server/tests/xpcshell/registertestactors-lazy.js
@@ -0,0 +1,43 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+var {
+  RetVal,
+  Actor,
+  FrontClassWithSpec,
+  generateActorSpec,
+} = require("resource://devtools/shared/protocol.js");
+
+const lazySpec = generateActorSpec({
+  typeName: "lazy",
+
+  methods: {
+    hello: {
+      response: { str: RetVal("string") },
+    },
+  },
+});
+
+class LazyActor extends Actor {
+  constructor(conn, id) {
+    super(conn, lazySpec);
+
+    Services.obs.notifyObservers(null, "actor", "instantiated");
+  }
+
+  hello(str) {
+    return "world";
+  }
+}
+exports.LazyActor = LazyActor;
+
+Services.obs.notifyObservers(null, "actor", "loaded");
+
+class LazyFront extends FrontClassWithSpec(lazySpec) {
+  constructor(client) {
+    super(client);
+  }
+}
+exports.LazyFront = LazyFront;
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-column-in-gcd-script.js b/devtools/server/tests/xpcshell/setBreakpoint-on-column-in-gcd-script.js
new file mode 100644
index 0000000000..575915c4fd
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-column-in-gcd-script.js
@@ -0,0 +1,7 @@
+"use strict";
+
+function f() {}
+
+(function () {
+  var a = 1; var b = 2; var c = 3;
+})();
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-column-minified.js b/devtools/server/tests/xpcshell/setBreakpoint-on-column-minified.js
new file mode 100644
index 0000000000..1fbf8ef16e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-column-minified.js
@@ -0,0 +1,8 @@
+"use strict";
+
+function other(){ var a = 1; } function test(){ var a = 1; var b = 2; var c = 3; }
+
+function f() {
+  other();
+  test();
+}
\ No newline at end of file
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-column-with-no-offsets-in-gcd-script.js b/devtools/server/tests/xpcshell/setBreakpoint-on-column-with-no-offsets-in-gcd-script.js
new file mode 100644
index 0000000000..adce39193d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-column-with-no-offsets-in-gcd-script.js
@@ -0,0 +1,7 @@
+"use strict";
+
+function f() {}
+
+(function () {
+  var a = 1;            var c = 3;
+})();
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-column-with-no-offsets.js b/devtools/server/tests/xpcshell/setBreakpoint-on-column-with-no-offsets.js
new file mode 100644
index 0000000000..5faefc3c88
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-column-with-no-offsets.js
@@ -0,0 +1,5 @@
+"use strict";
+
+function f() {
+  var a = 1;            var c = 3;
+}
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-column.js b/devtools/server/tests/xpcshell/setBreakpoint-on-column.js
new file mode 100644
index 0000000000..d92231e651
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-column.js
@@ -0,0 +1,5 @@
+"use strict";
+
+function f() {
+  var a = 1; var b = 2; var c = 3;
+}
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-line-in-gcd-script.js b/devtools/server/tests/xpcshell/setBreakpoint-on-line-in-gcd-script.js
new file mode 100644
index 0000000000..fb96be8aba
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-line-in-gcd-script.js
@@ -0,0 +1,9 @@
+"use strict";
+
+function f() {}
+
+(function () {
+  var a = 1;
+  var b = 2;
+  var c = 3;
+})();
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-multiple-offsets.js b/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-multiple-offsets.js
new file mode 100644
index 0000000000..b30ebb5049
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-multiple-offsets.js
@@ -0,0 +1,7 @@
+"use strict";
+
+function f() {
+  for (var i = 0; i < 1; ++i) {
+    ;
+  }
+}
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-multiple-statements.js b/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-multiple-statements.js
new file mode 100644
index 0000000000..d92231e651
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-multiple-statements.js
@@ -0,0 +1,5 @@
+"use strict";
+
+function f() {
+  var a = 1; var b = 2; var c = 3;
+}
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-no-offsets-in-gcd-script.js b/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-no-offsets-in-gcd-script.js
new file mode 100644
index 0000000000..b03d400794
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-no-offsets-in-gcd-script.js
@@ -0,0 +1,9 @@
+"use strict";
+
+function f() {}
+
+(function () {
+  var a = 1;
+
+  var c = 3;
+})();
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-no-offsets.js b/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-no-offsets.js
new file mode 100644
index 0000000000..1268cf8db0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-line-with-no-offsets.js
@@ -0,0 +1,7 @@
+"use strict";
+
+function f() {
+  var a = 1;
+
+  var c = 3;
+}
diff --git a/devtools/server/tests/xpcshell/setBreakpoint-on-line.js b/devtools/server/tests/xpcshell/setBreakpoint-on-line.js
new file mode 100644
index 0000000000..1b15e2a5e7
--- /dev/null
+++ b/devtools/server/tests/xpcshell/setBreakpoint-on-line.js
@@ -0,0 +1,7 @@
+"use strict";
+
+function f() {
+  var a = 1;
+  var b = 2;
+  var c = 3;
+}
diff --git a/devtools/server/tests/xpcshell/source-03.js b/devtools/server/tests/xpcshell/source-03.js
new file mode 100644
index 0000000000..af623a2eb2
--- /dev/null
+++ b/devtools/server/tests/xpcshell/source-03.js
@@ -0,0 +1,7 @@
+/* eslint-disable */
+
+function init() {
+  var a = foo();
+}
+
+function foo() {}
diff --git a/devtools/server/tests/xpcshell/source-map-data/sourcemapped.coffee b/devtools/server/tests/xpcshell/source-map-data/sourcemapped.coffee
new file mode 100644
index 0000000000..73a400a219
--- /dev/null
+++ b/devtools/server/tests/xpcshell/source-map-data/sourcemapped.coffee
@@ -0,0 +1,6 @@
+foo = (n) ->
+  return "foo" + i for i in [0...n]
+
+[first, second, third] = foo(3)
+
+debugger
\ No newline at end of file
diff --git a/devtools/server/tests/xpcshell/source-map-data/sourcemapped.map b/devtools/server/tests/xpcshell/source-map-data/sourcemapped.map
new file mode 100644
index 0000000000..dcee3c33c3
--- /dev/null
+++ b/devtools/server/tests/xpcshell/source-map-data/sourcemapped.map
@@ -0,0 +1,10 @@
+{
+  "version": 3,
+  "file": "sourcemapped.js",
+  "sourceRoot": "",
+  "sources": [
+    "sourcemapped.coffee"
+  ],
+  "names": [],
+  "mappings": ";AAAA;CAAA,KAAA,yBAAA;CAAA;CAAA,CAAA,CAAA,MAAO;CACL,IAAA,GAAA;AAAA,CAAA,EAAA,MAA0B,qDAA1B;CAAA,EAAe,EAAR,QAAA;CAAP,IADI;CAAN,EAAM;;CAAN,CAGA,CAAyB,IAAA;;CAEzB,UALA;CAAA"
+}
\ No newline at end of file
diff --git a/devtools/server/tests/xpcshell/sourcemapped.js b/devtools/server/tests/xpcshell/sourcemapped.js
new file mode 100644
index 0000000000..94d130903b
--- /dev/null
+++ b/devtools/server/tests/xpcshell/sourcemapped.js
@@ -0,0 +1,16 @@
+// Generated by CoffeeScript 1.6.1
+(function () {
+  var first, foo, second, third, _ref;
+
+  foo = function (n) {
+    var i, _i;
+    for (i = _i = 0; 0 <= n ? _i < n : _i > n; i = 0 <= n ? ++_i : --_i) {
+      return "foo" + i;
+    }
+  };
+
+  _ref = foo(3), first = _ref[0], second = _ref[1], third = _ref[2];
+
+  debugger;
+
+}).call(this);
diff --git a/devtools/server/tests/xpcshell/stepping-async.js b/devtools/server/tests/xpcshell/stepping-async.js
new file mode 100644
index 0000000000..0ee37883bc
--- /dev/null
+++ b/devtools/server/tests/xpcshell/stepping-async.js
@@ -0,0 +1,31 @@
+"use strict";
+/* exported stuff */
+
+async function timer() {
+  return Promise.resolve();
+}
+
+function oops() {
+  return `oops`;
+}
+
+async function inner() {
+  oops();
+  await timer();
+  Promise.resolve().then(async () => {
+    Promise.resolve().then(() => {
+      oops();
+    });
+    oops();
+  });
+  oops();
+}
+
+async function stuff() {
+  debugger;
+  const task = inner();
+  oops();
+  await task;
+  oops();
+  debugger;
+}
diff --git a/devtools/server/tests/xpcshell/stepping.js b/devtools/server/tests/xpcshell/stepping.js
new file mode 100644
index 0000000000..2134bea38d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/stepping.js
@@ -0,0 +1,36 @@
+"use strict";
+/* exported global arithmetic composition chaining nested */
+
+const obj = { b };
+
+function a() {
+  return obj;
+}
+
+function b() {
+  return 2;
+}
+
+function arithmetic() {
+  debugger;
+  a() + b();
+}
+
+function composition() {
+  debugger;
+  b(a());
+}
+
+function chaining() {
+  debugger;
+  a().b();
+}
+
+function c() {
+  return b();
+}
+
+function nested() {
+  debugger;
+  c();
+}
diff --git a/devtools/server/tests/xpcshell/test_MemoryActor_saveHeapSnapshot_01.js b/devtools/server/tests/xpcshell/test_MemoryActor_saveHeapSnapshot_01.js
new file mode 100644
index 0000000000..7df3cbd2ba
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_MemoryActor_saveHeapSnapshot_01.js
@@ -0,0 +1,22 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that we can tell the memory actor to take a heap snapshot over the RDP
+// and then create a HeapSnapshot instance from the resulting file.
+
+add_task(async () => {
+  const { memoryFront } = await createTabMemoryFront();
+
+  const snapshotFilePath = await memoryFront.saveHeapSnapshot();
+  ok(
+    !!(await IOUtils.stat(snapshotFilePath)),
+    "Should have the heap snapshot file"
+  );
+  const snapshot = ChromeUtils.readHeapSnapshot(snapshotFilePath);
+  ok(
+    HeapSnapshot.isInstance(snapshot),
+    "And we should be able to read a HeapSnapshot instance from the file"
+  );
+});
diff --git a/devtools/server/tests/xpcshell/test_MemoryActor_saveHeapSnapshot_02.js b/devtools/server/tests/xpcshell/test_MemoryActor_saveHeapSnapshot_02.js
new file mode 100644
index 0000000000..91593d845f
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_MemoryActor_saveHeapSnapshot_02.js
@@ -0,0 +1,24 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that we can properly stream heap snapshot files over the RDP as bulk
+// data.
+
+add_task(async () => {
+  const { memoryFront } = await createTabMemoryFront();
+
+  const snapshotFilePath = await memoryFront.saveHeapSnapshot({
+    forceCopy: true,
+  });
+  ok(
+    !!(await IOUtils.stat(snapshotFilePath)),
+    "Should have the heap snapshot file"
+  );
+  const snapshot = ChromeUtils.readHeapSnapshot(snapshotFilePath);
+  ok(
+    HeapSnapshot.isInstance(snapshot),
+    "And we should be able to read a HeapSnapshot instance from the file"
+  );
+});
diff --git a/devtools/server/tests/xpcshell/test_MemoryActor_saveHeapSnapshot_03.js b/devtools/server/tests/xpcshell/test_MemoryActor_saveHeapSnapshot_03.js
new file mode 100644
index 0000000000..b212abbced
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_MemoryActor_saveHeapSnapshot_03.js
@@ -0,0 +1,22 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that we can save full runtime heap snapshots when attached to the
+// ParentProcessTargetActor or a ContentProcessTargetActor.
+
+add_task(async () => {
+  const { memoryFront } = await createMainProcessMemoryFront();
+
+  const snapshotFilePath = await memoryFront.saveHeapSnapshot();
+  ok(
+    !!(await IOUtils.stat(snapshotFilePath)),
+    "Should have the heap snapshot file"
+  );
+  const snapshot = ChromeUtils.readHeapSnapshot(snapshotFilePath);
+  ok(
+    HeapSnapshot.isInstance(snapshot),
+    "And we should be able to read a HeapSnapshot instance from the file"
+  );
+});
diff --git a/devtools/server/tests/xpcshell/test_add_actors.js b/devtools/server/tests/xpcshell/test_add_actors.js
new file mode 100644
index 0000000000..8077109d71
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_add_actors.js
@@ -0,0 +1,107 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Get the object, from the server side, for a given actor ID
+function getActorInstance(connID, actorID) {
+  return DevToolsServer._connections[connID].getActor(actorID);
+}
+
+/**
+ * The purpose of these tests is to verify that it's possible to add actors
+ * both before and after the DevToolsServer has been initialized, so addons
+ * that add actors don't have to poll the object for its initialization state
+ * in order to add actors after initialization but rather can add actors anytime
+ * regardless of the object's state.
+ */
+add_task(async function () {
+  ActorRegistry.registerModule("resource://test/pre_init_global_actors.js", {
+    prefix: "preInitGlobal",
+    constructor: "PreInitGlobalActor",
+    type: { global: true },
+  });
+  ActorRegistry.registerModule(
+    "resource://test/pre_init_target_scoped_actors.js",
+    {
+      prefix: "preInitTargetScoped",
+      constructor: "PreInitTargetScopedActor",
+      type: { target: true },
+    }
+  );
+
+  const client = await startTestDevToolsServer("example tab");
+
+  ActorRegistry.registerModule("resource://test/post_init_global_actors.js", {
+    prefix: "postInitGlobal",
+    constructor: "PostInitGlobalActor",
+    type: { global: true },
+  });
+  ActorRegistry.registerModule(
+    "resource://test/post_init_target_scoped_actors.js",
+    {
+      prefix: "postInitTargetScoped",
+      constructor: "PostInitTargetScopedActor",
+      type: { target: true },
+    }
+  );
+
+  let actors = await client.mainRoot.rootForm;
+  const tabs = await client.mainRoot.listTabs();
+  const tabDescriptor = tabs[0];
+
+  // These xpcshell tests use mocked actors (xpcshell-test/testactors)
+  // which still don't support watcher actor.
+  // Because of that we still can't enable server side targets and target swiching.
+  tabDescriptor.disableTargetSwitching();
+
+  const tabTarget = await tabDescriptor.getTarget();
+
+  Assert.equal(tabs.length, 1);
+
+  let reply = await client.request({
+    to: actors.preInitGlobalActor,
+    type: "ping",
+  });
+  Assert.equal(reply.message, "pong");
+
+  reply = await client.request({
+    to: tabTarget.targetForm.preInitTargetScopedActor,
+    type: "ping",
+  });
+  Assert.equal(reply.message, "pong");
+
+  reply = await client.request({
+    to: actors.postInitGlobalActor,
+    type: "ping",
+  });
+  Assert.equal(reply.message, "pong");
+
+  reply = await client.request({
+    to: tabTarget.targetForm.postInitTargetScopedActor,
+    type: "ping",
+  });
+  Assert.equal(reply.message, "pong");
+
+  // Consider that there is only one connection, and the first one is ours
+  const connID = Object.keys(DevToolsServer._connections)[0];
+  const postInitGlobalActor = getActorInstance(
+    connID,
+    actors.postInitGlobalActor
+  );
+  const preInitGlobalActor = getActorInstance(
+    connID,
+    actors.preInitGlobalActor
+  );
+  actors = await client.mainRoot.getRoot();
+  Assert.equal(
+    postInitGlobalActor,
+    getActorInstance(connID, actors.postInitGlobalActor)
+  );
+  Assert.equal(
+    preInitGlobalActor,
+    getActorInstance(connID, actors.preInitGlobalActor)
+  );
+
+  await client.close();
+});
diff --git a/devtools/server/tests/xpcshell/test_addon_debugging_connect.js b/devtools/server/tests/xpcshell/test_addon_debugging_connect.js
new file mode 100644
index 0000000000..221e73d256
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_addon_debugging_connect.js
@@ -0,0 +1,158 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+const lazy = {};
+ChromeUtils.defineESModuleGetters(lazy, {
+  ExtensionParent: "resource://gre/modules/ExtensionParent.sys.mjs",
+});
+
+const { createAppInfo, promiseStartupManager } = AddonTestUtils;
+
+AddonTestUtils.init(this);
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+ExtensionTestUtils.init(this);
+
+function watchFrameUpdates(front) {
+  const collected = [];
+
+  const listener = data => {
+    collected.push(data);
+  };
+
+  front.on("frameUpdate", listener);
+  let unsubscribe = () => {
+    unsubscribe = null;
+    front.off("frameUpdate", listener);
+    return collected;
+  };
+
+  return unsubscribe;
+}
+
+function promiseFrameUpdate(front, matcher = () => true) {
+  return new Promise(resolve => {
+    const listener = data => {
+      if (matcher(data)) {
+        resolve();
+        front.off("frameUpdate", listener);
+      }
+    };
+
+    front.on("frameUpdate", listener);
+  });
+}
+
+// Bug 1302702 - Test connect to a webextension addon
+add_task(
+  {
+    // This test needs to run only when the extension are running in a separate
+    // child process, otherwise attachThread would pause the main process and this
+    // test would get stuck.
+    skip_if: () => !WebExtensionPolicy.useRemoteWebExtensions,
+  },
+  async function test_webextension_addon_debugging_connect() {
+    await promiseStartupManager();
+
+    // Install and start a test webextension.
+    const extension = ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      background() {
+        const { browser } = this;
+        browser.test.log("background script executed");
+        // window is available in background scripts
+        // eslint-disable-next-line no-undef
+        browser.test.sendMessage("background page ready", window.location.href);
+      },
+    });
+    await extension.startup();
+    const bgPageURL = await extension.awaitMessage("background page ready");
+
+    const commands = await CommandsFactory.forAddon(extension.id);
+
+    // Connect to the target addon actor and wait for the updated list of frames.
+    const addonTarget = await commands.descriptorFront.getTarget();
+    ok(addonTarget, "Got an RDP target");
+
+    const { frames } = await addonTarget.listFrames();
+    const backgroundPageFrame = frames
+      .filter(frame => {
+        return (
+          frame.url && frame.url.endsWith("/_generated_background_page.html")
+        );
+      })
+      .pop();
+    ok(backgroundPageFrame, "Found the frame for the background page");
+
+    const threadFront = await addonTarget.attachThread();
+
+    ok(threadFront, "Got a threadFront for the target addon");
+    equal(threadFront.paused, false, "The addon threadActor isn't paused");
+
+    equal(
+      lazy.ExtensionParent.DebugUtils.debugBrowserPromises.size,
+      1,
+      "The expected number of debug browser has been created by the addon actor"
+    );
+
+    const unwatchFrameUpdates = watchFrameUpdates(addonTarget);
+
+    const promiseBgPageFrameUpdate = promiseFrameUpdate(addonTarget, data => {
+      return data.frames?.some(frame => frame.url === bgPageURL);
+    });
+
+    // Reload the addon through the RDP protocol.
+    await addonTarget.reload();
+    info("Wait background page to be fully reloaded");
+    await extension.awaitMessage("background page ready");
+    info("Wait background page frameUpdate event");
+    await promiseBgPageFrameUpdate;
+
+    equal(
+      lazy.ExtensionParent.DebugUtils.debugBrowserPromises.size,
+      1,
+      "The number of debug browser has not been changed after an addon reload"
+    );
+
+    const frameUpdates = unwatchFrameUpdates();
+    const [frameUpdate] = frameUpdates;
+
+    equal(
+      frameUpdates.length,
+      1,
+      "Expect 1 frameUpdate events to have been received"
+    );
+    equal(
+      frameUpdate.frames?.length,
+      1,
+      "Expect 1 frame in the frameUpdate event "
+    );
+    Assert.deepEqual(
+      {
+        url: frameUpdate.frames[0].url,
+      },
+      {
+        url: bgPageURL,
+      },
+      "Got the expected frame update when the addon background page was loaded back"
+    );
+
+    await commands.destroy();
+
+    // Check that if we close the debugging client without uninstalling the addon,
+    // the webextension debugging actor should release the debug browser.
+    equal(
+      lazy.ExtensionParent.DebugUtils.debugBrowserPromises.size,
+      0,
+      "The debug browser has been released when the RDP connection has been closed"
+    );
+
+    await extension.unload();
+  }
+);
diff --git a/devtools/server/tests/xpcshell/test_addon_events.js b/devtools/server/tests/xpcshell/test_addon_events.js
new file mode 100644
index 0000000000..262a604953
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_addon_events.js
@@ -0,0 +1,60 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { AddonManager } = ChromeUtils.importESModule(
+  "resource://gre/modules/AddonManager.sys.mjs"
+);
+add_task(async function testReloadExitedAddon() {
+  await startupAddonsManager();
+
+  DevToolsServer.init();
+  DevToolsServer.registerAllActors();
+
+  const client = new DevToolsClient(DevToolsServer.connectPipe());
+  await client.connect();
+
+  // Retrieve the current list of addons to be notified of the next list update.
+  // We will also call listAddons every time we receive the event "addonListChanged" for
+  // the same reason.
+  await client.mainRoot.listAddons();
+
+  info("Install the addon");
+  const addonFile = do_get_file("addons/web-extension", false);
+
+  let installedAddon;
+  await expectAddonListChanged(client, async () => {
+    installedAddon = await AddonManager.installTemporaryAddon(addonFile);
+  });
+  ok(true, "Received onAddonListChanged when installing addon");
+
+  info("Disable the addon");
+  await expectAddonListChanged(client, () => installedAddon.disable());
+  ok(true, "Received onAddonListChanged when disabling addon");
+
+  info("Enable the addon");
+  await expectAddonListChanged(client, () => installedAddon.enable());
+  ok(true, "Received onAddonListChanged when enabling addon");
+
+  info("Put the addon in pending uninstall mode");
+  await expectAddonListChanged(client, () => installedAddon.uninstall(true));
+  ok(true, "Received onAddonListChanged when addon moves to pending uninstall");
+
+  info("Cancel uninstall for addon");
+  await expectAddonListChanged(client, () => installedAddon.cancelUninstall());
+  ok(true, "Received onAddonListChanged when addon uninstall is canceled");
+
+  info("Completely uninstall the addon");
+  await expectAddonListChanged(client, () => installedAddon.uninstall());
+  ok(true, "Received onAddonListChanged when addon is uninstalled");
+
+  await close(client);
+});
+
+async function expectAddonListChanged(client, predicate) {
+  const onAddonListChanged = client.mainRoot.once("addonListChanged");
+  await predicate();
+  await onAddonListChanged;
+  await client.mainRoot.listAddons();
+}
diff --git a/devtools/server/tests/xpcshell/test_addon_reload.js b/devtools/server/tests/xpcshell/test_addon_reload.js
new file mode 100644
index 0000000000..e0054f03cc
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_addon_reload.js
@@ -0,0 +1,116 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { AddonManager } = ChromeUtils.importESModule(
+  "resource://gre/modules/AddonManager.sys.mjs"
+);
+
+function promiseAddonEvent(event) {
+  return new Promise(resolve => {
+    const listener = {
+      [event](...args) {
+        AddonManager.removeAddonListener(listener);
+        resolve(args);
+      },
+    };
+
+    AddonManager.addAddonListener(listener);
+  });
+}
+
+function promiseWebExtensionStartup() {
+  const { Management } = ChromeUtils.importESModule(
+    "resource://gre/modules/Extension.sys.mjs"
+  );
+
+  return new Promise(resolve => {
+    const listener = (evt, extension) => {
+      Management.off("ready", listener);
+      resolve(extension);
+    };
+
+    Management.on("ready", listener);
+  });
+}
+
+async function reloadAddon(addonFront) {
+  // The add-on will be re-installed after a successful reload.
+  const onInstalled = promiseAddonEvent("onInstalled");
+  await addonFront.reload();
+  await onInstalled;
+}
+
+function getSupportFile(path) {
+  const allowMissing = false;
+  return do_get_file(path, allowMissing);
+}
+
+add_task(async function testReloadExitedAddon() {
+  await startupAddonsManager();
+
+  DevToolsServer.init();
+  DevToolsServer.registerAllActors();
+
+  const client = new DevToolsClient(DevToolsServer.connectPipe());
+  await client.connect();
+
+  // Install our main add-on to trigger reloads on.
+  const addonFile = getSupportFile("addons/web-extension");
+  const [installedAddon] = await Promise.all([
+    AddonManager.installTemporaryAddon(addonFile),
+    promiseWebExtensionStartup(),
+  ]);
+
+  // Install a decoy add-on.
+  const addonFile2 = getSupportFile("addons/web-extension2");
+  const [installedAddon2] = await Promise.all([
+    AddonManager.installTemporaryAddon(addonFile2),
+    promiseWebExtensionStartup(),
+  ]);
+
+  const addonFront = await client.mainRoot.getAddon({ id: installedAddon.id });
+
+  await Promise.all([reloadAddon(addonFront), promiseWebExtensionStartup()]);
+
+  // Uninstall the decoy add-on, which should cause its actor to exit.
+  const onUninstalled = promiseAddonEvent("onUninstalled");
+  installedAddon2.uninstall();
+  await onUninstalled;
+
+  // Try to re-list all add-ons after a reload.
+  // This was throwing an exception because of the exited actor.
+  const newAddonFront = await client.mainRoot.getAddon({
+    id: installedAddon.id,
+  });
+  equal(newAddonFront.id, addonFront.id);
+
+  // The fronts should be the same after the reload
+  equal(newAddonFront, addonFront);
+
+  const onAddonListChanged = client.mainRoot.once("addonListChanged");
+
+  // Install an upgrade version of the first add-on.
+  const addonUpgradeFile = getSupportFile("addons/web-extension-upgrade");
+  const [upgradedAddon] = await Promise.all([
+    AddonManager.installTemporaryAddon(addonUpgradeFile),
+    promiseWebExtensionStartup(),
+  ]);
+
+  // Waiting for addonListChanged unsolicited event
+  await onAddonListChanged;
+
+  // re-list all add-ons after an upgrade.
+  const upgradedAddonFront = await client.mainRoot.getAddon({
+    id: upgradedAddon.id,
+  });
+  equal(upgradedAddonFront.id, addonFront.id);
+  // The fronts should be the same after the upgrade.
+  equal(upgradedAddonFront, addonFront);
+
+  // The addon metadata has been updated.
+  equal(upgradedAddonFront.name, "Test Addons Actor Upgrade");
+
+  await close(client);
+});
diff --git a/devtools/server/tests/xpcshell/test_addons_actor.js b/devtools/server/tests/xpcshell/test_addons_actor.js
new file mode 100644
index 0000000000..ba9fda6c3d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_addons_actor.js
@@ -0,0 +1,55 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+async function connect() {
+  DevToolsServer.init();
+  DevToolsServer.registerAllActors();
+
+  const client = new DevToolsClient(DevToolsServer.connectPipe());
+  await client.connect();
+
+  const addons = await client.mainRoot.getFront("addons");
+  return [client, addons];
+}
+
+// The AddonsManager test helper can only be called once per test script.
+// This `setup` task will run first.
+add_task(async function setup() {
+  await startupAddonsManager();
+});
+
+add_task(async function testSuccessfulInstall() {
+  const [client, addons] = await connect();
+
+  const allowMissing = false;
+  const usePlatformSeparator = true;
+  const addonPath = getFilePath(
+    "addons/web-extension",
+    allowMissing,
+    usePlatformSeparator
+  );
+  const installedAddon = await addons.installTemporaryAddon(addonPath, false);
+  equal(installedAddon.id, "test-addons-actor@mozilla.org");
+  // The returned object is currently not a proper actor.
+  equal(installedAddon.actor, false);
+
+  const addonList = await client.mainRoot.listAddons();
+  ok(addonList && addonList.map(a => a.name), "Received list of add-ons");
+  const addon = addonList.find(a => a.id === installedAddon.id);
+  ok(addon, "Test add-on appeared in root install list");
+
+  await close(client);
+});
+
+add_task(async function testNonExistantPath() {
+  const [client, addons] = await connect();
+
+  await Assert.rejects(
+    addons.installTemporaryAddon("some-non-existant-path", false),
+    /Could not install add-on.*Component returned failure/
+  );
+
+  await close(client);
+});
diff --git a/devtools/server/tests/xpcshell/test_animation_name.js b/devtools/server/tests/xpcshell/test_animation_name.js
new file mode 100644
index 0000000000..e88911334c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_animation_name.js
@@ -0,0 +1,93 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+// Test that AnimationPlayerActor.getName returns the right name depending on
+// the type of an animation and the various properties available on it.
+
+const {
+  AnimationPlayerActor,
+} = require("resource://devtools/server/actors/animation.js");
+
+function run_test() {
+  // Mock a window with just the properties the AnimationPlayerActor uses.
+  const window = {};
+  window.MutationObserver = class {
+    constructor() {
+      this.observe = () => {};
+    }
+  };
+  window.Animation = class {
+    constructor() {
+      this.effect = { target: getMockNode() };
+    }
+  };
+
+  window.CSSAnimation = class extends window.Animation {};
+  window.CSSTransition = class extends window.Animation {};
+
+  // Helper to get a mock DOM node.
+  function getMockNode() {
+    return {
+      ownerDocument: {
+        defaultView: window,
+      },
+    };
+  }
+
+  // Objects in this array should contain the following properties:
+  // - desc {String} For logging
+  // - animation {Object} An animation object instantiated from one of the mock
+  //   window animation constructors.
+  // - props {Objet} Properties of this object will be added to the animation
+  //   object.
+  // - expectedName {String} The expected name returned by
+  //   AnimationPlayerActor.getName.
+  const TEST_DATA = [
+    {
+      desc: "Animation with an id",
+      animation: new window.Animation(),
+      props: { id: "animation-id" },
+      expectedName: "animation-id",
+    },
+    {
+      desc: "Animation without an id",
+      animation: new window.Animation(),
+      props: {},
+      expectedName: "",
+    },
+    {
+      desc: "CSSTransition with an id",
+      animation: new window.CSSTransition(),
+      props: { id: "transition-with-id", transitionProperty: "width" },
+      expectedName: "transition-with-id",
+    },
+    {
+      desc: "CSSAnimation with an id",
+      animation: new window.CSSAnimation(),
+      props: { id: "animation-with-id", animationName: "move" },
+      expectedName: "animation-with-id",
+    },
+    {
+      desc: "CSSTransition without an id",
+      animation: new window.CSSTransition(),
+      props: { transitionProperty: "width" },
+      expectedName: "width",
+    },
+    {
+      desc: "CSSAnimation without an id",
+      animation: new window.CSSAnimation(),
+      props: { animationName: "move" },
+      expectedName: "move",
+    },
+  ];
+
+  for (const { desc, animation, props, expectedName } of TEST_DATA) {
+    info(desc);
+    for (const key in props) {
+      animation[key] = props[key];
+    }
+    const actor = new AnimationPlayerActor({}, animation);
+    Assert.equal(actor.getName(), expectedName);
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_animation_type.js b/devtools/server/tests/xpcshell/test_animation_type.js
new file mode 100644
index 0000000000..261b5ef2ac
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_animation_type.js
@@ -0,0 +1,72 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+// Test the output of AnimationPlayerActor.getType().
+
+const {
+  ANIMATION_TYPES,
+  AnimationPlayerActor,
+} = require("resource://devtools/server/actors/animation.js");
+
+function run_test() {
+  // Mock a window with just the properties the AnimationPlayerActor uses.
+  const window = {};
+  window.MutationObserver = class {
+    constructor() {
+      this.observe = () => {};
+    }
+  };
+  window.Animation = class {
+    constructor() {
+      this.effect = { target: getMockNode() };
+    }
+  };
+
+  window.CSSAnimation = class extends window.Animation {};
+  window.CSSTransition = class extends window.Animation {};
+
+  // Helper to get a mock DOM node.
+  function getMockNode() {
+    return {
+      ownerDocument: {
+        defaultView: window,
+      },
+    };
+  }
+
+  // Objects in this array should contain the following properties:
+  // - desc {String} For logging
+  // - animation {Object} An animation object instantiated from one of the mock
+  //   window animation constructors.
+  // - expectedType {String} The expected type returned by
+  //   AnimationPlayerActor.getType.
+  const TEST_DATA = [
+    {
+      desc: "Test CSSAnimation type",
+      animation: new window.CSSAnimation(),
+      expectedType: ANIMATION_TYPES.CSS_ANIMATION,
+    },
+    {
+      desc: "Test CSSTransition type",
+      animation: new window.CSSTransition(),
+      expectedType: ANIMATION_TYPES.CSS_TRANSITION,
+    },
+    {
+      desc: "Test ScriptAnimation type",
+      animation: new window.Animation(),
+      expectedType: ANIMATION_TYPES.SCRIPT_ANIMATION,
+    },
+    {
+      desc: "Test unknown type",
+      animation: { effect: { target: getMockNode() } },
+      expectedType: ANIMATION_TYPES.UNKNOWN,
+    },
+  ];
+
+  for (const { desc, animation, expectedType } of TEST_DATA) {
+    info(desc);
+    const actor = new AnimationPlayerActor({}, animation);
+    Assert.equal(actor.getType(), expectedType);
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_attach.js b/devtools/server/tests/xpcshell/test_attach.js
new file mode 100644
index 0000000000..fb7d232e76
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_attach.js
@@ -0,0 +1,28 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ThreadFront } = require("resource://devtools/client/fronts/thread.js");
+const {
+  WindowGlobalTargetFront,
+} = require("resource://devtools/client/fronts/targets/window-global.js");
+
+/**
+ * Very naive test that checks threadClearTest helper.
+ * It ensures that the thread front is correctly attached.
+ */
+add_task(
+  threadFrontTest(({ threadFront, debuggee, client, targetFront }) => {
+    ok(true, "Thread actor was able to attach");
+    ok(threadFront instanceof ThreadFront, "Thread Front is valid");
+    Assert.equal(threadFront.state, "attached", "Thread Front is resumed");
+    Assert.equal(
+      Cu.getSandboxMetadata(debuggee),
+      undefined,
+      "Debuggee client is valid (getSandboxMetadata did not fail)"
+    );
+    ok(client instanceof DevToolsClient, "Client is valid");
+    ok(targetFront instanceof WindowGlobalTargetFront, "TargetFront is valid");
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_blackboxing-01.js b/devtools/server/tests/xpcshell/test_blackboxing-01.js
new file mode 100644
index 0000000000..6c549b908e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_blackboxing-01.js
@@ -0,0 +1,155 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test basic black boxing.
+ */
+
+var gDebuggee;
+var gThreadFront;
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    gThreadFront = threadFront;
+    gDebuggee = debuggee;
+    await testBlackBox();
+  })
+);
+
+const BLACK_BOXED_URL = "http://example.com/blackboxme.js";
+const SOURCE_URL = "http://example.com/source.js";
+
+const testBlackBox = async function () {
+  const packet = await executeOnNextTickAndWaitForPause(evalCode, gThreadFront);
+
+  const bpSource = await getSourceById(gThreadFront, packet.frame.where.actor);
+
+  await setBreakpoint(gThreadFront, { sourceUrl: bpSource.url, line: 2 });
+  await resume(gThreadFront);
+
+  let sourceForm = await getSourceForm(gThreadFront, BLACK_BOXED_URL);
+
+  Assert.ok(
+    !sourceForm.isBlackBoxed,
+    "By default the source is not black boxed."
+  );
+
+  // Test that we can step into `doStuff` when we are not black boxed.
+  await runTest(
+    async function onSteppedLocation(location) {
+      const source = await getSourceFormById(gThreadFront, location.actor);
+      Assert.equal(source.url, BLACK_BOXED_URL);
+      Assert.equal(location.line, 2);
+    },
+    async function onDebuggerStatementFrames(frames) {
+      for (const frame of frames) {
+        const source = await getSourceFormById(gThreadFront, frame.where.actor);
+        Assert.ok(!source.isBlackBoxed);
+      }
+    }
+  );
+
+  const blackboxedSource = await getSource(gThreadFront, BLACK_BOXED_URL);
+  await blackBox(blackboxedSource);
+  sourceForm = await getSourceForm(gThreadFront, BLACK_BOXED_URL);
+  Assert.ok(sourceForm.isBlackBoxed);
+
+  // Test that we step through `doStuff` when we are black boxed and its frame
+  // doesn't show up.
+  await runTest(
+    async function onSteppedLocation(location) {
+      const source = await getSourceFormById(gThreadFront, location.actor);
+      Assert.equal(source.url, SOURCE_URL);
+      Assert.equal(location.line, 4);
+    },
+    async function onDebuggerStatementFrames(frames) {
+      for (const frame of frames) {
+        const source = await getSourceFormById(gThreadFront, frame.where.actor);
+        if (source.url == BLACK_BOXED_URL) {
+          Assert.ok(source.isBlackBoxed);
+        } else {
+          Assert.ok(!source.isBlackBoxed);
+        }
+      }
+    }
+  );
+
+  await unBlackBox(blackboxedSource);
+  sourceForm = await getSourceForm(gThreadFront, BLACK_BOXED_URL);
+  Assert.ok(!sourceForm.isBlackBoxed);
+
+  // Test that we can step into `doStuff` again.
+  await runTest(
+    async function onSteppedLocation(location) {
+      const source = await getSourceFormById(gThreadFront, location.actor);
+      Assert.equal(source.url, BLACK_BOXED_URL);
+      Assert.equal(location.line, 2);
+    },
+    async function onDebuggerStatementFrames(frames) {
+      for (const frame of frames) {
+        const source = await getSourceFormById(gThreadFront, frame.where.actor);
+        Assert.ok(!source.isBlackBoxed);
+      }
+    }
+  );
+};
+
+function evalCode() {
+  /* eslint-disable mozilla/var-only-at-top-level, no-undef */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" + function doStuff(k) { // line 1
+      var arg = 15;            // line 2 - Step in here
+      k(arg);                  // line 3
+    },                         // line 4
+    gDebuggee,
+    "1.8",
+    BLACK_BOXED_URL,
+    1
+  );
+
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" + function runTest() { // line 1
+      doStuff(                // line 2 - Break here
+        function (n) {        // line 3 - Step through `doStuff` to here
+          (() => {})();       // line 4
+          debugger;           // line 5
+        }                     // line 6
+      );                      // line 7
+    } + "\n"                  // line 8
+    + "debugger;",            // line 9
+    gDebuggee,
+    "1.8",
+    SOURCE_URL,
+    1
+  );
+}
+
+const runTest = async function (onSteppedLocation, onDebuggerStatementFrames) {
+  let packet = await executeOnNextTickAndWaitForPause(
+    gDebuggee.runTest,
+    gThreadFront
+  );
+  Assert.equal(packet.why.type, "breakpoint");
+
+  await stepIn(gThreadFront);
+
+  const location = await getCurrentLocation();
+  await onSteppedLocation(location);
+
+  packet = await resumeAndWaitForPause(gThreadFront);
+  Assert.equal(packet.why.type, "debuggerStatement");
+
+  const { frames } = await getFrames(gThreadFront, 0, 100);
+  await onDebuggerStatementFrames(frames);
+
+  return resume(gThreadFront);
+};
+
+const getCurrentLocation = async function () {
+  const response = await getFrames(gThreadFront, 0, 1);
+  return response.frames[0].where;
+};
diff --git a/devtools/server/tests/xpcshell/test_blackboxing-02.js b/devtools/server/tests/xpcshell/test_blackboxing-02.js
new file mode 100644
index 0000000000..66efaee6c8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_blackboxing-02.js
@@ -0,0 +1,95 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that we don't hit breakpoints in black boxed sources, and that when we
+ * unblack box the source again, the breakpoint hasn't disappeared and we will
+ * hit it again.
+ */
+
+const BLACK_BOXED_URL = "http://example.com/blackboxme.js";
+const SOURCE_URL = "http://example.com/source.js";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    // Set up
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    threadFront.setBreakpoint({ sourceUrl: BLACK_BOXED_URL, line: 2 }, {});
+    await threadFront.resume();
+
+    // Test the breakpoint in the black boxed source
+    const { error, sources } = await threadFront.getSources();
+    Assert.ok(!error, "Should not get an error: " + error);
+    const sourceFront = threadFront.source(
+      sources.filter(s => s.url == BLACK_BOXED_URL)[0]
+    );
+
+    await blackBox(sourceFront);
+
+    const packet1 = await executeOnNextTickAndWaitForPause(
+      debuggee.runTest,
+      threadFront
+    );
+
+    Assert.equal(
+      packet1.why.type,
+      "debuggerStatement",
+      "We should pass over the breakpoint since the source is black boxed."
+    );
+
+    await threadFront.resume();
+
+    // Test the breakpoint in the unblack boxed source
+    await unBlackBox(sourceFront);
+
+    const packet2 = await executeOnNextTickAndWaitForPause(
+      debuggee.runTest,
+      threadFront
+    );
+
+    Assert.equal(
+      packet2.why.type,
+      "breakpoint",
+      "We should hit the breakpoint again"
+    );
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable no-undef */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" + function doStuff(k) { // line 1
+      const arg = 15;          // line 2 - Break here
+      k(arg);                  // line 3
+    },                         // line 4
+    debuggee,
+    "1.8",
+    BLACK_BOXED_URL,
+    1
+  );
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" + function runTest() { // line 1
+      doStuff(                // line 2
+        function(n) {         // line 3
+          debugger;           // line 5
+        }                     // line 6
+      );                      // line 7
+    }                         // line 8
+    + "\n debugger;",         // line 9
+    debuggee,
+    "1.8",
+    SOURCE_URL,
+    1
+  );
+  /* eslint-enable no-undef */
+}
diff --git a/devtools/server/tests/xpcshell/test_blackboxing-03.js b/devtools/server/tests/xpcshell/test_blackboxing-03.js
new file mode 100644
index 0000000000..f97c8e70f4
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_blackboxing-03.js
@@ -0,0 +1,115 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that we don't stop at debugger statements inside black boxed sources.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    // Set up
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    threadFront.setBreakpoint({ sourceUrl: source.url, line: 4 }, {});
+    await threadFront.resume();
+
+    // Test the debugger statement in the black boxed source
+    await threadFront.getSources();
+    const sourceFront = await getSource(threadFront, BLACK_BOXED_URL);
+
+    await blackBox(sourceFront);
+
+    const packet2 = await executeOnNextTickAndWaitForPause(
+      debuggee.runTest,
+      threadFront
+    );
+
+    Assert.equal(
+      packet2.why.type,
+      "breakpoint",
+      "We should pass over the debugger statement."
+    );
+
+    threadFront.removeBreakpoint({ sourceUrl: source.url, line: 4 }, {});
+
+    await threadFront.resume();
+
+    // Test the debugger statement in the unblack boxed source
+    await unBlackBox(sourceFront);
+
+    const packet3 = await executeOnNextTickAndWaitForPause(
+      debuggee.runTest,
+      threadFront
+    );
+
+    Assert.equal(
+      packet3.why.type,
+      "debuggerStatement",
+      "We should stop at the debugger statement again"
+    );
+    await threadFront.resume();
+
+    // Test the debugger statement in the black boxed range
+    threadFront.setBreakpoint({ sourceUrl: source.url, line: 4 }, {});
+
+    await blackBox(sourceFront, {
+      start: { line: 1, column: 0 },
+      end: { line: 9, column: 0 },
+    });
+
+    const packet4 = await executeOnNextTickAndWaitForPause(
+      debuggee.runTest,
+      threadFront
+    );
+
+    Assert.equal(
+      packet4.why.type,
+      "breakpoint",
+      "We should pass over the debugger statement."
+    );
+
+    threadFront.removeBreakpoint({ sourceUrl: source.url, line: 4 }, {});
+    await unBlackBox(sourceFront);
+    await threadFront.resume();
+  })
+);
+
+const BLACK_BOXED_URL = "http://example.com/blackboxme.js";
+const SOURCE_URL = "http://example.com/source.js";
+
+function evalCode(debuggee) {
+  /* eslint-disable no-multi-spaces, no-undef */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" + function doStuff(k) { // line 1
+      debugger;                // line 2 - Break here
+      k(100);                  // line 3
+    },                         // line 4
+    debuggee,
+    "1.8",
+    BLACK_BOXED_URL,
+    1
+  );
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" + function runTest() { // line 1
+      doStuff(                // line 2
+        function(n) {         // line 3
+          Math.abs(n);        // line 4 - Break here
+        }                     // line 5
+      );                      // line 6
+    }                         // line 7
+    + "\n debugger;",         // line 8
+    debuggee,
+    "1.8",
+    SOURCE_URL,
+    1
+  );
+  /* eslint-enable no-multi-spaces, no-undef */
+}
diff --git a/devtools/server/tests/xpcshell/test_blackboxing-04.js b/devtools/server/tests/xpcshell/test_blackboxing-04.js
new file mode 100644
index 0000000000..13345c40e8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_blackboxing-04.js
@@ -0,0 +1,70 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test behavior of blackboxing sources we are currently paused in.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    // Set up
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    threadFront.setBreakpoint({ sourceUrl: BLACK_BOXED_URL, line: 2 }, {});
+
+    // Test black boxing a source while pausing in the source
+    const { error, sources } = await threadFront.getSources();
+    Assert.ok(!error, "Should not get an error: " + error);
+    const sourceFront = threadFront.source(
+      sources.filter(s => s.url == BLACK_BOXED_URL)[0]
+    );
+
+    const pausedInSource = await blackBox(sourceFront);
+    Assert.ok(
+      pausedInSource,
+      "We should be notified that we are currently paused in this source"
+    );
+    await threadFront.resume();
+  })
+);
+
+const BLACK_BOXED_URL = "http://example.com/blackboxme.js";
+const SOURCE_URL = "http://example.com/source.js";
+
+function evalCode(debuggee) {
+  /* eslint-disable no-multi-spaces, no-undef */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" +
+      function doStuff(k) { // line 1
+        debugger;           // line 2
+        k(100);             // line 3
+      },                    // line 4
+    debuggee,
+    "1.8",
+    BLACK_BOXED_URL,
+    1
+  );
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" +
+    function runTest() { // line 1
+      doStuff(           // line 2
+        function(n) {    // line 3
+          return n;      // line 4
+        }                // line 5
+      );                 // line 6
+    } +                  // line 7
+      "\n runTest();",   // line 8
+    debuggee,
+    "1.8",
+    SOURCE_URL,
+    1
+  );
+  /* eslint-enable no-multi-spaces, no-undef */
+}
diff --git a/devtools/server/tests/xpcshell/test_blackboxing-05.js b/devtools/server/tests/xpcshell/test_blackboxing-05.js
new file mode 100644
index 0000000000..388c87da88
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_blackboxing-05.js
@@ -0,0 +1,97 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test exceptions inside black boxed sources.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, commands }) => {
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const { error } = await threadFront.getSources();
+    Assert.ok(!error, "Should not get an error: " + error);
+
+    const sourceFront = await getSource(threadFront, BLACK_BOXED_URL);
+    await blackBox(sourceFront);
+    await commands.threadConfigurationCommand.updateConfiguration({
+      pauseOnExceptions: true,
+      ignoreCaughtExceptions: false,
+    });
+
+    const packet = await resumeAndWaitForPause(threadFront);
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+
+    Assert.equal(
+      source.url,
+      SOURCE_URL,
+      "We shouldn't pause while in the black boxed source."
+    );
+
+    await unBlackBox(sourceFront);
+    await blackBox(sourceFront, {
+      start: { line: 1, column: 0 },
+      end: { line: 4, column: 0 },
+    });
+
+    await threadFront.resume();
+
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const packet2 = await resumeAndWaitForPause(threadFront);
+    const source2 = await getSourceById(threadFront, packet2.frame.where.actor);
+
+    Assert.equal(
+      source2.url,
+      SOURCE_URL,
+      "We shouldn't pause while in the black boxed source."
+    );
+
+    await threadFront.resume();
+  })
+);
+
+const BLACK_BOXED_URL = "http://example.com/blackboxme.js";
+const SOURCE_URL = "http://example.com/source.js";
+
+function evalCode(debuggee) {
+  /* eslint-disable no-multi-spaces, no-unreachable, no-undef */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" +
+      function doStuff(k) {           // line 1
+        throw new Error("error msg"); // line 2
+        k(100);                       // line 3
+      },                              // line 4
+    debuggee,
+    "1.8",
+    BLACK_BOXED_URL,
+    1
+  );
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" +
+    function runTest() { // line 1
+      doStuff(           // line 2
+        function(n) {    // line 3
+          debugger;      // line 4
+        }                // line 5
+      );                 // line 6
+    } +                  // line 7
+    "\ndebugger;\n" +    // line 8
+      "try { runTest() } catch (ex) { }", // line 9
+    debuggee,
+    "1.8",
+    SOURCE_URL,
+    1
+  );
+  /* eslint-enable no-multi-spaces, no-unreachable, no-undef */
+}
diff --git a/devtools/server/tests/xpcshell/test_blackboxing-08.js b/devtools/server/tests/xpcshell/test_blackboxing-08.js
new file mode 100644
index 0000000000..d20d8b3966
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_blackboxing-08.js
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test blackbox ranges
+ */
+
+async function testFinish({ threadFront, devToolsClient }) {
+  await threadFront.resume();
+  await close(devToolsClient);
+
+  do_test_finished();
+}
+
+async function invokeAndPause({ global, threadFront }, expression) {
+  return executeOnNextTickAndWaitForPause(
+    () => Cu.evalInSandbox(expression, global),
+    threadFront
+  );
+}
+
+function run_test() {
+  return (async function () {
+    const dbg = await setupTestFromUrl("stepping.js");
+    const { threadFront } = dbg;
+
+    await invokeAndPause(dbg, `chaining()`);
+
+    const { sources } = await getSources(threadFront);
+    const sourceFront = threadFront.source(sources[0]);
+
+    await setBreakpoint(threadFront, { sourceUrl: sourceFront.url, line: 7 });
+    await setBreakpoint(threadFront, { sourceUrl: sourceFront.url, line: 11 });
+
+    // 1. lets blackbox function a, and assert that we pause in b
+    const range = { start: { line: 6, column: 0 }, end: { line: 8, colum: 1 } };
+    blackBox(sourceFront, range);
+    const paused = await resumeAndWaitForPause(threadFront);
+    equal(paused.frame.where.line, 11, "paused inside of b");
+    await threadFront.resume();
+
+    // 2. lets unblackbox function a, and assert that we pause in a
+    unBlackBox(sourceFront, range);
+    await invokeAndPause(dbg, `chaining()`);
+    const paused2 = await resumeAndWaitForPause(threadFront);
+    equal(paused2.frame.where.line, 7, "paused inside of a");
+
+    await testFinish(dbg);
+  })();
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-01.js b/devtools/server/tests/xpcshell/test_breakpoint-01.js
new file mode 100644
index 0000000000..be46d97cfb
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-01.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check basic breakpoint functionality.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    info("Wait for the debugger statement to be hit");
+    const packet1 = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    const source = await getSourceById(threadFront, packet1.frame.where.actor);
+    const location = { sourceUrl: source.url, line: debuggee.line0 + 3 };
+
+    threadFront.setBreakpoint(location, {});
+
+    const packet2 = await resumeAndWaitForPause(threadFront);
+
+    info("Paused at the breakpoint");
+    Assert.equal(packet2.frame.where.actor, source.actor);
+    Assert.equal(packet2.frame.where.line, location.line);
+    Assert.equal(packet2.why.type, "breakpoint");
+
+    info("Check that the breakpoint worked.");
+    Assert.equal(debuggee.a, 1);
+    Assert.equal(debuggee.b, undefined);
+
+    await threadFront.resume();
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  /*
+   * Be sure to run debuggee code in its own HTML 'task', so that when we call
+   * the onDebuggerStatement hook, the test's own microtasks don't get suspended
+   * along with the debuggee's.
+   */
+  do_timeout(0, () => {
+    // prettier-ignore
+    Cu.evalInSandbox(
+      "var line0 = Error().lineNumber;\n" +
+      "debugger;\n" + // line0 + 1
+      "var a = 1;\n" + // line0 + 2
+      "var b = 2;\n", // line0 + 3
+      debuggee
+    );
+  });
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-03.js b/devtools/server/tests/xpcshell/test_breakpoint-03.js
new file mode 100644
index 0000000000..f598660a98
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-03.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Check that setting a breakpoint on a line without code will skip
+ * forward when we know the script isn't GCed (the debugger is connected,
+ * so it's kept alive).
+ */
+
+var test_no_skip_breakpoint = async function (source, location, debuggee) {
+  const [response, bpClient] = await source.setBreakpoint(
+    Object.assign({}, location, { noSliding: true })
+  );
+
+  Assert.ok(!response.actualLocation);
+  Assert.equal(bpClient.location.line, debuggee.line0 + 3);
+  await bpClient.remove();
+};
+
+add_task(
+  threadFrontTest(({ threadFront, debuggee }) => {
+    return new Promise(resolve => {
+      threadFront.once("paused", async function (packet) {
+        const location = { line: debuggee.line0 + 3 };
+        const source = await getSourceById(
+          threadFront,
+          packet.frame.where.actor
+        );
+        // First, make sure that we can disable sliding with the
+        // `noSliding` option.
+        await test_no_skip_breakpoint(source, location, debuggee);
+
+        // Now make sure that the breakpoint properly slides forward one line.
+        const [response, bpClient] = await source.setBreakpoint(location);
+        Assert.ok(!!response.actualLocation);
+        Assert.equal(response.actualLocation.source.actor, source.actor);
+        Assert.equal(response.actualLocation.line, location.line + 1);
+
+        threadFront.once("paused", function (packet) {
+          // Check the return value.
+          Assert.equal(packet.frame.where.actor, source.actor);
+          Assert.equal(packet.frame.where.line, location.line + 1);
+          Assert.equal(packet.why.type, "breakpoint");
+          Assert.equal(packet.why.actors[0], bpClient.actor);
+          // Check that the breakpoint worked.
+          Assert.equal(debuggee.a, 1);
+          Assert.equal(debuggee.b, undefined);
+
+          // Remove the breakpoint.
+          bpClient.remove(function (response) {
+            threadFront.resume().then(resolve);
+          });
+        });
+
+        threadFront.resume();
+      });
+
+      // Use `evalInSandbox` to make the debugger treat it as normal
+      // globally-scoped code, where breakpoint sliding rules apply.
+      // prettier-ignore
+      Cu.evalInSandbox(
+        "var line0 = Error().lineNumber;\n" +
+        "debugger;\n" +      // line0 + 1
+        "var a = 1;\n" +     // line0 + 2
+        "// A comment.\n" +  // line0 + 3
+        "var b = 2;",        // line0 + 4
+        debuggee
+      );
+    });
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-04.js b/devtools/server/tests/xpcshell/test_breakpoint-04.js
new file mode 100644
index 0000000000..8b7137f85d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-04.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that setting a breakpoint in a line in a child script works.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, client, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    const location = { sourceUrl: source.url, line: debuggee.line0 + 3 };
+
+    //Pause at debugger statement.
+    Assert.equal(packet.frame.where.line, debuggee.line0 + 5);
+    Assert.equal(packet.why.type, "debuggerStatement");
+
+    threadFront.setBreakpoint(location, {});
+    await client.waitForRequestsToSettle();
+    await resume(threadFront);
+
+    const packet2 = await waitForPause(threadFront);
+    // Check the return value.
+    Assert.equal(packet2.frame.where.actor, source.actor);
+    Assert.equal(packet2.frame.where.line, location.line);
+    Assert.equal(packet2.why.type, "breakpoint");
+    // Check that the breakpoint worked.
+    Assert.equal(debuggee.a, 1);
+    Assert.equal(debuggee.b, undefined);
+
+    // Remove the breakpoint.
+    threadFront.removeBreakpoint(location);
+    await client.waitForRequestsToSettle();
+
+    await resume(threadFront);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "var line0 = Error().lineNumber;\n" +
+    "function foo() {\n" + // line0 + 1
+    "  this.a = 1;\n" +    // line0 + 2
+    "  this.b = 2;\n" +    // line0 + 3
+    "}\n" +                // line0 + 4
+    "debugger;\n" +        // line0 + 5
+    "foo();\n",            // line0 + 6
+    debuggee
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-05.js b/devtools/server/tests/xpcshell/test_breakpoint-05.js
new file mode 100644
index 0000000000..f678b285b1
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-05.js
@@ -0,0 +1,62 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Check that setting a breakpoint in a line without code in a child script
+ * will skip forward.
+ */
+
+add_task(
+  threadFrontTest(({ threadFront, debuggee }) => {
+    return new Promise(resolve => {
+      threadFront.once("paused", async function (packet) {
+        const source = await getSourceById(
+          threadFront,
+          packet.frame.where.actor
+        );
+        const location = { line: debuggee.line0 + 3 };
+
+        source.setBreakpoint(location).then(function ([response, bpClient]) {
+          // Check that the breakpoint has properly skipped forward one line.
+          Assert.equal(response.actualLocation.source.actor, source.actor);
+          Assert.equal(response.actualLocation.line, location.line + 1);
+
+          threadFront.once("paused", function (packet) {
+            // Check the return value.
+            Assert.equal(packet.frame.where.actor, source.actor);
+            Assert.equal(packet.frame.where.line, location.line + 1);
+            Assert.equal(packet.why.type, "breakpoint");
+            Assert.equal(packet.why.actors[0], bpClient.actor);
+            // Check that the breakpoint worked.
+            Assert.equal(debuggee.a, 1);
+            Assert.equal(debuggee.b, undefined);
+
+            // Remove the breakpoint.
+            bpClient.remove(function (response) {
+              threadFront.resume().then(resolve);
+            });
+          });
+
+          // Continue until the breakpoint is hit.
+          threadFront.resume();
+        });
+      });
+
+      // prettier-ignore
+      Cu.evalInSandbox(
+        "var line0 = Error().lineNumber;\n" +
+        "function foo() {\n" + // line0 + 1
+        "  this.a = 1;\n" +    // line0 + 2
+        "  // A comment.\n" +  // line0 + 3
+        "  this.b = 2;\n" +    // line0 + 4
+        "}\n" +                // line0 + 5
+        "debugger;\n" +        // line0 + 6
+        "foo();\n",            // line0 + 7
+        debuggee
+      );
+    });
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-06.js b/devtools/server/tests/xpcshell/test_breakpoint-06.js
new file mode 100644
index 0000000000..79ddcdc3d4
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-06.js
@@ -0,0 +1,68 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Check that setting a breakpoint in a line without code in a deeply-nested
+ * child script will skip forward.
+ */
+
+add_task(
+  threadFrontTest(({ threadFront, debuggee }) => {
+    return new Promise(resolve => {
+      threadFront.once("paused", async function (packet) {
+        const source = await getSourceById(
+          threadFront,
+          packet.frame.where.actor
+        );
+        const location = { line: debuggee.line0 + 5 };
+
+        source.setBreakpoint(location).then(function ([response, bpClient]) {
+          // Check that the breakpoint has properly skipped forward one line.
+          Assert.equal(response.actualLocation.source.actor, source.actor);
+          Assert.equal(response.actualLocation.line, location.line + 1);
+
+          threadFront.once("paused", function (packet) {
+            // Check the return value.
+            Assert.equal(packet.frame.where.actor, source.actor);
+            Assert.equal(packet.frame.where.line, location.line + 1);
+            Assert.equal(packet.why.type, "breakpoint");
+            Assert.equal(packet.why.actors[0], bpClient.actor);
+            // Check that the breakpoint worked.
+            Assert.equal(debuggee.a, 1);
+            Assert.equal(debuggee.b, undefined);
+
+            // Remove the breakpoint.
+            bpClient.remove(function (response) {
+              threadFront.resume().then(resolve);
+            });
+          });
+
+          // Continue until the breakpoint is hit.
+          threadFront.resume();
+        });
+      });
+
+      // prettier-ignore
+      Cu.evalInSandbox(
+        "var line0 = Error().lineNumber;\n" +
+        "function foo() {\n" +     // line0 + 1
+        "  function bar() {\n" +   // line0 + 2
+        "    function baz() {\n" + // line0 + 3
+        "      this.a = 1;\n" +    // line0 + 4
+        "      // A comment.\n" +  // line0 + 5
+        "      this.b = 2;\n" +    // line0 + 6
+        "    }\n" +                // line0 + 7
+        "    baz();\n" +           // line0 + 8
+        "  }\n" +                  // line0 + 9
+        "  bar();\n" +             // line0 + 10
+        "}\n" +                    // line0 + 11
+        "debugger;\n" +            // line0 + 12
+        "foo();\n",               // line0 + 13
+        debuggee
+      );
+    });
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-07.js b/devtools/server/tests/xpcshell/test_breakpoint-07.js
new file mode 100644
index 0000000000..e6391747bb
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-07.js
@@ -0,0 +1,65 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Check that setting a breakpoint in a line without code in the second child
+ * script will skip forward.
+ */
+
+add_task(
+  threadFrontTest(({ threadFront, debuggee }) => {
+    return new Promise(resolve => {
+      threadFront.once("paused", async function (packet) {
+        const source = await getSourceById(
+          threadFront,
+          packet.frame.where.actor
+        );
+        const location = { line: debuggee.line0 + 6 };
+
+        source.setBreakpoint(location).then(function ([response, bpClient]) {
+          // Check that the breakpoint has properly skipped forward one line.
+          Assert.equal(response.actualLocation.source.actor, source.actor);
+          Assert.equal(response.actualLocation.line, location.line + 1);
+
+          threadFront.once("paused", function (packet) {
+            // Check the return value.
+            Assert.equal(packet.frame.where.actor, source.actor);
+            Assert.equal(packet.frame.where.line, location.line + 1);
+            Assert.equal(packet.why.type, "breakpoint");
+            Assert.equal(packet.why.actors[0], bpClient.actor);
+            // Check that the breakpoint worked.
+            Assert.equal(debuggee.a, 1);
+            Assert.equal(debuggee.b, undefined);
+
+            // Remove the breakpoint.
+            bpClient.remove(function (response) {
+              threadFront.resume().then(resolve);
+            });
+          });
+
+          // Continue until the breakpoint is hit.
+          threadFront.resume();
+        });
+      });
+
+      // prettier-ignore
+      Cu.evalInSandbox(
+        "var line0 = Error().lineNumber;\n" +
+        "function foo() {\n" + // line0 + 1
+        "  bar();\n" +         // line0 + 2
+        "}\n" +                // line0 + 3
+        "function bar() {\n" + // line0 + 4
+        "  this.a = 1;\n" +    // line0 + 5
+        "  // A comment.\n" +  // line0 + 6
+        "  this.b = 2;\n" +    // line0 + 7
+        "}\n" +                // line0 + 8
+        "debugger;\n" +        // line0 + 9
+        "foo();\n",           // line0 + 10
+        debuggee
+      );
+    });
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-08.js b/devtools/server/tests/xpcshell/test_breakpoint-08.js
new file mode 100644
index 0000000000..bff0cc3b52
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-08.js
@@ -0,0 +1,75 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Check that setting a breakpoint in a line without code in a child script
+ * will skip forward, in a file with two scripts.
+ */
+
+add_task(
+  threadFrontTest(({ threadFront, debuggee }) => {
+    return new Promise(resolve => {
+      threadFront.once("paused", async function (packet) {
+        const line = debuggee.line0 + 3;
+        const source = await getSourceById(
+          threadFront,
+          packet.frame.where.actor
+        );
+
+        // this test has been disabled for a long time so the functionality doesn't work
+        const response = await threadFront.setBreakpoint(
+          { sourceUrl: source.url, line },
+          {}
+        );
+        // check that the breakpoint has properly skipped forward one line.
+        assert.equal(response.actuallocation.source.actor, source.actor);
+        // This is wrong - location is not defined, but the test has been disabled
+        // for a long time and currently doesn't work.
+        // eslint-disable-next-line no-undef
+        Assert.equal(response.actualLocation.line, location.line + 1);
+
+        threadFront.once("paused", function (packet) {
+          // Check the return value.
+          Assert.equal(packet.frame.where.actor, source.actor);
+          // eslint-disable-next-line no-undef
+          Assert.equal(packet.frame.where.line, location.line + 1);
+          Assert.equal(packet.why.type, "breakpoint");
+          Assert.equal(packet.why.actors[0], response.bpClient.actor);
+          // Check that the breakpoint worked.
+          Assert.equal(debuggee.a, 1);
+          Assert.equal(debuggee.b, undefined);
+
+          // Remove the breakpoint.
+          response.bpClient.remove(function (response) {
+            threadFront.resume().then(resolve);
+          });
+        });
+
+        // Continue until the breakpoint is hit.
+        threadFront.resume();
+      });
+
+      // prettier-ignore
+      Cu.evalInSandbox("var line0 = Error().lineNumber;\n" +
+                       "function foo() {\n" + // line0 + 1
+                       "  this.a = 1;\n" +    // line0 + 2
+                       "  // A comment.\n" +  // line0 + 3
+                       "  this.b = 2;\n" +    // line0 + 4
+                       "}\n",                 // line0 + 5
+                       debuggee,
+                       "1.7",
+                       "script1.js");
+
+      // prettier-ignore
+      Cu.evalInSandbox("var line1 = Error().lineNumber;\n" +
+                       "debugger;\n" +        // line1 + 1
+                       "foo();\n",           // line1 + 2
+                       debuggee,
+                       "1.7",
+                       "script2.js");
+    });
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-09.js b/devtools/server/tests/xpcshell/test_breakpoint-09.js
new file mode 100644
index 0000000000..90b334102d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-09.js
@@ -0,0 +1,72 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Check that removing a breakpoint works.
+ */
+
+let done = false;
+
+add_task(
+  threadFrontTest(async ({ threadFront, client, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    const location = { sourceUrl: source.url, line: debuggee.line0 + 2 };
+
+    //Pause at debugger statement.
+    Assert.equal(packet.frame.where.line, debuggee.line0 + 7);
+    Assert.equal(packet.why.type, "debuggerStatement");
+
+    threadFront.setBreakpoint(location, {});
+    await client.waitForRequestsToSettle();
+
+    await resume(threadFront);
+
+    const packet2 = await waitForPause(threadFront);
+
+    // Check the return value.
+    Assert.equal(packet2.frame.where.actor, source.actorID);
+    Assert.equal(packet2.frame.where.line, location.line);
+    Assert.equal(packet2.why.type, "breakpoint");
+    // Check that the breakpoint worked.
+    Assert.equal(debuggee.a, undefined);
+
+    // Remove the breakpoint.
+    threadFront.removeBreakpoint(location);
+    await client.waitForRequestsToSettle();
+
+    done = true;
+    threadFront.once("paused", function (packet) {
+      // The breakpoint should not be hit again.
+      threadFront.resume().then(function () {
+        Assert.ok(false);
+      });
+    });
+
+    await resume(threadFront);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox("var line0 = Error().lineNumber;\n" +
+                    "function foo(stop) {\n" + // line0 + 1
+                    "  this.a = 1;\n" +        // line0 + 2
+                    "  if (stop) return;\n" +  // line0 + 3
+                    "  delete this.a;\n" +     // line0 + 4
+                    "  foo(true);\n" +         // line0 + 5
+                    "}\n" +                    // line0 + 6
+                    "debugger;\n" +            // line0 + 7
+                    "foo();\n",                // line0 + 8
+                    debuggee);
+  if (!done) {
+    Assert.ok(false);
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-10.js b/devtools/server/tests/xpcshell/test_breakpoint-10.js
new file mode 100644
index 0000000000..fd114f173d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-10.js
@@ -0,0 +1,81 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that setting a breakpoint in a line with multiple entry points
+ * triggers no matter which entry point we reach.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, client, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    const location = {
+      sourceUrl: source.url,
+      line: debuggee.line0 + 3,
+      column: 5,
+    };
+
+    //Pause at debugger statement.
+    Assert.equal(packet.frame.where.line, debuggee.line0 + 1);
+    Assert.equal(packet.why.type, "debuggerStatement");
+
+    threadFront.setBreakpoint(location, {});
+    await client.waitForRequestsToSettle();
+
+    await resume(threadFront);
+
+    const packet2 = await waitForPause(threadFront);
+    // Check the return value.
+    Assert.equal(packet2.why.type, "breakpoint");
+    // Check that the breakpoint worked.
+    Assert.equal(debuggee.i, 0);
+    // Check pause location
+    Assert.equal(packet2.frame.where.line, debuggee.line0 + 3);
+    Assert.equal(packet2.frame.where.column, 5);
+
+    // Remove the breakpoint.
+    threadFront.removeBreakpoint(location);
+    await client.waitForRequestsToSettle();
+
+    const location2 = {
+      sourceUrl: source.url,
+      line: debuggee.line0 + 3,
+      column: 12,
+    };
+    threadFront.setBreakpoint(location2, {});
+    await client.waitForRequestsToSettle();
+
+    await resume(threadFront);
+    const packet3 = await waitForPause(threadFront);
+    // Check the return value.
+    Assert.equal(packet3.why.type, "breakpoint");
+    // Check that the breakpoint worked.
+    Assert.equal(debuggee.i, 1);
+    // Check execution location
+    Assert.equal(packet3.frame.where.line, debuggee.line0 + 3);
+    Assert.equal(packet3.frame.where.column, 12);
+
+    // Remove the breakpoint.
+    threadFront.removeBreakpoint(location2);
+    await client.waitForRequestsToSettle();
+
+    await resume(threadFront);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox("var line0 = Error().lineNumber;\n" +
+                   "debugger;\n" +                      // line0 + 1
+                   "var a, i = 0;\n" +                  // line0 + 2
+                   "for (i = 1; i <= 2; i++) {\n" +     // line0 + 3
+                   "  a = i;\n" +                       // line0 + 4
+                   "}\n",                               // line0 + 5
+                   debuggee);
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-11.js b/devtools/server/tests/xpcshell/test_breakpoint-11.js
new file mode 100644
index 0000000000..a29cd2f768
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-11.js
@@ -0,0 +1,77 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Make sure that setting a breakpoint in a line with bytecodes in multiple
+ * scripts, sets the breakpoint in all of them (bug 793214).
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, client, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    const location = {
+      sourceUrl: source.url,
+      line: debuggee.line0 + 2,
+      column: 8,
+    };
+
+    //Pause at debugger statement.
+    Assert.equal(packet.frame.where.line, debuggee.line0 + 1);
+    Assert.equal(packet.why.type, "debuggerStatement");
+
+    threadFront.setBreakpoint(location, {});
+    await resume(threadFront);
+
+    const packet2 = await waitForPause(threadFront);
+
+    // Check the return value.
+    Assert.equal(packet2.why.type, "breakpoint");
+    // Check that the breakpoint worked.
+    Assert.equal(debuggee.a, undefined);
+    // Check execution location
+    Assert.equal(packet2.frame.where.line, debuggee.line0 + 2);
+    Assert.equal(packet2.frame.where.column, 8);
+
+    // Remove the breakpoint.
+    threadFront.removeBreakpoint(location);
+
+    const location2 = {
+      sourceUrl: source.url,
+      line: debuggee.line0 + 2,
+      column: 32,
+    };
+    threadFront.setBreakpoint(location2, {});
+
+    await resume(threadFront);
+    const packet3 = await waitForPause(threadFront);
+
+    // Check the return value.
+    Assert.equal(packet3.why.type, "breakpoint");
+    // Check that the breakpoint worked.
+    Assert.equal(debuggee.a.b, 1);
+    Assert.equal(debuggee.res, undefined);
+    // Check execution location
+    Assert.equal(packet3.frame.where.line, debuggee.line0 + 2);
+    Assert.equal(packet3.frame.where.column, 32);
+
+    // Remove the breakpoint.
+    threadFront.removeBreakpoint(location2);
+
+    await resume(threadFront);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox("var line0 = Error().lineNumber;\n" +
+                   "debugger;\n" +                      // line0 + 1
+                   "var a = { b: 1, f: function() { return 2; } };\n" + // line0+2
+                   "var res = a.f();\n",               // line0 + 3
+                   debuggee);
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-12.js b/devtools/server/tests/xpcshell/test_breakpoint-12.js
new file mode 100644
index 0000000000..44b524f1cf
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-12.js
@@ -0,0 +1,93 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Make sure that setting a breakpoint twice in a line without bytecodes works
+ * as expected.
+ */
+
+const NUM_BREAKPOINTS = 10;
+var gBpActor;
+var gCount;
+
+add_task(
+  threadFrontTest(({ threadFront, debuggee }) => {
+    return new Promise(resolve => {
+      threadFront.once("paused", async function (packet) {
+        const source = await getSourceById(
+          threadFront,
+          packet.frame.where.actor
+        );
+        const location = { line: debuggee.line0 + 3 };
+
+        source.setBreakpoint(location).then(function ([response, bpClient]) {
+          // Check that the breakpoint has properly skipped forward one line.
+          Assert.equal(response.actualLocation.source.actor, source.actor);
+          Assert.equal(response.actualLocation.line, location.line + 1);
+          gBpActor = response.actor;
+
+          // Set more breakpoints at the same location.
+          set_breakpoints(source, location);
+        });
+      });
+
+      /* eslint-disable no-multi-spaces */
+      Cu.evalInSandbox(
+        "var line0 = Error().lineNumber;\n" +
+          "function foo() {\n" + // line0 + 1
+          "  this.a = 1;\n" + // line0 + 2
+          "  // A comment.\n" + // line0 + 3
+          "  this.b = 2;\n" + // line0 + 4
+          "}\n" + // line0 + 5
+          "debugger;\n" + // line0 + 6
+          "foo();\n", // line0 + 7
+        debuggee
+      );
+      /* eslint-enable no-multi-spaces */
+
+      // Set many breakpoints at the same location.
+      function set_breakpoints(source, location) {
+        Assert.notEqual(gCount, NUM_BREAKPOINTS);
+        source.setBreakpoint(location).then(function ([response, bpClient]) {
+          // Check that the breakpoint has properly skipped forward one line.
+          Assert.equal(response.actualLocation.source.actor, source.actor);
+          Assert.equal(response.actualLocation.line, location.line + 1);
+          // Check that the same breakpoint actor was returned.
+          Assert.equal(response.actor, gBpActor);
+
+          if (++gCount < NUM_BREAKPOINTS) {
+            set_breakpoints(source, location);
+            return;
+          }
+
+          // After setting all the breakpoints, check that only one has effectively
+          // remained.
+          threadFront.once("paused", function (packet) {
+            // Check the return value.
+            Assert.equal(packet.frame.where.actor, source.actor);
+            Assert.equal(packet.frame.where.line, location.line + 1);
+            Assert.equal(packet.why.type, "breakpoint");
+            Assert.equal(packet.why.actors[0], bpClient.actor);
+            // Check that the breakpoint worked.
+            Assert.equal(debuggee.a, 1);
+            Assert.equal(debuggee.b, undefined);
+
+            threadFront.once("paused", function (packet) {
+              // We don't expect any more pauses after the breakpoint was hit once.
+              Assert.ok(false);
+            });
+            threadFront.resume().then(function () {
+              // Give any remaining breakpoints a chance to trigger.
+              do_timeout(1000, resolve);
+            });
+          });
+          // Continue until the breakpoint is hit.
+          threadFront.resume();
+        });
+      }
+    });
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-13.js b/devtools/server/tests/xpcshell/test_breakpoint-13.js
new file mode 100644
index 0000000000..2265f3449a
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-13.js
@@ -0,0 +1,78 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that execution doesn't pause twice while stepping, when encountering
+ * either a breakpoint or a debugger statement.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    await threadFront.setBreakpoint(
+      { sourceUrl: source.url, line: 3, column: 6 },
+      {}
+    );
+
+    info("Check that the stepping worked.");
+    const packet1 = await stepIn(threadFront);
+    Assert.equal(packet1.frame.where.line, 6);
+    Assert.equal(packet1.why.type, "resumeLimit");
+
+    info("Entered the foo function call frame.");
+    const packet2 = await stepIn(threadFront);
+    Assert.equal(packet2.frame.where.line, 3);
+    Assert.equal(packet2.why.type, "resumeLimit");
+
+    info("Check that the breakpoint wasn't the reason for this pause");
+    const packet3 = await stepIn(threadFront);
+    Assert.equal(packet3.frame.where.line, 4);
+    Assert.equal(packet3.why.type, "resumeLimit");
+    Assert.equal(packet3.why.frameFinished.return.type, "undefined");
+
+    info("Check that the debugger statement wasn't the reason for this pause.");
+    const packet4 = await stepIn(threadFront);
+    Assert.equal(debuggee.a, 1);
+    Assert.equal(debuggee.b, undefined);
+    Assert.equal(packet4.frame.where.line, 7);
+    Assert.equal(packet4.why.type, "resumeLimit");
+
+    info("Check that the debugger statement wasn't the reason for this pause.");
+    const packet5 = await stepIn(threadFront);
+    Assert.equal(packet5.frame.where.line, 8);
+    Assert.equal(packet5.why.type, "resumeLimit");
+
+    info("Remove the breakpoint and finish.");
+    await stepIn(threadFront);
+    threadFront.removeBreakpoint({ sourceUrl: source.url, line: 3 });
+
+    await resume(threadFront);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    `
+  function foo() {
+    this.a = 1; // <-- breakpoint set here
+  }
+  debugger;
+  foo();
+  debugger;
+  var b = 2;
+  `,
+    debuggee,
+    "1.8",
+    "test_breakpoint-13.js",
+    1
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-14.js b/devtools/server/tests/xpcshell/test_breakpoint-14.js
new file mode 100644
index 0000000000..835edb1385
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-14.js
@@ -0,0 +1,90 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow */
+
+"use strict";
+
+/**
+ * Check that a breakpoint or a debugger statement cause execution to pause even
+ * in a stepped-over function.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, client, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    const location = {
+      sourceUrl: source.url,
+      line: debuggee.line0 + 2,
+    };
+
+    //Pause at debugger statement.
+    Assert.equal(packet.frame.where.line, debuggee.line0 + 4);
+    Assert.equal(packet.why.type, "debuggerStatement");
+
+    threadFront.setBreakpoint(location, {});
+
+    const testCallbacks = [
+      function (packet) {
+        // Check that the stepping worked.
+        Assert.equal(packet.frame.where.line, debuggee.line0 + 5);
+        Assert.equal(packet.why.type, "resumeLimit");
+      },
+      function (packet) {
+        // Reached the breakpoint.
+        Assert.equal(packet.frame.where.line, location.line);
+        Assert.equal(packet.why.type, "breakpoint");
+        Assert.notEqual(packet.why.type, "resumeLimit");
+      },
+      function (packet) {
+        // The frame is about to be popped while stepping.
+        Assert.equal(packet.frame.where.line, debuggee.line0 + 3);
+        Assert.notEqual(packet.why.type, "breakpoint");
+        Assert.equal(packet.why.type, "resumeLimit");
+        Assert.equal(packet.why.frameFinished.return.type, "undefined");
+      },
+      function (packet) {
+        // Check that the debugger statement wasn't the reason for this pause.
+        Assert.equal(debuggee.a, 1);
+        Assert.equal(debuggee.b, undefined);
+        Assert.equal(packet.frame.where.line, debuggee.line0 + 6);
+        Assert.notEqual(packet.why.type, "debuggerStatement");
+        Assert.equal(packet.why.type, "resumeLimit");
+      },
+      function (packet) {
+        // Check that the debugger statement wasn't the reason for this pause.
+        Assert.equal(packet.frame.where.line, debuggee.line0 + 7);
+        Assert.notEqual(packet.why.type, "debuggerStatement");
+        Assert.equal(packet.why.type, "resumeLimit");
+      },
+    ];
+
+    for (const callback of testCallbacks) {
+      const waiter = waitForPause(threadFront);
+      threadFront.stepOver();
+      const packet = await waiter;
+      callback(packet);
+    }
+
+    // Remove the breakpoint and finish.
+    threadFront.removeBreakpoint(location);
+
+    await threadFront.resume();
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox("var line0 = Error().lineNumber;\n" +
+                   "function foo() {\n" + // line0 + 1
+                   "  this.a = 1;\n" +    // line0 + 2 <-- Breakpoint is set here.
+                   "}\n" +                // line0 + 3
+                   "debugger;\n" +        // line0 + 4
+                   "foo();\n" +           // line0 + 5
+                   "debugger;\n" +        // line0 + 6
+                   "var b = 2;\n",        // line0 + 7
+                   debuggee);
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-16.js b/devtools/server/tests/xpcshell/test_breakpoint-16.js
new file mode 100644
index 0000000000..a42306eee1
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-16.js
@@ -0,0 +1,70 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Check that we can set breakpoints in columns, not just lines.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, client, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    const location = {
+      sourceUrl: source.url,
+      line: debuggee.line0 + 1,
+      column: 55,
+    };
+
+    let timesBreakpointHit = 0;
+    threadFront.setBreakpoint(location, {});
+
+    while (timesBreakpointHit < 3) {
+      await resume(threadFront);
+      const packet = await waitForPause(threadFront);
+      await testAssertions(
+        packet,
+        debuggee,
+        source,
+        location,
+        timesBreakpointHit
+      );
+
+      timesBreakpointHit++;
+    }
+
+    threadFront.removeBreakpoint(location);
+    await threadFront.resume();
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "var line0 = Error().lineNumber;\n" +
+    "(function () { debugger; this.acc = 0; for (var i = 0; i < 3; i++) this.acc++; }());",
+    debuggee
+  );
+}
+
+async function testAssertions(
+  packet,
+  debuggee,
+  source,
+  location,
+  timesBreakpointHit
+) {
+  Assert.equal(packet.why.type, "breakpoint");
+  Assert.equal(packet.frame.where.actor, source.actor);
+  Assert.equal(packet.frame.where.line, location.line);
+  Assert.equal(packet.frame.where.column, location.column);
+
+  Assert.equal(debuggee.acc, timesBreakpointHit);
+  const environment = await packet.frame.getEnvironment();
+  Assert.equal(environment.bindings.variables.i.value, timesBreakpointHit);
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-17.js b/devtools/server/tests/xpcshell/test_breakpoint-17.js
new file mode 100644
index 0000000000..c52e6547ef
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-17.js
@@ -0,0 +1,130 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow */
+
+"use strict";
+
+/**
+ * Test that when we add 2 breakpoints to the same line at different columns and
+ * then remove one of them, we don't remove them both.
+ */
+
+const code =
+  "(" +
+  function (global) {
+    global.foo = function () {
+      Math.abs(-1);
+      Math.log(0.5);
+      debugger;
+    };
+    debugger;
+  } +
+  "(this))";
+
+const firstLocation = {
+  line: 3,
+  column: 4,
+};
+
+const secondLocation = {
+  line: 3,
+  column: 18,
+};
+
+add_task(
+  threadFrontTest(({ threadFront, debuggee }) => {
+    return new Promise(resolve => {
+      threadFront.on("paused", async packet => {
+        const [first, second] = await set_breakpoints(packet, threadFront);
+        test_different_actors(first, second);
+        await test_remove_one(first, second, threadFront, debuggee);
+        resolve();
+      });
+
+      Cu.evalInSandbox(code, debuggee, "1.8", "http://example.com/", 1);
+    });
+  })
+);
+
+async function set_breakpoints(packet, threadFront) {
+  const source = await getSourceById(threadFront, packet.frame.where.actor);
+  return new Promise(resolve => {
+    let first, second;
+
+    source
+      .setBreakpoint(firstLocation)
+      .then(function ([{ actualLocation }, breakpointClient]) {
+        Assert.ok(!actualLocation, "Should not get an actualLocation");
+        first = breakpointClient;
+
+        source
+          .setBreakpoint(secondLocation)
+          .then(function ([{ actualLocation }, breakpointClient]) {
+            Assert.ok(!actualLocation, "Should not get an actualLocation");
+            second = breakpointClient;
+
+            resolve([first, second]);
+          });
+      });
+  });
+}
+
+function test_different_actors(first, second) {
+  Assert.notEqual(
+    first.actor,
+    second.actor,
+    "Each breakpoint should have a different actor"
+  );
+}
+
+function test_remove_one(first, second, threadFront, debuggee) {
+  return new Promise(resolve => {
+    first.remove(function ({ error }) {
+      Assert.ok(!error, "Should not get an error removing a breakpoint");
+
+      let hitSecond;
+      threadFront.on("paused", function _onPaused({ why, frame }) {
+        if (why.type == "breakpoint") {
+          hitSecond = true;
+          Assert.equal(
+            why.actors.length,
+            1,
+            "Should only be paused because of one breakpoint actor"
+          );
+          Assert.equal(
+            why.actors[0],
+            second.actor,
+            "Should be paused because of the correct breakpoint actor"
+          );
+          Assert.equal(
+            frame.where.line,
+            secondLocation.line,
+            "Should be at the right line"
+          );
+          Assert.equal(
+            frame.where.column,
+            secondLocation.column,
+            "Should be at the right column"
+          );
+          threadFront.resume();
+          return;
+        }
+
+        if (why.type == "debuggerStatement") {
+          threadFront.off("paused", _onPaused);
+          Assert.ok(
+            hitSecond,
+            "We should still hit `second`, but not `first`."
+          );
+
+          resolve();
+          return;
+        }
+
+        Assert.ok(false, "Should never get here");
+      });
+
+      threadFront.resume().then(() => debuggee.foo());
+    });
+  });
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-18.js b/devtools/server/tests/xpcshell/test_breakpoint-18.js
new file mode 100644
index 0000000000..b2c86458d0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-18.js
@@ -0,0 +1,60 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that we only break on offsets that are entry points for the line we are
+ * breaking on. Bug 907278.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, client, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    const location = { sourceUrl: source.url, line: 3 };
+    threadFront.setBreakpoint(location, {});
+    await client.waitForRequestsToSettle();
+
+    debuggee.console = { log: x => void x };
+
+    await resume(threadFront);
+
+    const packet2 = await executeOnNextTickAndWaitForPause(
+      debuggee.test,
+      threadFront
+    );
+    Assert.equal(packet2.why.type, "breakpoint");
+
+    const packet3 = await resumeAndWaitForPause(threadFront);
+    testDbgStatement(packet3);
+
+    await resume(threadFront);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  Cu.evalInSandbox(
+    "debugger;\n" +
+      function test() {
+        console.log("foo bar");
+        debugger;
+      },
+    debuggee,
+    "1.8",
+    "http://example.com/",
+    1
+  );
+}
+
+function testDbgStatement({ why }) {
+  // Should continue to the debugger statement.
+  Assert.equal(why.type, "debuggerStatement");
+  // Not break on another offset from the same line (that isn't an entry point
+  // to the line)
+  Assert.notEqual(why.type, "breakpoint");
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-19.js b/devtools/server/tests/xpcshell/test_breakpoint-19.js
new file mode 100644
index 0000000000..013acdfaf1
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-19.js
@@ -0,0 +1,45 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Make sure that setting a breakpoint in a not-yet-existing script doesn't throw
+ * an error (see bug 897567). Also make sure that this breakpoint works.
+ */
+
+const URL = "test.js";
+
+function setUpCode(debuggee) {
+  /* eslint-disable mozilla/var-only-at-top-level, no-unused-vars */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "" + function test() { // 1
+      var a = 1;           // 2
+      debugger;            // 3
+    } +                    // 4
+    "\ndebugger;",         // 5
+    debuggee,
+    "1.8",
+    URL
+  );
+  /* eslint-enable mozilla/var-only-at-top-level, no-unused-vars */
+}
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    setBreakpoint(threadFront, { sourceUrl: URL, line: 2 });
+
+    await executeOnNextTickAndWaitForPause(
+      () => setUpCode(debuggee),
+      threadFront
+    );
+    await resume(threadFront);
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      debuggee.test,
+      threadFront
+    );
+    equal(packet.why.type, "breakpoint");
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-20.js b/devtools/server/tests/xpcshell/test_breakpoint-20.js
new file mode 100644
index 0000000000..886d44164d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-20.js
@@ -0,0 +1,109 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Verify that when two of the "same" source are loaded concurrently (like e10s
+ * frame scripts), breakpoints get hit in scripts defined by all sources.
+ */
+
+var gDebuggee;
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    gDebuggee = debuggee;
+    await testBreakpoint(threadFront);
+  })
+);
+
+const testBreakpoint = async function (threadFront) {
+  evalSetupCode();
+
+  // Load the test source once.
+
+  evalTestCode();
+  equal(
+    gDebuggee.functions.length,
+    1,
+    "The test code should have added a function."
+  );
+
+  // Set a breakpoint in the test source.
+
+  const source = await getSource(threadFront, "test.js");
+  setBreakpoint(threadFront, { sourceUrl: source.url, line: 3 });
+
+  // Load the test source again.
+
+  evalTestCode();
+  equal(
+    gDebuggee.functions.length,
+    2,
+    "The test code should have added another function."
+  );
+
+  // Should hit our breakpoint in a script defined by the first instance of the
+  // test source.
+
+  const bpPause1 = await executeOnNextTickAndWaitForPause(
+    gDebuggee.functions[0],
+    threadFront
+  );
+  equal(
+    bpPause1.why.type,
+    "breakpoint",
+    "Should pause because of hitting our breakpoint (not debugger statement)."
+  );
+  const dbgStmtPause1 = await executeOnNextTickAndWaitForPause(
+    () => resume(threadFront),
+    threadFront
+  );
+  equal(
+    dbgStmtPause1.why.type,
+    "debuggerStatement",
+    "And we should hit the debugger statement after the pause."
+  );
+  await resume(threadFront);
+
+  // Should also hit our breakpoint in a script defined by the second instance
+  // of the test source.
+
+  const bpPause2 = await executeOnNextTickAndWaitForPause(
+    gDebuggee.functions[1],
+    threadFront
+  );
+  equal(
+    bpPause2.why.type,
+    "breakpoint",
+    "Should pause because of hitting our breakpoint (not debugger statement)."
+  );
+  const dbgStmtPause2 = await executeOnNextTickAndWaitForPause(
+    () => resume(threadFront),
+    threadFront
+  );
+  equal(
+    dbgStmtPause2.why.type,
+    "debuggerStatement",
+    "And we should hit the debugger statement after the pause."
+  );
+};
+
+function evalSetupCode() {
+  Cu.evalInSandbox("this.functions = [];", gDebuggee, "1.8", "setup.js", 1);
+}
+
+function evalTestCode() {
+  Cu.evalInSandbox(
+    `                                 // 1
+    this.functions.push(function () { // 2
+      var setBreakpointHere = 1;      // 3
+      debugger;                       // 4
+    });                               // 5
+    `,
+    gDebuggee,
+    "1.8",
+    "test.js",
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-21.js b/devtools/server/tests/xpcshell/test_breakpoint-21.js
new file mode 100644
index 0000000000..da7a87f91c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-21.js
@@ -0,0 +1,62 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Bug 1122064 - make sure that scripts introduced via onNewScripts
+ * properly populate the `ScriptStore` with all there nested child
+ * scripts, so you can set breakpoints on deeply nested scripts
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    // Populate the `ScriptStore` so that we only test that the script
+    // is added through `onNewScript`
+    await getSources(threadFront);
+
+    let packet = await executeOnNextTickAndWaitForPause(() => {
+      evalCode(debuggee);
+    }, threadFront);
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+    const location = {
+      sourceUrl: source.url,
+      line: debuggee.line0 + 8,
+    };
+
+    setBreakpoint(threadFront, location);
+
+    await resume(threadFront);
+    packet = await waitForPause(threadFront);
+    Assert.equal(packet.why.type, "breakpoint");
+    Assert.equal(packet.frame.where.actor, source.actor);
+    Assert.equal(packet.frame.where.line, location.line);
+
+    await resume(threadFront);
+  })
+);
+
+function evalCode(debuggee) {
+  // Start a new script
+  /* eslint-disable mozilla/var-only-at-top-level, max-nested-callbacks, no-unused-vars */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "var line0 = Error().lineNumber;\n(" + function () {
+      debugger;
+      var a = (function () {
+        return (function () {
+          return (function () {
+            return (function () {
+              return (function () {
+                var x = 10; // This line gets a breakpoint
+                return 1;
+              })();
+            })();
+          })();
+        })();
+      })();
+    } + ")()",
+    debuggee
+  );
+  /* eslint-enable mozilla/var-only-at-top-level, max-nested-callbacks, no-unused-vars */
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-22.js b/devtools/server/tests/xpcshell/test_breakpoint-22.js
new file mode 100644
index 0000000000..067dfa3fa2
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-22.js
@@ -0,0 +1,60 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Bug 1333219 - make that setBreakpoint fails when script is not found
+ * at the specified line.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    // Populate the `ScriptStore` so that we only test that the script
+    // is added through `onNewScript`
+    await getSources(threadFront);
+
+    const packet = await executeOnNextTickAndWaitForPause(() => {
+      evalCode(debuggee);
+    }, threadFront);
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+
+    const location = {
+      line: debuggee.line0 + 2,
+    };
+
+    const [res] = await setBreakpoint(source, location);
+    ok(!res.error);
+
+    const location2 = {
+      line: debuggee.line0 + 7,
+    };
+
+    await source.setBreakpoint(location2).then(
+      () => {
+        do_throw("no code shall not be found the specified line or below it");
+      },
+      reason => {
+        Assert.equal(reason.error, "noCodeAtLineColumn");
+        ok(reason.message);
+      }
+    );
+
+    await resume(threadFront);
+  })
+);
+
+function evalCode(debuggee) {
+  // Start a new script
+  Cu.evalInSandbox(
+    `
+var line0 = Error().lineNumber;
+function some_function() {
+  // breakpoint is valid here -- it slides one line below (line0 + 2)
+}
+debugger;
+// no breakpoint is allowed after the EOF (line0 + 6)
+`,
+    debuggee
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-23.js b/devtools/server/tests/xpcshell/test_breakpoint-23.js
new file mode 100644
index 0000000000..8f07190ea9
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-23.js
@@ -0,0 +1,35 @@
+/* eslint-disable max-nested-callbacks */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Bug 1552453 - Verify that breakpoints are hit for evaluated
+ * scripts that contain a source url pragma.
+ */
+add_task(
+  threadFrontTest(async ({ commands, threadFront }) => {
+    await threadFront.setBreakpoint(
+      { sourceUrl: "http://example.com/code.js", line: 2, column: 1 },
+      {}
+    );
+
+    info("Create a new script with the displayUrl code.js");
+    const onNewSource = waitForEvent(threadFront, "newSource");
+    await commands.scriptCommand.execute(
+      "function f() {\n return 5; \n}\n//# sourceURL=http://example.com/code.js"
+    );
+    const sourcePacket = await onNewSource;
+
+    equal(sourcePacket.source.url, "http://example.com/code.js");
+
+    info("Evaluate f() and pause at line 2");
+    const onExecutionDone = commands.scriptCommand.execute("f()");
+    const pausedPacket = await waitForPause(threadFront);
+    equal(pausedPacket.why.type, "breakpoint");
+    equal(pausedPacket.frame.where.line, 2);
+    resume(threadFront);
+    await onExecutionDone;
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-24.js b/devtools/server/tests/xpcshell/test_breakpoint-24.js
new file mode 100644
index 0000000000..a240a237f0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-24.js
@@ -0,0 +1,239 @@
+/* eslint-disable max-nested-callbacks */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Bug 1441183 - Verify that the debugger advances to a new location
+ * when encountering debugger statements and brakpoints
+ *
+ * Bug 1613165 - Verify that debugger statement is not disabled by
+ *  adding/removing a breakpoint
+ */
+add_task(
+  threadFrontTest(async props => {
+    await testDebuggerStatements(props);
+    await testBreakpoints(props);
+    await testBreakpointsAndDebuggerStatements(props);
+    await testLoops(props);
+    await testRemovingBreakpoint(props);
+    await testAddingBreakpoint(props);
+  })
+);
+
+// Ensure that we advance to the next line when we
+// step to a debugger statement and resume.
+async function testDebuggerStatements({ commands, threadFront }) {
+  commands.scriptCommand.execute(`function foo(stop) {
+      debugger;
+      debugger;
+      debugger;
+    }
+    foo();
+    //# sourceURL=http://example.com/code.js`);
+
+  await performActions(threadFront, [
+    [
+      "paused at first debugger statement",
+      { line: 2, type: "debuggerStatement" },
+      "stepOver",
+    ],
+    [
+      "paused at the second debugger statement",
+      { line: 3, type: "resumeLimit" },
+      "resume",
+    ],
+    [
+      "paused at the third debugger statement",
+      { line: 4, type: "debuggerStatement" },
+      "resume",
+    ],
+  ]);
+}
+
+// Ensure that we advance to the next line when we hit a breakpoint
+// on a line with a debugger statement and resume.
+async function testBreakpointsAndDebuggerStatements({ commands, threadFront }) {
+  commands.scriptCommand.execute(`function foo(stop) {
+      debugger;
+      debugger;
+      debugger;
+    }
+    foo();
+    //# sourceURL=http://example.com/testBreakpointsAndDebuggerStatements.js`);
+
+  threadFront.setBreakpoint(
+    {
+      sourceUrl: "http://example.com/testBreakpointsAndDebuggerStatements.js",
+      line: 3,
+    },
+    {}
+  );
+
+  await performActions(threadFront, [
+    [
+      "paused at first debugger statement",
+      { line: 2, type: "debuggerStatement" },
+      "resume",
+    ],
+    [
+      "paused at the breakpoint at the second debugger statement",
+      { line: 3, type: "breakpoint" },
+      "resume",
+    ],
+    [
+      "pause at the third debugger statement",
+      { line: 4, type: "debuggerStatement" },
+      "resume",
+    ],
+  ]);
+}
+
+// Ensure that we advance to the next line when we step to
+// a line with a breakpoint and resume.
+async function testBreakpoints({ commands, threadFront }) {
+  commands.scriptCommand.execute(`function foo(stop) {
+      debugger;
+      a();
+      debugger;
+    }
+    function a() {}
+    foo();
+    //# sourceURL=http://example.com/testBreakpoints.js`);
+
+  threadFront.setBreakpoint(
+    { sourceUrl: "http://example.com/testBreakpoints.js", line: 3, column: 6 },
+    {}
+  );
+
+  await performActions(threadFront, [
+    [
+      "paused at first debugger statement",
+      { line: 2, type: "debuggerStatement" },
+      "stepOver",
+    ],
+    ["paused at a()", { line: 3, type: "resumeLimit" }, "resume"],
+    [
+      "pause at the second debugger satement",
+      { line: 4, type: "debuggerStatement" },
+      "resume",
+    ],
+  ]);
+}
+
+// Ensure that we advance to the next line when we step to
+// a line with a breakpoint and resume.
+async function testLoops({ commands, threadFront }) {
+  commands.scriptCommand.execute(`function foo(stop) {
+      let i = 0;
+      debugger;
+      while (i++ < 2) {
+        debugger;
+      }
+      debugger;
+    }
+    foo();
+    //# sourceURL=http://example.com/testLoops.js`);
+
+  await performActions(threadFront, [
+    [
+      "paused at first debugger statement",
+      { line: 3, type: "debuggerStatement" },
+      "resume",
+    ],
+    [
+      "pause at the second debugger satement",
+      { line: 5, type: "debuggerStatement" },
+      "resume",
+    ],
+    [
+      "pause at the second debugger satement (2nd time)",
+      { line: 5, type: "debuggerStatement" },
+      "resume",
+    ],
+    [
+      "pause at the third debugger satement",
+      { line: 7, type: "debuggerStatement" },
+      "resume",
+    ],
+  ]);
+}
+
+// Bug 1613165 - ensure that if you pause on a breakpoint on a line with
+// debugger statement, remove the breakpoint, and try to pause on the
+// debugger statement before pausing anywhere else, debugger pauses instead of
+// skipping debugger statement.
+async function testRemovingBreakpoint({ commands, threadFront }) {
+  commands.scriptCommand.execute(`function foo(stop) {
+      debugger;
+    }
+    foo();
+    foo();
+    //# sourceURL=http://example.com/testRemovingBreakpoint.js`);
+
+  const location = {
+    sourceUrl: "http://example.com/testRemovingBreakpoint.js",
+    line: 2,
+    column: 6,
+  };
+
+  threadFront.setBreakpoint(location, {});
+
+  info("paused at the breakpoint at the first debugger statement");
+  const packet = await waitForEvent(threadFront, "paused");
+  Assert.equal(packet.frame.where.line, 2);
+  Assert.equal(packet.why.type, "breakpoint");
+  threadFront.removeBreakpoint(location);
+
+  info("paused at the first debugger statement");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 2);
+  Assert.equal(packet2.why.type, "debuggerStatement");
+  await threadFront.resume();
+}
+
+// Bug 1613165 - ensure if you pause on a debugger statement, add a
+// breakpoint on the same line, and try to pause on the breakpoint
+// before pausing anywhere else, debugger pauses on that line instead of
+// skipping breakpoint.
+async function testAddingBreakpoint({ commands, threadFront }) {
+  commands.scriptCommand.execute(`function foo(stop) {
+      debugger;
+    }
+    foo();
+    foo();
+    //# sourceURL=http://example.com/testAddingBreakpoint.js`);
+
+  const location = {
+    sourceUrl: "http://example.com/testAddingBreakpoint.js",
+    line: 2,
+    column: 6,
+  };
+
+  info("paused at the first debugger statement");
+  const packet = await waitForEvent(threadFront, "paused");
+  Assert.equal(packet.frame.where.line, 2);
+  Assert.equal(packet.why.type, "debuggerStatement");
+  threadFront.setBreakpoint(location, {});
+
+  info("paused at the breakpoint at the first debugger statement");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 2);
+  Assert.equal(packet2.why.type, "breakpoint");
+  await threadFront.resume();
+}
+
+async function performActions(threadFront, actions) {
+  for (const action of actions) {
+    await performAction(threadFront, action);
+  }
+}
+
+async function performAction(threadFront, [description, result, action]) {
+  info(description);
+  const packet = await waitForEvent(threadFront, "paused");
+  Assert.equal(packet.frame.where.line, result.line);
+  Assert.equal(packet.why.type, result.type);
+  await threadFront[action]();
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-25.js b/devtools/server/tests/xpcshell/test_breakpoint-25.js
new file mode 100644
index 0000000000..f155234c96
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-25.js
@@ -0,0 +1,79 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Ensure that the debugger resume page execution when the connection drops
+ * and when the target is detached.
+ */
+
+add_task(
+  threadFrontTest(({ threadFront, debuggee, targetFront }) => {
+    return new Promise(resolve => {
+      (async () => {
+        await executeOnNextTickAndWaitForPause(evalCode, threadFront);
+
+        ok(true, "The page is paused");
+        ok(!debuggee.foo, "foo is still false after we hit the breakpoint");
+
+        await targetFront.detach();
+
+        // Closing the connection will force the thread actor to resume page
+        // execution
+        ok(debuggee.foo, "foo is true after target's detach request");
+
+        resolve();
+      })();
+
+      function evalCode() {
+        /* eslint-disable */
+        Cu.evalInSandbox("var foo = false;\n", debuggee);
+        /* eslint-enable */
+        ok(!debuggee.foo, "foo is false at startup");
+
+        /* eslint-disable */
+        Cu.evalInSandbox("debugger;\n" + "foo = true;\n", debuggee);
+        /* eslint-enable */
+      }
+    });
+  })
+);
+
+add_task(
+  threadFrontTest(({ threadFront, client, debuggee }) => {
+    return new Promise(resolve => {
+      (async () => {
+        await executeOnNextTickAndWaitForPause(evalCode, threadFront);
+
+        ok(true, "The page is paused");
+        ok(!debuggee.foo, "foo is still false after we hit the breakpoint");
+
+        await client.close();
+
+        // `close` will force the destruction of the thread actor, which,
+        // will resume the page execution. But all of that seems to be
+        // synchronous and we have to spin the event loop in order to ensure
+        // having the content javascript to execute the resumed code.
+        await new Promise(executeSoon);
+
+        // Closing the connection will force the thread actor to resume page
+        // execution
+        ok(debuggee.foo, "foo is true after client close");
+        executeSoon(resolve);
+        dump("resolved\n");
+      })();
+
+      function evalCode() {
+        /* eslint-disable */
+        Cu.evalInSandbox("var foo = false;\n", debuggee);
+        /* eslint-enable */
+        ok(!debuggee.foo, "foo is false at startup");
+
+        /* eslint-disable */
+        Cu.evalInSandbox("debugger;\n" + "foo = true;\n", debuggee);
+        /* eslint-enable */
+      }
+    });
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-26.js b/devtools/server/tests/xpcshell/test_breakpoint-26.js
new file mode 100644
index 0000000000..8624171252
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-26.js
@@ -0,0 +1,63 @@
+/* eslint-disable max-nested-callbacks */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Bug 925269 - Verify that debugger statements are skipped
+ * if there is a falsey conditional breakpoint at the same location.
+ */
+add_task(
+  threadFrontTest(async props => {
+    await testBreakpointsAndDebuggerStatements(props);
+  })
+);
+
+async function testBreakpointsAndDebuggerStatements({ commands, threadFront }) {
+  commands.scriptCommand.execute(
+    `function foo(stop) {
+      debugger;
+      debugger;
+      debugger;
+    }
+    foo();
+    //# sourceURL=http://example.com/testBreakpointsAndDebuggerStatements.js`
+  );
+
+  threadFront.setBreakpoint(
+    {
+      sourceUrl: "http://example.com/testBreakpointsAndDebuggerStatements.js",
+      line: 3,
+      column: 6,
+    },
+    { condition: "false" }
+  );
+
+  await performActions(threadFront, [
+    [
+      "paused at first debugger statement",
+      { line: 2, type: "debuggerStatement" },
+      "resume",
+    ],
+    [
+      "pause at the third debugger statement",
+      { line: 4, type: "debuggerStatement" },
+      "resume",
+    ],
+  ]);
+}
+
+async function performActions(threadFront, actions) {
+  for (const action of actions) {
+    await performAction(threadFront, action);
+  }
+}
+
+async function performAction(threadFront, [description, result, action]) {
+  info(description);
+  const packet = await waitForEvent(threadFront, "paused");
+  Assert.equal(packet.frame.where.line, result.line);
+  Assert.equal(packet.why.type, result.type);
+  await threadFront[action]();
+}
diff --git a/devtools/server/tests/xpcshell/test_breakpoint-actor-map.js b/devtools/server/tests/xpcshell/test_breakpoint-actor-map.js
new file mode 100644
index 0000000000..e45096095e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_breakpoint-actor-map.js
@@ -0,0 +1,257 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test the functionality of the BreakpointActorMap object.
+
+const {
+  BreakpointActorMap,
+} = require("resource://devtools/server/actors/utils/breakpoint-actor-map.js");
+
+function run_test() {
+  test_get_actor();
+  test_set_actor();
+  test_delete_actor();
+  test_find_actors();
+  test_duplicate_actors();
+}
+
+function test_get_actor() {
+  const bpStore = new BreakpointActorMap();
+  const location = {
+    generatedSourceActor: { actor: "actor1" },
+    generatedLine: 3,
+  };
+  const columnLocation = {
+    generatedSourceActor: { actor: "actor2" },
+    generatedLine: 5,
+    generatedColumn: 15,
+  };
+
+  // Shouldn't have breakpoint
+  Assert.equal(
+    null,
+    bpStore.getActor(location),
+    "Breakpoint not added and shouldn't exist."
+  );
+
+  bpStore.setActor(location, {});
+  Assert.ok(
+    !!bpStore.getActor(location),
+    "Breakpoint added but not found in Breakpoint Store."
+  );
+
+  bpStore.deleteActor(location);
+  Assert.equal(
+    null,
+    bpStore.getActor(location),
+    "Breakpoint removed but still exists."
+  );
+
+  // Same checks for breakpoint with a column
+  Assert.equal(
+    null,
+    bpStore.getActor(columnLocation),
+    "Breakpoint with column not added and shouldn't exist."
+  );
+
+  bpStore.setActor(columnLocation, {});
+  Assert.ok(
+    !!bpStore.getActor(columnLocation),
+    "Breakpoint with column added but not found in Breakpoint Store."
+  );
+
+  bpStore.deleteActor(columnLocation);
+  Assert.equal(
+    null,
+    bpStore.getActor(columnLocation),
+    "Breakpoint with column removed but still exists in Breakpoint Store."
+  );
+}
+
+function test_set_actor() {
+  // Breakpoint with column
+  const bpStore = new BreakpointActorMap();
+  let location = {
+    generatedSourceActor: { actor: "actor1" },
+    generatedLine: 10,
+    generatedColumn: 9,
+  };
+  bpStore.setActor(location, {});
+  Assert.ok(
+    !!bpStore.getActor(location),
+    "We should have the column breakpoint we just added"
+  );
+
+  // Breakpoint without column (whole line breakpoint)
+  location = {
+    generatedSourceActor: { actor: "actor2" },
+    generatedLine: 103,
+  };
+  bpStore.setActor(location, {});
+  Assert.ok(
+    !!bpStore.getActor(location),
+    "We should have the whole line breakpoint we just added"
+  );
+}
+
+function test_delete_actor() {
+  // Breakpoint with column
+  const bpStore = new BreakpointActorMap();
+  let location = {
+    generatedSourceActor: { actor: "actor1" },
+    generatedLine: 10,
+    generatedColumn: 9,
+  };
+  bpStore.setActor(location, {});
+  bpStore.deleteActor(location);
+  Assert.equal(
+    bpStore.getActor(location),
+    null,
+    "We should not have the column breakpoint anymore"
+  );
+
+  // Breakpoint without column (whole line breakpoint)
+  location = {
+    generatedSourceActor: { actor: "actor2" },
+    generatedLine: 103,
+  };
+  bpStore.setActor(location, {});
+  bpStore.deleteActor(location);
+  Assert.equal(
+    bpStore.getActor(location),
+    null,
+    "We should not have the whole line breakpoint anymore"
+  );
+}
+
+function test_find_actors() {
+  const bps = [
+    { generatedSourceActor: { actor: "actor1" }, generatedLine: 10 },
+    {
+      generatedSourceActor: { actor: "actor1" },
+      generatedLine: 10,
+      generatedColumn: 3,
+    },
+    {
+      generatedSourceActor: { actor: "actor1" },
+      generatedLine: 10,
+      generatedColumn: 10,
+    },
+    {
+      generatedSourceActor: { actor: "actor1" },
+      generatedLine: 23,
+      generatedColumn: 89,
+    },
+    {
+      generatedSourceActor: { actor: "actor2" },
+      generatedLine: 10,
+      generatedColumn: 1,
+    },
+    {
+      generatedSourceActor: { actor: "actor2" },
+      generatedLine: 20,
+      generatedColumn: 5,
+    },
+    {
+      generatedSourceActor: { actor: "actor2" },
+      generatedLine: 30,
+      generatedColumn: 34,
+    },
+    {
+      generatedSourceActor: { actor: "actor2" },
+      generatedLine: 40,
+      generatedColumn: 56,
+    },
+  ];
+
+  const bpStore = new BreakpointActorMap();
+
+  for (const bp of bps) {
+    bpStore.setActor(bp, bp);
+  }
+
+  // All breakpoints
+
+  let bpSet = new Set(bps);
+  for (const bp of bpStore.findActors()) {
+    bpSet.delete(bp);
+  }
+  Assert.equal(bpSet.size, 0, "Should be able to iterate over all breakpoints");
+
+  // Breakpoints by URL
+
+  bpSet = new Set(
+    bps.filter(bp => {
+      return bp.generatedSourceActor.actorID === "actor1";
+    })
+  );
+  for (const bp of bpStore.findActors({
+    generatedSourceActor: { actorID: "actor1" },
+  })) {
+    bpSet.delete(bp);
+  }
+  Assert.equal(bpSet.size, 0, "Should be able to filter the iteration by url");
+
+  // Breakpoints by URL and line
+
+  bpSet = new Set(
+    bps.filter(bp => {
+      return (
+        bp.generatedSourceActor.actorID === "actor1" && bp.generatedLine === 10
+      );
+    })
+  );
+  let first = true;
+  for (const bp of bpStore.findActors({
+    generatedSourceActor: { actorID: "actor1" },
+    generatedLine: 10,
+  })) {
+    if (first) {
+      Assert.equal(
+        bp.generatedColumn,
+        undefined,
+        "Should always get the whole line breakpoint first"
+      );
+      first = false;
+    } else {
+      Assert.notEqual(
+        bp.generatedColumn,
+        undefined,
+        "Should not get the whole line breakpoint any time other than first."
+      );
+    }
+    bpSet.delete(bp);
+  }
+  Assert.equal(
+    bpSet.size,
+    0,
+    "Should be able to filter the iteration by url and line"
+  );
+}
+
+function test_duplicate_actors() {
+  const bpStore = new BreakpointActorMap();
+
+  // Breakpoint with column
+  let location = {
+    generatedSourceActor: { actorID: "foo-actor" },
+    generatedLine: 10,
+    generatedColumn: 9,
+  };
+  bpStore.setActor(location, {});
+  bpStore.setActor(location, {});
+  Assert.equal(bpStore.size, 1, "We should have only 1 column breakpoint");
+  bpStore.deleteActor(location);
+
+  // Breakpoint without column (whole line breakpoint)
+  location = {
+    generatedSourceActor: { actorID: "foo-actor" },
+    generatedLine: 15,
+  };
+  bpStore.setActor(location, {});
+  bpStore.setActor(location, {});
+  Assert.equal(bpStore.size, 1, "We should have only 1 whole line breakpoint");
+  bpStore.deleteActor(location);
+}
diff --git a/devtools/server/tests/xpcshell/test_client_request.js b/devtools/server/tests/xpcshell/test_client_request.js
new file mode 100644
index 0000000000..3fc897281c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_client_request.js
@@ -0,0 +1,261 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test the DevToolsClient.request API.
+
+var gClient, gActorId;
+
+const { Actor } = require("resource://devtools/shared/protocol/Actor.js");
+
+class TestActor extends Actor {
+  constructor(conn) {
+    super(conn, { typeName: "test", methods: [] });
+
+    this.requestTypes = {
+      hello: this.hello,
+      error: this.error,
+    };
+  }
+
+  hello() {
+    return { hello: "world" };
+  }
+
+  error() {
+    return { error: "code", message: "human message" };
+  }
+}
+
+function run_test() {
+  ActorRegistry.addGlobalActor(
+    {
+      constructorName: "TestActor",
+      constructorFun: TestActor,
+    },
+    "test"
+  );
+
+  DevToolsServer.init();
+  DevToolsServer.registerAllActors();
+
+  add_test(init);
+  add_test(test_client_request_callback);
+  add_test(test_client_request_promise);
+  add_test(test_client_request_promise_error);
+  add_test(test_client_request_event_emitter);
+  add_test(test_close_client_while_sending_requests);
+  add_test(test_client_request_after_close);
+  add_test(test_client_request_after_close_callback);
+  run_next_test();
+}
+
+function init() {
+  gClient = new DevToolsClient(DevToolsServer.connectPipe());
+  gClient
+    .connect()
+    .then(() => gClient.mainRoot.rootForm)
+    .then(response => {
+      gActorId = response.test;
+      run_next_test();
+    });
+}
+
+function checkStack(expectedName) {
+  let stack = Components.stack;
+  while (stack) {
+    info(stack.name);
+    if (stack.name == expectedName) {
+      // Reached back to outer function before request
+      ok(true, "Complete stack");
+      return;
+    }
+    stack = stack.asyncCaller || stack.caller;
+  }
+  ok(false, "Incomplete stack");
+}
+
+function test_client_request_callback() {
+  // Test that DevToolsClient.request accepts a `onResponse` callback as 2nd argument
+  gClient.request(
+    {
+      to: gActorId,
+      type: "hello",
+    },
+    response => {
+      Assert.equal(response.from, gActorId);
+      Assert.equal(response.hello, "world");
+      checkStack("test_client_request_callback");
+      run_next_test();
+    }
+  );
+}
+
+function test_client_request_promise() {
+  // Test that DevToolsClient.request returns a promise that resolves on response
+  const request = gClient.request({
+    to: gActorId,
+    type: "hello",
+  });
+
+  request.then(response => {
+    Assert.equal(response.from, gActorId);
+    Assert.equal(response.hello, "world");
+    checkStack("test_client_request_promise/<");
+    run_next_test();
+  });
+}
+
+function test_client_request_promise_error() {
+  // Test that DevToolsClient.request returns a promise that reject when server
+  // returns an explicit error message
+  const request = gClient.request({
+    to: gActorId,
+    type: "error",
+  });
+
+  request.then(
+    () => {
+      do_throw("Promise shouldn't be resolved on error");
+    },
+    response => {
+      Assert.equal(response.from, gActorId);
+      Assert.equal(response.error, "code");
+      Assert.equal(response.message, "human message");
+      checkStack("test_client_request_promise_error/<");
+      run_next_test();
+    }
+  );
+}
+
+function test_client_request_event_emitter() {
+  // Test that DevToolsClient.request returns also an EventEmitter object
+  const request = gClient.request({
+    to: gActorId,
+    type: "hello",
+  });
+  request.on("json-reply", reply => {
+    Assert.equal(reply.from, gActorId);
+    Assert.equal(reply.hello, "world");
+    checkStack("test_client_request_event_emitter");
+    run_next_test();
+  });
+}
+
+function test_close_client_while_sending_requests() {
+  // First send a first request that will be "active"
+  // while the connection is closed.
+  // i.e. will be sent but no response received yet.
+  const activeRequest = gClient.request({
+    to: gActorId,
+    type: "hello",
+  });
+
+  // Pile up a second one that will be "pending".
+  // i.e. won't event be sent.
+  const pendingRequest = gClient.request({
+    to: gActorId,
+    type: "hello",
+  });
+
+  const expectReply = new Promise(resolve => {
+    gClient.expectReply("root", function (response) {
+      Assert.equal(response.error, "connectionClosed");
+      Assert.equal(
+        response.message,
+        "server side packet can't be received as the connection just closed."
+      );
+      resolve();
+    });
+  });
+
+  gClient.close().then(() => {
+    activeRequest
+      .then(
+        () => {
+          ok(
+            false,
+            "First request unexpectedly succeed while closing the connection"
+          );
+        },
+        response => {
+          Assert.equal(response.error, "connectionClosed");
+          Assert.equal(
+            response.message,
+            "'hello' active request packet to '" +
+              gActorId +
+              "' can't be sent as the connection just closed."
+          );
+        }
+      )
+      .then(() => pendingRequest)
+      .then(
+        () => {
+          ok(
+            false,
+            "Second request unexpectedly succeed while closing the connection"
+          );
+        },
+        response => {
+          Assert.equal(response.error, "connectionClosed");
+          Assert.equal(
+            response.message,
+            "'hello' pending request packet to '" +
+              gActorId +
+              "' can't be sent as the connection just closed."
+          );
+        }
+      )
+      .then(() => expectReply)
+      .then(run_next_test);
+  });
+}
+
+function test_client_request_after_close() {
+  // Test that DevToolsClient.request fails after we called client.close()
+  // (with promise API)
+  const request = gClient.request({
+    to: gActorId,
+    type: "hello",
+  });
+
+  request.then(
+    response => {
+      ok(false, "Request succeed even after client.close");
+    },
+    response => {
+      ok(true, "Request failed after client.close");
+      Assert.equal(response.error, "connectionClosed");
+      ok(
+        response.message.match(
+          /'hello' request packet to '.*' can't be sent as the connection is closed./
+        )
+      );
+      run_next_test();
+    }
+  );
+}
+
+function test_client_request_after_close_callback() {
+  // Test that DevToolsClient.request fails after we called client.close()
+  // (with callback API)
+  gClient
+    .request(
+      {
+        to: gActorId,
+        type: "hello",
+      },
+      response => {
+        ok(true, "Request failed after client.close");
+        Assert.equal(response.error, "connectionClosed");
+        ok(
+          response.message.match(
+            /'hello' request packet to '.*' can't be sent as the connection is closed./
+          )
+        );
+        run_next_test();
+      }
+    )
+    .catch(() => info("Caught rejected promise as expected"));
+}
diff --git a/devtools/server/tests/xpcshell/test_conditional_breakpoint-01.js b/devtools/server/tests/xpcshell/test_conditional_breakpoint-01.js
new file mode 100644
index 0000000000..8f2e58f651
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_conditional_breakpoint-01.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check conditional breakpoint when condition evaluates to true.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    let hitBreakpoint = false;
+
+    const packet1 = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet1.frame.where.actor);
+    const location = { sourceUrl: source.url, line: 3 };
+    threadFront.setBreakpoint(location, { condition: "a === 1" });
+
+    // Continue until the breakpoint is hit.
+    const packet2 = await resumeAndWaitForPause(threadFront);
+
+    Assert.equal(hitBreakpoint, false);
+    hitBreakpoint = true;
+
+    // Check the return value.
+    Assert.equal(packet2.why.type, "breakpoint");
+    Assert.equal(packet2.frame.where.line, 3);
+
+    // Remove the breakpoint.
+    await threadFront.removeBreakpoint(location);
+
+    await threadFront.resume();
+
+    Assert.equal(hitBreakpoint, true);
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    "debugger;\n" + // line 1
+      "var a = 1;\n" + // line 2
+      "var b = 2;\n", // line 3
+    debuggee,
+    "1.8",
+    "test.js",
+    1
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_conditional_breakpoint-02.js b/devtools/server/tests/xpcshell/test_conditional_breakpoint-02.js
new file mode 100644
index 0000000000..18742c4048
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_conditional_breakpoint-02.js
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check conditional breakpoint when condition evaluates to false.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet1 = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet1.frame.where.actor);
+    const location1 = { sourceUrl: source.url, line: 3 };
+    threadFront.setBreakpoint(location1, { condition: "a === 2" });
+
+    const location2 = { sourceUrl: source.url, line: 4 };
+    threadFront.setBreakpoint(location2, { condition: "a === 1" });
+
+    // Continue until the breakpoint is hit.
+    const packet2 = await resumeAndWaitForPause(threadFront);
+
+    // Check the return value.
+    Assert.equal(packet2.why.type, "breakpoint");
+    Assert.equal(packet2.frame.where.line, 4);
+
+    // Remove the breakpoint.
+    await threadFront.removeBreakpoint(location2);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    "debugger;\n" + // line 1
+      "var a = 1;\n" + // line 2
+      "var b = 2;\n" + // line 3
+      "b++;" + // line 4
+      "debugger;", // line 5
+    debuggee,
+    "1.8",
+    "test.js",
+    1
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_conditional_breakpoint-03.js b/devtools/server/tests/xpcshell/test_conditional_breakpoint-03.js
new file mode 100644
index 0000000000..7b26614a2c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_conditional_breakpoint-03.js
@@ -0,0 +1,60 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * If pauseOnExceptions is checked, when condition throws,
+ * make sure conditional breakpoint pauses.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, commands }) => {
+    const packet1 = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet1.frame.where.actor);
+
+    await commands.threadConfigurationCommand.updateConfiguration({
+      pauseOnExceptions: true,
+      ignoreCaughtExceptions: false,
+    });
+    const location = { sourceUrl: source.url, line: 3 };
+    threadFront.setBreakpoint(location, { condition: "throw new Error()" });
+
+    // Continue until the breakpoint is hit.
+    const packet2 = await resumeAndWaitForPause(threadFront);
+
+    // Check the return value.
+    Assert.equal(packet2.why.type, "exception");
+    Assert.equal(packet2.frame.where.line, 1);
+
+    // Step over twice.
+    await stepOver(threadFront);
+    const packet3 = await stepOver(threadFront);
+
+    // Check the return value.
+    Assert.equal(packet3.why.type, "breakpointConditionThrown");
+    Assert.equal(packet3.frame.where.line, 3);
+
+    // Remove the breakpoint.
+    await threadFront.removeBreakpoint(location);
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    "debugger;\n" + // line 1
+      "var a = 1;\n" + // line 2
+      "var b = 2;\n", // line 3
+    debuggee,
+    "1.8",
+    "test.js",
+    1
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_conditional_breakpoint-04.js b/devtools/server/tests/xpcshell/test_conditional_breakpoint-04.js
new file mode 100644
index 0000000000..508f67fef8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_conditional_breakpoint-04.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Confirm that we ignore breakpoint condition exceptions
+ * unless pause-on-exceptions is set to true.
+ *
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    await threadFront.setBreakpoint(
+      { sourceUrl: "conditional_breakpoint-04.js", line: 3 },
+      { condition: "throw new Error()" }
+    );
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    Assert.equal(packet.frame.where.line, 1);
+    Assert.equal(packet.why.type, "debuggerStatement");
+
+    const pausedPacket = await resumeAndWaitForPause(threadFront);
+    Assert.equal(pausedPacket.frame.where.line, 4);
+    Assert.equal(pausedPacket.why.type, "debuggerStatement");
+
+    // Remove the breakpoint.
+    await threadFront.removeBreakpoint({
+      sourceUrl: "conditional_breakpoint-04.js",
+      line: 3,
+    });
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    `debugger;
+    var a = 1;
+    var b = 2;
+    debugger;`,
+    debuggee,
+    "1.8",
+    "conditional_breakpoint-04.js",
+    1
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_connection_closes_all_pools.js b/devtools/server/tests/xpcshell/test_connection_closes_all_pools.js
new file mode 100644
index 0000000000..d69291485d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_connection_closes_all_pools.js
@@ -0,0 +1,100 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { Pool } = require("resource://devtools/shared/protocol/Pool.js");
+const {
+  DevToolsServerConnection,
+} = require("resource://devtools/server/devtools-server-connection.js");
+const {
+  LocalDebuggerTransport,
+} = require("resource://devtools/shared/transport/local-transport.js");
+
+// Helper class to assert how many times a Pool was destroyed
+class FakeActor extends Pool {
+  constructor(...args) {
+    super(...args);
+    this.destroyedCount = 0;
+  }
+
+  destroy() {
+    this.destroyedCount++;
+    super.destroy();
+  }
+}
+
+add_task(async function () {
+  const transport = new LocalDebuggerTransport();
+  const conn = new DevToolsServerConnection("prefix", transport);
+
+  // Setup a flat pool hierarchy with multiple pools:
+  //
+  // - pool1
+  //   |
+  //   \- actor1
+  //
+  // - pool2
+  //   |
+  //   |- actor2a
+  //   |
+  //   \- actor2b
+  //
+  // From the point of view of the DevToolsServerConnection, the only pools
+  // registered in _extraPools should be pool1 and pool2. Even though actor1,
+  // actor2a and actor2b extend Pool, they don't manage other pools.
+  const actor1 = new FakeActor(conn);
+  const pool1 = new Pool(conn, "pool-1");
+  pool1.manage(actor1);
+
+  const actor2a = new FakeActor(conn);
+  const actor2b = new FakeActor(conn);
+  const pool2 = new Pool(conn, "pool-2");
+  pool2.manage(actor2a);
+  pool2.manage(actor2b);
+
+  ok(!!actor1.actorID, "actor1 has a valid actorID");
+  ok(!!actor2a.actorID, "actor2a has a valid actorID");
+  ok(!!actor2b.actorID, "actor2b has a valid actorID");
+
+  conn.close();
+
+  equal(actor1.destroyedCount, 1, "actor1 was successfully destroyed");
+  equal(actor2a.destroyedCount, 1, "actor2 was successfully destroyed");
+  equal(actor2b.destroyedCount, 1, "actor2 was successfully destroyed");
+});
+
+add_task(async function () {
+  const transport = new LocalDebuggerTransport();
+  const conn = new DevToolsServerConnection("prefix", transport);
+
+  // Setup a nested pool hierarchy:
+  //
+  // - pool
+  //   |
+  //   \- parentActor
+  //      |
+  //      \- childActor
+  //
+  // Since parentActor is also a Pool from the point of view of the
+  // DevToolsServerConnection, it will attempt to destroy it when looping on
+  // this._extraPools. But since `parentActor` is also a direct child of `pool`,
+  // it has already been destroyed by the Pool destroy() mechanism.
+  //
+  // Here we check that we don't call destroy() too many times on a single Pool.
+  // Even though Pool::destroy() is stable when called multiple times, we can't
+  // guarantee the same for classes inheriting Pool.
+  const childActor = new FakeActor(conn);
+  const parentActor = new FakeActor(conn);
+  const pool = new Pool(conn, "pool");
+  pool.manage(parentActor);
+  parentActor.manage(childActor);
+
+  ok(!!parentActor.actorID, "customActor has a valid actorID");
+  ok(!!childActor.actorID, "childActor has a valid actorID");
+
+  conn.close();
+
+  equal(parentActor.destroyedCount, 1, "parentActor was destroyed once");
+  equal(parentActor.destroyedCount, 1, "customActor was destroyed once");
+});
diff --git a/devtools/server/tests/xpcshell/test_console_eval-01.js b/devtools/server/tests/xpcshell/test_console_eval-01.js
new file mode 100644
index 0000000000..abb6ddc605
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_console_eval-01.js
@@ -0,0 +1,33 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/*
+ * Check that is possible to evaluate JS with evaluation timeouts in place.
+ */
+
+add_task(
+  threadFrontTest(async ({ commands }) => {
+    await commands.scriptCommand.execute(`
+      function fib(n) {
+        if (n == 1 || n == 0) {
+          return 1;
+        }
+
+        return fib(n-1) + fib(n-2)
+      }
+    `);
+
+    const normalResult = await commands.scriptCommand.execute("fib(1)", {
+      eager: true,
+    });
+    Assert.equal(normalResult.result, 1, "normal eval");
+
+    const timeoutResult = await commands.scriptCommand.execute("fib(100)", {
+      eager: true,
+    });
+    Assert.equal(typeof timeoutResult.result, "object", "timeout eval");
+    Assert.equal(timeoutResult.result.type, "undefined", "timeout eval type");
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_console_eval-02.js b/devtools/server/tests/xpcshell/test_console_eval-02.js
new file mode 100644
index 0000000000..11b3d130b4
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_console_eval-02.js
@@ -0,0 +1,22 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/*
+ * Check that bound functions can be eagerly evaluated.
+ */
+
+add_task(
+  threadFrontTest(async ({ commands }) => {
+    await commands.scriptCommand.execute(`
+      var obj = [1, 2, 3];
+      var fn = obj.includes.bind(obj, 2);
+    `);
+
+    const normalResult = await commands.scriptCommand.execute("fn()", {
+      eager: true,
+    });
+    Assert.equal(normalResult.result, true, "normal eval");
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_dbgactor.js b/devtools/server/tests/xpcshell/test_dbgactor.js
new file mode 100644
index 0000000000..cb0cf8f7d7
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_dbgactor.js
@@ -0,0 +1,46 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const xpcInspector = Cc["@mozilla.org/jsinspector;1"].getService(
+  Ci.nsIJSInspector
+);
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    Assert.equal(xpcInspector.eventLoopNestLevel, 0);
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    Assert.equal(false, "error" in packet);
+    Assert.ok("actor" in packet);
+    Assert.ok("why" in packet);
+    Assert.equal(packet.why.type, "debuggerStatement");
+
+    // Reach around the protocol to check that the debuggee is in the state
+    // we expect.
+    Assert.ok(debuggee.a);
+    Assert.ok(!debuggee.b);
+
+    Assert.equal(xpcInspector.eventLoopNestLevel, 1);
+
+    // Let the debuggee continue execution.
+    await threadFront.resume();
+
+    // Now make sure that we've run the code after the debugger statement...
+    Assert.ok(debuggee.b);
+
+    Assert.equal(xpcInspector.eventLoopNestLevel, 0);
+  })
+);
+
+function evalCode(debuggee) {
+  Cu.evalInSandbox(
+    "var a = true; var b = false; debugger; var b = true;",
+    debuggee
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_dbgclient_debuggerstatement.js b/devtools/server/tests/xpcshell/test_dbgclient_debuggerstatement.js
new file mode 100644
index 0000000000..254f582460
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_dbgclient_debuggerstatement.js
@@ -0,0 +1,39 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const xpcInspector = Cc["@mozilla.org/jsinspector;1"].getService(
+  Ci.nsIJSInspector
+);
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    Assert.equal(threadFront.state, "paused");
+    // Reach around the protocol to check that the debuggee is in the state
+    // we expect.
+    Assert.ok(debuggee.a);
+    Assert.ok(!debuggee.b);
+
+    Assert.equal(xpcInspector.eventLoopNestLevel, 1);
+
+    await threadFront.resume();
+
+    // Now make sure that we've run the code after the debugger statement...
+    Assert.ok(debuggee.b);
+
+    Assert.equal(xpcInspector.eventLoopNestLevel, 0);
+  })
+);
+
+function evalCode(debuggee) {
+  Cu.evalInSandbox(
+    "var a = true; var b = false; debugger; var b = true;",
+    debuggee
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_dbgglobal.js b/devtools/server/tests/xpcshell/test_dbgglobal.js
new file mode 100644
index 0000000000..407e270da4
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_dbgglobal.js
@@ -0,0 +1,86 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  SocketListener,
+} = require("resource://devtools/shared/security/socket.js");
+
+function run_test() {
+  // Should get an exception if we try to interact with DevToolsServer
+  // before we initialize it...
+  const socketListener = new SocketListener(DevToolsServer, {});
+  Assert.throws(
+    () => DevToolsServer.addSocketListener(socketListener),
+    /DevToolsServer has not been initialized/,
+    "addSocketListener should throw before it has been initialized"
+  );
+  Assert.throws(
+    DevToolsServer.closeAllSocketListeners,
+    /this is undefined/,
+    "closeAllSocketListeners should throw before it has been initialized"
+  );
+  Assert.throws(
+    DevToolsServer.connectPipe,
+    /this is undefined/,
+    "connectPipe should throw before it has been initialized"
+  );
+
+  // Allow incoming connections.
+  DevToolsServer.init();
+
+  // These should still fail because we haven't added a createRootActor
+  // implementation yet.
+  Assert.throws(
+    DevToolsServer.closeAllSocketListeners,
+    /this is undefined/,
+    "closeAllSocketListeners should throw if createRootActor hasn't been added"
+  );
+  Assert.throws(
+    DevToolsServer.connectPipe,
+    /this is undefined/,
+    "closeAllSocketListeners should throw if createRootActor hasn't been added"
+  );
+
+  const { createRootActor } = require("xpcshell-test/testactors");
+  DevToolsServer.setRootActor(createRootActor);
+
+  // Now they should work.
+  DevToolsServer.addSocketListener(socketListener);
+  DevToolsServer.closeAllSocketListeners();
+
+  // Make sure we got the test's root actor all set up.
+  const client1 = DevToolsServer.connectPipe();
+  client1.hooks = {
+    onPacket(packet1) {
+      Assert.equal(packet1.from, "root");
+      Assert.equal(packet1.applicationType, "xpcshell-tests");
+
+      // Spin up a second connection, make sure it has its own root
+      // actor.
+      const client2 = DevToolsServer.connectPipe();
+      client2.hooks = {
+        onPacket(packet2) {
+          Assert.equal(packet2.from, "root");
+          Assert.notEqual(
+            packet1.testConnectionPrefix,
+            packet2.testConnectionPrefix
+          );
+          client2.close();
+        },
+        onTransportClosed(result) {
+          client1.close();
+        },
+      };
+      client2.ready();
+    },
+
+    onTransportClosed(result) {
+      do_test_finished();
+    },
+  };
+
+  client1.ready();
+  do_test_pending();
+}
diff --git a/devtools/server/tests/xpcshell/test_extension_storage_actor.js b/devtools/server/tests/xpcshell/test_extension_storage_actor.js
new file mode 100644
index 0000000000..9816854cf8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_extension_storage_actor.js
@@ -0,0 +1,1155 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* globals browser */
+
+"use strict";
+
+const { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+const { TestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TestUtils.sys.mjs"
+);
+
+const {
+  createMissingIndexedDBDirs,
+  extensionScriptWithMessageListener,
+  ext_no_bg,
+  getExtensionConfig,
+  openAddonStoragePanel,
+  shutdown,
+  startupExtension,
+} = require("resource://test/webextension-helpers.js");
+
+const l10n = new Localization(["devtools/client/storage.ftl"], true);
+const sessionString = l10n.formatValueSync("storage-expires-session");
+
+// Ignore rejection related to the storage.onChanged listener being removed while the extension context is being closed.
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(
+  /Message manager disconnected/
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(
+  /sendRemoveListener on closed conduit/
+);
+
+const { createAppInfo, promiseStartupManager } = AddonTestUtils;
+
+const LEAVE_UUID_PREF = "extensions.webextensions.keepUuidOnUninstall";
+const LEAVE_STORAGE_PREF = "extensions.webextensions.keepStorageOnUninstall";
+
+AddonTestUtils.init(this);
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+ExtensionTestUtils.init(this);
+
+add_setup(async function setup() {
+  await promiseStartupManager();
+  const dir = createMissingIndexedDBDirs();
+
+  Assert.ok(
+    dir.exists(),
+    "Should have a 'storage/permanent' dir in the profile dir"
+  );
+});
+
+add_task(async function test_extension_store_exists() {
+  const extension = await startupExtension(getExtensionConfig());
+
+  const { commands, extensionStorage } = await openAddonStoragePanel(
+    extension.id
+  );
+
+  ok(extensionStorage, "Should have an extensionStorage store");
+
+  await shutdown(extension, commands);
+});
+
+add_task(
+  {
+    // This test currently fails if the extension runs in the main process
+    // like in Thunderbird (see bug 1575183 comment #15 for details).
+    skip_if: () => !WebExtensionPolicy.useRemoteWebExtensions,
+  },
+  async function test_extension_origin_matches_debugger_target() {
+    async function background() {
+      // window is available in background scripts
+      // eslint-disable-next-line no-undef
+      browser.test.sendMessage("extension-origin", window.location.origin);
+    }
+
+    const extension = await startupExtension(
+      getExtensionConfig({ background })
+    );
+
+    const { commands, extensionStorage } = await openAddonStoragePanel(
+      extension.id
+    );
+
+    const { hosts } = extensionStorage;
+    const expectedHost = await extension.awaitMessage("extension-origin");
+    ok(
+      expectedHost in hosts,
+      "Should have the expected extension host in the extensionStorage store"
+    );
+
+    await shutdown(extension, commands);
+  }
+);
+
+/**
+ * Test case: Background page modifies items while storage panel is open.
+ * - Load extension with background page.
+ * - Open the add-on debugger storage panel.
+ * - With the panel still open, from the extension background page:
+ *   - Bulk add storage items
+ *   - Edit the values of some of the storage items
+ *   - Remove some storage items
+ *   - Clear all storage items
+ * - For each modification, the storage data in the panel should match the
+ *   changes made by the extension.
+ */
+add_task(async function test_panel_live_updates() {
+  const extension = await startupExtension(
+    getExtensionConfig({ background: extensionScriptWithMessageListener })
+  );
+
+  const { commands, extensionStorage } = await openAddonStoragePanel(
+    extension.id
+  );
+
+  const host = await extension.awaitMessage("extension-origin");
+
+  let { data } = await extensionStorage.getStoreObjects(host);
+  Assert.deepEqual(data, [], "Got the expected results on empty storage.local");
+
+  info("Waiting for extension to bulk add 50 items to storage local");
+  const bulkStorageItems = {};
+  // limited by MAX_STORE_OBJECT_COUNT in devtools/server/actors/resources/storage/index.js
+  const numItems = 2;
+  for (let i = 1; i <= numItems; i++) {
+    bulkStorageItems[i] = i;
+  }
+
+  // fireOnChanged avoids the race condition where the extension
+  // modifies storage then immediately tries to access storage before
+  // the storage actor has finished updating.
+  extension.sendMessage("storage-local-fireOnChanged");
+  extension.sendMessage("storage-local-set", {
+    ...bulkStorageItems,
+    a: 123,
+    b: [4, 5],
+    c: { d: 678 },
+    d: true,
+    e: "hi",
+    f: null,
+  });
+  await extension.awaitMessage("storage-local-set:done");
+  await extension.awaitMessage("storage-local-onChanged");
+
+  info(
+    "Confirming items added by extension match items in extensionStorage store"
+  );
+  const bulkStorageObjects = [];
+  for (const [name, value] of Object.entries(bulkStorageItems)) {
+    bulkStorageObjects.push({
+      area: "local",
+      name,
+      value: { str: String(value) },
+      isValueEditable: true,
+    });
+  }
+  data = (await extensionStorage.getStoreObjects(host, null, { sessionString }))
+    .data;
+  Assert.deepEqual(
+    data,
+    [
+      ...bulkStorageObjects,
+      {
+        area: "local",
+        name: "a",
+        value: { str: "123" },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "b",
+        value: { str: "[4,5]" },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "c",
+        value: { str: '{"d":678}' },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "d",
+        value: { str: "true" },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "e",
+        value: { str: "hi" },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "f",
+        value: { str: "null" },
+        isValueEditable: true,
+      },
+    ],
+    "Got the expected results on populated storage.local"
+  );
+
+  info("Waiting for extension to edit a few storage item values");
+  extension.sendMessage("storage-local-fireOnChanged");
+  extension.sendMessage("storage-local-set", {
+    a: ["c", "d"],
+    b: 456,
+    c: false,
+  });
+  await extension.awaitMessage("storage-local-set:done");
+  await extension.awaitMessage("storage-local-onChanged");
+
+  info(
+    "Confirming items edited by extension match items in extensionStorage store"
+  );
+  data = (await extensionStorage.getStoreObjects(host, null, { sessionString }))
+    .data;
+  Assert.deepEqual(
+    data,
+    [
+      ...bulkStorageObjects,
+      {
+        area: "local",
+        name: "a",
+        value: { str: '["c","d"]' },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "b",
+        value: { str: "456" },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "c",
+        value: { str: "false" },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "d",
+        value: { str: "true" },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "e",
+        value: { str: "hi" },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "f",
+        value: { str: "null" },
+        isValueEditable: true,
+      },
+    ],
+    "Got the expected results on populated storage.local"
+  );
+
+  info("Waiting for extension to remove a few storage item values");
+  extension.sendMessage("storage-local-fireOnChanged");
+  extension.sendMessage("storage-local-remove", ["d", "e", "f"]);
+  await extension.awaitMessage("storage-local-remove:done");
+  await extension.awaitMessage("storage-local-onChanged");
+
+  info(
+    "Confirming items removed by extension were removed in extensionStorage store"
+  );
+  data = (await extensionStorage.getStoreObjects(host, null, { sessionString }))
+    .data;
+  Assert.deepEqual(
+    data,
+    [
+      ...bulkStorageObjects,
+      {
+        area: "local",
+        name: "a",
+        value: { str: '["c","d"]' },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "b",
+        value: { str: "456" },
+        isValueEditable: true,
+      },
+      {
+        area: "local",
+        name: "c",
+        value: { str: "false" },
+        isValueEditable: true,
+      },
+    ],
+    "Got the expected results on populated storage.local"
+  );
+
+  info("Waiting for extension to remove all remaining storage items");
+  extension.sendMessage("storage-local-fireOnChanged");
+  extension.sendMessage("storage-local-clear");
+  await extension.awaitMessage("storage-local-clear:done");
+  await extension.awaitMessage("storage-local-onChanged");
+
+  info("Confirming extensionStorage store was cleared");
+  data = (await extensionStorage.getStoreObjects(host)).data;
+  Assert.deepEqual(
+    data,
+    [],
+    "Got the expected results on populated storage.local"
+  );
+
+  await shutdown(extension, commands);
+});
+
+/**
+ * Test case: No bg page. Transient page adds item before storage panel opened.
+ * - Load extension with no background page.
+ * - Open an extension page in a tab that adds a local storage item.
+ * - With the extension page still open, open the add-on storage panel.
+ * - The data in the storage panel should match the items added by the extension.
+ */
+add_task(
+  async function test_panel_data_matches_extension_with_transient_page_open() {
+    const extension = await startupExtension(
+      getExtensionConfig({ files: ext_no_bg.files })
+    );
+
+    const url = extension.extension.baseURI.resolve(
+      "extension_page_in_tab.html"
+    );
+    const contentPage = await ExtensionTestUtils.loadContentPage(url, {
+      extension,
+    });
+
+    const host = await extension.awaitMessage("extension-origin");
+
+    extension.sendMessage("storage-local-set", { a: 123 });
+    await extension.awaitMessage("storage-local-set:done");
+
+    const { commands, extensionStorage } = await openAddonStoragePanel(
+      extension.id
+    );
+
+    const { data } = await extensionStorage.getStoreObjects(host);
+    Assert.deepEqual(
+      data,
+      [
+        {
+          area: "local",
+          name: "a",
+          value: { str: "123" },
+          isValueEditable: true,
+        },
+      ],
+      "Got the expected results on populated storage.local"
+    );
+
+    await contentPage.close();
+    await shutdown(extension, commands);
+  }
+);
+
+/**
+ * Test case: No bg page. Transient page adds item then closes before storage panel opened.
+ * - Load extension with no background page.
+ * - Open an extension page in a tab that adds a local storage item.
+ * - Close all extension pages.
+ * - Open the add-on storage panel.
+ * - The data in the storage panel should match the item added by the extension.
+ */
+add_task(async function test_panel_data_matches_extension_with_no_pages_open() {
+  const extension = await startupExtension(
+    getExtensionConfig({ files: ext_no_bg.files })
+  );
+
+  const url = extension.extension.baseURI.resolve("extension_page_in_tab.html");
+  const contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    extension,
+  });
+
+  const host = await extension.awaitMessage("extension-origin");
+
+  extension.sendMessage("storage-local-fireOnChanged");
+  extension.sendMessage("storage-local-set", { a: 123 });
+  await extension.awaitMessage("storage-local-set:done");
+  await extension.awaitMessage("storage-local-onChanged");
+  await contentPage.close();
+
+  const { commands, extensionStorage } = await openAddonStoragePanel(
+    extension.id
+  );
+
+  const { data } = await extensionStorage.getStoreObjects(host);
+  Assert.deepEqual(
+    data,
+    [
+      {
+        area: "local",
+        name: "a",
+        value: { str: "123" },
+        isValueEditable: true,
+      },
+    ],
+    "Got the expected results on populated storage.local"
+  );
+
+  await shutdown(extension, commands);
+});
+
+/**
+ * Test case: No bg page. Storage panel live updates when a transient page adds an item.
+ * - Load extension with no background page.
+ * - Open the add-on storage panel.
+ * - With the storage panel still open, open an extension page in a new tab that adds an
+ *   item.
+ * - The data in the storage panel should live update to match the item added by the
+ *   extension.
+ * - If an extension page adds the same data again, the data in the storage panel should
+ *   not change.
+ */
+add_task(
+  async function test_panel_data_live_updates_for_extension_without_bg_page() {
+    const extension = await startupExtension(
+      getExtensionConfig({ files: ext_no_bg.files })
+    );
+
+    const { commands, extensionStorage } = await openAddonStoragePanel(
+      extension.id
+    );
+
+    const url = extension.extension.baseURI.resolve(
+      "extension_page_in_tab.html"
+    );
+    const contentPage = await ExtensionTestUtils.loadContentPage(url, {
+      extension,
+    });
+
+    const host = await extension.awaitMessage("extension-origin");
+
+    let { data } = await extensionStorage.getStoreObjects(host);
+    Assert.deepEqual(
+      data,
+      [],
+      "Got the expected results on empty storage.local"
+    );
+
+    extension.sendMessage("storage-local-fireOnChanged");
+    extension.sendMessage("storage-local-set", { a: 123 });
+    await extension.awaitMessage("storage-local-set:done");
+    await extension.awaitMessage("storage-local-onChanged");
+
+    data = (await extensionStorage.getStoreObjects(host)).data;
+    Assert.deepEqual(
+      data,
+      [
+        {
+          area: "local",
+          name: "a",
+          value: { str: "123" },
+          isValueEditable: true,
+        },
+      ],
+      "Got the expected results on populated storage.local"
+    );
+
+    extension.sendMessage("storage-local-fireOnChanged");
+    extension.sendMessage("storage-local-set", { a: 123 });
+    await extension.awaitMessage("storage-local-set:done");
+    await extension.awaitMessage("storage-local-onChanged");
+
+    data = (await extensionStorage.getStoreObjects(host)).data;
+    Assert.deepEqual(
+      data,
+      [
+        {
+          area: "local",
+          name: "a",
+          value: { str: "123" },
+          isValueEditable: true,
+        },
+      ],
+      "The results are unchanged when an extension page adds duplicate items"
+    );
+
+    await contentPage.close();
+    await shutdown(extension, commands);
+  }
+);
+
+/**
+ * Test case: Bg page adds item while storage panel is open. Panel edits item's value.
+ * - Load extension with background page.
+ * - Open the add-on storage panel.
+ * - With the storage panel still open, add item from the background page.
+ * - Edit the value of the item in the storage panel
+ * - The data in the storage panel should match the item added by the extension.
+ * - The storage actor is correctly parsing and setting the string representation of
+ *     the value in the storage local database when the item's value is edited in the
+ *     storage panel
+ */
+add_task(
+  async function test_editing_items_in_panel_parses_supported_values_correctly() {
+    const extension = await startupExtension(
+      getExtensionConfig({ background: extensionScriptWithMessageListener })
+    );
+
+    const host = await extension.awaitMessage("extension-origin");
+
+    const { commands, extensionStorage } = await openAddonStoragePanel(
+      extension.id
+    );
+
+    const oldItem = { a: 123 };
+    const key = Object.keys(oldItem)[0];
+    const oldValue = oldItem[key];
+    // A tuple representing information for a new value entered into the panel for oldItem:
+    // [
+    //   value,
+    //   editItem string representation of value,
+    //   toStoreObject string representation of value,
+    // ]
+    const valueInfo = [
+      [true, "true", "true"],
+      ["hi", "hi", "hi"],
+      [456, "456", "456"],
+      [{ b: 789 }, "{b: 789}", '{"b":789}'],
+      [[1, 2, 3], "[1, 2, 3]", "[1,2,3]"],
+      [null, "null", "null"],
+    ];
+    for (const [value, editItemValueStr, toStoreObjectValueStr] of valueInfo) {
+      info("Setting a storage item through the extension");
+      extension.sendMessage("storage-local-fireOnChanged");
+      extension.sendMessage("storage-local-set", oldItem);
+      await extension.awaitMessage("storage-local-set:done");
+      await extension.awaitMessage("storage-local-onChanged");
+
+      info(
+        "Editing the storage item in the panel with a new value of a different type"
+      );
+      // When the user edits an item in the panel, they are entering a string into a
+      // textbox. This string is parsed by the storage actor's editItem method.
+      await extensionStorage.editItem({
+        host,
+        field: "value",
+        items: { name: key, value: editItemValueStr },
+        oldValue,
+      });
+
+      info(
+        "Verifying item in the storage actor matches the item edited in the panel"
+      );
+      const { data } = await extensionStorage.getStoreObjects(host);
+      Assert.deepEqual(
+        data,
+        [
+          {
+            area: "local",
+            name: key,
+            value: { str: toStoreObjectValueStr },
+            isValueEditable: true,
+          },
+        ],
+        "Got the expected results on populated storage.local"
+      );
+
+      // The view layer is separate from the database layer; therefore while values are
+      // stringified (via toStoreObject) for display in the client, the value (and its type)
+      // in the database is unchanged.
+      info(
+        "Verifying the expected new value matches the value fetched in the extension"
+      );
+      extension.sendMessage("storage-local-get", key);
+      const extItem = await extension.awaitMessage("storage-local-get:done");
+      Assert.deepEqual(
+        value,
+        extItem[key],
+        `The string value ${editItemValueStr} was correctly parsed to ${value}`
+      );
+    }
+
+    await shutdown(extension, commands);
+  }
+);
+
+/**
+ * Test case: Modifying storage items from the panel update extension storage local data.
+ * - Load extension with background page.
+ * - Open the add-on storage panel. From the panel:
+ *   - Edit the value of a storage item,
+ *   - Remove a storage item,
+ *   - Remove all of the storage items,
+ * - For each modification, the storage data retrieved by the extension should match the
+ *   data in the panel.
+ */
+add_task(
+  async function test_modifying_items_in_panel_updates_extension_storage_data() {
+    const extension = await startupExtension(
+      getExtensionConfig({ background: extensionScriptWithMessageListener })
+    );
+
+    const host = await extension.awaitMessage("extension-origin");
+
+    const { commands, extensionStorage } = await openAddonStoragePanel(
+      extension.id
+    );
+
+    const DEFAULT_VALUE = "value"; // global in devtools/server/actors/resources/storage/index.js
+    let items = {
+      guid_1: DEFAULT_VALUE,
+      guid_2: DEFAULT_VALUE,
+      guid_3: DEFAULT_VALUE,
+    };
+
+    info("Adding storage items from the extension");
+    let storesUpdate = extensionStorage.once("single-store-update");
+    extension.sendMessage("storage-local-set", items);
+    await extension.awaitMessage("storage-local-set:done");
+
+    info("Waiting for the storage actor to emit a 'stores-update' event");
+    let data = await storesUpdate;
+    Assert.deepEqual(
+      {
+        added: {
+          extensionStorage: {
+            [host]: ["guid_1", "guid_2", "guid_3"],
+          },
+        },
+        changed: undefined,
+        deleted: undefined,
+      },
+      data,
+      "The change data from the storage actor's 'stores-update' event matches the changes made in the client."
+    );
+
+    info("Waiting for panel to edit some items");
+    storesUpdate = extensionStorage.once("single-store-update");
+    await extensionStorage.editItem({
+      host,
+      field: "value",
+      items: { name: "guid_1", value: "anotherValue" },
+      DEFAULT_VALUE,
+    });
+
+    info("Waiting for the storage actor to emit a 'stores-update' event");
+    data = await storesUpdate;
+    Assert.deepEqual(
+      {
+        added: undefined,
+        changed: {
+          extensionStorage: {
+            [host]: ["guid_1"],
+          },
+        },
+        deleted: undefined,
+      },
+      data,
+      "The change data from the storage actor's 'stores-update' event matches the changes made in the client."
+    );
+
+    items = {
+      guid_1: "anotherValue",
+      guid_2: DEFAULT_VALUE,
+      guid_3: DEFAULT_VALUE,
+    };
+    extension.sendMessage("storage-local-get", Object.keys(items));
+    let extItems = await extension.awaitMessage("storage-local-get:done");
+    Assert.deepEqual(
+      items,
+      extItems,
+      `The storage items in the extension match the items in the panel`
+    );
+
+    info("Waiting for panel to remove an item");
+    storesUpdate = extensionStorage.once("single-store-update");
+    await extensionStorage.removeItem(host, "guid_3");
+
+    info("Waiting for the storage actor to emit a 'stores-update' event");
+    data = await storesUpdate;
+    Assert.deepEqual(
+      {
+        added: undefined,
+        changed: undefined,
+        deleted: {
+          extensionStorage: {
+            [host]: ["guid_3"],
+          },
+        },
+      },
+      data,
+      "The change data from the storage actor's 'stores-update' event matches the changes made in the client."
+    );
+
+    items = {
+      guid_1: "anotherValue",
+      guid_2: DEFAULT_VALUE,
+    };
+    extension.sendMessage("storage-local-get", Object.keys(items));
+    extItems = await extension.awaitMessage("storage-local-get:done");
+    Assert.deepEqual(
+      items,
+      extItems,
+      `The storage items in the extension match the items in the panel`
+    );
+
+    info("Waiting for panel to remove all items");
+    const storesCleared = extensionStorage.once("single-store-cleared");
+    await extensionStorage.removeAll(host);
+
+    info("Waiting for the storage actor to emit a 'stores-cleared' event");
+    data = await storesCleared;
+    Assert.deepEqual(
+      {
+        clearedHostsOrPaths: {
+          [host]: [],
+        },
+      },
+      data,
+      "The change data from the storage actor's 'stores-cleared' event matches the changes made in the client."
+    );
+
+    items = {};
+    extension.sendMessage("storage-local-get", Object.keys(items));
+    extItems = await extension.awaitMessage("storage-local-get:done");
+    Assert.deepEqual(
+      items,
+      extItems,
+      `The storage items in the extension match the items in the panel`
+    );
+
+    await shutdown(extension, commands);
+  }
+);
+
+/**
+ * Test case: Storage panel shows extension storage data added prior to extension startup
+ * - Load extension that adds a storage item
+ * - Uninstall the extension
+ * - Reinstall the extension
+ * - Open the add-on storage panel.
+ * - The data in the storage panel should match the data added the first time the extension
+ *   was installed
+ * Related test case: Storage panel shows extension storage data when an extension that has
+ * already migrated to the IndexedDB storage backend prior to extension startup adds
+ * another storage item.
+ * - (Building from previous steps)
+ * - The reinstalled extension adds a storage item
+ * - The data in the storage panel should live update with both items: the item added from
+ *   the first and the item added from the reinstall.
+ */
+add_task(
+  async function test_panel_data_matches_data_added_prior_to_ext_startup() {
+    // The pref to leave the addonid->uuid mapping around after uninstall so that we can
+    // re-attach to the same storage
+    Services.prefs.setBoolPref(LEAVE_UUID_PREF, true);
+
+    // The pref to prevent cleaning up storage on uninstall
+    Services.prefs.setBoolPref(LEAVE_STORAGE_PREF, true);
+
+    let extension = await startupExtension(
+      getExtensionConfig({ background: extensionScriptWithMessageListener })
+    );
+
+    const host = await extension.awaitMessage("extension-origin");
+
+    extension.sendMessage("storage-local-set", { a: 123 });
+    await extension.awaitMessage("storage-local-set:done");
+
+    await shutdown(extension);
+
+    // Reinstall the same extension
+    extension = await startupExtension(
+      getExtensionConfig({ background: extensionScriptWithMessageListener })
+    );
+
+    await extension.awaitMessage("extension-origin");
+
+    const { commands, extensionStorage } = await openAddonStoragePanel(
+      extension.id
+    );
+
+    let { data } = await extensionStorage.getStoreObjects(host);
+    Assert.deepEqual(
+      data,
+      [
+        {
+          area: "local",
+          name: "a",
+          value: { str: "123" },
+          isValueEditable: true,
+        },
+      ],
+      "Got the expected results on populated storage.local"
+    );
+
+    // Related test case
+    extension.sendMessage("storage-local-fireOnChanged");
+    extension.sendMessage("storage-local-set", { b: 456 });
+    await extension.awaitMessage("storage-local-set:done");
+    await extension.awaitMessage("storage-local-onChanged");
+
+    data = (
+      await extensionStorage.getStoreObjects(host, null, { sessionString })
+    ).data;
+    Assert.deepEqual(
+      data,
+      [
+        {
+          area: "local",
+          name: "a",
+          value: { str: "123" },
+          isValueEditable: true,
+        },
+        {
+          area: "local",
+          name: "b",
+          value: { str: "456" },
+          isValueEditable: true,
+        },
+      ],
+      "Got the expected results on populated storage.local"
+    );
+
+    Services.prefs.setBoolPref(LEAVE_STORAGE_PREF, false);
+    Services.prefs.setBoolPref(LEAVE_UUID_PREF, false);
+
+    await shutdown(extension, commands);
+  }
+);
+
+add_task(
+  function cleanup_for_test_panel_data_matches_data_added_prior_to_ext_startup() {
+    Services.prefs.clearUserPref(LEAVE_UUID_PREF);
+    Services.prefs.clearUserPref(LEAVE_STORAGE_PREF);
+  }
+);
+
+/**
+ * Test case: Transient page adds an item to storage. With storage panel open,
+ * reload extension.
+ * - Load extension with no background page.
+ * - Open transient page that adds a storage item on message.
+ * - Open the add-on storage panel.
+ * - With the storage panel still open, reload the extension.
+ * - The data in the storage panel should match the item added prior to reloading.
+ */
+add_task(async function test_panel_live_reload_for_extension_without_bg_page() {
+  const EXTENSION_ID = "test_local_storage_live_reload@xpcshell.mozilla.org";
+  let manifest = {
+    version: "1.0",
+    browser_specific_settings: {
+      gecko: {
+        id: EXTENSION_ID,
+      },
+    },
+  };
+
+  info("Loading and starting extension version 1.0");
+  const extension = await startupExtension(
+    getExtensionConfig({
+      manifest,
+      files: ext_no_bg.files,
+    })
+  );
+
+  info("Opening extension page in a tab");
+  const url = extension.extension.baseURI.resolve("extension_page_in_tab.html");
+  const contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    extension,
+  });
+
+  const host = await extension.awaitMessage("extension-origin");
+
+  info("Waiting for extension page in a tab to add storage item");
+  extension.sendMessage("storage-local-fireOnChanged");
+  extension.sendMessage("storage-local-set", { a: 123 });
+  await extension.awaitMessage("storage-local-set:done");
+  await extension.awaitMessage("storage-local-onChanged");
+  await contentPage.close();
+
+  info("Opening storage panel");
+  const { commands, extensionStorage } = await openAddonStoragePanel(
+    extension.id
+  );
+
+  manifest = {
+    ...manifest,
+    version: "2.0",
+  };
+  // "Reload" is most similar to an upgrade, as e.g. storage data is preserved
+  info("Updating extension to version 2.0");
+  await extension.upgrade(
+    getExtensionConfig({
+      manifest,
+      files: ext_no_bg.files,
+    })
+  );
+
+  const { data } = await extensionStorage.getStoreObjects(host);
+  Assert.deepEqual(
+    data,
+    [
+      {
+        area: "local",
+        name: "a",
+        value: { str: "123" },
+        isValueEditable: true,
+      },
+    ],
+    "Got the expected results on populated storage.local"
+  );
+
+  await shutdown(extension, commands);
+});
+
+/**
+ * Test case: Bg page auto adds item(s). With storage panel open, reload extension.
+ * - Load extension with background page that automatically adds a storage item on startup.
+ * - Open the add-on storage panel.
+ * - With the storage panel still open, reload the extension.
+ * - The data in the storage panel should match the item(s) added by the reloaded
+ *   extension.
+ */
+add_task(
+  async function test_panel_live_reload_when_extension_auto_adds_items() {
+    async function background() {
+      await browser.storage.local.set({ a: { b: 123 }, c: { d: 456 } });
+      // window is available in background scripts
+      // eslint-disable-next-line no-undef
+      browser.test.sendMessage("extension-origin", window.location.origin);
+    }
+    const EXTENSION_ID = "test_local_storage_live_reload@xpcshell.mozilla.org";
+    let manifest = {
+      version: "1.0",
+      browser_specific_settings: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    };
+
+    info("Loading and starting extension version 1.0");
+    const extension = await startupExtension(
+      getExtensionConfig({ manifest, background })
+    );
+
+    info("Waiting for message from test extension");
+    const host = await extension.awaitMessage("extension-origin");
+
+    info("Opening storage panel");
+    const { commands, extensionStorage } = await openAddonStoragePanel(
+      extension.id
+    );
+
+    manifest = {
+      ...manifest,
+      version: "2.0",
+    };
+    // "Reload" is most similar to an upgrade, as e.g. storage data is preserved
+    info("Update to version 2.0");
+    await extension.upgrade(
+      getExtensionConfig({
+        manifest,
+        background,
+      })
+    );
+
+    await extension.awaitMessage("extension-origin");
+
+    const { data } = await extensionStorage.getStoreObjects(host, null, {
+      sessionString,
+    });
+    Assert.deepEqual(
+      data,
+      [
+        {
+          area: "local",
+          name: "a",
+          value: { str: '{"b":123}' },
+          isValueEditable: true,
+        },
+        {
+          area: "local",
+          name: "c",
+          value: { str: '{"d":456}' },
+          isValueEditable: true,
+        },
+      ],
+      "Got the expected results on populated storage.local"
+    );
+
+    await shutdown(extension, commands);
+  }
+);
+
+/**
+ * Test case: Bg page adds one storage.local item and one storage.sync item.
+ * - Load extension with background page that automatically adds two storage items on startup.
+ * - Open the add-on storage panel.
+ * - Assert that only the storage.local item is shown in the panel.
+ */
+add_task(
+  async function test_panel_data_only_updates_for_storage_local_changes() {
+    async function background() {
+      await browser.storage.local.set({ a: { b: 123 } });
+      await browser.storage.sync.set({ c: { d: 456 } });
+      // window is available in background scripts
+      // eslint-disable-next-line no-undef
+      browser.test.sendMessage("extension-origin", window.location.origin);
+    }
+
+    // Using the storage.sync API requires a non-temporary extension ID, see Bug 1323228.
+    const EXTENSION_ID =
+      "test_panel_data_only_updates_for_storage_local_changes@xpcshell.mozilla.org";
+    const manifest = {
+      browser_specific_settings: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    };
+
+    info("Loading and starting extension");
+    const extension = await startupExtension(
+      getExtensionConfig({ manifest, background })
+    );
+
+    info("Waiting for message from test extension");
+    const host = await extension.awaitMessage("extension-origin");
+
+    info("Opening storage panel");
+    const { commands, extensionStorage } = await openAddonStoragePanel(
+      extension.id
+    );
+
+    const { data } = await extensionStorage.getStoreObjects(host);
+    Assert.deepEqual(
+      data,
+      [
+        {
+          area: "local",
+          name: "a",
+          value: { str: '{"b":123}' },
+          isValueEditable: true,
+        },
+      ],
+      "Got the expected results on populated storage.local"
+    );
+
+    await shutdown(extension, commands);
+  }
+);
+
+// This test verifies that Bug 1802929 fix doesn't regress.
+add_task(async function test_live_update_with_no_extension_listener() {
+  const EXTENSION_ID = "test_with_no_listeners@xpcshell.mozilla.org";
+  let manifest = {
+    version: "1.0",
+    browser_specific_settings: {
+      gecko: {
+        id: EXTENSION_ID,
+      },
+    },
+  };
+
+  function background() {
+    browser.test.onMessage.addListener(async (msg, ...args) => {
+      if (msg !== "storage-local-api-call") {
+        browser.test.fail(`Got unexpected test message: ${msg}`);
+        return;
+      }
+
+      const [{ method, methodArgs }] = args;
+      const res = await browser.storage.local[method](...methodArgs);
+      browser.test.sendMessage(`${msg}:done`, res);
+    });
+  }
+
+  const extension = await startupExtension(
+    getExtensionConfig({ manifest, background })
+  );
+
+  const { target, extensionStorage } = await openAddonStoragePanel(
+    extension.id
+  );
+
+  const { baseURI } = extension.extension;
+  const host = `${baseURI.scheme}://${baseURI.host}`;
+
+  let { data } = await extensionStorage.getStoreObjects(host);
+  Assert.deepEqual(data, [], "Got the expected results on empty storage.local");
+
+  async function testStorageLocalUpdate(storageValue) {
+    info("Store extension data");
+    await extension.sendMessage("storage-local-api-call", {
+      method: "set",
+      methodArgs: [{ storageKeyName: storageValue }],
+    });
+    await extension.awaitMessage("storage-local-api-call:done");
+
+    info("Verify stored extension data");
+    await extension.sendMessage("storage-local-api-call", {
+      method: "get",
+      methodArgs: [],
+    });
+
+    Assert.deepEqual(
+      await extension.awaitMessage("storage-local-api-call:done"),
+      { storageKeyName: storageValue },
+      "Got the expected value from browser.storage.local.get"
+    );
+
+    await TestUtils.waitForCondition(async () => {
+      const res = await extensionStorage.getStoreObjects(host);
+      return res.data?.length > 0;
+    }, "Wait for the extension storage panel updates");
+
+    data = (await extensionStorage.getStoreObjects(host)).data;
+    Assert.deepEqual(
+      data,
+      [
+        {
+          area: "local",
+          name: "storageKeyName",
+          value: { str: `${storageValue}` },
+          isValueEditable: true,
+        },
+      ],
+      "Expected DevTools Storage panel data to have been updated"
+    );
+  }
+
+  await testStorageLocalUpdate("aStorageValue 01");
+
+  manifest = {
+    ...manifest,
+    version: "2.0",
+  };
+  // "Reload" is most similar to an upgrade, as e.g. storage data is preserved
+  info("Update to version 2.0");
+  await extension.upgrade(getExtensionConfig({ manifest, background }));
+
+  await testStorageLocalUpdate("aStorageValue 02");
+
+  await shutdown(extension, target);
+});
diff --git a/devtools/server/tests/xpcshell/test_extension_storage_actor_upgrade.js b/devtools/server/tests/xpcshell/test_extension_storage_actor_upgrade.js
new file mode 100644
index 0000000000..5d2285b9e8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_extension_storage_actor_upgrade.js
@@ -0,0 +1,142 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Note: this test used to be in test_extension_storage_actor.js, but seems to
+ * fail frequently as soon as we start auto-attaching targets.
+ * See Bug 1618059.
+ */
+
+const { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+const {
+  createMissingIndexedDBDirs,
+  extensionScriptWithMessageListener,
+  getExtensionConfig,
+  openAddonStoragePanel,
+  shutdown,
+  startupExtension,
+} = require("resource://test/webextension-helpers.js");
+
+const l10n = new Localization(["devtools/client/storage.ftl"], true);
+const sessionString = l10n.formatValueSync("storage-expires-session");
+
+// Ignore rejection related to the storage.onChanged listener being removed while the extension context is being closed.
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(
+  /Message manager disconnected/
+);
+
+const { createAppInfo, promiseStartupManager } = AddonTestUtils;
+
+AddonTestUtils.init(this);
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+ExtensionTestUtils.init(this);
+
+add_task(async function setup() {
+  await promiseStartupManager();
+  const dir = createMissingIndexedDBDirs();
+
+  Assert.ok(
+    dir.exists(),
+    "Should have a 'storage/permanent' dir in the profile dir"
+  );
+});
+
+/**
+ * Test case: Bg page adds an item to storage. With storage panel open, reload extension.
+ * - Load extension with background page that adds a storage item on message.
+ * - Open the add-on storage panel.
+ * - With the storage panel still open, reload the extension.
+ * - The data in the storage panel should match the item added prior to reloading.
+ */
+add_task(async function test_panel_live_reload() {
+  const EXTENSION_ID = "test_panel_live_reload@xpcshell.mozilla.org";
+  let manifest = {
+    version: "1.0",
+    browser_specific_settings: {
+      gecko: {
+        id: EXTENSION_ID,
+      },
+    },
+  };
+
+  info("Loading extension version 1.0");
+  const extension = await startupExtension(
+    getExtensionConfig({
+      manifest,
+      background: extensionScriptWithMessageListener,
+    })
+  );
+
+  info("Waiting for message from test extension");
+  const host = await extension.awaitMessage("extension-origin");
+
+  info("Adding storage item");
+  extension.sendMessage("storage-local-set", { a: 123 });
+  await extension.awaitMessage("storage-local-set:done");
+
+  const { commands, extensionStorage } = await openAddonStoragePanel(
+    extension.id
+  );
+
+  manifest = {
+    ...manifest,
+    version: "2.0",
+  };
+  // "Reload" is most similar to an upgrade, as e.g. storage data is preserved
+  info("Update to version 2.0");
+
+  // Wait for the storage front to receive an event for the storage panel refresh
+  // when the extension has been reloaded.
+  const promiseStoragePanelUpdated = new Promise(resolve => {
+    extensionStorage.on(
+      "single-store-update",
+      function updateListener(updates) {
+        info(`Got stores-update event: ${JSON.stringify(updates)}`);
+        const extStorageAdded = updates.added?.extensionStorage;
+        if (host in extStorageAdded && extStorageAdded[host].length) {
+          extensionStorage.off("single-store-update", updateListener);
+          resolve();
+        }
+      }
+    );
+  });
+
+  await extension.upgrade(
+    getExtensionConfig({
+      manifest,
+      background: extensionScriptWithMessageListener,
+    })
+  );
+
+  await Promise.all([
+    extension.awaitMessage("extension-origin"),
+    promiseStoragePanelUpdated,
+  ]);
+
+  const { data } = await extensionStorage.getStoreObjects(host, null, {
+    sessionString,
+  });
+  Assert.deepEqual(
+    data,
+    [
+      {
+        area: "local",
+        name: "a",
+        value: { str: "123" },
+        isValueEditable: true,
+      },
+    ],
+    "Got the expected results on populated storage.local"
+  );
+
+  await shutdown(extension, commands);
+});
diff --git a/devtools/server/tests/xpcshell/test_format_command.js b/devtools/server/tests/xpcshell/test_format_command.js
new file mode 100644
index 0000000000..529e560a0f
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_format_command.js
@@ -0,0 +1,111 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  formatCommand,
+} = require("resource://devtools/server/actors/webconsole/commands/parser.js");
+
+const testcases = [
+  { input: ":help", expectedOutput: "help()" },
+  {
+    input: ":screenshot  --fullscreen",
+    expectedOutput: 'screenshot({"fullscreen":true})',
+  },
+  {
+    input: ":screenshot  --fullscreen true",
+    expectedOutput: 'screenshot({"fullscreen":true})',
+  },
+  { input: ":screenshot  ", expectedOutput: "screenshot()" },
+  {
+    input: ":screenshot --dpr 0.5 --fullpage --chrome",
+    expectedOutput: 'screenshot({"dpr":0.5,"fullpage":true,"chrome":true})',
+  },
+  {
+    input: ":screenshot 'filename'",
+    expectedOutput: 'screenshot({"filename":"filename"})',
+  },
+  {
+    input: ":screenshot filename",
+    expectedOutput: 'screenshot({"filename":"filename"})',
+  },
+  {
+    input:
+      ":screenshot --name 'filename' --name `filename` --name \"filename\"",
+    expectedOutput: 'screenshot({"name":["filename","filename","filename"]})',
+  },
+  {
+    input: ":screenshot 'filename1' 'filename2' 'filename3'",
+    expectedOutput: 'screenshot({"filename":"filename1"})',
+  },
+  {
+    input: ":screenshot --chrome --chrome",
+    expectedOutput: 'screenshot({"chrome":true})',
+  },
+  {
+    input: ':screenshot "file name with spaces"',
+    expectedOutput: 'screenshot({"filename":"file name with spaces"})',
+  },
+  {
+    input: ":screenshot 'filename1' --name 'filename2'",
+    expectedOutput: 'screenshot({"filename":"filename1","name":"filename2"})',
+  },
+  {
+    input: ":screenshot --name 'filename1' 'filename2'",
+    expectedOutput: 'screenshot({"name":"filename1","filename":"filename2"})',
+  },
+  {
+    input: ':screenshot "fo\\"o bar"',
+    expectedOutput: 'screenshot({"filename":"fo\\\\\\"o bar"})',
+  },
+  {
+    input: ':screenshot "foo b\\"ar"',
+    expectedOutput: 'screenshot({"filename":"foo b\\\\\\"ar"})',
+  },
+];
+
+const edgecases = [
+  { input: ":", expectedError: /'' is not a valid command/ },
+  { input: ":invalid", expectedError: /'invalid' is not a valid command/ },
+  { input: ":screenshot :help", expectedError: /Invalid command/ },
+  { input: ":screenshot --", expectedError: /invalid flag/ },
+  {
+    input: ':screenshot "fo"o bar',
+    expectedError:
+      /String has unescaped `"` in \["fo"o\.\.\.\], may miss a space between arguments/,
+  },
+  {
+    input: ':screenshot "foo b"ar',
+    expectedError:
+      // eslint-disable-next-line max-len
+      /String has unescaped `"` in \["foo b"ar\.\.\.\], may miss a space between arguments/,
+  },
+  { input: ": screenshot", expectedError: /'' is not a valid command/ },
+  {
+    input: ':screenshot "file name',
+    expectedError: /String does not terminate/,
+  },
+  {
+    input: ':screenshot "file name --clipboard',
+    expectedError: /String does not terminate before flag "clipboard"/,
+  },
+  {
+    input: "::screenshot",
+    expectedError: /':screenshot' is not a valid command/,
+  },
+];
+
+function run_test() {
+  testcases.forEach(testcase => {
+    Assert.equal(formatCommand(testcase.input), testcase.expectedOutput);
+  });
+
+  edgecases.forEach(testcase => {
+    Assert.throws(
+      () => formatCommand(testcase.input),
+      testcase.expectedError,
+      `"${testcase.input}" should throw expected error`
+    );
+  });
+}
diff --git a/devtools/server/tests/xpcshell/test_forwardingprefix.js b/devtools/server/tests/xpcshell/test_forwardingprefix.js
new file mode 100644
index 0000000000..e917350da5
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_forwardingprefix.js
@@ -0,0 +1,226 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* Exercise prefix-based forwarding of packets to other transports. */
+
+const { RootActor } = require("resource://devtools/server/actors/root.js");
+
+var gMainConnection, gMainTransport;
+var gSubconnection1, gSubconnection2;
+var gClient;
+
+function run_test() {
+  DevToolsServer.init();
+
+  add_test(createMainConnection);
+  add_test(TestNoForwardingYet);
+  add_test(createSubconnection1);
+  add_test(TestForwardPrefix1OnlyRoot);
+  add_test(createSubconnection2);
+  add_test(TestForwardPrefix12OnlyRoot);
+  add_test(TestForwardPrefix12WithActor1);
+  add_test(TestForwardPrefix12WithActor12);
+  run_next_test();
+}
+
+/*
+ * Create a pipe connection, and return an object |{ conn, transport }|,
+ * where |conn| is the new DevToolsServerConnection instance, and
+ * |transport| is the client side of the transport on which it communicates
+ * (that is, packets sent on |transport| go to the new connection, and
+ * |transport|'s hooks receive replies).
+ *
+ * |prefix| is optional; if present, it's the prefix (minus the '/') for
+ * actors in the new connection.
+ */
+function newConnection(prefix) {
+  let conn;
+  DevToolsServer.createRootActor = function (connection) {
+    conn = connection;
+    return new RootActor(connection, {});
+  };
+
+  const transport = DevToolsServer.connectPipe(prefix);
+
+  return { conn, transport };
+}
+
+/* Create the main connection for these tests. */
+function createMainConnection() {
+  ({ conn: gMainConnection, transport: gMainTransport } = newConnection());
+  gClient = new DevToolsClient(gMainTransport);
+  gClient.connect().then(([type, traits]) => run_next_test());
+}
+
+/*
+ * Exchange 'echo' messages with five actors:
+ * - root
+ * - prefix1/root
+ * - prefix1/actor
+ * - prefix2/root
+ * - prefix2/actor
+ *
+ * Expect proper echos from those named in |reachables|, and 'noSuchActor'
+ * errors from the others. When we've gotten all our replies (errors or
+ * otherwise), call |completed|.
+ *
+ * To avoid deep stacks, we call completed from the next tick.
+ */
+async function tryActors(reachables, completed) {
+  for (const actor of [
+    "root",
+    "prefix1/root",
+    "prefix1/actor",
+    "prefix2/root",
+    "prefix2/actor",
+  ]) {
+    let response;
+    try {
+      if (actor.endsWith("root")) {
+        // Root actor doesn't expose any echo method,
+        // so fallback on getRoot which returns `{ from: "root" }`.
+        // For the top level root actor, we have to use its front.
+        if (actor == "root") {
+          response = await gClient.mainRoot.getRoot();
+        } else {
+          response = await gClient.request({ to: actor, type: "getRoot" });
+        }
+      } else {
+        response = await gClient.request({
+          to: actor,
+          type: "echo",
+          value: "tango",
+        });
+      }
+    } catch (e) {
+      response = e;
+    }
+    if (reachables.has(actor)) {
+      if (actor.endsWith("root")) {
+        // RootActor's getRoot response is almost empty on xpcshell
+        Assert.deepEqual({ from: actor }, response);
+      } else {
+        Assert.deepEqual(
+          { from: actor, to: actor, type: "echo", value: "tango" },
+          response
+        );
+      }
+    } else {
+      Assert.deepEqual(
+        {
+          from: actor,
+          error: "noSuchActor",
+          message: "No such actor for ID: " + actor,
+        },
+        response
+      );
+    }
+  }
+  executeSoon(completed, "tryActors callback " + completed.name);
+}
+
+/*
+ * With no forwarding established, sending messages to root should work,
+ * but sending messages to prefixed actor names, or anyone else, should get
+ * an error.
+ */
+function TestNoForwardingYet() {
+  tryActors(new Set(["root"]), run_next_test);
+}
+
+/*
+ * Create a new pipe connection which forwards its reply packets to
+ * gMainConnection's client, and to which gMainConnection forwards packets
+ * directed to actors whose names begin with |prefix + '/'|, and.
+ *
+ * Return an object { conn, transport }, as for newConnection.
+ */
+function newSubconnection(prefix) {
+  const { conn, transport } = newConnection(prefix);
+  transport.hooks = {
+    onPacket: packet => gMainConnection.send(packet),
+  };
+  gMainConnection.setForwarding(prefix, transport);
+
+  return { conn, transport };
+}
+
+/* Create a second root actor, to which we can forward things. */
+function createSubconnection1() {
+  const { conn, transport } = newSubconnection("prefix1");
+  gSubconnection1 = conn;
+  transport.ready();
+  gClient.expectReply("prefix1/root", reply => run_next_test());
+}
+
+// Establish forwarding, but don't put any actors in that server.
+function TestForwardPrefix1OnlyRoot() {
+  tryActors(new Set(["root", "prefix1/root"]), run_next_test);
+}
+
+/* Create a third root actor, to which we can forward things. */
+function createSubconnection2() {
+  const { conn, transport } = newSubconnection("prefix2");
+  gSubconnection2 = conn;
+  transport.ready();
+  gClient.expectReply("prefix2/root", reply => run_next_test());
+}
+
+function TestForwardPrefix12OnlyRoot() {
+  tryActors(new Set(["root", "prefix1/root", "prefix2/root"]), run_next_test);
+}
+
+// A dumb actor that implements 'echo'.
+//
+// It's okay that both subconnections' actors behave identically, because
+// the reply-sending code attaches the replying actor's name to the packet,
+// so simply matching the 'from' field in the reply ensures that we heard
+// from the right actor.
+const { Actor } = require("resource://devtools/shared/protocol/Actor.js");
+class EchoActor extends Actor {
+  constructor(conn) {
+    super(conn, { typeName: "EchoActor", methods: [] });
+
+    this.requestTypes = {
+      echo: EchoActor.prototype.onEcho,
+    };
+  }
+
+  onEcho(request) {
+    /*
+     * Request packets are frozen. Copy request, so that
+     * DevToolsServerConnection.onPacket can attach a 'from' property.
+     */
+    return JSON.parse(JSON.stringify(request));
+  }
+}
+
+function TestForwardPrefix12WithActor1() {
+  const actor = new EchoActor(gSubconnection1);
+  actor.actorID = "prefix1/actor";
+  gSubconnection1.addActor(actor);
+
+  tryActors(
+    new Set(["root", "prefix1/root", "prefix1/actor", "prefix2/root"]),
+    run_next_test
+  );
+}
+
+function TestForwardPrefix12WithActor12() {
+  const actor = new EchoActor(gSubconnection2);
+  actor.actorID = "prefix2/actor";
+  gSubconnection2.addActor(actor);
+
+  tryActors(
+    new Set([
+      "root",
+      "prefix1/root",
+      "prefix1/actor",
+      "prefix2/root",
+      "prefix2/actor",
+    ]),
+    run_next_test
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_frameactor-01.js b/devtools/server/tests/xpcshell/test_frameactor-01.js
new file mode 100644
index 0000000000..18c75d0abe
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_frameactor-01.js
@@ -0,0 +1,35 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Verify that we get a frame actor along with a debugger statement.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    Assert.ok(!!packet.frame);
+    Assert.ok(!!packet.frame.getActorByID);
+    Assert.equal(packet.frame.displayName, "stopMe");
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe() {
+          debugger;
+        }
+        stopMe();
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_frameactor-02.js b/devtools/server/tests/xpcshell/test_frameactor-02.js
new file mode 100644
index 0000000000..9529d2f324
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_frameactor-02.js
@@ -0,0 +1,36 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Verify that two pauses in a row will keep the same frame actor.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet1 = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const packet2 = await resumeAndWaitForPause(threadFront);
+
+    Assert.equal(packet1.frame.actor, packet2.frame.actor);
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe() {
+          debugger;
+          debugger;
+        }
+        stopMe();
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_frameactor-03.js b/devtools/server/tests/xpcshell/test_frameactor-03.js
new file mode 100644
index 0000000000..7feecd14e0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_frameactor-03.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Verify that a frame actor is properly expired when the frame goes away.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+    const frameActorID = packet.frame.actorID;
+    {
+      const { frames } = await threadFront.getFrames(0, null);
+      ok(
+        frames.some(f => f.actorID === frameActorID),
+        "The paused frame is returned by getFrames"
+      );
+
+      Assert.equal(frames.length, 3, "Thread front has 3 frames");
+    }
+
+    await resumeAndWaitForPause(threadFront);
+    await checkFramesLength(threadFront, 2);
+    {
+      const { frames } = await threadFront.getFrames(0, null);
+      ok(
+        !frames.some(f => f.actorID === frameActorID),
+        "The paused frame is no longer returned by getFrames"
+      );
+
+      Assert.equal(frames.length, 2, "Thread front has 2 frames");
+    }
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe() {
+          debugger;
+        }
+        stopMe();
+        debugger;
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_frameactor-04.js b/devtools/server/tests/xpcshell/test_frameactor-04.js
new file mode 100644
index 0000000000..200ee9968d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_frameactor-04.js
@@ -0,0 +1,64 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Verify the "frames" request on the thread.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const response = await threadFront.getFrames(0, 1000);
+    for (let i = 0; i < response.frames.length; i++) {
+      const expected = frameFixtures[i];
+      const actual = response.frames[i];
+
+      Assert.equal(
+        expected.displayname,
+        actual.displayname,
+        "Frame displayname"
+      );
+      Assert.equal(expected.type, actual.type, "Frame displayname");
+    }
+
+    await threadFront.resume();
+  })
+);
+
+var frameFixtures = [
+  // Function calls...
+  { type: "call", displayName: "depth3" },
+  { type: "call", displayName: "depth2" },
+  { type: "call", displayName: "depth1" },
+
+  // Anonymous function call in our eval...
+  { type: "call", displayName: undefined },
+
+  // The eval itself.
+  { type: "eval", displayName: "(eval)" },
+];
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function depth3() {
+          debugger;
+        }
+        function depth2() {
+          depth3();
+        }
+        function depth1() {
+          depth2();
+        }
+        depth1();
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_frameactor-05.js b/devtools/server/tests/xpcshell/test_frameactor-05.js
new file mode 100644
index 0000000000..90456191e7
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_frameactor-05.js
@@ -0,0 +1,39 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+    await checkFramesLength(threadFront, 5);
+
+    await resumeAndWaitForPause(threadFront);
+    await checkFramesLength(threadFront, 2);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function depth3() {
+          debugger;
+        }
+        function depth2() {
+          depth3();
+        }
+        function depth1() {
+          depth2();
+        }
+        depth1();
+        debugger;
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_frameactor_wasm-01.js b/devtools/server/tests/xpcshell/test_frameactor_wasm-01.js
new file mode 100644
index 0000000000..5967e8a086
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_frameactor_wasm-01.js
@@ -0,0 +1,67 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Verify that wasm frame(s) can be requested from the client.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    await threadFront.reconfigure({
+      observeAsmJS: true,
+      observeWasm: true,
+    });
+
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const frameResponse = await threadFront.getFrames(0, null);
+
+    Assert.equal(frameResponse.frames.length, 4);
+
+    const wasmFrame = frameResponse.frames[1];
+    Assert.equal(wasmFrame.type, "wasmcall");
+    Assert.equal(wasmFrame.this, undefined);
+
+    const location = wasmFrame.where;
+    const source = await getSourceById(threadFront, location.actor);
+    Assert.equal(location.line > 0, true);
+    Assert.equal(location.column > 0, true);
+    Assert.equal(/^wasm:(?:[^:]*:)*?[0-9a-f]{16}$/.test(source.url), true);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable comma-spacing, max-len */
+  debuggee.eval(
+    "(" +
+      function () {
+        // WebAssembly bytecode was generated by running:
+        // js -e 'print(wasmTextToBinary("(module(import \"a\" \"b\")(func(export \"c\")call 0))"))'
+        const m = new WebAssembly.Module(
+          new Uint8Array([
+            0, 97, 115, 109, 1, 0, 0, 0, 1, 132, 128, 128, 128, 0, 1, 96, 0, 0,
+            2, 135, 128, 128, 128, 0, 1, 1, 97, 1, 98, 0, 0, 3, 130, 128, 128,
+            128, 0, 1, 0, 6, 129, 128, 128, 128, 0, 0, 7, 133, 128, 128, 128, 0,
+            1, 1, 99, 0, 1, 10, 138, 128, 128, 128, 0, 1, 132, 128, 128, 128, 0,
+            0, 16, 0, 11,
+          ])
+        );
+        const i = new WebAssembly.Instance(m, {
+          a: {
+            b: () => {
+              debugger;
+            },
+          },
+        });
+        i.exports.c();
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_framearguments-01.js b/devtools/server/tests/xpcshell/test_framearguments-01.js
new file mode 100644
index 0000000000..524d43f58c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_framearguments-01.js
@@ -0,0 +1,43 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check a frame actor's arguments property.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const args = packet.frame.arguments;
+    Assert.equal(args.length, 6);
+    Assert.equal(args[0], 42);
+    Assert.equal(args[1], true);
+    Assert.equal(args[2], "nasu");
+    Assert.equal(args[3].type, "null");
+    Assert.equal(args[4].type, "undefined");
+    Assert.equal(args[5].type, "object");
+    Assert.equal(args[5].class, "Object");
+    Assert.ok(!!args[5].actor);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(number, bool, string, null_, undef, object) {
+          debugger;
+        }
+        stopMe(42, true, "nasu", null, undefined, { foo: "bar" });
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_framebindings-01.js b/devtools/server/tests/xpcshell/test_framebindings-01.js
new file mode 100644
index 0000000000..ecf6f02e97
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_framebindings-01.js
@@ -0,0 +1,71 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check a frame actor's bindings property.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const environment = await packet.frame.getEnvironment();
+    const bindings = environment.bindings;
+    const args = bindings.arguments;
+    const vars = bindings.variables;
+
+    Assert.equal(args.length, 6);
+    Assert.equal(args[0].number.value, 42);
+    Assert.equal(args[1].bool.value, true);
+    Assert.equal(args[2].string.value, "nasu");
+    Assert.equal(args[3].null_.value.type, "null");
+    Assert.equal(args[4].undef.value.type, "undefined");
+    Assert.equal(args[5].object.value.type, "object");
+    Assert.equal(args[5].object.value.class, "Object");
+    Assert.ok(!!args[5].object.value.actor);
+
+    Assert.equal(vars.a.value, 1);
+    Assert.equal(vars.b.value, true);
+    Assert.equal(vars.c.value.type, "object");
+    Assert.equal(vars.c.value.class, "Object");
+    Assert.ok(!!vars.c.value.actor);
+
+    const objClient = threadFront.pauseGrip(vars.c.value);
+    const response = await objClient.getPrototypeAndProperties();
+    Assert.equal(response.ownProperties.a.configurable, true);
+    Assert.equal(response.ownProperties.a.enumerable, true);
+    Assert.equal(response.ownProperties.a.writable, true);
+    Assert.equal(response.ownProperties.a.value, "a");
+
+    Assert.equal(response.ownProperties.b.configurable, true);
+    Assert.equal(response.ownProperties.b.enumerable, true);
+    Assert.equal(response.ownProperties.b.writable, true);
+    Assert.equal(response.ownProperties.b.value.type, "undefined");
+    Assert.equal(false, "class" in response.ownProperties.b.value);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(number, bool, string, null_, undef, object) {
+          var a = 1;
+          var b = true;
+          var c = { a: "a", b: undefined };
+          debugger;
+        }
+        stopMe(42, true, "nasu", null, undefined, { foo: "bar" });
+      } +
+      ")()"
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_framebindings-02.js b/devtools/server/tests/xpcshell/test_framebindings-02.js
new file mode 100644
index 0000000000..48c243193b
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_framebindings-02.js
@@ -0,0 +1,60 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check a frame actor's parent bindings.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const environment = await packet.frame.getEnvironment();
+    let parentEnv = environment.parent;
+    const bindings = parentEnv.bindings;
+    const args = bindings.arguments;
+    const vars = bindings.variables;
+    Assert.notEqual(parentEnv, undefined);
+    Assert.equal(args.length, 0);
+    Assert.equal(vars.stopMe.value.type, "object");
+    Assert.equal(vars.stopMe.value.class, "Function");
+    Assert.ok(!!vars.stopMe.value.actor);
+
+    // Skip the global lexical scope.
+    parentEnv = parentEnv.parent.parent;
+    Assert.notEqual(parentEnv, undefined);
+    const objClient = threadFront.pauseGrip(parentEnv.object);
+    const response = await objClient.getPrototypeAndProperties();
+    Assert.equal(response.ownProperties.Object.value.getGrip().type, "object");
+    Assert.equal(
+      response.ownProperties.Object.value.getGrip().class,
+      "Function"
+    );
+    Assert.ok(!!response.ownProperties.Object.value.actorID);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(number, bool, string, null_, undef, object) {
+          var a = 1;
+          var b = true;
+          var c = { a: "a" };
+          eval("");
+          debugger;
+        }
+        stopMe(42, true, "nasu", null, undefined, { foo: "bar" });
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_framebindings-03.js b/devtools/server/tests/xpcshell/test_framebindings-03.js
new file mode 100644
index 0000000000..46dc777ef1
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_framebindings-03.js
@@ -0,0 +1,63 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* strict mode code may not contain 'with' statements */
+/* eslint-disable strict */
+
+/**
+ * Check a |with| frame actor's bindings.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const env = await packet.frame.getEnvironment();
+    Assert.notEqual(env, undefined);
+
+    const parentEnv = env.parent;
+    Assert.notEqual(parentEnv, undefined);
+
+    const bindings = parentEnv.bindings;
+    const args = bindings.arguments;
+    const vars = bindings.variables;
+    Assert.equal(args.length, 1);
+    Assert.equal(args[0].number.value, 10);
+    Assert.equal(vars.r.value, 10);
+    Assert.equal(vars.a.value, Math.PI * 100);
+    Assert.equal(vars.arguments.value.class, "Arguments");
+    Assert.ok(!!vars.arguments.value.actor);
+
+    const objClient = threadFront.pauseGrip(env.object);
+    const response = await objClient.getPrototypeAndProperties();
+    Assert.equal(response.ownProperties.PI.value, Math.PI);
+    Assert.equal(response.ownProperties.cos.value.getGrip().type, "object");
+    Assert.equal(response.ownProperties.cos.value.getGrip().class, "Function");
+    Assert.ok(!!response.ownProperties.cos.value.actorID);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(number) {
+          var a;
+          var r = number;
+          with (Math) {
+            a = PI * r * r;
+            debugger;
+          }
+        }
+        stopMe(10);
+      } +
+      ")()"
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_framebindings-04.js b/devtools/server/tests/xpcshell/test_framebindings-04.js
new file mode 100644
index 0000000000..1e3cc1485c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_framebindings-04.js
@@ -0,0 +1,77 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* strict mode code may not contain 'with' statements */
+/* eslint-disable strict */
+
+/**
+ * Check the environment bindings of a  |with| within a |with|.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const env = await packet.frame.getEnvironment();
+    Assert.notEqual(env, undefined);
+
+    const objClient = threadFront.pauseGrip(env.object);
+    let response = await objClient.getPrototypeAndProperties();
+    Assert.equal(response.ownProperties.one.value, 1);
+    Assert.equal(response.ownProperties.two.value, 2);
+    Assert.equal(response.ownProperties.foo, undefined);
+
+    let parentEnv = env.parent;
+    Assert.notEqual(parentEnv, undefined);
+
+    const parentClient = threadFront.pauseGrip(parentEnv.object);
+    response = await parentClient.getPrototypeAndProperties();
+    Assert.equal(response.ownProperties.PI.value, Math.PI);
+    Assert.equal(response.ownProperties.cos.value.getGrip().type, "object");
+    Assert.equal(response.ownProperties.cos.value.getGrip().class, "Function");
+    Assert.ok(!!response.ownProperties.cos.value.actorID);
+
+    parentEnv = parentEnv.parent;
+    Assert.notEqual(parentEnv, undefined);
+
+    const bindings = parentEnv.bindings;
+    const args = bindings.arguments;
+    const vars = bindings.variables;
+    Assert.equal(args.length, 1);
+    Assert.equal(args[0].number.value, 10);
+    Assert.equal(vars.r.value, 10);
+    Assert.equal(vars.a.value, Math.PI * 100);
+    Assert.equal(vars.arguments.value.class, "Arguments");
+    Assert.ok(!!vars.arguments.value.actor);
+    Assert.equal(vars.foo.value, 2 * Math.PI);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(number) {
+          var a,
+            obj = { one: 1, two: 2 };
+          var r = number;
+          with (Math) {
+            a = PI * r * r;
+            with (obj) {
+              var foo = two * PI;
+              debugger;
+            }
+          }
+        }
+        stopMe(10);
+      } +
+      ")()"
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_framebindings-05.js b/devtools/server/tests/xpcshell/test_framebindings-05.js
new file mode 100644
index 0000000000..6206fe8668
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_framebindings-05.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check the environment bindings of a |with| in global scope.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const env = await packet.frame.getEnvironment();
+    Assert.notEqual(env, undefined);
+
+    const objClient = threadFront.pauseGrip(env.object);
+    let response = await objClient.getPrototypeAndProperties();
+    Assert.equal(response.ownProperties.PI.value, Math.PI);
+    Assert.equal(response.ownProperties.cos.value.getGrip().type, "object");
+    Assert.equal(response.ownProperties.cos.value.getGrip().class, "Function");
+    Assert.ok(!!response.ownProperties.cos.value.actorID);
+
+    // Skip the global lexical scope.
+    const parentEnv = env.parent.parent;
+    Assert.notEqual(parentEnv, undefined);
+
+    const parentClient = threadFront.pauseGrip(parentEnv.object);
+    response = await parentClient.getPrototypeAndProperties();
+    Assert.equal(response.ownProperties.a.value, Math.PI * 100);
+    Assert.equal(response.ownProperties.r.value, 10);
+    Assert.equal(response.ownProperties.Object.value.getGrip().type, "object");
+    Assert.equal(
+      response.ownProperties.Object.value.getGrip().class,
+      "Function"
+    );
+    Assert.ok(!!response.ownProperties.Object.value.actorID);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    "var a, r = 10;\n" +
+      "with (Math) {\n" +
+      "  a = PI * r * r;\n" +
+      "  debugger;\n" +
+      "}"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_framebindings-06.js b/devtools/server/tests/xpcshell/test_framebindings-06.js
new file mode 100644
index 0000000000..52ab0cfe7c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_framebindings-06.js
@@ -0,0 +1,45 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const env = await packet.frame.getEnvironment();
+    equal(env.type, "function");
+    equal(env.function.displayName, "banana3");
+    let parent = env.parent;
+    equal(parent.type, "block");
+    ok("banana3" in parent.bindings.variables);
+    parent = parent.parent;
+    equal(parent.type, "function");
+    equal(parent.function.displayName, "banana2");
+    parent = parent.parent;
+    equal(parent.type, "block");
+    ok("banana2" in parent.bindings.variables);
+    parent = parent.parent;
+    equal(parent.type, "function");
+    equal(parent.function.displayName, "banana");
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    "function banana(x) {\n" +
+      "  return function banana2(y) {\n" +
+      "    return function banana3(z) {\n" +
+      '      eval("");\n' +
+      "      debugger;\n" +
+      "    };\n" +
+      "  };\n" +
+      "}\n" +
+      "banana('x')('y')('z');\n"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_framebindings-07.js b/devtools/server/tests/xpcshell/test_framebindings-07.js
new file mode 100644
index 0000000000..77d43dfba8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_framebindings-07.js
@@ -0,0 +1,41 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const environment = await packet.frame.getEnvironment();
+    Assert.equal(environment.type, "function");
+    Assert.equal(environment.bindings.arguments[0].z.value, "z");
+
+    const parent = environment.parent;
+    Assert.equal(parent.type, "block");
+    Assert.equal(parent.bindings.variables.banana3.value.class, "Function");
+
+    const grandpa = parent.parent;
+    Assert.equal(grandpa.type, "function");
+    Assert.equal(grandpa.bindings.arguments[0].y.value, "y");
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    "function banana(x) {\n" +
+      "  return function banana2(y) {\n" +
+      "    return function banana3(z) {\n" +
+      '      eval("");\n' +
+      "      debugger;\n" +
+      "    };\n" +
+      "  };\n" +
+      "}\n" +
+      "banana('x')('y')('z');\n"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_front_destroy.js b/devtools/server/tests/xpcshell/test_front_destroy.js
new file mode 100644
index 0000000000..33e2ac827a
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_front_destroy.js
@@ -0,0 +1,42 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Test that fronts throw errors if they are called after being destroyed.
+ */
+
+"use strict";
+
+// HACK: ServiceWorkerManager requires the "profile-change-teardown" to cleanly
+// shutdown, and setting _profileInitialized to `true` will trigger those
+// notifications (see /testing/xpcshell/head.js).
+// eslint-disable-next-line no-undef
+_profileInitialized = true;
+
+add_task(async function test() {
+  DevToolsServer.init();
+  DevToolsServer.registerAllActors();
+
+  info("Create and connect the DevToolsClient");
+  const transport = DevToolsServer.connectPipe();
+  const client = new DevToolsClient(transport);
+  await client.connect();
+
+  info("Get the device front and check calling getDescription() on it");
+  const front = await client.mainRoot.getFront("device");
+  const description = await front.getDescription();
+  ok(
+    !!description,
+    "Check that the getDescription() method returns a valid response."
+  );
+
+  info("Destroy the device front and try calling getDescription again");
+  front.destroy();
+  Assert.throws(
+    () => front.getDescription(),
+    /Can not send request 'getDescription' because front 'device' is already destroyed\./,
+    "Check device front throws when getDescription() is called after destroy()"
+  );
+
+  await client.close();
+});
diff --git a/devtools/server/tests/xpcshell/test_functiongrips-01.js b/devtools/server/tests/xpcshell/test_functiongrips-01.js
new file mode 100644
index 0000000000..5abce26875
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_functiongrips-01.js
@@ -0,0 +1,64 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    // Test named function
+    function evalCode() {
+      debuggee.eval(
+        function stopMe(arg1) {
+          debugger;
+        }.toString()
+      );
+      debuggee.eval("stopMe(stopMe)");
+    }
+
+    const packet1 = await executeOnNextTickAndWaitForPause(
+      () => evalCode(),
+      threadFront
+    );
+
+    const args1 = packet1.frame.arguments;
+
+    Assert.equal(args1[0].class, "Function");
+    Assert.equal(args1[0].name, "stopMe");
+    Assert.equal(args1[0].displayName, "stopMe");
+
+    await threadFront.resume();
+
+    // Test inferred name function
+    const packet2 = await executeOnNextTickAndWaitForPause(
+      () =>
+        debuggee.eval(
+          "var o = { m: function(foo, bar, baz) { } }; stopMe(o.m)"
+        ),
+      threadFront
+    );
+
+    const args2 = packet2.frame.arguments;
+
+    Assert.equal(args2[0].class, "Function");
+    // No name for an anonymous function, but it should have an inferred name.
+    Assert.equal(args2[0].name, undefined);
+    Assert.equal(args2[0].displayName, "m");
+
+    await threadFront.resume();
+
+    // Test anonymous function
+    const packet3 = await executeOnNextTickAndWaitForPause(
+      () => debuggee.eval("stopMe(function(foo, bar, baz) { })"),
+      threadFront
+    );
+
+    const args3 = packet3.frame.arguments;
+
+    Assert.equal(args3[0].class, "Function");
+    // No name for an anonymous function, and no inferred name, either.
+    Assert.equal(args3[0].name, undefined);
+    Assert.equal(args3[0].displayName, undefined);
+
+    await threadFront.resume();
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_getRuleText.js b/devtools/server/tests/xpcshell/test_getRuleText.js
new file mode 100644
index 0000000000..fe53dca158
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_getRuleText.js
@@ -0,0 +1,143 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  getRuleText,
+} = require("resource://devtools/server/actors/utils/style-utils.js");
+
+const TEST_DATA = [
+  {
+    desc: "Empty input",
+    input: "",
+    line: 1,
+    column: 1,
+    throws: true,
+  },
+  {
+    desc: "Simplest test case",
+    input: "#id{color:red;background:yellow;}",
+    line: 1,
+    column: 1,
+    expected: { offset: 4, text: "color:red;background:yellow;" },
+  },
+  {
+    desc: "Multiple rules test case",
+    input:
+      "#id{color:red;background:yellow;}.class-one .class-two " +
+      "{ position:absolute; line-height: 45px}",
+    line: 1,
+    column: 34,
+    expected: { offset: 56, text: " position:absolute; line-height: 45px" },
+  },
+  {
+    desc: "Unclosed rule",
+    input: "#id{color:red;background:yellow;",
+    line: 1,
+    column: 1,
+    expected: { offset: 4, text: "color:red;background:yellow;" },
+  },
+  {
+    desc: "Null input",
+    input: null,
+    line: 1,
+    column: 1,
+    throws: true,
+  },
+  {
+    desc: "Missing loc",
+    input: "#id{color:red;background:yellow;}",
+    throws: true,
+  },
+  {
+    desc: "Multi-lines CSS",
+    input: [
+      "/* this is a multi line css */",
+      "body {",
+      "  color: green;",
+      "  background-repeat: no-repeat",
+      "}",
+      " /*something else here */",
+      "* {",
+      "  color: purple;",
+      "}",
+    ].join("\n"),
+    line: 7,
+    column: 1,
+    expected: { offset: 116, text: "\n  color: purple;\n" },
+  },
+  {
+    desc: "Multi-lines CSS and multi-line rule",
+    input: [
+      "/* ",
+      "* some comments",
+      "*/",
+      "",
+      "body {",
+      "    margin: 0;",
+      "    padding: 15px 15px 2px 15px;",
+      "    color: red;",
+      "}",
+      "",
+      "#header .btn, #header .txt {",
+      "    font-size: 100%;",
+      "}",
+      "",
+      "#header #information {",
+      "    color: #dddddd;",
+      "    font-size: small;",
+      "}",
+    ].join("\n"),
+    line: 5,
+    column: 1,
+    expected: {
+      offset: 30,
+      text: "\n    margin: 0;\n    padding: 15px 15px 2px 15px;\n    color: red;\n",
+    },
+  },
+  {
+    desc: "Content string containing a } character",
+    input: "   #id{border:1px solid red;content: '}';color:red;}",
+    line: 1,
+    column: 4,
+    expected: {
+      offset: 7,
+      text: "border:1px solid red;content: '}';color:red;",
+    },
+  },
+  {
+    desc: "Rule contains no tokens",
+    input: "div{}",
+    line: 1,
+    column: 1,
+    expected: { offset: 4, text: "" },
+  },
+];
+
+function run_test() {
+  for (const test of TEST_DATA) {
+    info("Starting test: " + test.desc);
+    info("Input string " + test.input);
+    let output;
+    try {
+      output = getRuleText(test.input, test.line, test.column);
+      if (test.throws) {
+        info("Test should have thrown");
+        Assert.ok(false);
+      }
+    } catch (e) {
+      info("getRuleText threw an exception with the given input string");
+      if (test.throws) {
+        info("Exception expected");
+        Assert.ok(true);
+      } else {
+        info("Exception unexpected\n" + e);
+        Assert.ok(false);
+      }
+    }
+    if (output) {
+      deepEqual(output, test.expected);
+    }
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_getTextAtLineColumn.js b/devtools/server/tests/xpcshell/test_getTextAtLineColumn.js
new file mode 100644
index 0000000000..3aa9915192
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_getTextAtLineColumn.js
@@ -0,0 +1,35 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  getTextAtLineColumn,
+} = require("resource://devtools/server/actors/utils/style-utils.js");
+
+const TEST_DATA = [
+  {
+    desc: "simplest",
+    input: "#id{color:red;background:yellow;}",
+    line: 1,
+    column: 5,
+    expected: { offset: 4, text: "color:red;background:yellow;}" },
+  },
+  {
+    desc: "multiple lines",
+    input: "one\n two\n  three",
+    line: 3,
+    column: 3,
+    expected: { offset: 11, text: "three" },
+  },
+];
+
+function run_test() {
+  for (const test of TEST_DATA) {
+    info("Starting test: " + test.desc);
+    info("Input string " + test.input);
+
+    const output = getTextAtLineColumn(test.input, test.line, test.column);
+    deepEqual(output, test.expected);
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_getyoungestframe.js b/devtools/server/tests/xpcshell/test_getyoungestframe.js
new file mode 100644
index 0000000000..f08628b7ed
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_getyoungestframe.js
@@ -0,0 +1,38 @@
+/* eslint-disable strict */
+function run_test() {
+  Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+  });
+  const { addDebuggerToGlobal } = ChromeUtils.importESModule(
+    "resource://gre/modules/jsdebugger.sys.mjs"
+  );
+  addDebuggerToGlobal(globalThis);
+  const xpcInspector = Cc["@mozilla.org/jsinspector;1"].getService(
+    Ci.nsIJSInspector
+  );
+  const g = createTestGlobal("test1");
+
+  const dbg = makeDebugger();
+  dbg.uncaughtExceptionHook = testExceptionHook;
+
+  dbg.addDebuggee(g);
+  dbg.onDebuggerStatement = function (frame) {
+    Assert.ok(frame === dbg.getNewestFrame());
+    // Execute from the nested event loop, dbg.getNewestFrame() won't
+    // be working anymore.
+
+    executeSoon(function () {
+      try {
+        Assert.ok(frame === dbg.getNewestFrame());
+      } finally {
+        xpcInspector.exitNestedEventLoop("test");
+      }
+    });
+    xpcInspector.enterNestedEventLoop("test");
+  };
+
+  g.eval("function debuggerStatement() { debugger; }; debuggerStatement();");
+
+  dbg.disable();
+}
diff --git a/devtools/server/tests/xpcshell/test_ignore_caught_exceptions.js b/devtools/server/tests/xpcshell/test_ignore_caught_exceptions.js
new file mode 100644
index 0000000000..fe04161aab
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_ignore_caught_exceptions.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that setting ignoreCaughtExceptions will cause the debugger to ignore
+ * caught exceptions, but not uncaught ones.
+ */
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee, commands }) => {
+      await executeOnNextTickAndWaitForPause(
+        () => evaluateTestCode(debuggee),
+        threadFront
+      );
+
+      await commands.threadConfigurationCommand.updateConfiguration({
+        pauseOnExceptions: true,
+        ignoreCaughtExceptions: true,
+      });
+      await resume(threadFront);
+      const paused = await waitForPause(threadFront);
+      Assert.equal(paused.why.type, "exception");
+      equal(paused.frame.where.line, 6, "paused at throw");
+
+      await resume(threadFront);
+    },
+    {
+      // Bug 1508289, exception tests fails in worker scope
+      doNotRunWorker: true,
+    }
+  )
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  try {
+  Cu.evalInSandbox(`                    // 1
+   debugger;                            // 2
+   try {                                // 3
+     throw "foo";                       // 4
+   } catch (e) {}                       // 5
+   throw "bar";                         // 6
+  `,                                    // 7
+    debuggee,
+    "1.8",
+    "test_pause_exceptions-03.js",
+    1
+  );
+  } catch (e) {}
+}
diff --git a/devtools/server/tests/xpcshell/test_ignore_no_interface_exceptions.js b/devtools/server/tests/xpcshell/test_ignore_no_interface_exceptions.js
new file mode 100644
index 0000000000..50d28ffdc0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_ignore_no_interface_exceptions.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that the debugger automatically ignores NS_ERROR_NO_INTERFACE
+ * exceptions, but not normal ones.
+ */
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee }) => {
+      await threadFront.pauseOnExceptions(true, false);
+      const paused = await executeOnNextTickAndWaitForPause(
+        () => evaluateTestCode(debuggee),
+        threadFront
+      );
+      equal(paused.frame.where.line, 6, "paused at throw");
+
+      await resume(threadFront);
+    },
+    {
+      // Bug 1508289, exception tests fails in worker scope
+      doNotRunWorker: true,
+    }
+  )
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox(`                    // 1
+    function QueryInterface() {         // 2
+      throw Cr.NS_ERROR_NO_INTERFACE;   // 3
+    }                                   // 4
+    function stopMe() {                 // 5
+      throw 42;                         // 6
+    }                                   // 7
+    try {                               // 8
+      QueryInterface();                 // 9
+    } catch (e) {}                      // 10
+    try {                               // 11
+      stopMe();                         // 12
+    } catch (e) {}`,                    // 13
+    debuggee,
+    "1.8",
+    "test_ignore_no_interface_exceptions.js",
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_interrupt.js b/devtools/server/tests/xpcshell/test_interrupt.js
new file mode 100644
index 0000000000..07593a7360
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_interrupt.js
@@ -0,0 +1,15 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client, targetFront }) => {
+    const onPaused = waitForEvent(threadFront, "paused");
+    await threadFront.interrupt();
+    await onPaused;
+    Assert.equal(threadFront.paused, true);
+    await threadFront.resume();
+    Assert.equal(threadFront.paused, false);
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_layout-reflows-observer.js b/devtools/server/tests/xpcshell/test_layout-reflows-observer.js
new file mode 100644
index 0000000000..74f31b97fe
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_layout-reflows-observer.js
@@ -0,0 +1,311 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test the LayoutChangesObserver
+
+/* eslint-disable mozilla/use-chromeutils-generateqi */
+
+var {
+  getLayoutChangesObserver,
+  releaseLayoutChangesObserver,
+  LayoutChangesObserver,
+} = require("resource://devtools/server/actors/reflow.js");
+const EventEmitter = require("resource://devtools/shared/event-emitter.js");
+
+// Override set/clearTimeout on LayoutChangesObserver to avoid depending on
+// time in this unit test. This means that LayoutChangesObserver.eventLoopTimer
+// will be the timeout callback instead of the timeout itself, so test cases
+// will need to execute it to fake a timeout
+LayoutChangesObserver.prototype._setTimeout = cb => cb;
+LayoutChangesObserver.prototype._clearTimeout = function () {};
+
+// Mock the targetActor since we only really want to test the LayoutChangesObserver
+// and don't want to depend on a window object, nor want to test protocol.js
+class MockTargetActor extends EventEmitter {
+  constructor() {
+    super();
+    this.docShell = new MockDocShell();
+    this.window = new MockWindow(this.docShell);
+    this.windows = [this.window];
+    this.attached = true;
+  }
+
+  get chromeEventHandler() {
+    return this.docShell.chromeEventHandler;
+  }
+
+  isDestroyed() {
+    return false;
+  }
+}
+
+function MockWindow(docShell) {
+  this.docShell = docShell;
+}
+MockWindow.prototype = {
+  QueryInterface() {
+    const self = this;
+    return {
+      getInterface() {
+        return {
+          QueryInterface() {
+            return self.docShell;
+          },
+        };
+      },
+    };
+  },
+  setTimeout(cb) {
+    // Simply return the cb itself so that we can execute it in the test instead
+    // of depending on a real timeout
+    return cb;
+  },
+  clearTimeout() {},
+};
+
+function MockDocShell() {
+  this.observer = null;
+}
+MockDocShell.prototype = {
+  addWeakReflowObserver(observer) {
+    this.observer = observer;
+  },
+  removeWeakReflowObserver() {},
+  get chromeEventHandler() {
+    return {
+      addEventListener: (type, cb) => {
+        if (type === "resize") {
+          this.resizeCb = cb;
+        }
+      },
+      removeEventListener: (type, cb) => {
+        if (type === "resize" && cb === this.resizeCb) {
+          this.resizeCb = null;
+        }
+      },
+    };
+  },
+  mockResize() {
+    if (this.resizeCb) {
+      this.resizeCb();
+    }
+  },
+};
+
+function run_test() {
+  instancesOfObserversAreSharedBetweenWindows();
+  eventsAreBatched();
+  noEventsAreSentWhenThereAreNoReflowsAndLoopTimeouts();
+  observerIsAlreadyStarted();
+  destroyStopsObserving();
+  stoppingAndStartingSeveralTimesWorksCorrectly();
+  reflowsArentStackedWhenStopped();
+  stackedReflowsAreResetOnStop();
+}
+
+function instancesOfObserversAreSharedBetweenWindows() {
+  info(
+    "Checking that when requesting twice an instances of the observer " +
+      "for the same WindowGlobalTargetActor, the instance is shared"
+  );
+
+  info("Checking 2 instances of the observer for the targetActor 1");
+  const targetActor1 = new MockTargetActor();
+  const obs11 = getLayoutChangesObserver(targetActor1);
+  const obs12 = getLayoutChangesObserver(targetActor1);
+  Assert.equal(obs11, obs12);
+
+  info("Checking 2 instances of the observer for the targetActor 2");
+  const targetActor2 = new MockTargetActor();
+  const obs21 = getLayoutChangesObserver(targetActor2);
+  const obs22 = getLayoutChangesObserver(targetActor2);
+  Assert.equal(obs21, obs22);
+
+  info(
+    "Checking that observers instances for 2 different targetActors are " +
+      "different"
+  );
+  Assert.notEqual(obs11, obs21);
+
+  releaseLayoutChangesObserver(targetActor1);
+  releaseLayoutChangesObserver(targetActor1);
+  releaseLayoutChangesObserver(targetActor2);
+  releaseLayoutChangesObserver(targetActor2);
+}
+
+function eventsAreBatched() {
+  info(
+    "Checking that reflow events are batched and only sent when the " +
+      "timeout expires"
+  );
+
+  // Note that in this test, we mock the target actor and its window property, so we also
+  // mock the setTimeout/clearTimeout mechanism and just call the callback manually
+  const targetActor = new MockTargetActor();
+  const observer = getLayoutChangesObserver(targetActor);
+
+  const reflowsEvents = [];
+  const onReflows = reflows => reflowsEvents.push(reflows);
+  observer.on("reflows", onReflows);
+
+  const resizeEvents = [];
+  const onResize = () => resizeEvents.push("resize");
+  observer.on("resize", onResize);
+
+  info("Fake one reflow event");
+  targetActor.window.docShell.observer.reflow();
+  info("Checking that no batched reflow event has been emitted");
+  Assert.equal(reflowsEvents.length, 0);
+
+  info("Fake another reflow event");
+  targetActor.window.docShell.observer.reflow();
+  info("Checking that still no batched reflow event has been emitted");
+  Assert.equal(reflowsEvents.length, 0);
+
+  info("Fake a few of resize events too");
+  targetActor.window.docShell.mockResize();
+  targetActor.window.docShell.mockResize();
+  targetActor.window.docShell.mockResize();
+  info("Checking that still no batched resize event has been emitted");
+  Assert.equal(resizeEvents.length, 0);
+
+  info("Faking timeout expiration and checking that events are sent");
+  observer.eventLoopTimer();
+  Assert.equal(reflowsEvents.length, 1);
+  Assert.equal(reflowsEvents[0].length, 2);
+  Assert.equal(resizeEvents.length, 1);
+
+  observer.off("reflows", onReflows);
+  observer.off("resize", onResize);
+  releaseLayoutChangesObserver(targetActor);
+}
+
+function noEventsAreSentWhenThereAreNoReflowsAndLoopTimeouts() {
+  info(
+    "Checking that if no reflows were detected and the event batching " +
+      "loop expires, then no reflows event is sent"
+  );
+
+  const targetActor = new MockTargetActor();
+  const observer = getLayoutChangesObserver(targetActor);
+
+  const reflowsEvents = [];
+  const onReflows = reflows => reflowsEvents.push(reflows);
+  observer.on("reflows", onReflows);
+
+  info("Faking timeout expiration and checking for reflows");
+  observer.eventLoopTimer();
+  Assert.equal(reflowsEvents.length, 0);
+
+  observer.off("reflows", onReflows);
+  releaseLayoutChangesObserver(targetActor);
+}
+
+function observerIsAlreadyStarted() {
+  info("Checking that the observer is already started when getting it");
+
+  const targetActor = new MockTargetActor();
+  const observer = getLayoutChangesObserver(targetActor);
+  Assert.ok(observer.isObserving);
+
+  observer.stop();
+  Assert.ok(!observer.isObserving);
+
+  observer.start();
+  Assert.ok(observer.isObserving);
+
+  releaseLayoutChangesObserver(targetActor);
+}
+
+function destroyStopsObserving() {
+  info("Checking that the destroying the observer stops it");
+
+  const targetActor = new MockTargetActor();
+  const observer = getLayoutChangesObserver(targetActor);
+  Assert.ok(observer.isObserving);
+
+  observer.destroy();
+  Assert.ok(!observer.isObserving);
+
+  releaseLayoutChangesObserver(targetActor);
+}
+
+function stoppingAndStartingSeveralTimesWorksCorrectly() {
+  info(
+    "Checking that the stopping and starting several times the observer" +
+      " works correctly"
+  );
+
+  const targetActor = new MockTargetActor();
+  const observer = getLayoutChangesObserver(targetActor);
+
+  Assert.ok(observer.isObserving);
+  observer.start();
+  observer.start();
+  observer.start();
+  Assert.ok(observer.isObserving);
+
+  observer.stop();
+  Assert.ok(!observer.isObserving);
+
+  observer.stop();
+  observer.stop();
+  Assert.ok(!observer.isObserving);
+
+  releaseLayoutChangesObserver(targetActor);
+}
+
+function reflowsArentStackedWhenStopped() {
+  info("Checking that when stopped, reflows aren't stacked in the observer");
+
+  const targetActor = new MockTargetActor();
+  const observer = getLayoutChangesObserver(targetActor);
+
+  info("Stoping the observer");
+  observer.stop();
+
+  info("Faking reflows");
+  targetActor.window.docShell.observer.reflow();
+  targetActor.window.docShell.observer.reflow();
+  targetActor.window.docShell.observer.reflow();
+
+  info("Checking that reflows aren't recorded");
+  Assert.equal(observer.reflows.length, 0);
+
+  info("Starting the observer and faking more reflows");
+  observer.start();
+  targetActor.window.docShell.observer.reflow();
+  targetActor.window.docShell.observer.reflow();
+  targetActor.window.docShell.observer.reflow();
+
+  info("Checking that reflows are recorded");
+  Assert.equal(observer.reflows.length, 3);
+
+  releaseLayoutChangesObserver(targetActor);
+}
+
+function stackedReflowsAreResetOnStop() {
+  info("Checking that stacked reflows are reset on stop");
+
+  const targetActor = new MockTargetActor();
+  const observer = getLayoutChangesObserver(targetActor);
+
+  targetActor.window.docShell.observer.reflow();
+  Assert.equal(observer.reflows.length, 1);
+
+  observer.stop();
+  Assert.equal(observer.reflows.length, 0);
+
+  targetActor.window.docShell.observer.reflow();
+  Assert.equal(observer.reflows.length, 0);
+
+  observer.start();
+  Assert.equal(observer.reflows.length, 0);
+
+  targetActor.window.docShell.observer.reflow();
+  Assert.equal(observer.reflows.length, 1);
+
+  releaseLayoutChangesObserver(targetActor);
+}
diff --git a/devtools/server/tests/xpcshell/test_listsources-01.js b/devtools/server/tests/xpcshell/test_listsources-01.js
new file mode 100644
index 0000000000..306825278c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_listsources-01.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check basic getSources functionality.
+ */
+
+var gNumTimesSourcesSent = 0;
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client }) => {
+    client.request = (function (origRequest) {
+      return function (request, onResponse) {
+        if (request.type === "sources") {
+          ++gNumTimesSourcesSent;
+        }
+        return origRequest.call(this, request, onResponse);
+      };
+    })(client.request);
+
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const response = await threadFront.getSources();
+
+    Assert.ok(
+      response.sources.some(function (s) {
+        return s.url && s.url.match(/test_listsources-01.js/);
+      })
+    );
+
+    Assert.ok(
+      gNumTimesSourcesSent <= 1,
+      "Should only send one sources request at most, even though we" +
+        " might have had to send one to determine feature support."
+    );
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    "var line0 = Error().lineNumber;\n" +
+      "debugger;\n" + // line0 + 1
+      "var a = 1;\n" + // line0 + 2
+      "var b = 2;\n", // line0 + 3
+    debuggee
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_listsources-02.js b/devtools/server/tests/xpcshell/test_listsources-02.js
new file mode 100644
index 0000000000..a2f9cc3bda
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_listsources-02.js
@@ -0,0 +1,36 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check getting sources before there are any.
+ */
+
+var gNumTimesSourcesSent = 0;
+
+add_task(
+  threadFrontTest(async ({ threadFront, client }) => {
+    client.request = (function (origRequest) {
+      return function (request, onResponse) {
+        if (request.type === "sources") {
+          ++gNumTimesSourcesSent;
+        }
+        return origRequest.call(this, request, onResponse);
+      };
+    })(client.request);
+
+    // Test listing zero sources
+    const packet = await threadFront.getSources();
+
+    Assert.ok(!packet.error);
+    Assert.ok(!!packet.sources);
+    Assert.equal(packet.sources.length, 0);
+
+    Assert.ok(
+      gNumTimesSourcesSent <= 1,
+      "Should only send one sources request at most, even though we" +
+        " might have had to send one to determine feature support."
+    );
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_listsources-03.js b/devtools/server/tests/xpcshell/test_listsources-03.js
new file mode 100644
index 0000000000..f8af5aca6e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_listsources-03.js
@@ -0,0 +1,45 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check getSources functionality when there are lots of sources.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const response = await threadFront.getSources();
+
+    Assert.ok(
+      !response.error,
+      "There shouldn't be an error fetching large amounts of sources."
+    );
+
+    Assert.ok(
+      response.sources.some(function (s) {
+        return s.url.match(/foo-999.js$/);
+      })
+    );
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  for (let i = 0; i < 1000; i++) {
+    Cu.evalInSandbox(
+      "function foo###() {return ###;}".replace(/###/g, i),
+      debuggee,
+      "1.8",
+      "http://example.com/foo-" + i + ".js",
+      1
+    );
+  }
+  debuggee.eval("debugger;");
+}
diff --git a/devtools/server/tests/xpcshell/test_logpoint-01.js b/devtools/server/tests/xpcshell/test_logpoint-01.js
new file mode 100644
index 0000000000..a5cb4f2197
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_logpoint-01.js
@@ -0,0 +1,83 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that logpoints generate console messages.
+ */
+
+const Resources = require("resource://devtools/server/actors/resources/index.js");
+
+add_task(
+  threadFrontTest(async ({ threadActor, threadFront, debuggee, client }) => {
+    let lastMessage, lastExpression;
+    const targetActor = threadActor._parent;
+    // Only Workers are evaluating through the WebConsoleActor.
+    // Tabs will be evaluating directly via the frame object.
+    targetActor._consoleActor = {
+      evaluateJS(expression) {
+        lastExpression = expression;
+      },
+    };
+
+    // And then listen for resource RDP event.
+    // Bug 1646677: But we should probably migrate this test to ResourceCommand so that
+    // we don't have to hack the server side via Resource.watchResources call.
+    targetActor.on("resource-available-form", resources => {
+      if (resources[0].resourceType == Resources.TYPES.CONSOLE_MESSAGE) {
+        lastMessage = resources[0].message;
+      }
+    });
+
+    // But both tabs and processes will be going through the ConsoleMessages module
+    // We force watching for console message first,
+    await Resources.watchResources(targetActor, [
+      Resources.TYPES.CONSOLE_MESSAGE,
+    ]);
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+
+    // Set a logpoint which should invoke console.log.
+    threadFront.setBreakpoint(
+      {
+        sourceUrl: source.url,
+        line: 3,
+      },
+      { logValue: "a" }
+    );
+    await client.waitForRequestsToSettle();
+
+    // Execute the rest of the code.
+    await threadFront.resume();
+
+    // NOTE: logpoints evaluated in a worker have a lastExpression
+    if (lastMessage) {
+      Assert.equal(lastMessage.level, "logPoint");
+      Assert.equal(lastMessage.arguments[0], "three");
+      Assert.ok(/\d+\.\d+/.test(lastMessage.timeStamp));
+    } else {
+      Assert.equal(lastExpression.text, "console.log(...[a])");
+      Assert.equal(lastExpression.lineNumber, 3);
+    }
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    "debugger;\n" + // 1
+      "var a = 'three';\n" + // 2
+      "var b = 2;\n", // 3
+    debuggee,
+    "1.8",
+    "test.js",
+    1
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_logpoint-02.js b/devtools/server/tests/xpcshell/test_logpoint-02.js
new file mode 100644
index 0000000000..d84d3fc324
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_logpoint-02.js
@@ -0,0 +1,85 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that conditions are respected when specified in a logpoint.
+ */
+
+const Resources = require("resource://devtools/server/actors/resources/index.js");
+
+add_task(
+  threadFrontTest(async ({ threadActor, threadFront, debuggee, client }) => {
+    let lastMessage, lastExpression;
+    const targetActor = threadActor._parent;
+    // Only Workers are evaluating through the WebConsoleActor.
+    // Tabs will be evaluating directly via the frame object.
+    targetActor._consoleActor = {
+      evaluateJS(expression) {
+        lastExpression = expression;
+      },
+    };
+
+    // And then listen for resource RDP event.
+    // Bug 1646677: But we should probably migrate this test to ResourceCommand so that
+    // we don't have to hack the server side via Resource.watchResources call.
+    targetActor.on("resource-available-form", resources => {
+      if (resources[0].resourceType == Resources.TYPES.CONSOLE_MESSAGE) {
+        lastMessage = resources[0].message;
+      }
+    });
+
+    // But both tabs and processes will be going through the ConsoleMessages module
+    // We force watching for console message first,
+    await Resources.watchResources(targetActor, [
+      Resources.TYPES.CONSOLE_MESSAGE,
+    ]);
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+
+    // Set a logpoint which should invoke console.log.
+    threadFront.setBreakpoint(
+      {
+        sourceUrl: source.url,
+        line: 4,
+      },
+      { logValue: "a", condition: "a === 5" }
+    );
+    await client.waitForRequestsToSettle();
+
+    // Execute the rest of the code.
+    await threadFront.resume();
+
+    // NOTE: logpoints evaluated in a worker have a lastExpression
+    if (lastMessage) {
+      Assert.equal(lastMessage.level, "logPoint");
+      Assert.equal(lastMessage.arguments[0], 5);
+      Assert.ok(/\d+\.\d+/.test(lastMessage.timeStamp));
+    } else {
+      Assert.equal(lastExpression.text, "console.log(...[a])");
+      Assert.equal(lastExpression.lineNumber, 4);
+    }
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    "debugger;\n" + // 1
+      "var a = 1;\n" + // 2
+      "while (a < 10) {\n" + // 3
+      "  a++;\n" + // 4
+      "}",
+    debuggee,
+    "1.8",
+    "test.js",
+    1
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_logpoint-03.js b/devtools/server/tests/xpcshell/test_logpoint-03.js
new file mode 100644
index 0000000000..b5d4440889
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_logpoint-03.js
@@ -0,0 +1,82 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that logpoints generate console errors if the logpoint statement is invalid.
+ */
+
+const Resources = require("resource://devtools/server/actors/resources/index.js");
+
+add_task(
+  threadFrontTest(async ({ threadActor, threadFront, debuggee, client }) => {
+    let lastMessage, lastExpression;
+    const targetActor = threadActor._parent;
+    // Only Workers are evaluating through the WebConsoleActor.
+    // Tabs will be evaluating directly via the frame object.
+    targetActor._consoleActor = {
+      evaluateJS(expression) {
+        lastExpression = expression;
+      },
+    };
+
+    // And then listen for resource RDP event.
+    // Bug 1646677: But we should probably migrate this test to ResourceCommand so that
+    // we don't have to hack the server side via Resource.watchResources call.
+    targetActor.on("resource-available-form", resources => {
+      if (resources[0].resourceType == Resources.TYPES.CONSOLE_MESSAGE) {
+        lastMessage = resources[0].message;
+      }
+    });
+
+    // But both tabs and processes will be going through the ConsoleMessages module
+    // We force watching for console message first,
+    await Resources.watchResources(targetActor, [
+      Resources.TYPES.CONSOLE_MESSAGE,
+    ]);
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const source = await getSourceById(threadFront, packet.frame.where.actor);
+
+    // Set a logpoint which should throw an error message.
+    await threadFront.setBreakpoint(
+      {
+        sourceUrl: source.url,
+        line: 3,
+      },
+      { logValue: "c" }
+    );
+
+    // Execute the rest of the code.
+    await threadFront.resume();
+
+    // NOTE: logpoints evaluated in a worker have a lastExpression
+    if (lastMessage) {
+      Assert.equal(lastMessage.level, "logPointError");
+      Assert.equal(lastMessage.arguments[0], "c is not defined");
+      Assert.ok(/\d+\.\d+/.test(lastMessage.timeStamp));
+    } else {
+      Assert.equal(lastExpression.text, "console.log(...[c])");
+      Assert.equal(lastExpression.lineNumber, 3);
+    }
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    "debugger;\n" + // 1
+      "var a = 'three';\n" + // 2
+      "var b = 2;\n", // 3
+    debuggee,
+    "1.8",
+    "test.js",
+    1
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_longstringgrips-01.js b/devtools/server/tests/xpcshell/test_longstringgrips-01.js
new file mode 100644
index 0000000000..ac0b228c17
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_longstringgrips-01.js
@@ -0,0 +1,75 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+var gDebuggee;
+var gClient;
+var gThreadFront;
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee, client }) => {
+      gThreadFront = threadFront;
+      gDebuggee = debuggee;
+      gClient = client;
+      test_longstring_grip();
+    },
+    { waitForFinish: true }
+  )
+);
+
+function test_longstring_grip() {
+  const longString =
+    "All I want is to be a monkey of moderate intelligence who" +
+    " wears a suit... that's why I'm transferring to business school! Maybe I" +
+    " love you so much, I love you no matter who you are pretending to be." +
+    " Enough about your promiscuous mother, Hermes! We have bigger problems." +
+    " For example, if you killed your grandfather, you'd cease to exist! What" +
+    " kind of a father would I be if I said no? Yep, I remember. They came in" +
+    " last at the Olympics, then retired to promote alcoholic beverages! And" +
+    " remember, don't do anything that affects anything, unless it turns out" +
+    " you were supposed to, in which case, for the love of God, don't not do" +
+    " it!";
+
+  DevToolsServer.LONG_STRING_LENGTH = 200;
+
+  gThreadFront.once("paused", function (packet) {
+    const args = packet.frame.arguments;
+    Assert.equal(args.length, 1);
+    const grip = args[0];
+
+    try {
+      Assert.equal(grip.type, "longString");
+      Assert.equal(grip.length, longString.length);
+      Assert.equal(
+        grip.initial,
+        longString.substr(0, DevToolsServer.LONG_STRING_INITIAL_LENGTH)
+      );
+
+      const longStringFront = createLongStringFront(gClient, grip);
+      longStringFront.substring(22, 28).then(function (response) {
+        try {
+          Assert.equal(response, "monkey");
+        } finally {
+          gThreadFront.resume().then(function () {
+            finishClient(gClient);
+          });
+        }
+      });
+    } catch (error) {
+      gThreadFront.resume().then(function () {
+        finishClient(gClient);
+        do_throw(error);
+      });
+    }
+  });
+
+  gDebuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+
+  gDebuggee.eval('stopMe("' + longString + '")');
+}
diff --git a/devtools/server/tests/xpcshell/test_nativewrappers.js b/devtools/server/tests/xpcshell/test_nativewrappers.js
new file mode 100644
index 0000000000..170a2a1e6e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_nativewrappers.js
@@ -0,0 +1,39 @@
+/* eslint-disable strict */
+function run_test() {
+  Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+  });
+  const { addDebuggerToGlobal } = ChromeUtils.importESModule(
+    "resource://gre/modules/jsdebugger.sys.mjs"
+  );
+  addDebuggerToGlobal(globalThis);
+  const g = createTestGlobal("test1");
+
+  const dbg = makeDebugger();
+  dbg.addDebuggee(g);
+  dbg.onDebuggerStatement = function (frame) {
+    const args = frame.arguments;
+    try {
+      args[0];
+      Assert.ok(true);
+    } catch (ex) {
+      Assert.ok(false);
+    }
+  };
+
+  g.eval("function stopMe(arg) {debugger;}");
+
+  const g2 = createTestGlobal("test2");
+  g2.g = g;
+  // Not using the "stringify a function" trick because that runs afoul of the
+  // Cu.importGlobalProperties lint and we don't need it here anyway.
+  g2.eval(`(function createBadEvent() {
+    Cu.importGlobalProperties(["DOMParser"]);
+    let parser = new DOMParser();
+    let doc = parser.parseFromString("<foo></foo>", "text/xml");
+    g.stopMe(doc.createEvent("MouseEvent"));
+  } )()`);
+
+  dbg.disable();
+}
diff --git a/devtools/server/tests/xpcshell/test_nesting-03.js b/devtools/server/tests/xpcshell/test_nesting-03.js
new file mode 100644
index 0000000000..0a64e751cd
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_nesting-03.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that we can detect nested event loops in tabs with the same URL.
+
+add_task(async function () {
+  const GLOBAL_NAME = "test-nesting1";
+
+  initTestDevToolsServer();
+  addTestGlobal(GLOBAL_NAME);
+  addTestGlobal(GLOBAL_NAME);
+
+  // Connect two thread actors, debugging the same debuggee, and both being paused.
+  const firstClient = new DevToolsClient(DevToolsServer.connectPipe());
+  await firstClient.connect();
+  const { threadFront: firstThreadFront } = await attachTestThread(
+    firstClient,
+    GLOBAL_NAME
+  );
+  await firstThreadFront.interrupt();
+
+  const secondClient = new DevToolsClient(DevToolsServer.connectPipe());
+  await secondClient.connect();
+  const { threadFront: secondThreadFront } = await attachTestThread(
+    secondClient,
+    GLOBAL_NAME
+  );
+  await secondThreadFront.interrupt();
+
+  // Then check how concurrent resume work
+  let result;
+  try {
+    result = await firstThreadFront.resume();
+  } catch (e) {
+    Assert.ok(e.includes("wrongOrder"), "rejects with the wrong order");
+  }
+  Assert.ok(!result, "no response");
+
+  result = await secondThreadFront.resume();
+  Assert.ok(true, "resumed as expected");
+
+  await firstThreadFront.resume();
+
+  Assert.ok(true, "resumed as expected");
+  await firstClient.close();
+
+  await finishClient(secondClient);
+});
diff --git a/devtools/server/tests/xpcshell/test_nesting-04.js b/devtools/server/tests/xpcshell/test_nesting-04.js
new file mode 100644
index 0000000000..dcee257c40
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_nesting-04.js
@@ -0,0 +1,86 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Verify that we never pause while being already paused.
+ * i.e. we don't support more than one nested event loops.
+ */
+
+add_task(
+  threadFrontTest(async ({ commands, threadFront, debuggee }) => {
+    await threadFront.setBreakpoint({ sourceUrl: "nesting-04.js", line: 2 });
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    Assert.equal(packet.frame.where.line, 5);
+    Assert.equal(packet.why.type, "debuggerStatement");
+
+    info("Test calling interrupt");
+    const onPaused = waitForPause(threadFront);
+    await threadFront.interrupt();
+    // interrupt() doesn't return anything, but bailout while emitting a paused packet
+    // But we don't pause again, the reason prove it so
+    const paused = await onPaused;
+    equal(paused.why.type, "alreadyPaused");
+
+    info("Test by evaluating code via the console");
+    const { result } = await commands.scriptCommand.execute(
+      "debugger; functionWithDebuggerStatement()",
+      {
+        frameActor: packet.frame.actorID,
+      }
+    );
+    // The fact that it returned immediately means that we did not pause
+    equal(result, 42);
+
+    info("Test by calling code from chrome context");
+    // This should be equivalent to any actor somehow triggering some page's JS
+    const rv = debuggee.functionWithDebuggerStatement();
+    // The fact that it returned immediately means that we did not pause
+    equal(rv, 42);
+
+    info("Test by stepping over a function that breaks");
+    // This will only step over the debugger; statement we just break on
+    const step1 = await stepOver(threadFront);
+    equal(step1.why.type, "resumeLimit");
+    equal(step1.frame.where.line, 6);
+
+    // stepOver will actually resume and re-pause on the breakpoint
+    const step2 = await stepOver(threadFront);
+    equal(step2.why.type, "breakpoint");
+    equal(step2.frame.where.line, 2);
+
+    // Sanity check to ensure that the functionWithDebuggerStatement really pauses
+    info("Resume and pause on the breakpoint");
+    const pausedPacket = await resumeAndWaitForPause(threadFront);
+    Assert.equal(pausedPacket.frame.where.line, 2);
+    // The breakpoint takes over the debugger statement
+    Assert.equal(pausedPacket.why.type, "breakpoint");
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  Cu.evalInSandbox(
+    `function functionWithDebuggerStatement() {
+      debugger;
+      return 42;
+    }
+    debugger;
+    functionWithDebuggerStatement();
+    var a = 1;
+    functionWithDebuggerStatement();`,
+    debuggee,
+    "1.8",
+    "nesting-04.js",
+    1
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_new_source-01.js b/devtools/server/tests/xpcshell/test_new_source-01.js
new file mode 100644
index 0000000000..929865baa8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_new_source-01.js
@@ -0,0 +1,24 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check basic newSource packet sent from server.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    Cu.evalInSandbox(
+      function inc(n) {
+        return n + 1;
+      }.toString(),
+      debuggee
+    );
+
+    const sourcePacket = await waitForEvent(threadFront, "newSource");
+
+    Assert.ok(!!sourcePacket.source);
+    Assert.ok(!!sourcePacket.source.url.match(/test_new_source-01.js$/));
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_new_source-02.js b/devtools/server/tests/xpcshell/test_new_source-02.js
new file mode 100644
index 0000000000..15259b884a
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_new_source-02.js
@@ -0,0 +1,46 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that sourceURL has the correct effect when using threadFront.eval.
+ */
+
+add_task(
+  threadFrontTest(async ({ commands, threadFront, debuggee }) => {
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const packet1 = await waitForEvent(threadFront, "newSource");
+
+    Assert.ok(!!packet1.source);
+    Assert.ok(packet1.source.introductionType, "eval");
+
+    commands.scriptCommand.execute(
+      "function f() { }\n//# sourceURL=http://example.com/code.js"
+    );
+
+    const packet2 = await waitForEvent(threadFront, "newSource");
+    dump(JSON.stringify(packet2, null, 2));
+    Assert.ok(!!packet2.source);
+    Assert.ok(!!packet2.source.url.match(/example\.com/));
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable */
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(arg1) {
+          debugger;
+        }
+        stopMe({ obj: true });
+      } +
+      ")()"
+  );
+  /* eslint-enable */
+}
diff --git a/devtools/server/tests/xpcshell/test_nodelistactor.js b/devtools/server/tests/xpcshell/test_nodelistactor.js
new file mode 100644
index 0000000000..eab6bb07e8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_nodelistactor.js
@@ -0,0 +1,30 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+// Test that a NodeListActor initialized with null nodelist doesn't cause
+// exceptions when calling NodeListActor.form.
+
+const {
+  NodeListActor,
+} = require("resource://devtools/server/actors/inspector/node.js");
+
+function run_test() {
+  check_actor_for_list(null);
+  check_actor_for_list([]);
+  check_actor_for_list(["fakenode"]);
+}
+
+function check_actor_for_list(nodelist) {
+  info("Checking NodeListActor with nodelist '" + nodelist + "' works.");
+  const actor = new NodeListActor({}, nodelist);
+  const form = actor.form();
+
+  // No exception occured as a exceptions abort the test.
+  ok(true, "No exceptions occured.");
+  equal(
+    form.length,
+    nodelist ? nodelist.length : 0,
+    "NodeListActor reported correct length."
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-02.js b/devtools/server/tests/xpcshell/test_objectgrips-02.js
new file mode 100644
index 0000000000..810a5009c0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-02.js
@@ -0,0 +1,44 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const args = packet.frame.arguments;
+
+    Assert.equal(args[0].class, "Object");
+
+    const objectFront = threadFront.pauseGrip(args[0]);
+    const response = await objectFront.getPrototype();
+    Assert.ok(response.prototype != undefined);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+  debuggee.eval(
+    function Constr() {
+      this.a = 1;
+    }.toString()
+  );
+  debuggee.eval(
+    "Constr.prototype = { b: true, c: 'foo' }; var o = new Constr(); stopMe(o)"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-03.js b/devtools/server/tests/xpcshell/test_objectgrips-03.js
new file mode 100644
index 0000000000..c8a51d41d3
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-03.js
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+    const args = packet.frame.arguments;
+
+    Assert.equal(args[0].class, "Object");
+
+    const objClient = threadFront.pauseGrip(args[0]);
+    let response = await objClient.getProperty("x");
+    Assert.equal(response.descriptor.configurable, true);
+    Assert.equal(response.descriptor.enumerable, true);
+    Assert.equal(response.descriptor.writable, true);
+    Assert.equal(response.descriptor.value, 10);
+
+    response = await objClient.getProperty("y");
+    Assert.equal(response.descriptor.configurable, true);
+    Assert.equal(response.descriptor.enumerable, true);
+    Assert.equal(response.descriptor.writable, true);
+    Assert.equal(response.descriptor.value, "kaiju");
+
+    response = await objClient.getProperty("a");
+    Assert.equal(response.descriptor.configurable, true);
+    Assert.equal(response.descriptor.enumerable, true);
+    Assert.equal(response.descriptor.get.type, "object");
+    Assert.equal(response.descriptor.get.class, "Function");
+    Assert.equal(response.descriptor.set.type, "undefined");
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+  debuggee.eval("stopMe({ x: 10, y: 'kaiju', get a() { return 42; } })");
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-04.js b/devtools/server/tests/xpcshell/test_objectgrips-04.js
new file mode 100644
index 0000000000..d08705db3c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-04.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const args = packet.frame.arguments;
+
+    Assert.equal(args[0].class, "Object");
+
+    const objectFront = threadFront.pauseGrip(args[0]);
+    const { ownProperties, prototype } =
+      await objectFront.getPrototypeAndProperties();
+    Assert.equal(ownProperties.x.configurable, true);
+    Assert.equal(ownProperties.x.enumerable, true);
+    Assert.equal(ownProperties.x.writable, true);
+    Assert.equal(ownProperties.x.value, 10);
+
+    Assert.equal(ownProperties.y.configurable, true);
+    Assert.equal(ownProperties.y.enumerable, true);
+    Assert.equal(ownProperties.y.writable, true);
+    Assert.equal(ownProperties.y.value, "kaiju");
+
+    Assert.equal(ownProperties.a.configurable, true);
+    Assert.equal(ownProperties.a.enumerable, true);
+    Assert.equal(ownProperties.a.get.getGrip().type, "object");
+    Assert.equal(ownProperties.a.get.getGrip().class, "Function");
+    Assert.equal(ownProperties.a.set.type, "undefined");
+
+    Assert.ok(prototype != undefined);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+  debuggee.eval("stopMe({ x: 10, y: 'kaiju', get a() { return 42; } })");
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-05.js b/devtools/server/tests/xpcshell/test_objectgrips-05.js
new file mode 100644
index 0000000000..4c6f0f107a
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-05.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * This test checks that frozen objects report themselves as frozen in their
+ * grip.
+ */
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const obj1 = packet.frame.arguments[0];
+    Assert.ok(obj1.frozen);
+
+    const obj1Client = threadFront.pauseGrip(obj1);
+    Assert.ok(obj1Client.isFrozen);
+
+    const obj2 = packet.frame.arguments[1];
+    Assert.ok(!obj2.frozen);
+
+    const obj2Client = threadFront.pauseGrip(obj2);
+    Assert.ok(!obj2Client.isFrozen);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+  /* eslint-disable no-undef */
+  debuggee.eval(
+    "(" +
+      function () {
+        const obj1 = {};
+        Object.freeze(obj1);
+        stopMe(obj1, {});
+      } +
+      "())"
+  );
+  /* eslint-enable no-undef */
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-06.js b/devtools/server/tests/xpcshell/test_objectgrips-06.js
new file mode 100644
index 0000000000..ef3d2b5b66
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-06.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * This test checks that sealed objects report themselves as sealed in their
+ * grip.
+ */
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const obj1 = packet.frame.arguments[0];
+    Assert.ok(obj1.sealed);
+
+    const obj1Client = threadFront.pauseGrip(obj1);
+    Assert.ok(obj1Client.isSealed);
+
+    const obj2 = packet.frame.arguments[1];
+    Assert.ok(!obj2.sealed);
+
+    const obj2Client = threadFront.pauseGrip(obj2);
+    Assert.ok(!obj2Client.isSealed);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+  /* eslint-disable no-undef */
+  debuggee.eval(
+    "(" +
+      function () {
+        const obj1 = {};
+        Object.seal(obj1);
+        stopMe(obj1, {});
+      } +
+      "())"
+  );
+  /* eslint-enable no-undef */
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-07.js b/devtools/server/tests/xpcshell/test_objectgrips-07.js
new file mode 100644
index 0000000000..2a3a0bf00e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-07.js
@@ -0,0 +1,65 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * This test checks that objects which are not extensible report themselves as
+ * such.
+ */
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const [f, s, ne, e] = packet.frame.arguments;
+    const [fClient, sClient, neClient, eClient] = packet.frame.arguments.map(
+      a => threadFront.pauseGrip(a)
+    );
+
+    Assert.ok(!f.extensible);
+    Assert.ok(!fClient.isExtensible);
+
+    Assert.ok(!s.extensible);
+    Assert.ok(!sClient.isExtensible);
+
+    Assert.ok(!ne.extensible);
+    Assert.ok(!neClient.isExtensible);
+
+    Assert.ok(e.extensible);
+    Assert.ok(eClient.isExtensible);
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+  /* eslint-disable no-undef */
+  debuggee.eval(
+    "(" +
+      function () {
+        const f = {};
+        Object.freeze(f);
+        const s = {};
+        Object.seal(s);
+        const ne = {};
+        Object.preventExtensions(ne);
+        stopMe(f, s, ne, {});
+      } +
+      "())"
+  );
+  /* eslint-enable no-undef */
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-08.js b/devtools/server/tests/xpcshell/test_objectgrips-08.js
new file mode 100644
index 0000000000..1a37f19fb8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-08.js
@@ -0,0 +1,61 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const args = packet.frame.arguments;
+
+    Assert.equal(args[0].class, "Object");
+
+    const objClient = threadFront.pauseGrip(args[0]);
+    const response = await objClient.getPrototypeAndProperties();
+    const { a, b, c, d, e, f, g } = response.ownProperties;
+    testPropertyType(a, "Infinity");
+    testPropertyType(b, "-Infinity");
+    testPropertyType(c, "NaN");
+    testPropertyType(d, "-0");
+    testPropertyType(e, "BigInt");
+    testPropertyType(f, "BigInt");
+    testPropertyType(g, "BigInt");
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+  debuggee.eval(
+    `stopMe({
+      a: Infinity,
+      b: -Infinity,
+      c: NaN,
+      d: -0,
+      e: 1n,
+      f: -2n,
+      g: 0n,
+    })`
+  );
+}
+
+function testPropertyType(prop, expectedType) {
+  Assert.equal(prop.configurable, true);
+  Assert.equal(prop.enumerable, true);
+  Assert.equal(prop.writable, true);
+  Assert.equal(prop.value.type, expectedType);
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-14.js b/devtools/server/tests/xpcshell/test_objectgrips-14.js
new file mode 100644
index 0000000000..cff8611e7d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-14.js
@@ -0,0 +1,55 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test out of scope objects with synchronous functions.
+ */
+
+var gDebuggee;
+var gThreadFront;
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    gThreadFront = threadFront;
+    gDebuggee = debuggee;
+    await testObjectGroup();
+  })
+);
+
+function evalCode() {
+  evalCallback(gDebuggee, function runTest() {
+    const ugh = [];
+    let i = 0;
+
+    (function () {
+      (function () {
+        ugh.push(i++);
+        debugger;
+      })();
+    })();
+
+    debugger;
+  });
+}
+
+const testObjectGroup = async function () {
+  let packet = await executeOnNextTickAndWaitForPause(evalCode, gThreadFront);
+
+  const environment = await packet.frame.getEnvironment();
+  const ugh = environment.parent.parent.bindings.variables.ugh;
+  const ughClient = await gThreadFront.pauseGrip(ugh.value);
+
+  packet = await getPrototypeAndProperties(ughClient);
+  packet = await resumeAndWaitForPause(gThreadFront);
+
+  const environment2 = await packet.frame.getEnvironment();
+  const ugh2 = environment2.bindings.variables.ugh;
+  const ugh2Client = gThreadFront.pauseGrip(ugh2.value);
+
+  packet = await getPrototypeAndProperties(ugh2Client);
+  Assert.equal(packet.ownProperties.length.value, 1);
+
+  await resume(gThreadFront);
+};
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-15.js b/devtools/server/tests/xpcshell/test_objectgrips-15.js
new file mode 100644
index 0000000000..3a7aba89c8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-15.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test out of scope objects with async functions.
+ */
+
+var gDebuggee;
+var gThreadFront;
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    gThreadFront = threadFront;
+    gDebuggee = debuggee;
+    await testObjectGroup();
+  })
+);
+
+function evalCode() {
+  evalCallback(gDebuggee, function runTest() {
+    const ugh = [];
+    let i = 0;
+
+    function foo() {
+      ugh.push(i++);
+      debugger;
+    }
+
+    Promise.resolve().then(foo).then(foo);
+  });
+}
+
+const testObjectGroup = async function () {
+  let packet = await executeOnNextTickAndWaitForPause(evalCode, gThreadFront);
+
+  const environment = await packet.frame.getEnvironment();
+  const ugh = environment.parent.bindings.variables.ugh;
+  const ughClient = await gThreadFront.pauseGrip(ugh.value);
+
+  packet = await getPrototypeAndProperties(ughClient);
+
+  packet = await resumeAndWaitForPause(gThreadFront);
+  const environment2 = await packet.frame.getEnvironment();
+  const ugh2 = environment2.parent.bindings.variables.ugh;
+  const ugh2Client = gThreadFront.pauseGrip(ugh2.value);
+
+  packet = await getPrototypeAndProperties(ugh2Client);
+  Assert.equal(packet.ownProperties.length.value, 2);
+
+  await resume(gThreadFront);
+};
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-16.js b/devtools/server/tests/xpcshell/test_objectgrips-16.js
new file mode 100644
index 0000000000..785c3bc36d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-16.js
@@ -0,0 +1,139 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      eval_code,
+      threadFront
+    );
+    const [grip] = packet.frame.arguments;
+
+    // Checks grip.preview properties.
+    check_preview(grip);
+
+    const objClient = threadFront.pauseGrip(grip);
+    const response = await objClient.getPrototypeAndProperties();
+    // Checks the result of getPrototypeAndProperties.
+    check_prototype_and_properties(response);
+
+    await threadFront.resume();
+
+    function eval_code() {
+      debuggee.eval(
+        function stopMe(arg1) {
+          debugger;
+        }.toString()
+      );
+      debuggee.eval(`
+        stopMe({
+          [Symbol()]: "first unnamed symbol",
+          [Symbol()]: "second unnamed symbol",
+          [Symbol("named")] : "named symbol",
+          [Symbol.iterator] : function* () {
+            yield 1;
+            yield 2;
+          },
+          x: 10,
+        });
+      `);
+    }
+
+    function check_preview(grip) {
+      Assert.equal(grip.class, "Object");
+
+      const { preview } = grip;
+      Assert.equal(preview.ownProperties.x.configurable, true);
+      Assert.equal(preview.ownProperties.x.enumerable, true);
+      Assert.equal(preview.ownProperties.x.writable, true);
+      Assert.equal(preview.ownProperties.x.value, 10);
+
+      const [
+        firstUnnamedSymbol,
+        secondUnnamedSymbol,
+        namedSymbol,
+        iteratorSymbol,
+      ] = preview.ownSymbols;
+
+      Assert.equal(firstUnnamedSymbol.name, undefined);
+      Assert.equal(firstUnnamedSymbol.type, "symbol");
+      Assert.equal(firstUnnamedSymbol.descriptor.configurable, true);
+      Assert.equal(firstUnnamedSymbol.descriptor.enumerable, true);
+      Assert.equal(firstUnnamedSymbol.descriptor.writable, true);
+      Assert.equal(firstUnnamedSymbol.descriptor.value, "first unnamed symbol");
+
+      Assert.equal(secondUnnamedSymbol.name, undefined);
+      Assert.equal(secondUnnamedSymbol.type, "symbol");
+      Assert.equal(secondUnnamedSymbol.descriptor.configurable, true);
+      Assert.equal(secondUnnamedSymbol.descriptor.enumerable, true);
+      Assert.equal(secondUnnamedSymbol.descriptor.writable, true);
+      Assert.equal(
+        secondUnnamedSymbol.descriptor.value,
+        "second unnamed symbol"
+      );
+
+      Assert.equal(namedSymbol.name, "named");
+      Assert.equal(namedSymbol.type, "symbol");
+      Assert.equal(namedSymbol.descriptor.configurable, true);
+      Assert.equal(namedSymbol.descriptor.enumerable, true);
+      Assert.equal(namedSymbol.descriptor.writable, true);
+      Assert.equal(namedSymbol.descriptor.value, "named symbol");
+
+      Assert.equal(iteratorSymbol.name, "Symbol.iterator");
+      Assert.equal(iteratorSymbol.type, "symbol");
+      Assert.equal(iteratorSymbol.descriptor.configurable, true);
+      Assert.equal(iteratorSymbol.descriptor.enumerable, true);
+      Assert.equal(iteratorSymbol.descriptor.writable, true);
+      Assert.equal(iteratorSymbol.descriptor.value.class, "Function");
+    }
+
+    function check_prototype_and_properties(response) {
+      Assert.equal(response.ownProperties.x.configurable, true);
+      Assert.equal(response.ownProperties.x.enumerable, true);
+      Assert.equal(response.ownProperties.x.writable, true);
+      Assert.equal(response.ownProperties.x.value, 10);
+
+      const [
+        firstUnnamedSymbol,
+        secondUnnamedSymbol,
+        namedSymbol,
+        iteratorSymbol,
+      ] = response.ownSymbols;
+
+      Assert.equal(firstUnnamedSymbol.name, "Symbol()");
+      Assert.equal(firstUnnamedSymbol.descriptor.configurable, true);
+      Assert.equal(firstUnnamedSymbol.descriptor.enumerable, true);
+      Assert.equal(firstUnnamedSymbol.descriptor.writable, true);
+      Assert.equal(firstUnnamedSymbol.descriptor.value, "first unnamed symbol");
+
+      Assert.equal(secondUnnamedSymbol.name, "Symbol()");
+      Assert.equal(secondUnnamedSymbol.descriptor.configurable, true);
+      Assert.equal(secondUnnamedSymbol.descriptor.enumerable, true);
+      Assert.equal(secondUnnamedSymbol.descriptor.writable, true);
+      Assert.equal(
+        secondUnnamedSymbol.descriptor.value,
+        "second unnamed symbol"
+      );
+
+      Assert.equal(namedSymbol.name, "Symbol(named)");
+      Assert.equal(namedSymbol.descriptor.configurable, true);
+      Assert.equal(namedSymbol.descriptor.enumerable, true);
+      Assert.equal(namedSymbol.descriptor.writable, true);
+      Assert.equal(namedSymbol.descriptor.value, "named symbol");
+
+      Assert.equal(iteratorSymbol.name, "Symbol(Symbol.iterator)");
+      Assert.equal(iteratorSymbol.descriptor.configurable, true);
+      Assert.equal(iteratorSymbol.descriptor.enumerable, true);
+      Assert.equal(iteratorSymbol.descriptor.writable, true);
+      Assert.equal(iteratorSymbol.descriptor.value.class, "Function");
+    }
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-17.js b/devtools/server/tests/xpcshell/test_objectgrips-17.js
new file mode 100644
index 0000000000..edaea88eaa
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-17.js
@@ -0,0 +1,320 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+async function testPrincipal(options, globalPrincipal, debuggeeHasXrays) {
+  const { debuggee } = options;
+  // Create a global object with the specified security principal.
+  // If none is specified, use the debuggee.
+  if (globalPrincipal === undefined) {
+    await test(options, {
+      global: debuggee,
+      subsumes: true,
+      isOpaque: false,
+      globalIsInvisible: false,
+    });
+    return;
+  }
+
+  const debuggeePrincipal = Cu.getObjectPrincipal(debuggee);
+  const sameOrigin = debuggeePrincipal.origin === globalPrincipal.origin;
+  const subsumes = debuggeePrincipal.subsumes(globalPrincipal);
+  for (const globalHasXrays of [true, false]) {
+    const isOpaque =
+      subsumes &&
+      globalPrincipal !== systemPrincipal &&
+      ((sameOrigin && debuggeeHasXrays) || globalHasXrays);
+    for (const globalIsInvisible of [true, false]) {
+      let global = Cu.Sandbox(globalPrincipal, {
+        wantXrays: globalHasXrays,
+        invisibleToDebugger: globalIsInvisible,
+      });
+      // Previously, the Sandbox constructor would (bizarrely) waive xrays on
+      // the return Sandbox if wantXrays was false. This has now been fixed,
+      // but we need to mimic that behavior here to make the test continue
+      // to pass.
+      if (!globalHasXrays) {
+        global = Cu.waiveXrays(global);
+      }
+      await test(options, { global, subsumes, isOpaque, globalIsInvisible });
+    }
+  }
+}
+
+async function test({ threadFront, debuggee }, testOptions) {
+  const { global } = testOptions;
+  const packet = await executeOnNextTickAndWaitForPause(eval_code, threadFront);
+  // Get the grips.
+  const [proxyGrip, inheritsProxyGrip, inheritsProxy2Grip] =
+    packet.frame.arguments;
+
+  // Check the grip of the proxy object.
+  check_proxy_grip(debuggee, testOptions, proxyGrip);
+
+  // Check the target and handler slots of the proxy object.
+  const proxyClient = threadFront.pauseGrip(proxyGrip);
+  const proxySlots = await proxyClient.getProxySlots();
+  check_proxy_slots(debuggee, testOptions, proxyGrip, proxySlots);
+
+  // Check the prototype and properties of the proxy object.
+  const proxyResponse = await proxyClient.getPrototypeAndProperties();
+  check_properties(testOptions, proxyResponse.ownProperties, true, false);
+  check_prototype(debuggee, testOptions, proxyResponse.prototype, true, false);
+
+  // Check the prototype and properties of the object which inherits from the proxy.
+  const inheritsProxyClient = threadFront.pauseGrip(inheritsProxyGrip);
+  const inheritsProxyResponse =
+    await inheritsProxyClient.getPrototypeAndProperties();
+  check_properties(
+    testOptions,
+    inheritsProxyResponse.ownProperties,
+    false,
+    false
+  );
+  check_prototype(
+    debuggee,
+    testOptions,
+    inheritsProxyResponse.prototype,
+    false,
+    false
+  );
+
+  // The prototype chain was not iterated if the object was inaccessible, so now check
+  // another object which inherits from the proxy, but was created in the debuggee.
+  const inheritsProxy2Client = threadFront.pauseGrip(inheritsProxy2Grip);
+  const inheritsProxy2Response =
+    await inheritsProxy2Client.getPrototypeAndProperties();
+  check_properties(
+    testOptions,
+    inheritsProxy2Response.ownProperties,
+    false,
+    true
+  );
+  check_prototype(
+    debuggee,
+    testOptions,
+    inheritsProxy2Response.prototype,
+    false,
+    true
+  );
+
+  // Check that none of the above ran proxy traps.
+  strictEqual(global.trapDidRun, false, "No proxy trap did run.");
+
+  // Resume the debugger and finish the current test.
+  await threadFront.resume();
+
+  function eval_code() {
+    // Create objects in `global`, and debug them in `debuggee`. They may get various
+    // kinds of security wrappers, or no wrapper at all.
+    // To detect that no proxy trap runs, the proxy handler should define all possible
+    // traps, but the list is long and may change. Therefore a second proxy is used as
+    // the handler, so that a single `get` trap suffices.
+    global.eval(`
+      var trapDidRun = false;
+      var proxy = new Proxy({}, new Proxy({}, {get: (_, trap) => {
+        trapDidRun = true;
+        throw new Error("proxy trap '" + trap + "' was called.");
+      }}));
+      var inheritsProxy = Object.create(proxy, {x:{value:1}});
+    `);
+    const data = Cu.createObjectIn(debuggee, { defineAs: "data" });
+    data.proxy = global.proxy;
+    data.inheritsProxy = global.inheritsProxy;
+    debuggee.eval(`
+      var inheritsProxy2 = Object.create(data.proxy, {x:{value:1}});
+      stopMe(data.proxy, data.inheritsProxy, inheritsProxy2);
+    `);
+  }
+}
+
+function check_proxy_grip(debuggee, testOptions, grip) {
+  const { global, isOpaque, subsumes, globalIsInvisible } = testOptions;
+  const { preview } = grip;
+
+  if (global === debuggee) {
+    // The proxy has no security wrappers.
+    strictEqual(grip.class, "Proxy", "The grip has a Proxy class.");
+    strictEqual(
+      preview.ownPropertiesLength,
+      2,
+      "The preview has 2 properties."
+    );
+    const props = preview.ownProperties;
+    ok(props["<target>"].value, "<target> contains the [[ProxyTarget]].");
+    ok(props["<handler>"].value, "<handler> contains the [[ProxyHandler]].");
+  } else if (isOpaque) {
+    // The proxy has opaque security wrappers.
+    strictEqual(grip.class, "Opaque", "The grip has an Opaque class.");
+    strictEqual(grip.ownPropertyLength, 0, "The grip has no properties.");
+  } else if (!subsumes) {
+    // The proxy belongs to compartment not subsumed by the debuggee.
+    strictEqual(grip.class, "Restricted", "The grip has a Restricted class.");
+    strictEqual(
+      grip.ownPropertyLength,
+      undefined,
+      "The grip doesn't know the number of properties."
+    );
+  } else if (globalIsInvisible) {
+    // The proxy belongs to an invisible-to-debugger compartment.
+    strictEqual(
+      grip.class,
+      "InvisibleToDebugger: Object",
+      "The grip has an InvisibleToDebugger class."
+    );
+    ok(
+      !("ownPropertyLength" in grip),
+      "The grip doesn't know the number of properties."
+    );
+  } else {
+    // The proxy has non-opaque security wrappers.
+    strictEqual(grip.class, "Proxy", "The grip has a Proxy class.");
+    strictEqual(
+      preview.ownPropertiesLength,
+      0,
+      "The preview has no properties."
+    );
+    ok(!("<target>" in preview), "The preview has no <target> property.");
+    ok(!("<handler>" in preview), "The preview has no <handler> property.");
+  }
+}
+
+function check_proxy_slots(debuggee, testOptions, grip, proxySlots) {
+  const { global } = testOptions;
+
+  if (grip.class !== "Proxy") {
+    strictEqual(
+      proxySlots,
+      null,
+      "Slots can only be retrived for Proxy grips."
+    );
+  } else if (global === debuggee) {
+    const { proxyTarget, proxyHandler } = proxySlots;
+    strictEqual(
+      proxyTarget.getGrip().type,
+      "object",
+      "There is a [[ProxyTarget]] grip."
+    );
+    strictEqual(
+      proxyHandler.getGrip().type,
+      "object",
+      "There is a [[ProxyHandler]] grip."
+    );
+  } else {
+    const { proxyTarget, proxyHandler } = proxySlots;
+    strictEqual(
+      proxyTarget.type,
+      "undefined",
+      "There is no [[ProxyTarget]] grip."
+    );
+    strictEqual(
+      proxyHandler.type,
+      "undefined",
+      "There is no [[ProxyHandler]] grip."
+    );
+  }
+}
+
+function check_properties(testOptions, props, isProxy, createdInDebuggee) {
+  const { subsumes, globalIsInvisible } = testOptions;
+  const ownPropertiesLength = Reflect.ownKeys(props).length;
+
+  if (createdInDebuggee || (!isProxy && subsumes && !globalIsInvisible)) {
+    // The debuggee can access the properties.
+    strictEqual(ownPropertiesLength, 1, "1 own property was retrieved.");
+    strictEqual(props.x.value, 1, "The property has the right value.");
+  } else {
+    // The debuggee is not allowed to access the object.
+    strictEqual(ownPropertiesLength, 0, "No own property could be retrieved.");
+  }
+}
+
+function check_prototype(
+  debuggee,
+  testOptions,
+  proto,
+  isProxy,
+  createdInDebuggee
+) {
+  const { global, isOpaque, subsumes, globalIsInvisible } = testOptions;
+  if (isOpaque && !globalIsInvisible && !createdInDebuggee) {
+    // The object is or inherits from a proxy with opaque security wrappers.
+    // The debuggee sees `Object.prototype` when retrieving the prototype.
+    strictEqual(
+      proto.getGrip().class,
+      "Object",
+      "The prototype has a Object class."
+    );
+  } else if (isProxy && isOpaque && globalIsInvisible) {
+    // The object is a proxy with opaque security wrappers in an invisible global.
+    // The debuggee sees an inaccessible `Object.prototype` when retrieving the prototype.
+    strictEqual(
+      proto.getGrip().class,
+      "InvisibleToDebugger: Object",
+      "The prototype has an InvisibleToDebugger class."
+    );
+  } else if (
+    createdInDebuggee ||
+    (!isProxy && subsumes && !globalIsInvisible)
+  ) {
+    // The object inherits from a proxy and has no security wrappers or non-opaque ones.
+    // The debuggee sees the proxy when retrieving the prototype.
+    check_proxy_grip(
+      debuggee,
+      { global, isOpaque, subsumes, globalIsInvisible },
+      proto.getGrip()
+    );
+  } else {
+    // The debuggee is not allowed to access the object. It sees a null prototype.
+    strictEqual(proto.type, "null", "The prototype is null.");
+  }
+}
+
+function createNullPrincipal() {
+  return Services.scriptSecurityManager.createNullPrincipal({});
+}
+
+async function run_tests_in_principal(
+  options,
+  debuggeePrincipal,
+  debuggeeHasXrays
+) {
+  const { debuggee } = options;
+  debuggee.eval(
+    function stopMe(arg1, arg2) {
+      debugger;
+    }.toString()
+  );
+
+  // Test objects created in the debuggee.
+  await testPrincipal(options, undefined, debuggeeHasXrays);
+
+  // Test objects created in a system principal new global.
+  await testPrincipal(options, systemPrincipal, debuggeeHasXrays);
+
+  // Test objects created in a cross-origin null principal new global.
+  await testPrincipal(options, createNullPrincipal(), debuggeeHasXrays);
+
+  if (debuggeePrincipal != systemPrincipal) {
+    // Test objects created in a same-origin principal new global.
+    await testPrincipal(options, debuggeePrincipal, debuggeeHasXrays);
+  }
+}
+
+for (const principal of [systemPrincipal, createNullPrincipal()]) {
+  for (const wantXrays of [true, false]) {
+    add_task(
+      threadFrontTest(
+        options => run_tests_in_principal(options, principal, wantXrays),
+        { principal, wantXrays }
+      )
+    );
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-18.js b/devtools/server/tests/xpcshell/test_objectgrips-18.js
new file mode 100644
index 0000000000..90c38d99a9
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-18.js
@@ -0,0 +1,173 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      eval_code,
+      threadFront
+    );
+
+    const [grip] = packet.frame.arguments;
+
+    const objectFront = threadFront.pauseGrip(grip);
+
+    // Checks the result of enumProperties.
+    let response = await objectFront.enumProperties({});
+    await check_enum_properties(response);
+
+    // Checks the result of enumSymbols.
+    response = await objectFront.enumSymbols();
+    await check_enum_symbols(response);
+
+    await threadFront.resume();
+
+    function eval_code() {
+      debuggee.eval(
+        function stopMe(arg1) {
+          debugger;
+        }.toString()
+      );
+
+      debuggee.eval(`
+        var obj = Array.from({length: 10})
+          .reduce((res, _, i) => {
+            res["property_" + i + "_key"] = "property_" + i + "_value";
+            res[Symbol("symbol_" + i)] = "symbol_" + i + "_value";
+            return res;
+          }, {});
+
+        obj[Symbol()] = "first unnamed symbol";
+        obj[Symbol()] = "second unnamed symbol";
+        obj[Symbol.iterator] = function* () {
+          yield 1;
+          yield 2;
+        };
+
+        stopMe(obj);
+      `);
+    }
+
+    async function check_enum_properties(iterator) {
+      equal(iterator.count, 10, "iterator.count has the expected value");
+
+      info("Check iterator.slice response for all properties");
+      let sliceResponse = await iterator.slice(0, iterator.count);
+      ok(
+        sliceResponse &&
+          Object.getOwnPropertyNames(sliceResponse).includes("ownProperties"),
+        "The response object has an ownProperties property"
+      );
+
+      let { ownProperties } = sliceResponse;
+      let names = Object.keys(ownProperties);
+      equal(
+        names.length,
+        iterator.count,
+        "The response has the expected number of properties"
+      );
+      for (let i = 0; i < names.length; i++) {
+        const name = names[i];
+        equal(name, `property_${i}_key`);
+        equal(ownProperties[name].value, `property_${i}_value`);
+      }
+
+      info("Check iterator.all response");
+      const allResponse = await iterator.all();
+      deepEqual(
+        allResponse,
+        sliceResponse,
+        "iterator.all response has the expected data"
+      );
+
+      info("Check iterator response for 2 properties only");
+      sliceResponse = await iterator.slice(2, 2);
+      ok(
+        sliceResponse &&
+          Object.getOwnPropertyNames(sliceResponse).includes("ownProperties"),
+        "The response object has an ownProperties property"
+      );
+
+      ownProperties = sliceResponse.ownProperties;
+      names = Object.keys(ownProperties);
+      equal(
+        names.length,
+        2,
+        "The response has the expected number of properties"
+      );
+      equal(names[0], `property_2_key`);
+      equal(names[1], `property_3_key`);
+      equal(ownProperties[names[0]].value, `property_2_value`);
+      equal(ownProperties[names[1]].value, `property_3_value`);
+    }
+
+    async function check_enum_symbols(iterator) {
+      equal(iterator.count, 13, "iterator.count has the expected value");
+
+      info("Check iterator.slice response for all symbols");
+      let sliceResponse = await iterator.slice(0, iterator.count);
+      ok(
+        sliceResponse &&
+          Object.getOwnPropertyNames(sliceResponse).includes("ownSymbols"),
+        "The response object has an ownSymbols property"
+      );
+
+      let { ownSymbols } = sliceResponse;
+      equal(
+        ownSymbols.length,
+        iterator.count,
+        "The response has the expected number of symbols"
+      );
+      for (let i = 0; i < 10; i++) {
+        const symbol = ownSymbols[i];
+        equal(symbol.name, `Symbol(symbol_${i})`);
+        equal(symbol.descriptor.value, `symbol_${i}_value`);
+      }
+      const firstUnnamedSymbol = ownSymbols[10];
+      equal(firstUnnamedSymbol.name, "Symbol()");
+      equal(firstUnnamedSymbol.descriptor.value, "first unnamed symbol");
+
+      const secondUnnamedSymbol = ownSymbols[11];
+      equal(secondUnnamedSymbol.name, "Symbol()");
+      equal(secondUnnamedSymbol.descriptor.value, "second unnamed symbol");
+
+      const iteratorSymbol = ownSymbols[12];
+      equal(iteratorSymbol.name, "Symbol(Symbol.iterator)");
+      equal(iteratorSymbol.descriptor.value.getGrip().class, "Function");
+
+      info("Check iterator.all response");
+      const allResponse = await iterator.all();
+      deepEqual(
+        allResponse,
+        sliceResponse,
+        "iterator.all response has the expected data"
+      );
+
+      info("Check iterator response for 2 symbols only");
+      sliceResponse = await iterator.slice(9, 2);
+      ok(
+        sliceResponse &&
+          Object.getOwnPropertyNames(sliceResponse).includes("ownSymbols"),
+        "The response object has an ownSymbols property"
+      );
+
+      ownSymbols = sliceResponse.ownSymbols;
+      equal(
+        ownSymbols.length,
+        2,
+        "The response has the expected number of symbols"
+      );
+      equal(ownSymbols[0].name, "Symbol(symbol_9)");
+      equal(ownSymbols[0].descriptor.value, "symbol_9_value");
+      equal(ownSymbols[1].name, "Symbol()");
+      equal(ownSymbols[1].descriptor.value, "first unnamed symbol");
+    }
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-19.js b/devtools/server/tests/xpcshell/test_objectgrips-19.js
new file mode 100644
index 0000000000..655c7d0f43
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-19.js
@@ -0,0 +1,75 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client }) => {
+    debuggee.eval(
+      function stopMe(arg1) {
+        debugger;
+      }.toString()
+    );
+    const tests = [
+      {
+        value: true,
+        class: "Boolean",
+      },
+      {
+        value: 123,
+        class: "Number",
+      },
+      {
+        value: "foo",
+        class: "String",
+      },
+      {
+        value: Symbol("bar"),
+        class: "Symbol",
+        name: "bar",
+      },
+    ];
+    for (const data of tests) {
+      debuggee.primitive = data.value;
+      const packet = await executeOnNextTickAndWaitForPause(() => {
+        debuggee.eval("stopMe(Object(primitive));");
+      }, threadFront);
+
+      const [grip] = packet.frame.arguments;
+      check_wrapped_primitive_grip(grip, data);
+
+      await threadFront.resume();
+    }
+  })
+);
+
+function check_wrapped_primitive_grip(grip, data) {
+  strictEqual(grip.class, data.class, "The grip has the proper class.");
+
+  if (!grip.preview) {
+    // In a worker thread Cu does not exist, the objects are considered unsafe and
+    // can't be unwrapped, so there is no preview.
+    return;
+  }
+
+  const value = grip.preview.wrappedValue;
+  if (data.class === "Symbol") {
+    strictEqual(
+      value.type,
+      "symbol",
+      "The wrapped value grip has symbol type."
+    );
+    strictEqual(
+      value.name,
+      data.name,
+      "The wrapped value grip has the proper name."
+    );
+  } else {
+    strictEqual(value, data.value, "The wrapped value is the primitive one.");
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-20.js b/devtools/server/tests/xpcshell/test_objectgrips-20.js
new file mode 100644
index 0000000000..5027ca31a7
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-20.js
@@ -0,0 +1,387 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that onEnumProperties returns the expected data
+// when passing `ignoreNonIndexedProperties` and `ignoreIndexedProperties` options
+// with various objects. (See Bug 1403065)
+
+const DO_NOT_CHECK_VALUE = Symbol();
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client }) => {
+    debuggee.eval(
+      function stopMe(arg1) {
+        debugger;
+      }.toString()
+    );
+
+    const testCases = [
+      {
+        evaledObject: { a: 10 },
+        expectedIndexedProperties: [],
+        expectedNonIndexedProperties: [["a", 10]],
+      },
+      {
+        evaledObject: { length: 10 },
+        expectedIndexedProperties: [],
+        expectedNonIndexedProperties: [["length", 10]],
+      },
+      {
+        evaledObject: { a: 10, 0: "indexed" },
+        expectedIndexedProperties: [["0", "indexed"]],
+        expectedNonIndexedProperties: [["a", 10]],
+      },
+      {
+        evaledObject: { 1: 1, length: 42, a: 10 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [
+          ["length", 42],
+          ["a", 10],
+        ],
+      },
+      {
+        evaledObject: { 1: 1, length: 2.34, a: 10 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [
+          ["length", 2.34],
+          ["a", 10],
+        ],
+      },
+      {
+        evaledObject: { 1: 1, length: -0, a: 10 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [
+          ["length", -0],
+          ["a", 10],
+        ],
+      },
+      {
+        evaledObject: { 1: 1, length: -10, a: 10 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [
+          ["length", -10],
+          ["a", 10],
+        ],
+      },
+      {
+        evaledObject: { 1: 1, length: true, a: 10 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [
+          ["length", true],
+          ["a", 10],
+        ],
+      },
+      {
+        evaledObject: { 1: 1, length: null, a: 10 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [
+          ["length", DO_NOT_CHECK_VALUE],
+          ["a", 10],
+        ],
+      },
+      {
+        evaledObject: { 1: 1, length: Math.pow(2, 53), a: 10 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [
+          ["length", 9007199254740992],
+          ["a", 10],
+        ],
+      },
+      {
+        evaledObject: { 1: 1, length: "fake", a: 10 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [
+          ["length", "fake"],
+          ["a", 10],
+        ],
+      },
+      {
+        evaledObject: { 1: 1, length: Infinity, a: 10 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [
+          ["length", DO_NOT_CHECK_VALUE],
+          ["a", 10],
+        ],
+      },
+      {
+        evaledObject: { 0: 0, length: 0 },
+        expectedIndexedProperties: [["0", 0]],
+        expectedNonIndexedProperties: [["length", 0]],
+      },
+      {
+        evaledObject: { 0: 0, 1: 1, length: 1 },
+        expectedIndexedProperties: [
+          ["0", 0],
+          ["1", 1],
+        ],
+        expectedNonIndexedProperties: [["length", 1]],
+      },
+      {
+        evaledObject: { length: 0 },
+        expectedIndexedProperties: [],
+        expectedNonIndexedProperties: [["length", 0]],
+      },
+      {
+        evaledObject: { 1: 1 },
+        expectedIndexedProperties: [["1", 1]],
+        expectedNonIndexedProperties: [],
+      },
+      {
+        evaledObject: { a: 1, [2 ** 32 - 2]: 2, [2 ** 32 - 1]: 3 },
+        expectedIndexedProperties: [["4294967294", 2]],
+        expectedNonIndexedProperties: [
+          ["a", 1],
+          ["4294967295", 3],
+        ],
+      },
+      {
+        evaledObject: `(() => {
+          x = [12, 42];
+          x.foo = 90;
+          return x;
+        })()`,
+        expectedIndexedProperties: [
+          ["0", 12],
+          ["1", 42],
+        ],
+        expectedNonIndexedProperties: [
+          ["length", 2],
+          ["foo", 90],
+        ],
+      },
+      {
+        evaledObject: `(() => {
+          x = [12, 42];
+          x.length = 3;
+          return x;
+        })()`,
+        expectedIndexedProperties: [
+          ["0", 12],
+          ["1", 42],
+          ["2", undefined],
+        ],
+        expectedNonIndexedProperties: [["length", 3]],
+      },
+      {
+        evaledObject: `(() => {
+          x = [12, 42];
+          x.length = 1;
+          return x;
+        })()`,
+        expectedIndexedProperties: [["0", 12]],
+        expectedNonIndexedProperties: [["length", 1]],
+      },
+      {
+        evaledObject: `(() => {
+          x = [, 42,,];
+          x.foo = 90;
+          return x;
+        })()`,
+        expectedIndexedProperties: [
+          ["0", undefined],
+          ["1", 42],
+          ["2", undefined],
+        ],
+        expectedNonIndexedProperties: [
+          ["length", 3],
+          ["foo", 90],
+        ],
+      },
+      {
+        evaledObject: `(() => {
+          x = Array(2);
+          x.foo = "bar";
+          x.bar = "foo";
+          return x;
+        })()`,
+        expectedIndexedProperties: [
+          ["0", undefined],
+          ["1", undefined],
+        ],
+        expectedNonIndexedProperties: [
+          ["length", 2],
+          ["foo", "bar"],
+          ["bar", "foo"],
+        ],
+      },
+      {
+        evaledObject: `(() => {
+          x = new Int8Array(new ArrayBuffer(2));
+          x.foo = "bar";
+          x.bar = "foo";
+          return x;
+        })()`,
+        expectedIndexedProperties: [
+          ["0", 0],
+          ["1", 0],
+        ],
+        expectedNonIndexedProperties: [
+          ["foo", "bar"],
+          ["bar", "foo"],
+          ["length", 2],
+          ["buffer", DO_NOT_CHECK_VALUE],
+          ["byteLength", 2],
+          ["byteOffset", 0],
+        ],
+      },
+      {
+        evaledObject: `(() => {
+          x = new Int8Array([1, 2]);
+          Object.defineProperty(x, 'length', {value: 0});
+          return x;
+        })()`,
+        expectedIndexedProperties: [
+          ["0", 1],
+          ["1", 2],
+        ],
+        expectedNonIndexedProperties: [
+          ["length", 0],
+          ["buffer", DO_NOT_CHECK_VALUE],
+          ["byteLength", 2],
+          ["byteOffset", 0],
+        ],
+      },
+      {
+        evaledObject: `(() => {
+          x = new Int32Array([1, 2]);
+          Object.setPrototypeOf(x, null);
+          return x;
+        })()`,
+        expectedIndexedProperties: [
+          ["0", 1],
+          ["1", 2],
+        ],
+        expectedNonIndexedProperties: [],
+      },
+      {
+        evaledObject: `(() => {
+          return new (class extends Int8Array {})([1, 2]);
+        })()`,
+        expectedIndexedProperties: [
+          ["0", 1],
+          ["1", 2],
+        ],
+        expectedNonIndexedProperties: [
+          ["length", 2],
+          ["buffer", DO_NOT_CHECK_VALUE],
+          ["byteLength", 2],
+          ["byteOffset", 0],
+        ],
+      },
+    ];
+
+    for (const test of testCases) {
+      await test_object_grip(debuggee, client, threadFront, test);
+    }
+  })
+);
+
+async function test_object_grip(
+  debuggee,
+  dbgClient,
+  threadFront,
+  testData = {}
+) {
+  const {
+    evaledObject,
+    expectedIndexedProperties,
+    expectedNonIndexedProperties,
+  } = testData;
+
+  const packet = await executeOnNextTickAndWaitForPause(eval_code, threadFront);
+
+  const [grip] = packet.frame.arguments;
+
+  const objClient = threadFront.pauseGrip(grip);
+
+  info(`
+        Check enumProperties response for
+        ${
+          typeof evaledObject === "string"
+            ? evaledObject
+            : JSON.stringify(evaledObject)
+        }
+      `);
+
+  // Checks the result of enumProperties.
+  let response = await objClient.enumProperties({
+    ignoreNonIndexedProperties: true,
+  });
+  await check_enum_properties(response, expectedIndexedProperties);
+
+  response = await objClient.enumProperties({
+    ignoreIndexedProperties: true,
+  });
+  await check_enum_properties(response, expectedNonIndexedProperties);
+
+  await threadFront.resume();
+
+  function eval_code() {
+    // Be sure to run debuggee code in its own HTML 'task', so that when we call
+    // the onDebuggerStatement hook, the test's own microtasks don't get suspended
+    // along with the debuggee's.
+    do_timeout(0, () => {
+      debuggee.eval(`
+        stopMe(${
+          typeof evaledObject === "string"
+            ? evaledObject
+            : JSON.stringify(evaledObject)
+        });
+      `);
+    });
+  }
+}
+
+async function check_enum_properties(iterator, expected = []) {
+  equal(
+    iterator.count,
+    expected.length,
+    "iterator.count has the expected value"
+  );
+
+  info("Check iterator.slice response for all properties");
+  const sliceResponse = await iterator.slice(0, iterator.count);
+  ok(
+    sliceResponse &&
+      Object.getOwnPropertyNames(sliceResponse).includes("ownProperties"),
+    "The response object has an ownProperties property"
+  );
+
+  const { ownProperties } = sliceResponse;
+  const names = Object.getOwnPropertyNames(ownProperties);
+  equal(
+    names.length,
+    expected.length,
+    "The response has the expected number of properties"
+  );
+  for (let i = 0; i < names.length; i++) {
+    const name = names[i];
+    const [key, value] = expected[i];
+    equal(name, key, "Property has the expected name");
+    const property = ownProperties[name];
+
+    if (value === DO_NOT_CHECK_VALUE) {
+      return;
+    }
+
+    if (value === undefined) {
+      equal(
+        property,
+        undefined,
+        `Response has no value for the "${key}" property`
+      );
+    } else {
+      const propValue = property.hasOwnProperty("value")
+        ? property.value
+        : property.getterValue;
+      equal(propValue, value, `Property "${key}" has the expected value`);
+    }
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-21.js b/devtools/server/tests/xpcshell/test_objectgrips-21.js
new file mode 100644
index 0000000000..cfb4f7486f
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-21.js
@@ -0,0 +1,398 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+// Run test_unsafe_grips twice, one against a system principal debuggee
+// and another time with a null principal debuggee
+
+// The following tests work like this:
+// - The specified code is evaluated in a system principal.
+//   `Cu`, `systemPrincipal` and `Services` are provided as global variables.
+// - The resulting object is debugged in a system or null principal debuggee,
+//   depending on in which list the test is placed.
+//   It is tested according to the specified test parameters.
+// - An ordinary object that inherits from the resulting one is also debugged.
+//   This is just to check that it can be normally debugged even with an unsafe
+//   object in the prototype. The specified test parameters do not apply.
+
+// The following tests are defined via properties with the following defaults.
+const defaults = {
+  // The class of the grip.
+  class: "Restricted",
+
+  // The stringification of the object
+  string: "",
+
+  // Whether the object (not its grip) has class "Function".
+  isFunction: false,
+
+  // Whether the grip has a preview property.
+  hasPreview: true,
+
+  // Code that assigns the object to be tested into the obj variable.
+  code: "var obj = {}",
+
+  // The type of the grip of the prototype.
+  protoType: "null",
+
+  // Whether the object has some own string properties.
+  hasOwnPropertyNames: false,
+
+  // Whether the object has some own symbol properties.
+  hasOwnPropertySymbols: false,
+
+  // The descriptor obtained when retrieving property "x" or Symbol("x").
+  property: undefined,
+
+  // Code evaluated after the test, whose result is expected to be true.
+  afterTest: "true == true",
+};
+
+// The following tests use a system principal debuggee.
+const systemPrincipalTests = [
+  {
+    // Dead objects throw a TypeError when accessing properties.
+    class: "DeadObject",
+    string: "<dead object>",
+    code: `
+    var obj = Cu.Sandbox(null);
+    Cu.nukeSandbox(obj);
+  `,
+    property: descriptor({ value: "TypeError" }),
+  },
+  {
+    // This proxy checks that no trap runs (using a second proxy as the handler
+    // there is no need to maintain a list of all possible traps).
+    class: "Proxy",
+    string: "<proxy>",
+    code: `
+    var trapDidRun = false;
+    var obj = new Proxy({}, new Proxy({}, {get: (_, trap) => {
+      trapDidRun = true;
+      throw new Error("proxy trap '" + trap + "' was called.");
+    }}));
+  `,
+    afterTest: "trapDidRun === false",
+  },
+  {
+    // Like the previous test, but now the proxy has a Function class.
+    class: "Proxy",
+    string: "<proxy>",
+    isFunction: true,
+    code: `
+    var trapDidRun = false;
+    var obj = new Proxy(function(){}, new Proxy({}, {get: (_, trap) => {
+      trapDidRun = true;
+      throw new Error("proxy trap '" + trap + "' was called.(function)");
+    }}));
+  `,
+    afterTest: "trapDidRun === false",
+  },
+  {
+    // Invisisible-to-debugger objects can't be unwrapped, so we don't know if
+    // they are proxies. Thus they shouldn't be accessed.
+    class: "InvisibleToDebugger: Array",
+    string: "<invisibleToDebugger>",
+    hasPreview: false,
+    code: `
+    var s = Cu.Sandbox(systemPrincipal, {invisibleToDebugger: true});
+    var obj = s.eval("[1, 2, 3]");
+  `,
+  },
+  {
+    // Like the previous test, but now the object has a Function class.
+    class: "InvisibleToDebugger: Function",
+    string: "<invisibleToDebugger>",
+    isFunction: true,
+    hasPreview: false,
+    code: `
+    var s = Cu.Sandbox(systemPrincipal, {invisibleToDebugger: true});
+    var obj = s.eval("(function func(arg){})");
+  `,
+  },
+  {
+    // Cu.Sandbox is a WrappedNative that throws when accessing properties.
+    class: "nsXPCComponents_utils_Sandbox",
+    string: "[object nsXPCComponents_utils_Sandbox]",
+    code: `var obj = Cu.Sandbox;`,
+    protoType: "object",
+  },
+];
+
+// The following tests run code in a system principal, but the resulting object
+// is debugged in a null principal.
+const nullPrincipalTests = [
+  {
+    // The null principal gets undefined when attempting to access properties.
+    string: "[object Object]",
+    code: `var obj = {x: -1};`,
+  },
+  {
+    // For arrays it's an error instead of undefined.
+    string: "[object Object]",
+    code: `var obj = [1, 2, 3];`,
+    property: descriptor({ value: "Error" }),
+  },
+  {
+    // For functions it's also an error.
+    string: "function func(arg){}",
+    isFunction: true,
+    hasPreview: false,
+    code: `var obj = function func(arg){};`,
+    property: descriptor({ value: "Error" }),
+  },
+  {
+    // Check that no proxy trap runs.
+    string: "[object Object]",
+    code: `
+    var trapDidRun = false;
+    var obj = new Proxy([], new Proxy({}, {get: (_, trap) => {
+      trapDidRun = true;
+      throw new Error("proxy trap '" + trap + "' was called.");
+    }}));
+  `,
+    property: descriptor({ value: "Error" }),
+    afterTest: `trapDidRun === false`,
+  },
+  {
+    // Like the previous test, but now the object is a callable Proxy.
+    string: "function () {\n    [native code]\n}",
+    isFunction: true,
+    hasPreview: false,
+    code: `
+    var trapDidRun = false;
+    var obj = new Proxy(function(){}, new Proxy({}, {get: (_, trap) => {
+      trapDidRun = true;
+      throw new Error("proxy trap '" + trap + "' was called.");
+    }}));
+  `,
+    property: descriptor({ value: "Error" }),
+    afterTest: `trapDidRun === false`,
+  },
+  {
+    // Cross-origin Window objects do expose some properties and have a preview.
+    string: "[object Object]",
+    code: `var obj = Services.appShell.createWindowlessBrowser().document.defaultView;`,
+    hasOwnPropertyNames: true,
+    hasOwnPropertySymbols: true,
+    property: descriptor({ value: "SecurityError" }),
+    previewUrl: "about:blank",
+  },
+  {
+    // Cross-origin Location objects do expose some properties and have a preview.
+    string: "[object Object]",
+    code: `var obj = Services.appShell.createWindowlessBrowser().document.defaultView
+                   .location;`,
+    hasOwnPropertyNames: true,
+    hasOwnPropertySymbols: true,
+    property: descriptor({ value: "SecurityError" }),
+  },
+];
+
+function descriptor(descr) {
+  return Object.assign(
+    {
+      configurable: false,
+      writable: false,
+      enumerable: false,
+      value: undefined,
+    },
+    descr
+  );
+}
+
+async function test_unsafe_grips(
+  { threadFront, debuggee, isWorkerServer },
+  tests
+) {
+  debuggee.eval(
+    function stopMe(arg1, arg2) {
+      debugger;
+    }.toString()
+  );
+
+  for (let data of tests) {
+    data = { ...defaults, ...data };
+
+    // Run the code and test the results.
+    const sandbox = Cu.Sandbox(systemPrincipal);
+    Object.assign(sandbox, { Services, systemPrincipal, Cu });
+    sandbox.eval(data.code);
+    debuggee.obj = sandbox.obj;
+    const inherits = `Object.create(obj, {
+        x: {value: 1},
+        [Symbol.for("x")]: {value: 2}
+      })`;
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => debuggee.eval(`stopMe(obj, ${inherits});`),
+      threadFront
+    );
+
+    const [objGrip, inheritsGrip] = packet.frame.arguments;
+    for (const grip of [objGrip, inheritsGrip]) {
+      const isUnsafe = grip === objGrip;
+      // If `isUnsafe` is true, the parameters in `data` will be used to assert
+      // against `objGrip`, the grip of the object `obj` created by the test.
+      // Otherwise, the grip will refer to `inherits`, an ordinary object which
+      // inherits from `obj`. Then all checks are hardcoded because in every test
+      // all methods are expected to work the same on `inheritsGrip`.
+      check_grip(grip, data, isUnsafe, isWorkerServer);
+
+      const objClient = threadFront.pauseGrip(grip);
+      let response, slice;
+
+      response = await objClient.getPrototypeAndProperties();
+      check_properties(response.ownProperties, data, isUnsafe);
+      check_symbols(response.ownSymbols, data, isUnsafe);
+      check_prototype(response.prototype, data, isUnsafe, isWorkerServer);
+
+      response = await objClient.enumProperties({
+        ignoreIndexedProperties: true,
+      });
+      slice = await response.slice(0, response.count);
+      check_properties(slice.ownProperties, data, isUnsafe);
+
+      response = await objClient.enumProperties({});
+      slice = await response.slice(0, response.count);
+      check_properties(slice.ownProperties, data, isUnsafe);
+
+      response = await objClient.getProperty("x");
+      check_property(response.descriptor, data, isUnsafe);
+
+      response = await objClient.enumSymbols();
+      slice = await response.slice(0, response.count);
+      check_symbol_names(slice.ownSymbols, data, isUnsafe);
+
+      response = await objClient.getProperty(Symbol.for("x"));
+      check_symbol(response.descriptor, data, isUnsafe);
+
+      response = await objClient.getPrototype();
+      check_prototype(response.prototype, data, isUnsafe, isWorkerServer);
+
+      await objClient.release();
+    }
+
+    await threadFront.resume();
+
+    ok(sandbox.eval(data.afterTest), "Check after test passes");
+  }
+}
+
+function check_grip(grip, data, isUnsafe, isWorkerServer) {
+  if (isUnsafe) {
+    strictEqual(grip.class, data.class, "The grip has the proper class.");
+    strictEqual("preview" in grip, data.hasPreview, "Check preview presence.");
+    // preview.url isn't populated on worker server.
+    if (data.previewUrl && !isWorkerServer) {
+      console.trace();
+      strictEqual(
+        grip.preview.url,
+        data.previewUrl,
+        `Check preview.url for "${data.code}".`
+      );
+    }
+  } else {
+    strictEqual(grip.class, "Object", "The grip has 'Object' class.");
+    ok("preview" in grip, "The grip has a preview.");
+  }
+}
+
+function check_properties(props, data, isUnsafe) {
+  const propNames = Reflect.ownKeys(props);
+  check_property_names(propNames, data, isUnsafe);
+  if (isUnsafe) {
+    deepEqual(props.x, undefined, "The property does not exist.");
+  } else {
+    strictEqual(props.x.value, 1, "The property has the right value.");
+  }
+}
+
+function check_property_names(props, data, isUnsafe) {
+  if (isUnsafe) {
+    strictEqual(
+      !!props.length,
+      data.hasOwnPropertyNames,
+      "Check presence of own string properties."
+    );
+  } else {
+    strictEqual(props.length, 1, "1 own property was retrieved.");
+    strictEqual(props[0], "x", "The property has the right name.");
+  }
+}
+
+function check_property(descr, data, isUnsafe) {
+  if (isUnsafe) {
+    deepEqual(descr, data.property, "Got the right property descriptor.");
+  } else {
+    strictEqual(descr.value, 1, "The property has the right value.");
+  }
+}
+
+function check_symbols(symbols, data, isUnsafe) {
+  check_symbol_names(symbols, data, isUnsafe);
+  if (!isUnsafe) {
+    check_symbol(symbols[0].descriptor, data, isUnsafe);
+  }
+}
+
+function check_symbol_names(props, data, isUnsafe) {
+  if (isUnsafe) {
+    strictEqual(
+      !!props.length,
+      data.hasOwnPropertySymbols,
+      "Check presence of own symbol properties."
+    );
+  } else {
+    strictEqual(props.length, 1, "1 own symbol property was retrieved.");
+    strictEqual(props[0].name, "Symbol(x)", "The symbol has the right name.");
+  }
+}
+
+function check_symbol(descr, data, isUnsafe) {
+  if (isUnsafe) {
+    deepEqual(
+      descr,
+      data.property,
+      "Got the right symbol property descriptor."
+    );
+  } else {
+    strictEqual(descr.value, 2, "The symbol property has the right value.");
+  }
+}
+
+function check_prototype(proto, data, isUnsafe, isWorkerServer) {
+  const protoGrip = proto && proto.getGrip ? proto.getGrip() : proto;
+  if (isUnsafe) {
+    deepEqual(protoGrip.type, data.protoType, "Got the right prototype type.");
+  } else {
+    check_grip(protoGrip, data, true, isWorkerServer);
+  }
+}
+
+// threadFrontTest uses systemPrincipal by default, but let's be explicit here.
+add_task(
+  threadFrontTest(
+    options => {
+      return test_unsafe_grips(options, systemPrincipalTests, "system");
+    },
+    { principal: systemPrincipal }
+  )
+);
+
+const nullPrincipal = Services.scriptSecurityManager.createNullPrincipal({});
+add_task(
+  threadFrontTest(
+    options => {
+      return test_unsafe_grips(options, nullPrincipalTests, "null");
+    },
+    { principal: nullPrincipal }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-22.js b/devtools/server/tests/xpcshell/test_objectgrips-22.js
new file mode 100644
index 0000000000..34264f5534
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-22.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const [grip] = packet.frame.arguments;
+    const objClient = threadFront.pauseGrip(grip);
+    const iterator = await objClient.enumSymbols();
+    const { ownSymbols } = await iterator.slice(0, iterator.count);
+
+    strictEqual(ownSymbols.length, 1, "There is 1 symbol property.");
+    const { name, descriptor } = ownSymbols[0];
+    strictEqual(name, "Symbol(sym)", "Got right symbol name.");
+    deepEqual(
+      descriptor,
+      {
+        configurable: false,
+        enumerable: false,
+        writable: false,
+        value: 1,
+      },
+      "Got right property descriptor."
+    );
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+  debuggee.eval(
+    `stopMe(Object.defineProperty({}, Symbol("sym"), {value: 1}));`
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-23.js b/devtools/server/tests/xpcshell/test_objectgrips-23.js
new file mode 100644
index 0000000000..b44beb2c2d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-23.js
@@ -0,0 +1,45 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that ES6 classes grip have the expected properties.
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const [grip] = packet.frame.arguments;
+    strictEqual(
+      grip.class,
+      "Function",
+      `Grip has expected value for "class" property`
+    );
+    strictEqual(
+      grip.isClassConstructor,
+      true,
+      `Grip has expected value for "isClassConstructor" property`
+    );
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(`
+    class MyClass {};
+    stopMe(MyClass);
+
+    function stopMe(arg1) {
+      debugger;
+    }
+  `);
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-24.js b/devtools/server/tests/xpcshell/test_objectgrips-24.js
new file mode 100644
index 0000000000..9d541c108d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-24.js
@@ -0,0 +1,57 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that ES6 classes grip have the expected properties.
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    debuggee.eval(
+      function stopMe() {
+        debugger;
+      }.toString()
+    );
+
+    const tests = [
+      {
+        fn: `function(){}`,
+        isAsync: false,
+        isGenerator: false,
+      },
+      {
+        fn: `async function(){}`,
+        isAsync: true,
+        isGenerator: false,
+      },
+      {
+        fn: `function *(){}`,
+        isAsync: false,
+        isGenerator: true,
+      },
+      {
+        fn: `async function *(){}`,
+        isAsync: true,
+        isGenerator: true,
+      },
+    ];
+
+    for (const { fn, isAsync, isGenerator } of tests) {
+      const packet = await executeOnNextTickAndWaitForPause(
+        () => debuggee.eval(`stopMe(${fn})`),
+        threadFront
+      );
+      const [grip] = packet.frame.arguments;
+      strictEqual(grip.class, "Function");
+      strictEqual(grip.isAsync, isAsync);
+      strictEqual(grip.isGenerator, isGenerator);
+
+      await threadFront.resume();
+    }
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-25.js b/devtools/server/tests/xpcshell/test_objectgrips-25.js
new file mode 100644
index 0000000000..f80572bb19
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-25.js
@@ -0,0 +1,131 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test object with private properties (preview + enumPrivateProperties)
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(obj) {
+      debugger;
+    }.toString()
+  );
+  debuggee.eval(`
+    class MyClass {
+      constructor(name, password) {
+        this.name = name;
+        this.#password = password;
+      }
+
+      #password;
+      #salt = "sEcr3t";
+      #getSaltedPassword() {
+        return this.#password + this.#salt;
+      }
+    }
+
+    stopMe(new MyClass("Susie", "p4$$w0rD"));
+  `);
+}
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const [grip] = packet.frame.arguments;
+
+    let { privateProperties } = grip.preview;
+    strictEqual(
+      privateProperties.length,
+      2,
+      "There is 2 private properties in the grip preview"
+    );
+    let [password, salt] = privateProperties;
+
+    strictEqual(
+      password.name,
+      "#password",
+      "Got expected name for #password private property in preview"
+    );
+    deepEqual(
+      password.descriptor,
+      {
+        configurable: true,
+        enumerable: false,
+        writable: true,
+        value: "p4$$w0rD",
+      },
+      "Got expected property descriptor for #password in preview"
+    );
+
+    strictEqual(
+      salt.name,
+      "#salt",
+      "Got expected name for #salt private property in preview"
+    );
+    deepEqual(
+      salt.descriptor,
+      {
+        configurable: true,
+        enumerable: false,
+        writable: true,
+        value: "sEcr3t",
+      },
+      "Got expected property descriptor for #salt in preview"
+    );
+
+    const objClient = threadFront.pauseGrip(grip);
+    const iterator = await objClient.enumPrivateProperties();
+    ({ privateProperties } = await iterator.slice(0, iterator.count));
+
+    strictEqual(
+      privateProperties.length,
+      2,
+      "enumPrivateProperties returned 2 private properties."
+    );
+    [password, salt] = privateProperties;
+
+    strictEqual(
+      password.name,
+      "#password",
+      "Got expected name for #password private property via enumPrivateProperties"
+    );
+    deepEqual(
+      password.descriptor,
+      {
+        configurable: true,
+        enumerable: false,
+        writable: true,
+        value: "p4$$w0rD",
+      },
+      "Got expected property descriptor for #password via enumPrivateProperties"
+    );
+
+    strictEqual(
+      salt.name,
+      "#salt",
+      "Got expected name for #salt private property via enumPrivateProperties"
+    );
+    deepEqual(
+      salt.descriptor,
+      {
+        configurable: true,
+        enumerable: false,
+        writable: true,
+        value: "sEcr3t",
+      },
+      "Got expected property descriptor for #salt via enumPrivateProperties"
+    );
+
+    await threadFront.resume();
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-fn-apply-01.js b/devtools/server/tests/xpcshell/test_objectgrips-fn-apply-01.js
new file mode 100644
index 0000000000..f576f16a5e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-fn-apply-01.js
@@ -0,0 +1,117 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const arg1 = packet.frame.arguments[0];
+    Assert.equal(arg1.class, "Object");
+
+    const objectFront = threadFront.pauseGrip(arg1);
+
+    const obj1 = (
+      await objectFront.getPropertyValue("obj1", null)
+    ).value.return.getGrip();
+    const obj2 = (
+      await objectFront.getPropertyValue("obj2", null)
+    ).value.return.getGrip();
+
+    info(`Retrieve "context" function reference`);
+    const context = (await objectFront.getPropertyValue("context", null)).value
+      .return;
+    info(`Retrieve "sum" function reference`);
+    const sum = (await objectFront.getPropertyValue("sum", null)).value.return;
+    info(`Retrieve "error" function reference`);
+    const error = (await objectFront.getPropertyValue("error", null)).value
+      .return;
+
+    assert_response(await context.apply(obj1, [obj1]), {
+      return: "correct context",
+    });
+    assert_response(await context.apply(obj2, [obj2]), {
+      return: "correct context",
+    });
+    assert_response(await context.apply(obj1, [obj2]), {
+      return: "wrong context",
+    });
+    assert_response(await context.apply(obj2, [obj1]), {
+      return: "wrong context",
+    });
+    // eslint-disable-next-line no-useless-call
+    assert_response(await sum.apply(null, [1, 2, 3, 4, 5, 6, 7]), {
+      return: 1 + 2 + 3 + 4 + 5 + 6 + 7,
+    });
+    // eslint-disable-next-line no-useless-call
+    assert_response(await error.apply(null, []), {
+      throw: "an error",
+    });
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+
+  debuggee.eval(`
+    stopMe({
+      obj1: {},
+      obj2: {},
+      context(arg) {
+        return this === arg ? "correct context" : "wrong context";
+      },
+      sum(...parts) {
+        return parts.reduce((acc, v) => acc + v, 0);
+      },
+      error() {
+        throw "an error";
+      },
+    });
+  `);
+}
+
+function assert_response({ value }, expected) {
+  assert_completion(value, expected);
+}
+
+function assert_completion(value, expected) {
+  if (expected && "return" in expected) {
+    assert_value(value.return, expected.return);
+  }
+  if (expected && "throw" in expected) {
+    assert_value(value.throw, expected.throw);
+  }
+  if (!expected) {
+    assert_value(value, expected);
+  }
+}
+
+function assert_value(actual, expected) {
+  Assert.equal(typeof actual, typeof expected);
+
+  if (typeof expected === "object") {
+    // Note: We aren't using deepEqual here because we're only doing a cursory
+    // check of a few properties, not a full comparison of the result, since
+    // the full outputs includes stuff like preview info that we don't need.
+    for (const key of Object.keys(expected)) {
+      assert_value(actual[key], expected[key]);
+    }
+  } else {
+    Assert.equal(actual, expected);
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-fn-apply-02.js b/devtools/server/tests/xpcshell/test_objectgrips-fn-apply-02.js
new file mode 100644
index 0000000000..743286281c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-fn-apply-02.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const arg1 = packet.frame.arguments[0];
+    Assert.equal(arg1.class, "Object");
+
+    await threadFront.pauseGrip(arg1).threadGrip();
+    const obj = arg1;
+    await threadFront.resume();
+
+    const objectFront = threadFront.pauseGrip(obj);
+
+    const method = (await objectFront.getPropertyValue("method", null)).value
+      .return;
+
+    const methodCalled = method.apply(obj, []);
+
+    // Ensure that we actually paused at the `debugger;` line.
+    const packet2 = await waitForPause(threadFront);
+    Assert.equal(packet2.frame.where.line, 4);
+    Assert.equal(packet2.frame.where.column, 8);
+
+    await threadFront.resume();
+    await methodCalled;
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+
+  debuggee.eval(`
+    stopMe({
+      method(){
+        debugger;
+      },
+    });
+  `);
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-fn-apply-03.js b/devtools/server/tests/xpcshell/test_objectgrips-fn-apply-03.js
new file mode 100644
index 0000000000..6a3e919661
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-fn-apply-03.js
@@ -0,0 +1,51 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const arg1 = packet.frame.arguments[0];
+    Assert.equal(arg1.class, "Object");
+
+    await threadFront.pauseGrip(arg1).threadGrip();
+    const obj = arg1;
+
+    const objectFront = threadFront.pauseGrip(obj);
+
+    const method = (await objectFront.getPropertyValue("method", null)).value
+      .return;
+
+    try {
+      await method.apply(obj, []);
+      Assert.ok(false, "expected exception");
+    } catch (err) {
+      Assert.ok(!!err.message.match(/debugee object is not callable/));
+    }
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+
+  debuggee.eval(`
+    stopMe({
+      method: {},
+    });
+  `);
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-nested-promise.js b/devtools/server/tests/xpcshell/test_objectgrips-nested-promise.js
new file mode 100644
index 0000000000..b60b7328c2
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-nested-promise.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const [grip1, grip2] = packet.frame.arguments;
+    strictEqual(grip1.class, "Promise", "promise1 has a promise grip.");
+    strictEqual(grip2.class, "Promise", "promise2 has a promise grip.");
+
+    const objClient1 = threadFront.pauseGrip(grip1);
+    const objClient2 = threadFront.pauseGrip(grip2);
+    const { promiseState: state1 } = await objClient1.getPromiseState();
+    const { promiseState: state2 } = await objClient2.getPromiseState();
+
+    strictEqual(state1.state, "fulfilled", "promise1 was fulfilled.");
+    strictEqual(state1.value, objClient2, "promise1 fulfilled with promise2.");
+    ok(!state1.hasOwnProperty("reason"), "promise1 has no rejection reason.");
+
+    strictEqual(state2.state, "rejected", "promise2 was rejected.");
+    strictEqual(state2.reason, objClient1, "promise2 rejected with promise1.");
+    ok(!state2.hasOwnProperty("value"), "promise2 has no resolution value.");
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg) {
+      debugger;
+    }.toString()
+  );
+
+  debuggee.eval(`
+    var resolve;
+    var promise1 = new Promise(r => {resolve = r});
+    Object.setPrototypeOf(promise1, null);
+    var promise2 = Promise.reject(promise1);
+    promise2.catch(() => {});
+    Object.setPrototypeOf(promise2, null);
+    resolve(promise2);
+    stopMe(promise1, promise2);
+  `);
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-nested-proxy.js b/devtools/server/tests/xpcshell/test_objectgrips-nested-proxy.js
new file mode 100644
index 0000000000..5b0667c055
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-nested-proxy.js
@@ -0,0 +1,51 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const [grip] = packet.frame.arguments;
+    const objClient = threadFront.pauseGrip(grip);
+    const { proxyTarget, proxyHandler } = await objClient.getProxySlots();
+
+    strictEqual(grip.class, "Proxy", "Its a proxy grip.");
+    strictEqual(
+      proxyTarget.getGrip().class,
+      "Proxy",
+      "The target is also a proxy."
+    );
+    strictEqual(
+      proxyHandler.getGrip().class,
+      "Proxy",
+      "The handler is also a proxy."
+    );
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg) {
+      debugger;
+    }.toString()
+  );
+
+  debuggee.eval(`
+    var proxy = new Proxy({}, {});
+    for (let i = 0; i < 1e5; ++i)
+      proxy = new Proxy(proxy, proxy);
+    stopMe(proxy);
+  `);
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-property-value-01.js b/devtools/server/tests/xpcshell/test_objectgrips-property-value-01.js
new file mode 100644
index 0000000000..69da96a741
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-property-value-01.js
@@ -0,0 +1,148 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const arg1 = packet.frame.arguments[0];
+    Assert.equal(arg1.class, "Object");
+
+    const objFront = threadFront.pauseGrip(arg1);
+
+    const expectedValues = {
+      stringProp: {
+        return: "a value",
+      },
+      stringNormal: {
+        return: "a value",
+      },
+      stringAbrupt: {
+        throw: "a value",
+      },
+      objectNormal: {
+        return: {
+          _grip: {
+            type: "object",
+            class: "Object",
+            ownPropertyLength: 1,
+            preview: {
+              kind: "Object",
+              ownProperties: {
+                prop: {
+                  value: 4,
+                },
+              },
+            },
+          },
+        },
+      },
+      objectAbrupt: {
+        throw: {
+          _grip: {
+            type: "object",
+            class: "Object",
+            ownPropertyLength: 1,
+            preview: {
+              kind: "Object",
+              ownProperties: {
+                prop: {
+                  value: 4,
+                },
+              },
+            },
+          },
+        },
+      },
+      context: {
+        return: "correct context",
+      },
+      method: {
+        return: {
+          _grip: {
+            type: "object",
+            class: "Function",
+            name: "method",
+          },
+        },
+      },
+    };
+
+    for (const [key, expected] of Object.entries(expectedValues)) {
+      const { value } = await objFront.getPropertyValue(key, null);
+      assert_completion(value, expected);
+    }
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+
+  debuggee.eval(`
+    var obj = {
+      stringProp: "a value",
+      get stringNormal(){
+        return "a value";
+      },
+      get stringAbrupt() {
+        throw "a value";
+      },
+      get objectNormal() {
+        return { prop: 4 };
+      },
+      get objectAbrupt() {
+        throw { prop: 4 };
+      },
+      get context(){
+        return this === obj ? "correct context" : "wrong context";
+      },
+      method() {
+        return "a value";
+      },
+    };
+    stopMe(obj);
+  `);
+}
+
+function assert_completion(value, expected) {
+  if (expected && "return" in expected) {
+    assert_value(value.return, expected.return);
+  }
+  if (expected && "throw" in expected) {
+    assert_value(value.throw, expected.throw);
+  }
+  if (!expected) {
+    assert_value(value, expected);
+  }
+}
+
+function assert_value(actual, expected) {
+  Assert.equal(typeof actual, typeof expected);
+
+  if (typeof expected === "object") {
+    // Note: We aren't using deepEqual here because we're only doing a cursory
+    // check of a few properties, not a full comparison of the result, since
+    // the full outputs includes stuff like preview info that we don't need.
+    for (const key of Object.keys(expected)) {
+      assert_value(actual[key], expected[key]);
+    }
+  } else {
+    Assert.equal(actual, expected);
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-property-value-02.js b/devtools/server/tests/xpcshell/test_objectgrips-property-value-02.js
new file mode 100644
index 0000000000..bc7337128c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-property-value-02.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const arg1 = packet.frame.arguments[0];
+    Assert.equal(arg1.class, "Object");
+
+    const obj = threadFront.pauseGrip(arg1);
+    await obj.threadGrip();
+
+    const objClient = obj;
+    await threadFront.resume();
+
+    const objClientCalled = objClient.getPropertyValue("prop", null);
+
+    // Ensure that we actually paused at the `debugger;` line.
+    const packet2 = await waitForPause(threadFront);
+    Assert.equal(packet2.frame.where.line, 4);
+    Assert.equal(packet2.frame.where.column, 8);
+
+    await threadFront.resume();
+    await objClientCalled;
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arg1) {
+      debugger;
+    }.toString()
+  );
+
+  debuggee.eval(`
+    stopMe({
+      get prop(){
+        debugger;
+      },
+    });
+  `);
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-property-value-03.js b/devtools/server/tests/xpcshell/test_objectgrips-property-value-03.js
new file mode 100644
index 0000000000..e9b130db79
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-property-value-03.js
@@ -0,0 +1,63 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const { frame } = packet;
+    try {
+      const grips = frame.arguments;
+      const objClient = threadFront.pauseGrip(grips[0]);
+      const classes = [
+        "Object",
+        "Object",
+        "Array",
+        "Boolean",
+        "Number",
+        "String",
+      ];
+      for (const [i, grip] of grips.entries()) {
+        Assert.equal(grip.class, classes[i]);
+        await check_getter(objClient, grip.actor, i);
+      }
+      await check_getter(objClient, null, 0);
+      await check_getter(objClient, "invalid receiver actorId", 0);
+    } finally {
+      await threadFront.resume();
+    }
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe() {
+      debugger;
+    }.toString()
+  );
+
+  debuggee.eval(`
+    var obj = {
+      get getter() {
+        return objects.indexOf(this);
+      },
+    };
+    var objects = [obj, {}, [], new Boolean(), new Number(), new String()];
+    stopMe(...objects);
+  `);
+}
+
+async function check_getter(objClient, receiverId, expected) {
+  const { value } = await objClient.getPropertyValue("getter", receiverId);
+  Assert.equal(value.return, expected);
+}
diff --git a/devtools/server/tests/xpcshell/test_objectgrips-sparse-array.js b/devtools/server/tests/xpcshell/test_objectgrips-sparse-array.js
new file mode 100644
index 0000000000..76a6b32f4b
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_objectgrips-sparse-array.js
@@ -0,0 +1,40 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const [grip] = packet.frame.arguments;
+    await threadFront.resume();
+
+    strictEqual(grip.class, "Array", "The grip has an Array class");
+
+    const { items } = grip.preview;
+    strictEqual(items[0], null, "The empty slot has null as grip preview");
+    deepEqual(
+      items[1],
+      { type: "undefined" },
+      "The undefined value has grip value of type undefined"
+    );
+  })
+);
+
+function evalCode(debuggee) {
+  debuggee.eval(
+    function stopMe(arr) {
+      debugger;
+    }.toString()
+  );
+  debuggee.eval("stopMe([, undefined])");
+}
diff --git a/devtools/server/tests/xpcshell/test_pause_exceptions-01.js b/devtools/server/tests/xpcshell/test_pause_exceptions-01.js
new file mode 100644
index 0000000000..74bbae55c3
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_pause_exceptions-01.js
@@ -0,0 +1,43 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that setting pauseOnExceptions to true will cause the debuggee to pause
+ * when an exception is thrown.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, commands }) => {
+    await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    await commands.threadConfigurationCommand.updateConfiguration({
+      pauseOnExceptions: true,
+      ignoreCaughtExceptions: false,
+    });
+    const packet = await resumeAndWaitForPause(threadFront);
+    Assert.equal(packet.why.type, "exception");
+    Assert.equal(packet.why.exception, 42);
+
+    await threadFront.resume();
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  /* eslint-disable no-throw-literal */
+  // prettier-ignore
+  debuggee.eval("(" + function () {
+    function stopMe() {
+      debugger;
+      throw 42;
+    }
+    try {
+      stopMe();
+    } catch (e) {}
+  } + ")()");
+  /* eslint-enable no-throw-literal */
+}
diff --git a/devtools/server/tests/xpcshell/test_pause_exceptions-02.js b/devtools/server/tests/xpcshell/test_pause_exceptions-02.js
new file mode 100644
index 0000000000..00631b071f
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_pause_exceptions-02.js
@@ -0,0 +1,40 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that setting pauseOnExceptions to true when the debugger isn't in a
+ * paused state will not cause the debuggee to pause when an exception is thrown.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, commands }) => {
+    await commands.threadConfigurationCommand.updateConfiguration({
+      pauseOnExceptions: true,
+      ignoreCaughtExceptions: false,
+    });
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    Assert.equal(packet.why.type, "exception");
+    Assert.equal(packet.why.exception, 42);
+    await threadFront.resume();
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  /* eslint-disable no-throw-literal */
+  // prettier-ignore
+  debuggee.eval("(" + function () {    // 1
+    function stopMe() {                // 2
+      throw 42;                        // 3
+    }                                  // 4
+    try {                              // 5
+      stopMe();                        // 6
+    } catch (e) {}                     // 7
+  } + ")()");
+}
diff --git a/devtools/server/tests/xpcshell/test_pause_exceptions-03.js b/devtools/server/tests/xpcshell/test_pause_exceptions-03.js
new file mode 100644
index 0000000000..4fb13f4cf9
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_pause_exceptions-03.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that setting pauseOnExceptions to true will cause the debuggee to pause
+ * when an exception is thrown.
+ */
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee, commands }) => {
+      await executeOnNextTickAndWaitForPause(
+        () => evaluateTestCode(debuggee),
+        threadFront
+      );
+
+      await commands.threadConfigurationCommand.updateConfiguration({
+        pauseOnExceptions: true,
+        ignoreCaughtExceptions: false,
+      });
+      await resume(threadFront);
+      const paused = await waitForPause(threadFront);
+      Assert.equal(paused.why.type, "exception");
+      equal(paused.frame.where.line, 4, "paused at throw");
+
+      await resume(threadFront);
+    },
+    {
+      // Bug 1508289, exception tests fails in worker scope
+      doNotRunWorker: true,
+    }
+  )
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox(
+    `                                   // 1
+    function stopMe() {                 // 2
+      debugger;                         // 3
+      throw 42;                         // 4
+    }                                   // 5
+    try {                               // 6
+      stopMe();                         // 7
+    } catch (e) {}`,                    // 8
+    debuggee,
+    "1.8",
+    "test_pause_exceptions-03.js",
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_pause_exceptions-04.js b/devtools/server/tests/xpcshell/test_pause_exceptions-04.js
new file mode 100644
index 0000000000..6246b112e0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_pause_exceptions-04.js
@@ -0,0 +1,93 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { waitForTick } = require("resource://devtools/shared/DevToolsUtils.js");
+
+/**
+ * Test that setting pauseOnExceptions to true and then to false will not cause
+ * the debuggee to pause when an exception is thrown.
+ */
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, client, debuggee, commands }) => {
+      let onResume = null;
+      let packet = null;
+
+      threadFront.once("paused", function (pkt) {
+        packet = pkt;
+        onResume = threadFront.resume();
+      });
+
+      await commands.threadConfigurationCommand.updateConfiguration({
+        pauseOnExceptions: true,
+        ignoreCaughtExceptions: true,
+      });
+
+      await evaluateTestCode(debuggee, "42");
+
+      await onResume;
+
+      Assert.equal(!!packet, true);
+      Assert.equal(packet.why.type, "exception");
+      Assert.equal(packet.why.exception, "42");
+      packet = null;
+
+      threadFront.once("paused", function (pkt) {
+        packet = pkt;
+        onResume = threadFront.resume();
+      });
+
+      await commands.threadConfigurationCommand.updateConfiguration({
+        pauseOnExceptions: false,
+        ignoreCaughtExceptions: true,
+      });
+
+      await evaluateTestCode(debuggee, "43");
+
+      // Test that the paused listener callback hasn't been called
+      // on the thrown error from dontStopMe()
+      Assert.equal(!!packet, false);
+
+      await commands.threadConfigurationCommand.updateConfiguration({
+        pauseOnExceptions: true,
+        ignoreCaughtExceptions: true,
+      });
+
+      await evaluateTestCode(debuggee, "44");
+
+      await onResume;
+
+      // Test that the paused listener callback has been called
+      // on the thrown error from stopMeAgain()
+      Assert.equal(!!packet, true);
+      Assert.equal(packet.why.type, "exception");
+      Assert.equal(packet.why.exception, "44");
+    },
+    {
+      // Bug 1508289, exception tests fails in worker scope
+      doNotRunWorker: true,
+    }
+  )
+);
+
+async function evaluateTestCode(debuggee, throwValue) {
+  await waitForTick();
+  try {
+    // prettier-ignore
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMeAgain() {            // 2
+        throw ${throwValue};              // 3
+      }                                   // 4
+      stopMeAgain();                      // 5
+      `,                                  // 6
+      debuggee,
+      "1.8",
+      "test_pause_exceptions-04.js",
+      1
+    );
+  } catch (e) {}
+}
diff --git a/devtools/server/tests/xpcshell/test_pauselifetime-01.js b/devtools/server/tests/xpcshell/test_pauselifetime-01.js
new file mode 100644
index 0000000000..db20a02521
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_pauselifetime-01.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that pause-lifetime grips go away correctly after a resume.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const pauseActor = packet.actor;
+
+    // Make a bogus request to the pause-lifetime actor. Should get
+    // unrecognized-packet-type (and not no-such-actor).
+    try {
+      await client.request({ to: pauseActor, type: "bogusRequest" });
+      ok(false, "bogusRequest should throw");
+    } catch (e) {
+      ok(true, "bogusRequest thrown");
+      Assert.equal(e.error, "unrecognizedPacketType");
+    }
+
+    await threadFront.resume();
+
+    // Now that we've resumed, should get no-such-actor for the
+    // same request.
+    try {
+      await client.request({ to: pauseActor, type: "bogusRequest" });
+      ok(false, "bogusRequest should throw");
+    } catch (e) {
+      ok(true, "bogusRequest thrown");
+      Assert.equal(e.error, "noSuchActor");
+    }
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe() {
+          debugger;
+        }
+        stopMe();
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_pauselifetime-02.js b/devtools/server/tests/xpcshell/test_pauselifetime-02.js
new file mode 100644
index 0000000000..e936df6177
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_pauselifetime-02.js
@@ -0,0 +1,57 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that pause-lifetime grips go away correctly after a resume.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const args = packet.frame.arguments;
+    const objActor = args[0].actor;
+    Assert.equal(args[0].class, "Object");
+    Assert.ok(!!objActor);
+
+    // Make a bogus request to the grip actor. Should get
+    // unrecognized-packet-type (and not no-such-actor).
+    try {
+      await client.request({ to: objActor, type: "bogusRequest" });
+      ok(false, "bogusRequest should throw");
+    } catch (e) {
+      ok(true, "bogusRequest thrown");
+      Assert.equal(e.error, "unrecognizedPacketType");
+    }
+
+    await threadFront.resume();
+
+    // Now that we've resumed, should get no-such-actor for the
+    // same request.
+    try {
+      await client.request({ to: objActor, type: "bogusRequest" });
+      ok(false, "bogusRequest should throw");
+    } catch (e) {
+      ok(true, "bogusRequest thrown");
+      Assert.equal(e.error, "noSuchActor");
+    }
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(obj) {
+          debugger;
+        }
+        stopMe({ foo: "bar" });
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_pauselifetime-03.js b/devtools/server/tests/xpcshell/test_pauselifetime-03.js
new file mode 100644
index 0000000000..558ac8b910
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_pauselifetime-03.js
@@ -0,0 +1,64 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that pause-lifetime grip clients are marked invalid after a resume.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const args = packet.frame.arguments;
+    const objActor = args[0].actor;
+    Assert.equal(args[0].class, "Object");
+    Assert.ok(!!objActor);
+
+    const objectFront = threadFront.pauseGrip(args[0]);
+    Assert.ok(objectFront.valid);
+
+    // Make a bogus request to the grip actor.  Should get
+    // unrecognized-packet-type (and not no-such-actor).
+    try {
+      const objFront = client.getFrontByID(objActor);
+      await objFront.request({ to: objActor, type: "bogusRequest" });
+      ok(false, "bogusRequest should throw");
+    } catch (e) {
+      ok(true, "bogusRequest thrown");
+      Assert.ok(!!e.message.match(/unrecognizedPacketType/));
+    }
+    Assert.ok(objectFront.valid);
+
+    await threadFront.resume();
+
+    // Now that we've resumed, should get no-such-actor for the
+    // same request.
+    try {
+      const objFront = client.getFrontByID(objActor);
+      await objFront.request({ to: objActor, type: "bogusRequest" });
+      ok(false, "bogusRequest should throw");
+    } catch (e) {
+      ok(true, "bogusRequest thrown");
+      Assert.ok(!!e.message.match(/noSuchActor/));
+    }
+    Assert.ok(!objectFront.valid);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(obj) {
+          debugger;
+        }
+        stopMe({ foo: "bar" });
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_pauselifetime-04.js b/devtools/server/tests/xpcshell/test_pauselifetime-04.js
new file mode 100644
index 0000000000..7d226260f0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_pauselifetime-04.js
@@ -0,0 +1,40 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that requesting a pause actor for the same value multiple
+ * times returns the same actor.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const args = packet.frame.arguments;
+    const objActor1 = args[0].actor;
+
+    const response = await threadFront.getFrames(0, 1);
+    const frame = response.frames[0];
+    Assert.equal(objActor1, frame.arguments[0].actor);
+
+    await threadFront.resume();
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(obj) {
+          debugger;
+        }
+        stopMe({ foo: "bar" });
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_promise_state-01.js b/devtools/server/tests/xpcshell/test_promise_state-01.js
new file mode 100644
index 0000000000..d02b64a67e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_promise_state-01.js
@@ -0,0 +1,44 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Test that the preview in a Promise's grip is correct when the Promise is
+ * pending.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const environment = await packet.frame.getEnvironment();
+    const grip = environment.bindings.variables.p.value;
+
+    ok(grip.preview);
+    equal(grip.class, "Promise");
+    equal(grip.preview.ownProperties["<state>"].value, "pending");
+
+    const objClient = threadFront.pauseGrip(grip);
+    const { promiseState } = await objClient.getPromiseState();
+    equal(promiseState.state, "pending");
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable mozilla/var-only-at-top-level, no-unused-vars */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "doTest();\n" +
+    function doTest() {
+      var p = new Promise(function () {});
+      debugger;
+    },
+    debuggee
+  );
+  /* eslint-enable mozilla/var-only-at-top-level, no-unused-vars */
+}
diff --git a/devtools/server/tests/xpcshell/test_promise_state-02.js b/devtools/server/tests/xpcshell/test_promise_state-02.js
new file mode 100644
index 0000000000..e1219f545c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_promise_state-02.js
@@ -0,0 +1,59 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Test that the preview in a Promise's grip is correct when the Promise is
+ * fulfilled.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const environment = await packet.frame.getEnvironment();
+    const grip = environment.bindings.variables.p.value;
+
+    ok(grip.preview);
+    equal(grip.class, "Promise");
+    equal(grip.preview.ownProperties["<state>"].value, "fulfilled");
+    equal(
+      grip.preview.ownProperties["<value>"].value.actorID,
+      packet.frame.arguments[0].actorID,
+      "The promise's fulfilled state value in the preview should be the same " +
+        "value passed to the then function"
+    );
+
+    const objClient = threadFront.pauseGrip(grip);
+    const { promiseState } = await objClient.getPromiseState();
+    equal(promiseState.state, "fulfilled");
+    equal(
+      promiseState.value.getGrip().actorID,
+      packet.frame.arguments[0].actorID,
+      "The promise's fulfilled state value in getPromiseState() should be " +
+        "the same value passed to the then function"
+    );
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable mozilla/var-only-at-top-level, no-unused-vars */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "doTest();\n" +
+    function doTest() {
+      var resolved = Promise.resolve({});
+      resolved.then(() => {
+        var p = resolved;
+        debugger;
+      });
+    },
+    debuggee
+  );
+  /* eslint-enable mozilla/var-only-at-top-level, no-unused-vars */
+}
diff --git a/devtools/server/tests/xpcshell/test_promise_state-03.js b/devtools/server/tests/xpcshell/test_promise_state-03.js
new file mode 100644
index 0000000000..8ec1fa3717
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_promise_state-03.js
@@ -0,0 +1,58 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Test that the preview in a Promise's grip is correct when the Promise is
+ * rejected.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    const environment = await packet.frame.getEnvironment();
+    const grip = environment.bindings.variables.p.value;
+    ok(grip.preview);
+    equal(grip.class, "Promise");
+    equal(grip.preview.ownProperties["<state>"].value, "rejected");
+    equal(
+      grip.preview.ownProperties["<reason>"].value.actorID,
+      packet.frame.arguments[0].actorID,
+      "The promise's rejected state reason in the preview should be the same " +
+        "value passed to the then function"
+    );
+
+    const objClient = threadFront.pauseGrip(grip);
+    const { promiseState } = await objClient.getPromiseState();
+    equal(promiseState.state, "rejected");
+    equal(
+      promiseState.reason.getGrip().actorID,
+      packet.frame.arguments[0].actorID,
+      "The promise's rejected state value in getPromiseState() should be " +
+        "the same value passed to the then function"
+    );
+  })
+);
+
+function evalCode(debuggee) {
+  /* eslint-disable mozilla/var-only-at-top-level, no-unused-vars */
+  // prettier-ignore
+  Cu.evalInSandbox(
+    "doTest();\n" +
+    function doTest() {
+      var resolved = Promise.reject(new Error("uh oh"));
+      resolved.catch(() => {
+        var p = resolved;
+        debugger;
+      });
+    },
+    debuggee
+  );
+  /* eslint-enable mozilla/var-only-at-top-level, no-unused-vars */
+}
diff --git a/devtools/server/tests/xpcshell/test_promises_run_to_completion.js b/devtools/server/tests/xpcshell/test_promises_run_to_completion.js
new file mode 100644
index 0000000000..4d1e8745fe
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_promises_run_to_completion.js
@@ -0,0 +1,132 @@
+// Bug 1145201:  Promise then-handlers can still be executed while the debugger is paused.
+//
+// When a promise is resolved, for each of its callbacks, a microtask is queued
+// to run the callback. At various points, the HTML spec says the browser must
+// "perform a microtask checkpoint", which means to draw microtasks from the
+// queue and run them, until the queue is empty.
+//
+// The HTML spec is careful to perform a microtask checkpoint directly after
+// each invocation of an event handler or DOM callback, so that code using
+// promises can trust that its promise callbacks run promptly, in a
+// deterministic order, without DOM events or other outside influences
+// intervening.
+//
+// When the JavaScript debugger interrupts the execution of debuggee content
+// code, it naturally must process events for its own user interface and promise
+// callbacks. However, it must not run any debuggee microtasks. The debuggee has
+// been interrupted in the midst of executing some other code, and the
+// JavaScript spec promises developers: "Once execution of a Job is initiated,
+// the Job always executes to completion. No other Job may be initiated until
+// the currently running Job completes." [1] This promise would be broken if the
+// debugger's own event processing ran debuggee microtasks during the
+// interruption.
+//
+// Looking at things from the other side, a microtask checkpoint must be
+// performed before returning from a debugger callback, rather than being put
+// off until the debuggee performs its next microtask checkpoint, so that
+// debugger microtasks are not interleaved with debuggee microtasks. A debuggee
+// microtask could hit a breakpoint or otherwise re-enter the debugger, which
+// might be quite surprised to see a new debugger callback begin before its
+// previous promise callbacks could finish.
+//
+// [1]: https://www.ecma-international.org/ecma-262/9.0/index.html#sec-jobs-and-job-queues
+
+"use strict";
+
+const Debugger = require("Debugger");
+
+function test_promises_run_to_completion() {
+  const g = createTestGlobal(
+    "test global for test_promises_run_to_completion.js"
+  );
+  const dbg = new Debugger(g);
+  g.Assert = Assert;
+  const log = [""];
+  g.log = log;
+
+  dbg.onDebuggerStatement = function handleDebuggerStatement(frame) {
+    dbg.onDebuggerStatement = undefined;
+
+    // Exercise the promise machinery: resolve a promise and perform a microtask
+    // queue. When called from a debugger hook, the debuggee's microtasks should not
+    // run.
+    log[0] += "debug-handler(";
+    Promise.resolve(42).then(v => {
+      Assert.equal(
+        v,
+        42,
+        "debugger callback promise handler got the right value"
+      );
+      log[0] += "debug-react";
+    });
+    log[0] += "(";
+    force_microtask_checkpoint();
+    log[0] += ")";
+
+    Promise.resolve(42).then(v => {
+      // The microtask running this callback should be handled as we leave the
+      // onDebuggerStatement Debugger callback, and should not be interleaved
+      // with debuggee microtasks.
+      log[0] += "(trailing)";
+    });
+
+    log[0] += ")";
+  };
+
+  // Evaluate some debuggee code that resolves a promise, and then enters the debugger.
+  Cu.evalInSandbox(
+    `
+    log[0] += "eval(";
+    Promise.resolve(42).then(function debuggeePromiseCallback(v) {
+      Assert.equal(v, 42, "debuggee promise handler got the right value");
+      // Debugger microtask checkpoints must not run debuggee microtasks, so
+      // this callback should run at the next microtask checkpoint *not*
+      // performed by the debugger.
+      log[0] += "eval-react";
+    });
+
+    log[0] += "debugger(";
+    debugger;
+    log[0] += "))";
+  `,
+    g
+  );
+
+  // Let other microtasks run. This should run the debuggee's promise callback.
+  log[0] += "final(";
+  force_microtask_checkpoint();
+  log[0] += ")";
+
+  Assert.equal(
+    log[0],
+    `\
+eval(\
+debugger(\
+debug-handler(\
+(debug-react)\
+)\
+(trailing)\
+))\
+final(\
+eval-react\
+)`,
+    "microtasks ran as expected"
+  );
+
+  run_next_test();
+}
+
+function force_microtask_checkpoint() {
+  // Services.tm.spinEventLoopUntilEmpty only performs a microtask checkpoint if
+  // there is actually an event to run. So make one up.
+  let ran = false;
+  Services.tm.dispatchToMainThread(() => {
+    ran = true;
+  });
+  Services.tm.spinEventLoopUntil(
+    "Test(test_promises_run_to_completion.js:force_microtask_checkpoint)",
+    () => ran
+  );
+}
+
+add_test(test_promises_run_to_completion);
diff --git a/devtools/server/tests/xpcshell/test_register_actor.js b/devtools/server/tests/xpcshell/test_register_actor.js
new file mode 100644
index 0000000000..f38ab73572
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_register_actor.js
@@ -0,0 +1,94 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function run_test() {
+  // Allow incoming connections.
+  DevToolsServer.keepAlive = true;
+  DevToolsServer.init();
+  DevToolsServer.registerAllActors();
+
+  add_test(test_lazy_api);
+  add_test(manual_remove);
+  add_test(cleanup);
+  run_next_test();
+}
+
+// Bug 988237: Test the new lazy actor actor-register
+function test_lazy_api() {
+  let isActorLoaded = false;
+  let isActorInstantiated = false;
+  function onActorEvent(subject, topic, data) {
+    if (data == "loaded") {
+      isActorLoaded = true;
+    } else if (data == "instantiated") {
+      isActorInstantiated = true;
+    }
+  }
+  Services.obs.addObserver(onActorEvent, "actor");
+  ActorRegistry.registerModule("xpcshell-test/registertestactors-lazy", {
+    prefix: "lazy",
+    constructor: "LazyActor",
+    type: { global: true, target: true },
+  });
+  // The actor is immediatly registered, but not loaded
+  Assert.ok(
+    ActorRegistry.targetScopedActorFactories.hasOwnProperty("lazyActor")
+  );
+  Assert.ok(ActorRegistry.globalActorFactories.hasOwnProperty("lazyActor"));
+  Assert.ok(!isActorLoaded);
+  Assert.ok(!isActorInstantiated);
+
+  const client = new DevToolsClient(DevToolsServer.connectPipe());
+  client.connect().then(function onConnect() {
+    client.mainRoot.rootForm.then(onRootForm);
+  });
+  function onRootForm(response) {
+    // On rootForm, the actor is still not loaded,
+    // but we can see its name in the list of available actors
+    Assert.ok(!isActorLoaded);
+    Assert.ok(!isActorInstantiated);
+    Assert.ok("lazyActor" in response);
+
+    const { LazyFront } = require("xpcshell-test/registertestactors-lazy");
+    const front = new LazyFront(client);
+    // As this Front isn't instantiated by protocol.js, we have to manually
+    // set its actor ID and manage it:
+    front.actorID = response.lazyActor;
+    client.addActorPool(front);
+    front.manage(front);
+
+    front.hello().then(onRequest);
+  }
+  function onRequest(response) {
+    Assert.equal(response, "world");
+
+    // Finally, the actor is loaded on the first request being made to it
+    Assert.ok(isActorLoaded);
+    Assert.ok(isActorInstantiated);
+
+    Services.obs.removeObserver(onActorEvent, "actor");
+    client.close().then(() => run_next_test());
+  }
+}
+
+function manual_remove() {
+  Assert.ok(ActorRegistry.globalActorFactories.hasOwnProperty("lazyActor"));
+  ActorRegistry.removeGlobalActor("lazyActor");
+  Assert.ok(!ActorRegistry.globalActorFactories.hasOwnProperty("lazyActor"));
+
+  run_next_test();
+}
+
+function cleanup() {
+  DevToolsServer.destroy();
+
+  // Check that all actors are unregistered on server destruction
+  Assert.ok(
+    !ActorRegistry.targetScopedActorFactories.hasOwnProperty("lazyActor")
+  );
+  Assert.ok(!ActorRegistry.globalActorFactories.hasOwnProperty("lazyActor"));
+
+  run_next_test();
+}
diff --git a/devtools/server/tests/xpcshell/test_requestTypes.js b/devtools/server/tests/xpcshell/test_requestTypes.js
new file mode 100644
index 0000000000..8787ae5f85
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_requestTypes.js
@@ -0,0 +1,28 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { rootSpec } = require("resource://devtools/shared/specs/root.js");
+const {
+  generateRequestTypes,
+} = require("resource://devtools/shared/protocol/Actor.js");
+
+add_task(async function () {
+  DevToolsServer.init();
+  DevToolsServer.registerAllActors();
+
+  const client = new DevToolsClient(DevToolsServer.connectPipe());
+  await client.connect();
+
+  const response = await client.mainRoot.requestTypes();
+  const expectedRequestTypes = Object.keys(generateRequestTypes(rootSpec));
+
+  Assert.ok(Array.isArray(response.requestTypes));
+  Assert.equal(
+    JSON.stringify(response.requestTypes),
+    JSON.stringify(expectedRequestTypes)
+  );
+
+  await client.close();
+});
diff --git a/devtools/server/tests/xpcshell/test_restartFrame-01.js b/devtools/server/tests/xpcshell/test_restartFrame-01.js
new file mode 100644
index 0000000000..cb13ae2d7e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_restartFrame-01.js
@@ -0,0 +1,118 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check restarting a frame and stepping out of the
+ * restarted frame.
+ */
+
+async function testFinish({ threadFront, devToolsClient }) {
+  await close(devToolsClient);
+
+  do_test_finished();
+}
+
+async function invokeAndPause({ global, threadFront }, expression) {
+  return executeOnNextTickAndWaitForPause(
+    () => Cu.evalInSandbox(expression, global),
+    threadFront
+  );
+}
+
+async function steps(threadFront, sequence) {
+  const locations = [];
+  for (const cmd of sequence) {
+    const packet = await step(threadFront, cmd);
+    locations.push(getPauseLocation(packet));
+  }
+  return locations;
+}
+
+async function step(threadFront, cmd) {
+  return cmd(threadFront);
+}
+
+function getPauseLocation(packet) {
+  const { line, column } = packet.frame.where;
+  return { line, column };
+}
+
+async function restartFrame0(dbg, func, expectedLocation) {
+  const { threadFront } = dbg;
+
+  info("pause and step into a()");
+  await invokeAndPause(dbg, `${func}()`);
+  await steps(threadFront, [stepOver, stepIn]);
+
+  info("restart the youngest frame a()");
+  const { frames } = await threadFront.frames(0, 5);
+  const frameActorID = frames[0].actorID;
+  const packet = await restartFrame(threadFront, frameActorID);
+
+  deepEqual(
+    getPauseLocation(packet),
+    expectedLocation,
+    "pause location in the restarted frame a()"
+  );
+}
+
+async function restartFrame1(dbg, func, expectedLocation) {
+  const { threadFront } = dbg;
+
+  info("pause and step into b()");
+  await invokeAndPause(dbg, `${func}()`);
+  await steps(threadFront, [stepOver, stepIn, stepIn]);
+
+  info("restart the frame with index 1");
+  const { frames } = await threadFront.frames(0, 5);
+  const frameActorID = frames[1].actorID;
+  const packet = await restartFrame(threadFront, frameActorID);
+
+  deepEqual(
+    getPauseLocation(packet),
+    expectedLocation,
+    "pause location in the restarted frame c()"
+  );
+}
+
+async function stepOutRestartedFrame(
+  dbg,
+  restartedFrameName,
+  expectedLocation,
+  expectedCallstackLength
+) {
+  const { threadFront } = dbg;
+  const { frames } = await threadFront.frames(0, 5);
+
+  Assert.equal(
+    frames.length,
+    expectedCallstackLength,
+    `the callstack length after restarting frame ${restartedFrameName}()`
+  );
+
+  info(`step out of the restarted frame ${restartedFrameName}()`);
+  const frameActorID = frames[0].actorID;
+  const packet = await stepOut(threadFront, frameActorID);
+
+  deepEqual(getPauseLocation(packet), expectedLocation, `step out location`);
+}
+
+function run_test() {
+  return (async function () {
+    const dbg = await setupTestFromUrl("stepping.js");
+
+    info(`Test restarting the youngest frame`);
+    await restartFrame0(dbg, "arithmetic", { line: 7, column: 2 });
+    await stepOutRestartedFrame(dbg, "a", { line: 16, column: 8 }, 3);
+    await dbg.threadFront.resume();
+
+    info(`Test restarting the frame with the index 1`);
+    await restartFrame1(dbg, "nested", { line: 30, column: 2 });
+    await stepOutRestartedFrame(dbg, "c", { line: 36, column: 0 }, 3);
+    await dbg.threadFront.resume();
+
+    await testFinish(dbg);
+  })();
+}
diff --git a/devtools/server/tests/xpcshell/test_safe-getter.js b/devtools/server/tests/xpcshell/test_safe-getter.js
new file mode 100644
index 0000000000..65bf3414ea
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_safe-getter.js
@@ -0,0 +1,54 @@
+/* eslint-disable strict */
+function run_test() {
+  Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+  });
+  const { addDebuggerToGlobal } = ChromeUtils.importESModule(
+    "resource://gre/modules/jsdebugger.sys.mjs"
+  );
+  addDebuggerToGlobal(globalThis);
+  const g = createTestGlobal("test", {
+    wantGlobalProperties: ["ChromeUtils"],
+  });
+  const dbg = new Debugger();
+  const gw = dbg.addDebuggee(g);
+
+  g.eval(`
+    // This is not a CCW.
+    Object.defineProperty(this, "bar", {
+      get: function() { return "bar"; },
+      configurable: true,
+      enumerable: true
+    });
+
+    const { XPCOMUtils } = ChromeUtils.importESModule(
+      "resource://gre/modules/XPCOMUtils.sys.mjs"
+    );
+
+    // This is a CCW.
+    XPCOMUtils.defineLazyScriptGetter(
+      this, "foo", "chrome://global/content/viewZoomOverlay.js");
+  `);
+
+  // Neither scripted getter should be considered safe.
+  assert(!DevToolsUtils.hasSafeGetter(gw.getOwnPropertyDescriptor("bar")));
+  assert(!DevToolsUtils.hasSafeGetter(gw.getOwnPropertyDescriptor("foo")));
+
+  // Create an object in a less privileged sandbox.
+  const obj = gw.makeDebuggeeValue(
+    Cu.waiveXrays(
+      Cu.Sandbox(null).eval(`
+    Object.defineProperty({}, "bar", {
+      get: function() { return "bar"; },
+      configurable: true,
+      enumerable: true
+    });
+  `)
+    )
+  );
+
+  // After waiving Xrays, the object has 2 wrappers. Both must be removed
+  // in order to detect that the getter is not safe.
+  assert(!DevToolsUtils.hasSafeGetter(obj.getOwnPropertyDescriptor("bar")));
+}
diff --git a/devtools/server/tests/xpcshell/test_sessionDataHelpers.js b/devtools/server/tests/xpcshell/test_sessionDataHelpers.js
new file mode 100644
index 0000000000..847311811f
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_sessionDataHelpers.js
@@ -0,0 +1,79 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Test SessionDataHelpers.
+ */
+
+"use strict";
+
+const { SessionDataHelpers } = ChromeUtils.import(
+  "resource://devtools/server/actors/watcher/SessionDataHelpers.jsm"
+);
+const { SUPPORTED_DATA } = SessionDataHelpers;
+const { TARGETS } = SUPPORTED_DATA;
+
+function run_test() {
+  const sessionData = {
+    [TARGETS]: [],
+  };
+
+  SessionDataHelpers.addSessionDataEntry(sessionData, TARGETS, [
+    "frame",
+    "worker",
+  ]);
+  deepEqual(
+    sessionData[TARGETS],
+    ["frame", "worker"],
+    "the two elements were added"
+  );
+
+  SessionDataHelpers.addSessionDataEntry(sessionData, TARGETS, ["frame"]);
+  deepEqual(
+    sessionData[TARGETS],
+    ["frame", "worker"],
+    "addSessionDataEntry ignore duplicates"
+  );
+
+  SessionDataHelpers.addSessionDataEntry(sessionData, TARGETS, ["process"]);
+  deepEqual(
+    sessionData[TARGETS],
+    ["frame", "worker", "process"],
+    "the third element is added"
+  );
+
+  let removed = SessionDataHelpers.removeSessionDataEntry(
+    sessionData,
+    TARGETS,
+    ["process"]
+  );
+  ok(removed, "removedSessionDataEntry returned true as it removed an element");
+  deepEqual(
+    sessionData[TARGETS],
+    ["frame", "worker"],
+    "the element has been remove"
+  );
+
+  removed = SessionDataHelpers.removeSessionDataEntry(sessionData, TARGETS, [
+    "not-existing",
+  ]);
+  ok(
+    !removed,
+    "removedSessionDataEntry returned false as no element has been removed"
+  );
+  deepEqual(
+    sessionData[TARGETS],
+    ["frame", "worker"],
+    "no change made to the array"
+  );
+
+  removed = SessionDataHelpers.removeSessionDataEntry(sessionData, TARGETS, [
+    "frame",
+    "worker",
+  ]);
+  ok(
+    removed,
+    "removedSessionDataEntry returned true as elements have been removed"
+  );
+  deepEqual(sessionData[TARGETS], [], "all elements were removed");
+}
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-at-the-beginning-of-a-minified-fn.js b/devtools/server/tests/xpcshell/test_setBreakpoint-at-the-beginning-of-a-minified-fn.js
new file mode 100644
index 0000000000..9140e92d7c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-at-the-beginning-of-a-minified-fn.js
@@ -0,0 +1,41 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl("setBreakpoint-on-column-minified.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScript(SOURCE_URL, debuggee);
+      const { source } = await promise;
+
+      // Pause inside of the nested function so we can make sure that we don't
+      // add any other breakpoints at other places on this line.
+      const location = { sourceUrl: source.url, line: 3, column: 56 };
+      setBreakpoint(threadFront, location);
+
+      const packet = await executeOnNextTickAndWaitForPause(function () {
+        Cu.evalInSandbox("f()", debuggee);
+      }, threadFront);
+
+      const why = packet.why;
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+
+      const frame = packet.frame;
+      const where = frame.where;
+      Assert.equal(where.actor, source.actor);
+      Assert.equal(where.line, location.line);
+      Assert.equal(where.column, 56);
+
+      const environment = await packet.frame.getEnvironment();
+      const variables = environment.bindings.variables;
+      Assert.equal(variables.a.value.type, "undefined");
+      Assert.equal(variables.b.value.type, "undefined");
+      Assert.equal(variables.c.value.type, "undefined");
+
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-at-the-end-of-a-minified-fn.js b/devtools/server/tests/xpcshell/test_setBreakpoint-at-the-end-of-a-minified-fn.js
new file mode 100644
index 0000000000..f9df5adad4
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-at-the-end-of-a-minified-fn.js
@@ -0,0 +1,41 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl("setBreakpoint-on-column-minified.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScript(SOURCE_URL, debuggee);
+      const { source } = await promise;
+
+      // Pause inside of the nested function so we can make sure that we don't
+      // add any other breakpoints at other places on this line.
+      const location = { sourceUrl: source.url, line: 3, column: 81 };
+      setBreakpoint(threadFront, location);
+
+      const packet = await executeOnNextTickAndWaitForPause(function () {
+        Cu.evalInSandbox("f()", debuggee);
+      }, threadFront);
+
+      const why = packet.why;
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+
+      const frame = packet.frame;
+      const where = frame.where;
+      Assert.equal(where.actor, source.actor);
+      Assert.equal(where.line, location.line);
+      Assert.equal(where.column, 81);
+
+      const environment = await packet.frame.getEnvironment();
+      const variables = environment.bindings.variables;
+      Assert.equal(variables.a.value, 1);
+      Assert.equal(variables.b.value, 2);
+      Assert.equal(variables.c.value, 3);
+
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-on-column-in-gcd-script.js b/devtools/server/tests/xpcshell/test_setBreakpoint-on-column-in-gcd-script.js
new file mode 100644
index 0000000000..797cb6cd65
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-on-column-in-gcd-script.js
@@ -0,0 +1,46 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl("setBreakpoint-on-column-in-gcd-script.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee, targetFront }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScriptWithOptions(SOURCE_URL, {
+        target: debuggee,
+        ignoreCache: true,
+      });
+      Cu.forceGC();
+      Cu.forceGC();
+      Cu.forceGC();
+
+      const { source } = await promise;
+
+      const location = { sourceUrl: source.url, line: 6, column: 21 };
+      setBreakpoint(threadFront, location);
+
+      const packet = await executeOnNextTickAndWaitForPause(function () {
+        reload(targetFront).then(function () {
+          loadSubScriptWithOptions(SOURCE_URL, {
+            target: debuggee,
+            ignoreCache: true,
+          });
+        });
+      }, threadFront);
+      const environment = await packet.frame.getEnvironment();
+      const why = packet.why;
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+      const frame = packet.frame;
+      const where = frame.where;
+      Assert.equal(where.line, location.line);
+      Assert.equal(where.column, location.column);
+      const variables = environment.bindings.variables;
+      Assert.equal(variables.a.value, 1);
+      Assert.equal(variables.b.value.type, "undefined");
+      Assert.equal(variables.c.value.type, "undefined");
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-on-column.js b/devtools/server/tests/xpcshell/test_setBreakpoint-on-column.js
new file mode 100644
index 0000000000..200d8b44e6
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-on-column.js
@@ -0,0 +1,36 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl("setBreakpoint-on-column.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScript(SOURCE_URL, debuggee);
+      const { source } = await promise;
+
+      const location = { sourceUrl: source.url, line: 4, column: 21 };
+      setBreakpoint(threadFront, location);
+
+      const packet = await executeOnNextTickAndWaitForPause(function () {
+        Cu.evalInSandbox("f()", debuggee);
+      }, threadFront);
+      const environment = await packet.frame.getEnvironment();
+      const why = packet.why;
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+      const frame = packet.frame;
+      const where = frame.where;
+      Assert.equal(where.actor, source.actor);
+      Assert.equal(where.line, location.line);
+      Assert.equal(where.column, location.column);
+      const variables = environment.bindings.variables;
+      Assert.equal(variables.a.value, 1);
+      Assert.equal(variables.b.value.type, "undefined");
+      Assert.equal(variables.c.value.type, "undefined");
+
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-in-gcd-script.js b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-in-gcd-script.js
new file mode 100644
index 0000000000..565402551e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-in-gcd-script.js
@@ -0,0 +1,45 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl("setBreakpoint-on-line-in-gcd-script.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee, targetFront }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScriptWithOptions(SOURCE_URL, {
+        target: debuggee,
+        ignoreCache: true,
+      });
+      Cu.forceGC();
+      Cu.forceGC();
+      Cu.forceGC();
+
+      const { source } = await promise;
+
+      const location = { sourceUrl: source.url, line: 7 };
+      setBreakpoint(threadFront, location);
+
+      const packet = await executeOnNextTickAndWaitForPause(function () {
+        reload(targetFront).then(function () {
+          loadSubScriptWithOptions(SOURCE_URL, {
+            target: debuggee,
+            ignoreCache: true,
+          });
+        });
+      }, threadFront);
+      const why = packet.why;
+      const environment = await packet.frame.getEnvironment();
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+      const frame = packet.frame;
+      const where = frame.where;
+      Assert.equal(where.line, location.line);
+      const variables = environment.bindings.variables;
+      Assert.equal(variables.a.value, 1);
+      Assert.equal(variables.b.value.type, "undefined");
+      Assert.equal(variables.c.value.type, "undefined");
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-multiple-offsets.js b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-multiple-offsets.js
new file mode 100644
index 0000000000..2debc26b93
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-multiple-offsets.js
@@ -0,0 +1,52 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl("setBreakpoint-on-line-with-multiple-offsets.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScript(SOURCE_URL, debuggee);
+      const { source } = await promise;
+      const sourceFront = threadFront.source(source);
+
+      const location = { sourceUrl: sourceFront.url, line: 4 };
+      setBreakpoint(threadFront, location);
+
+      let packet = await executeOnNextTickAndWaitForPause(function () {
+        Cu.evalInSandbox("f()", debuggee);
+      }, threadFront);
+      let why = packet.why;
+      let environment = await packet.frame.getEnvironment();
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+      let frame = packet.frame;
+      let where = frame.where;
+      Assert.equal(where.actor, source.actor);
+      Assert.equal(where.line, location.line);
+      let variables = environment.bindings.variables;
+      Assert.equal(variables.i.value.type, "undefined");
+
+      const location2 = { sourceUrl: sourceFront.url, line: 7 };
+      setBreakpoint(threadFront, location2);
+
+      packet = await executeOnNextTickAndWaitForPause(
+        () => resume(threadFront),
+        threadFront
+      );
+      environment = await packet.frame.getEnvironment();
+      why = packet.why;
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+      frame = packet.frame;
+      where = frame.where;
+      Assert.equal(where.actor, source.actor);
+      Assert.equal(where.line, location2.line);
+      variables = environment.bindings.variables;
+      Assert.equal(variables.i.value, 1);
+
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-multiple-statements.js b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-multiple-statements.js
new file mode 100644
index 0000000000..f5ec75a353
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-multiple-statements.js
@@ -0,0 +1,38 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl(
+  "setBreakpoint-on-line-with-multiple-statements.js"
+);
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScript(SOURCE_URL, debuggee);
+      const { source } = await promise;
+      const sourceFront = threadFront.source(source);
+
+      const location = { sourceUrl: sourceFront.url, line: 4 };
+      setBreakpoint(threadFront, location);
+
+      const packet = await executeOnNextTickAndWaitForPause(function () {
+        Cu.evalInSandbox("f()", debuggee);
+      }, threadFront);
+      const why = packet.why;
+      const environment = await packet.frame.getEnvironment();
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+      const frame = packet.frame;
+      const where = frame.where;
+      Assert.equal(where.actor, source.actor);
+      Assert.equal(where.line, location.line);
+      const variables = environment.bindings.variables;
+      Assert.equal(variables.a.value.type, "undefined");
+      Assert.equal(variables.b.value.type, "undefined");
+      Assert.equal(variables.c.value.type, "undefined");
+
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-no-offsets-in-gcd-script.js b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-no-offsets-in-gcd-script.js
new file mode 100644
index 0000000000..1bcdadbe4a
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-no-offsets-in-gcd-script.js
@@ -0,0 +1,56 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl(
+  "setBreakpoint-on-line-with-no-offsets-in-gcd-script.js"
+);
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee, targetFront }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScriptWithOptions(SOURCE_URL, {
+        target: debuggee,
+        ignoreCache: true,
+      });
+      Cu.forceGC();
+      Cu.forceGC();
+      Cu.forceGC();
+
+      const { source } = await promise;
+      const sourceFront = threadFront.source(source);
+
+      const location = { line: 7 };
+      let [packet, breakpointClient] = await setBreakpoint(
+        sourceFront,
+        location
+      );
+      Assert.ok(packet.isPending);
+      Assert.equal(false, "actualLocation" in packet);
+
+      packet = await executeOnNextTickAndWaitForPause(function () {
+        reload(targetFront).then(function () {
+          loadSubScriptWithOptions(SOURCE_URL, {
+            target: debuggee,
+            ignoreCache: true,
+          });
+        });
+      }, threadFront);
+      const environment = await packet.frame.getEnvironment();
+      Assert.equal(packet.type, "paused");
+      const why = packet.why;
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+      Assert.equal(why.actors[0], breakpointClient.actor);
+      const frame = packet.frame;
+      const where = frame.where;
+      Assert.equal(where.actor, source.actor);
+      Assert.equal(where.line, 8);
+      const variables = environment.bindings.variables;
+      Assert.equal(variables.a.value, 1);
+      Assert.equal(variables.c.value.type, "undefined");
+
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-no-offsets.js b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-no-offsets.js
new file mode 100644
index 0000000000..5700097ea6
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line-with-no-offsets.js
@@ -0,0 +1,44 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl("setBreakpoint-on-line-with-no-offsets.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScript(SOURCE_URL, debuggee);
+      const { source } = await promise;
+      const sourceFront = threadFront.source(source);
+
+      const location = { line: 5 };
+      let [packet, breakpointClient] = await setBreakpoint(
+        sourceFront,
+        location
+      );
+      Assert.ok(!packet.isPending);
+      Assert.ok("actualLocation" in packet);
+      const actualLocation = packet.actualLocation;
+      Assert.equal(actualLocation.line, 6);
+
+      packet = await executeOnNextTickAndWaitForPause(function () {
+        Cu.evalInSandbox("f()", debuggee);
+      }, threadFront);
+      const environment = await packet.frame.getEnvironment();
+      Assert.equal(packet.type, "paused");
+      const why = packet.why;
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+      Assert.equal(why.actors[0], breakpointClient.actor);
+      const frame = packet.frame;
+      const where = frame.where;
+      Assert.equal(where.actor, source.actor);
+      Assert.equal(where.line, actualLocation.line);
+      const variables = environment.bindings.variables;
+      Assert.equal(variables.a.value, 1);
+      Assert.equal(variables.c.value.type, "undefined");
+
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_setBreakpoint-on-line.js b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line.js
new file mode 100644
index 0000000000..93e01b757c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_setBreakpoint-on-line.js
@@ -0,0 +1,36 @@
+"use strict";
+
+const SOURCE_URL = getFileUrl("setBreakpoint-on-line.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+      loadSubScript(SOURCE_URL, debuggee);
+      const { source } = await promise;
+      const sourceFront = threadFront.source(source);
+
+      const location = { sourceUrl: sourceFront.url, line: 5 };
+      setBreakpoint(threadFront, location);
+
+      const packet = await executeOnNextTickAndWaitForPause(function () {
+        Cu.evalInSandbox("f()", debuggee);
+      }, threadFront);
+      const environment = await packet.frame.getEnvironment();
+      const why = packet.why;
+      Assert.equal(why.type, "breakpoint");
+      Assert.equal(why.actors.length, 1);
+      const frame = packet.frame;
+      const where = frame.where;
+      Assert.equal(where.actor, source.actor);
+      Assert.equal(where.line, location.line);
+      const variables = environment.bindings.variables;
+      Assert.equal(variables.a.value, 1);
+      Assert.equal(variables.b.value.type, "undefined");
+      Assert.equal(variables.c.value.type, "undefined");
+
+      await resume(threadFront);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_shapes_highlighter_helpers.js b/devtools/server/tests/xpcshell/test_shapes_highlighter_helpers.js
new file mode 100644
index 0000000000..6876f0a532
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_shapes_highlighter_helpers.js
@@ -0,0 +1,274 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Test the helper functions of the shapes highlighter.
+ */
+
+"use strict";
+
+const {
+  splitCoords,
+  coordToPercent,
+  evalCalcExpression,
+  shapeModeToCssPropertyName,
+  getCirclePath,
+  getDecimalPrecision,
+  getUnit,
+} = require("resource://devtools/server/actors/highlighters/shapes.js");
+
+function run_test() {
+  test_split_coords();
+  test_coord_to_percent();
+  test_eval_calc_expression();
+  test_shape_mode_to_css_property_name();
+  test_get_circle_path();
+  test_get_decimal_precision();
+  test_get_unit();
+  run_next_test();
+}
+
+function test_split_coords() {
+  const tests = [
+    {
+      desc: "splitCoords for basic coordinate pair",
+      expr: "30% 20%",
+      expected: ["30%", "20%"],
+    },
+    {
+      desc: "splitCoords for coord pair with calc()",
+      expr: "calc(50px + 20%) 30%",
+      expected: ["calc(50px\u00a0+\u00a020%)", "30%"],
+    },
+  ];
+
+  for (const { desc, expr, expected } of tests) {
+    deepEqual(splitCoords(expr), expected, desc);
+  }
+}
+
+function test_coord_to_percent() {
+  const size = 1000;
+  const tests = [
+    {
+      desc: "coordToPercent for percent value",
+      expr: "50%",
+      expected: 50,
+    },
+    {
+      desc: "coordToPercent for px value",
+      expr: "500px",
+      expected: 50,
+    },
+    {
+      desc: "coordToPercent for zero value",
+      expr: "0",
+      expected: 0,
+    },
+  ];
+
+  for (const { desc, expr, expected } of tests) {
+    equal(coordToPercent(expr, size), expected, desc);
+  }
+}
+
+function test_eval_calc_expression() {
+  const size = 1000;
+  const tests = [
+    {
+      desc: "evalCalcExpression with one value",
+      expr: "50%",
+      expected: 50,
+    },
+    {
+      desc: "evalCalcExpression with percent and px values",
+      expr: "50% + 100px",
+      expected: 60,
+    },
+    {
+      desc: "evalCalcExpression with a zero value",
+      expr: "0 + 100px",
+      expected: 10,
+    },
+    {
+      desc: "evalCalcExpression with a negative value",
+      expr: "-200px+50%",
+      expected: 30,
+    },
+  ];
+
+  for (const { desc, expr, expected } of tests) {
+    equal(evalCalcExpression(expr, size), expected, desc);
+  }
+}
+
+function test_shape_mode_to_css_property_name() {
+  const tests = [
+    {
+      desc: "shapeModeToCssPropertyName for clip-path",
+      expr: "cssClipPath",
+      expected: "clipPath",
+    },
+    {
+      desc: "shapeModeToCssPropertyName for shape-outside",
+      expr: "cssShapeOutside",
+      expected: "shapeOutside",
+    },
+  ];
+
+  for (const { desc, expr, expected } of tests) {
+    equal(shapeModeToCssPropertyName(expr), expected, desc);
+  }
+}
+
+function test_get_circle_path() {
+  const tests = [
+    {
+      desc: "getCirclePath with size 5, no resizing, no zoom, 1:1 ratio",
+      size: 5,
+      cx: 0,
+      cy: 0,
+      width: 100,
+      height: 100,
+      zoom: 1,
+      expected: "M-5,0a5,5 0 1,0 10,0a5,5 0 1,0 -10,0",
+    },
+    {
+      desc: "getCirclePath with size 7, resizing, no zoom, 1:1 ratio",
+      size: 7,
+      cx: 0,
+      cy: 0,
+      width: 200,
+      height: 200,
+      zoom: 1,
+      expected: "M-3.5,0a3.5,3.5 0 1,0 7,0a3.5,3.5 0 1,0 -7,0",
+    },
+    {
+      desc: "getCirclePath with size 5, resizing, zoom, 1:1 ratio",
+      size: 5,
+      cx: 0,
+      cy: 0,
+      width: 200,
+      height: 200,
+      zoom: 2,
+      expected: "M-1.25,0a1.25,1.25 0 1,0 2.5,0a1.25,1.25 0 1,0 -2.5,0",
+    },
+    {
+      desc: "getCirclePath with size 5, resizing, zoom, non-square ratio",
+      size: 5,
+      cx: 0,
+      cy: 0,
+      width: 100,
+      height: 200,
+      zoom: 2,
+      expected: "M-2.5,0a2.5,1.25 0 1,0 5,0a2.5,1.25 0 1,0 -5,0",
+    },
+  ];
+
+  for (const { desc, size, cx, cy, width, height, zoom, expected } of tests) {
+    equal(getCirclePath(size, cx, cy, width, height, zoom), expected, desc);
+  }
+}
+
+function test_get_decimal_precision() {
+  const tests = [
+    {
+      desc: "getDecimalPrecision with px",
+      expr: "px",
+      expected: 0,
+    },
+    {
+      desc: "getDecimalPrecision with %",
+      expr: "%",
+      expected: 2,
+    },
+    {
+      desc: "getDecimalPrecision with em",
+      expr: "em",
+      expected: 2,
+    },
+    {
+      desc: "getDecimalPrecision with undefined",
+      expr: undefined,
+      expected: 0,
+    },
+    {
+      desc: "getDecimalPrecision with empty string",
+      expr: "",
+      expected: 0,
+    },
+  ];
+
+  for (const { desc, expr, expected } of tests) {
+    equal(getDecimalPrecision(expr), expected, desc);
+  }
+}
+
+function test_get_unit() {
+  const tests = [
+    {
+      desc: "getUnit with %",
+      expr: "30%",
+      expected: "%",
+    },
+    {
+      desc: "getUnit with px",
+      expr: "400px",
+      expected: "px",
+    },
+    {
+      desc: "getUnit with em",
+      expr: "4em",
+      expected: "em",
+    },
+    {
+      desc: "getUnit with 0",
+      expr: "0",
+      expected: "px",
+    },
+    {
+      desc: "getUnit with 0%",
+      expr: "0%",
+      expected: "%",
+    },
+    {
+      desc: "getUnit with 0.00%",
+      expr: "0.00%",
+      expected: "%",
+    },
+    {
+      desc: "getUnit with 0px",
+      expr: "0px",
+      expected: "px",
+    },
+    {
+      desc: "getUnit with 0em",
+      expr: "0em",
+      expected: "em",
+    },
+    {
+      desc: "getUnit with calc",
+      expr: "calc(30px + 5%)",
+      expected: "px",
+    },
+    {
+      desc: "getUnit with var",
+      expr: "var(--variable)",
+      expected: "px",
+    },
+    {
+      desc: "getUnit with closest-side",
+      expr: "closest-side",
+      expected: "px",
+    },
+    {
+      desc: "getUnit with farthest-side",
+      expr: "farthest-side",
+      expected: "px",
+    },
+  ];
+
+  for (const { desc, expr, expected } of tests) {
+    equal(getUnit(expr), expected, desc);
+  }
+}
diff --git a/devtools/server/tests/xpcshell/test_source-01.js b/devtools/server/tests/xpcshell/test_source-01.js
new file mode 100644
index 0000000000..5cb7a6da52
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_source-01.js
@@ -0,0 +1,58 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// This test ensures that we can create SourceActors and SourceFronts properly,
+// and that they can communicate over the protocol to fetch the source text for
+// a given script.
+
+const SOURCE_URL = "http://example.com/foobar.js";
+const SOURCE_CONTENT = "stopMe()";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    DevToolsServer.LONG_STRING_LENGTH = 200;
+
+    await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    const response = await threadFront.getSources();
+
+    Assert.ok(!!response);
+    Assert.ok(!!response.sources);
+
+    const source = response.sources.filter(function (s) {
+      return s.url === SOURCE_URL;
+    })[0];
+
+    Assert.ok(!!source);
+
+    const sourceFront = threadFront.source(source);
+    const response2 = await sourceFront.source();
+
+    Assert.ok(!!response2);
+    Assert.ok(!!response2.contentType);
+    Assert.ok(response2.contentType.includes("javascript"));
+
+    Assert.ok(!!response2.source);
+    Assert.equal(SOURCE_CONTENT, response2.source);
+
+    await threadFront.resume();
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  Cu.evalInSandbox(
+    "" +
+      function stopMe(arg1) {
+        debugger;
+      },
+    debuggee,
+    "1.8",
+    getFileUrl("test_source-01.js")
+  );
+
+  Cu.evalInSandbox(SOURCE_CONTENT, debuggee, "1.8", SOURCE_URL);
+}
diff --git a/devtools/server/tests/xpcshell/test_source-02.js b/devtools/server/tests/xpcshell/test_source-02.js
new file mode 100644
index 0000000000..9cb88cb0e4
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_source-02.js
@@ -0,0 +1,64 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// This test ensures that we can create SourceActors and SourceFronts properly,
+// and that they can communicate over the protocol to fetch the source text for
+// a given script.
+
+const SOURCE_URL = "http://example.com/foobar.js";
+const SOURCE_CONTENT = `
+  stopMe();
+  for(var i = 0; i < 2; i++) {
+    debugger;
+  }
+`;
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    DevToolsServer.LONG_STRING_LENGTH = 200;
+
+    await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    let response = await threadFront.getSources();
+    Assert.ok(!!response);
+    Assert.ok(!!response.sources);
+
+    const source = response.sources.filter(function (s) {
+      return s.url === SOURCE_URL;
+    })[0];
+
+    Assert.ok(!!source);
+
+    const sourceFront = threadFront.source(source);
+    response = await sourceFront.getBreakpointPositionsCompressed();
+    Assert.ok(!!response);
+
+    Assert.deepEqual(response, {
+      2: [2],
+      3: [14, 17, 24],
+      4: [4],
+      6: [0],
+    });
+
+    await threadFront.resume();
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  Cu.evalInSandbox(
+    "" +
+      function stopMe(arg1) {
+        debugger;
+      },
+    debuggee,
+    "1.8",
+    getFileUrl("test_source-02.js")
+  );
+
+  Cu.evalInSandbox(SOURCE_CONTENT, debuggee, "1.8", SOURCE_URL);
+}
diff --git a/devtools/server/tests/xpcshell/test_source-03.js b/devtools/server/tests/xpcshell/test_source-03.js
new file mode 100644
index 0000000000..d0cd4839a0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_source-03.js
@@ -0,0 +1,75 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const SOURCE_URL = getFileUrl("source-03.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, server }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+
+      // Create a two globals in the default junk sandbox compartment so that
+      // both globals are part of the same compartment.
+      server.allowNewThreadGlobals();
+      const debuggee1 = Cu.Sandbox(systemPrincipal);
+      debuggee1.__name = "debuggee2.js";
+      const debuggee2 = Cu.Sandbox(systemPrincipal);
+      debuggee2.__name = "debuggee2.js";
+      server.disallowNewThreadGlobals();
+
+      // Load two copies of the source file. The first call to "loadSubScript" will
+      // create a ScriptSourceObject and a JSScript which references it.
+      // The second call will attempt to re-use JSScript objects because that is
+      // what loadSubScript does for instances of the same file that are loaded
+      // in the system principal in the same compartment.
+      //
+      // We explicitly want this because it is an edge case of the server. Most
+      // of the time a Debugger.Source will only have a single Debugger.Script
+      // associated with a given function, but in the context of explicitly
+      // cloned JSScripts, this is not the case, and we need to handle that.
+      loadSubScript(SOURCE_URL, debuggee1);
+      loadSubScript(SOURCE_URL, debuggee2);
+
+      await promise;
+
+      // We want to set a breakpoint and make sure that the breakpoint is properly
+      // set on _both_ files backed
+      await setBreakpoint(threadFront, {
+        sourceUrl: SOURCE_URL,
+        line: 4,
+      });
+
+      const { sources } = await getSources(threadFront);
+
+      // Note: Since we load the file twice, we end up with two copies of the
+      // source object, and so two sources here.
+      Assert.equal(sources.length, 2);
+
+      // Ensure that the breakpoint was properly applied to the JSScipt loaded
+      // in the first global.
+      let pausedOne = false;
+      let onResumed = null;
+      threadFront.once("paused", function (packet) {
+        pausedOne = true;
+        onResumed = resume(threadFront);
+      });
+      Cu.evalInSandbox("init()", debuggee1, "1.8", "test.js", 1);
+      await onResumed;
+      Assert.equal(pausedOne, true);
+
+      // Ensure that the breakpoint was properly applied to the JSScipt loaded
+      // in the second global.
+      let pausedTwo = false;
+      threadFront.once("paused", function (packet) {
+        pausedTwo = true;
+        onResumed = resume(threadFront);
+      });
+      Cu.evalInSandbox("init()", debuggee2, "1.8", "test.js", 1);
+      await onResumed;
+      Assert.equal(pausedTwo, true);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_source-04.js b/devtools/server/tests/xpcshell/test_source-04.js
new file mode 100644
index 0000000000..a3e3bef25f
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_source-04.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const SOURCE_URL = getFileUrl("source-03.js");
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, server }) => {
+      const promise = waitForNewSource(threadFront, SOURCE_URL);
+
+      // Create two globals in the default junk sandbox compartment so that
+      // both globals are part of the same compartment.
+      server.allowNewThreadGlobals();
+      const debuggee1 = Cu.Sandbox(systemPrincipal);
+      debuggee1.__name = "debuggee2.js";
+      const debuggee2 = Cu.Sandbox(systemPrincipal);
+      debuggee2.__name = "debuggee2.js";
+      server.disallowNewThreadGlobals();
+
+      // Load first copy of the source file. The first call to "loadSubScript" will
+      // create a ScriptSourceObject and a JSScript which references it.
+      loadSubScript(SOURCE_URL, debuggee1);
+
+      await promise;
+
+      // We want to set a breakpoint and make sure that the breakpoint is properly
+      // set on _both_ files backed
+      await setBreakpoint(threadFront, {
+        sourceUrl: SOURCE_URL,
+        line: 4,
+      });
+
+      const { sources } = await getSources(threadFront);
+      Assert.equal(sources.length, 1);
+
+      // Ensure that the breakpoint was properly applied to the JSScipt loaded
+      // in the first global.
+      let pausedOne = false;
+      let onResumed = null;
+      threadFront.once("paused", function (packet) {
+        pausedOne = true;
+        onResumed = resume(threadFront);
+      });
+      Cu.evalInSandbox("init()", debuggee1, "1.8", "test.js", 1);
+      await onResumed;
+      Assert.equal(pausedOne, true);
+
+      // Load second copy of the source file. The second call will attempt to
+      // re-use JSScript objects because that is what loadSubScript does for
+      // instances of the same file that are loaded in the system principal in
+      // the same compartment.
+      //
+      // We explicitly want this because it is an edge case of the server. Most
+      // of the time a Debugger.Source will only have a single Debugger.Script
+      // associated with a given function, but in the context of explicitly
+      // cloned JSScripts, this is not the case, and we need to handle that.
+      loadSubScript(SOURCE_URL, debuggee2);
+
+      // Ensure that the breakpoint was properly applied to the JSScipt loaded
+      // in the second global.
+      let pausedTwo = false;
+      threadFront.once("paused", function (packet) {
+        pausedTwo = true;
+        onResumed = resume(threadFront);
+      });
+      Cu.evalInSandbox("init()", debuggee2, "1.8", "test.js", 1);
+      await onResumed;
+      Assert.equal(pausedTwo, true);
+    },
+    { doNotRunWorker: true }
+  )
+);
diff --git a/devtools/server/tests/xpcshell/test_stepping-01.js b/devtools/server/tests/xpcshell/test_stepping-01.js
new file mode 100644
index 0000000000..0c66404510
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-01.js
@@ -0,0 +1,94 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check scenarios where we're leaving function a and
+ * going to the function b's call-site.
+ */
+
+async function testFinish({ threadFront, devToolsClient }) {
+  await close(devToolsClient);
+
+  do_test_finished();
+}
+
+async function invokeAndPause({ global, threadFront }, expression) {
+  return executeOnNextTickAndWaitForPause(
+    () => Cu.evalInSandbox(expression, global),
+    threadFront
+  );
+}
+
+async function step(threadFront, cmd) {
+  return cmd(threadFront);
+}
+
+function getPauseLocation(packet) {
+  const { line, column } = packet.frame.where;
+  return { line, column };
+}
+
+function getPauseReturn(packet) {
+  return packet.why.frameFinished.return;
+}
+
+async function steps(threadFront, sequence) {
+  const locations = [];
+  for (const cmd of sequence) {
+    const packet = await step(threadFront, cmd);
+    locations.push(getPauseLocation(packet));
+  }
+  return locations;
+}
+
+async function stepOutOfA(dbg, func, expectedLocation) {
+  await invokeAndPause(dbg, `${func}()`);
+  const { threadFront } = dbg;
+  await steps(threadFront, [stepOver, stepIn]);
+
+  const packet = await stepOut(threadFront);
+
+  deepEqual(
+    getPauseLocation(packet),
+    expectedLocation,
+    `step out location in ${func}`
+  );
+
+  await threadFront.resume();
+}
+
+async function stepOverInA(dbg, func, expectedLocation) {
+  await invokeAndPause(dbg, `${func}()`);
+  const { threadFront } = dbg;
+  await steps(threadFront, [stepOver, stepIn]);
+
+  let packet = await stepOver(threadFront);
+  equal(getPauseReturn(packet).ownPropertyLength, 1, "a() is returning obj");
+
+  packet = await stepOver(threadFront);
+  deepEqual(
+    getPauseLocation(packet),
+    expectedLocation,
+    `step out location in ${func}`
+  );
+  await dbg.threadFront.resume();
+}
+
+async function testStep(dbg, func, expectedValue) {
+  await stepOverInA(dbg, func, expectedValue);
+  await stepOutOfA(dbg, func, expectedValue);
+}
+
+function run_test() {
+  return (async function () {
+    const dbg = await setupTestFromUrl("stepping.js");
+
+    await testStep(dbg, "arithmetic", { line: 16, column: 8 });
+    await testStep(dbg, "composition", { line: 21, column: 3 });
+    await testStep(dbg, "chaining", { line: 26, column: 6 });
+
+    await testFinish(dbg);
+  })();
+}
diff --git a/devtools/server/tests/xpcshell/test_stepping-02.js b/devtools/server/tests/xpcshell/test_stepping-02.js
new file mode 100644
index 0000000000..c9df671839
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-02.js
@@ -0,0 +1,57 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check basic step-in functionality.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+    const dbgStmt = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    equal(
+      dbgStmt.frame.where.line,
+      2,
+      "Should be at debugger statement on line 2"
+    );
+    equal(debuggee.a, undefined);
+    equal(debuggee.b, undefined);
+
+    const step1 = await stepIn(threadFront);
+    equal(step1.why.type, "resumeLimit");
+    equal(step1.frame.where.line, 3);
+    equal(debuggee.a, undefined);
+    equal(debuggee.b, undefined);
+
+    const step3 = await stepIn(threadFront);
+    equal(step3.why.type, "resumeLimit");
+    equal(step3.frame.where.line, 4);
+    equal(debuggee.a, 1);
+    equal(debuggee.b, undefined);
+
+    const step4 = await stepIn(threadFront);
+    equal(step4.why.type, "resumeLimit");
+    equal(step4.frame.where.line, 4);
+    equal(debuggee.a, 1);
+    equal(debuggee.b, 2);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox(
+    `                                   // 1
+    debugger;                           // 2
+    var a = 1;                          // 3
+    var b = 2;`,                        // 4
+    debuggee,
+    "1.8",
+    "test_stepping-01-test-code.js",
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_stepping-03.js b/devtools/server/tests/xpcshell/test_stepping-03.js
new file mode 100644
index 0000000000..88422ac0cc
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-03.js
@@ -0,0 +1,43 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check basic step-out functionality.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+    await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const step1 = await stepOut(threadFront);
+    equal(step1.frame.where.line, 8);
+    equal(step1.why.type, "resumeLimit");
+
+    equal(debuggee.a, 1);
+    equal(debuggee.b, 2);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox(
+    `                                   // 1
+    function f() {                      // 2
+      debugger;                         // 3
+      this.a = 1;                       // 4
+      this.b = 2;                       // 5
+    }                                   // 6
+    f();                                // 7
+    `,                                  // 8
+    debuggee,
+    "1.8",
+    "test_stepping-01-test-code.js",
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_stepping-04.js b/devtools/server/tests/xpcshell/test_stepping-04.js
new file mode 100644
index 0000000000..37a9f843d0
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-04.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that stepping over a function call does not pause inside the function.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+    await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    dumpn("Step Over to f()");
+    const step1 = await stepOver(threadFront);
+    equal(step1.why.type, "resumeLimit");
+    equal(step1.frame.where.line, 6);
+    equal(debuggee.a, undefined);
+    equal(debuggee.b, undefined);
+
+    dumpn("Step Over f()");
+    const step2 = await stepOver(threadFront);
+    equal(step2.frame.where.line, 7);
+    equal(step2.why.type, "resumeLimit");
+    equal(debuggee.a, 1);
+    equal(debuggee.b, undefined);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox(
+    `                                   // 1
+    function f() {                      // 2
+      this.a = 1;                       // 3
+    }                                   // 4
+    debugger;                           // 5
+    f();                                // 6
+    let b = 2;                          // 7
+    `,                                  // 8
+    debuggee,
+    "1.8",
+    "test_stepping-01-test-code.js",
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_stepping-05.js b/devtools/server/tests/xpcshell/test_stepping-05.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-05.js
diff --git a/devtools/server/tests/xpcshell/test_stepping-06.js b/devtools/server/tests/xpcshell/test_stepping-06.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-06.js
diff --git a/devtools/server/tests/xpcshell/test_stepping-07.js b/devtools/server/tests/xpcshell/test_stepping-07.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-07.js
diff --git a/devtools/server/tests/xpcshell/test_stepping-08.js b/devtools/server/tests/xpcshell/test_stepping-08.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-08.js
diff --git a/devtools/server/tests/xpcshell/test_stepping-09.js b/devtools/server/tests/xpcshell/test_stepping-09.js
new file mode 100644
index 0000000000..da59ed963c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-09.js
@@ -0,0 +1,47 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that step out stops at the end of the parent if it fails to stop
+ * anywhere else. Bug 1504358.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+    const dbgStmt = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    equal(
+      dbgStmt.frame.where.line,
+      2,
+      "Should be at debugger statement on line 2"
+    );
+
+    dumpn("Step out of inner and into outer");
+    const step2 = await stepOut(threadFront);
+    // The bug was that we'd step right past the end of the function and never pause.
+    equal(step2.frame.where.line, 2);
+    equal(step2.frame.where.column, 31);
+    deepEqual(step2.why.frameFinished.return, { type: "undefined" });
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // By placing the inner and outer on the same line, this triggers the server's
+  // logic to skip steps for these functions, meaning that onPop is the only
+  // thing that will cause it to pop.
+  Cu.evalInSandbox(
+    `
+    function outer(){ inner(); return 42; } function inner(){ debugger; }
+    outer();
+    `,
+    debuggee,
+    "1.8",
+    "test_stepping-09-test-code.js",
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_stepping-10.js b/devtools/server/tests/xpcshell/test_stepping-10.js
new file mode 100644
index 0000000000..6ea95c3fd3
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-10.js
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that step out stops at the parent and the parent's parent.
+ * This checks for the failure found in bug 1530549.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+    const dbgStmt = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    equal(
+      dbgStmt.frame.where.line,
+      3,
+      "Should be at debugger statement on line 3"
+    );
+
+    dumpn("Step out of inner and into var statement IIFE");
+    const step2 = await stepOut(threadFront);
+    equal(step2.frame.where.line, 4);
+    deepEqual(step2.why.frameFinished.return, { type: "undefined" });
+
+    dumpn("Step out of vars and into script body");
+    const step3 = await stepOut(threadFront);
+    equal(step3.frame.where.line, 9);
+    deepEqual(step3.why.frameFinished.return, { type: "undefined" });
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  Cu.evalInSandbox(
+    `
+      (function() {
+        (function(){debugger;})();
+        var a = 1;
+        a = 2;
+        a = 3;
+        a = 4;
+      })();
+    `,
+    debuggee,
+    "1.8",
+    "test_stepping-10-test-code.js",
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_stepping-11.js b/devtools/server/tests/xpcshell/test_stepping-11.js
new file mode 100644
index 0000000000..8cbd285d89
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-11.js
@@ -0,0 +1,25 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check basic stepping for console evaluations.
+ */
+
+add_task(
+  threadFrontTest(async ({ commands, threadFront }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+
+    commands.scriptCommand.execute(`(function(){
+        debugger;
+        var a = 1;
+        var b = 2;
+      })();`);
+
+    await waitForEvent(threadFront, "paused");
+    const packet = await stepOver(threadFront);
+    Assert.equal(packet.frame.where.line, 3, "step to line 3");
+    await threadFront.resume();
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_stepping-12.js b/devtools/server/tests/xpcshell/test_stepping-12.js
new file mode 100644
index 0000000000..de96faf59f
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-12.js
@@ -0,0 +1,162 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that step out stops at the parent and the parent's parent.
+ * This checks for the failure found in bug 1530549.
+ */
+
+const sourceUrl = "test_stepping-10-test-code.js";
+
+add_task(
+  threadFrontTest(async args => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+
+    await testGenerator(args);
+    await testAwait(args);
+    await testInterleaving(args);
+    await testMultipleSteps(args);
+  })
+);
+
+async function testAwait({ threadFront, debuggee }) {
+  function evaluateTestCode() {
+    Cu.evalInSandbox(
+      `
+        (async function() {
+          debugger;
+          r = await Promise.resolve('yay');
+          a = 4;
+        })();
+      `,
+      debuggee,
+      "1.8",
+      sourceUrl,
+      1
+    );
+  }
+
+  await executeOnNextTickAndWaitForPause(evaluateTestCode, threadFront);
+
+  dumpn("Step Over and land on line 5");
+  const step1 = await stepOver(threadFront);
+  equal(step1.frame.where.line, 4);
+  equal(step1.frame.where.column, 10);
+
+  const step2 = await stepOver(threadFront);
+  equal(step2.frame.where.line, 5);
+  equal(step2.frame.where.column, 10);
+  equal(debuggee.r, "yay");
+  await resume(threadFront);
+}
+
+async function testInterleaving({ threadFront, debuggee }) {
+  function evaluateTestCode() {
+    Cu.evalInSandbox(
+      `
+        (async function simpleRace() {
+          debugger;
+          this.result = await new Promise((r) => {
+            Promise.resolve().then(() => { debugger });
+            Promise.resolve().then(r('yay'))
+          })
+          var a = 2;
+          debugger;
+        })()
+      `,
+      debuggee,
+      "1.8",
+      sourceUrl,
+      1
+    );
+  }
+
+  await executeOnNextTickAndWaitForPause(evaluateTestCode, threadFront);
+
+  dumpn("Step Over and land on line 5");
+  const step1 = await stepOver(threadFront);
+  equal(step1.frame.where.line, 4);
+
+  const step2 = await stepOver(threadFront);
+  equal(step2.frame.where.line, 5);
+  equal(step2.frame.where.column, 43);
+
+  const step3 = await resumeAndWaitForPause(threadFront);
+  equal(step3.frame.where.line, 9);
+  equal(debuggee.result, "yay");
+
+  await resume(threadFront);
+}
+
+async function testMultipleSteps({ threadFront, debuggee }) {
+  function evaluateTestCode() {
+    Cu.evalInSandbox(
+      `
+        (async function simpleRace() {
+          debugger;
+          await Promise.resolve();
+          var a = 2;
+          await Promise.resolve();
+          var b = 2;
+          await Promise.resolve();
+          debugger;
+        })()
+      `,
+      debuggee,
+      "1.8",
+      sourceUrl,
+      1
+    );
+  }
+
+  await executeOnNextTickAndWaitForPause(evaluateTestCode, threadFront);
+
+  const step1 = await stepOver(threadFront);
+  equal(step1.frame.where.line, 4);
+
+  const step2 = await stepOver(threadFront);
+  equal(step2.frame.where.line, 5);
+
+  const step3 = await stepOver(threadFront);
+  equal(step3.frame.where.line, 6);
+  resume(threadFront);
+}
+
+async function testGenerator({ threadFront, debuggee }) {
+  function evaluateTestCode() {
+    Cu.evalInSandbox(
+      `
+        (async function() {
+          function* makeSteps() {
+            debugger;
+            yield 1;
+            yield 2;
+            return 3;
+          }
+          const s = makeSteps();
+          s.next();
+          s.next();
+          s.next();
+        })()
+      `,
+      debuggee,
+      "1.8",
+      sourceUrl,
+      1
+    );
+  }
+
+  await executeOnNextTickAndWaitForPause(evaluateTestCode, threadFront);
+
+  const step1 = await stepOver(threadFront);
+  equal(step1.frame.where.line, 5);
+
+  const step2 = await stepOver(threadFront);
+  equal(step2.frame.where.line, 6);
+
+  const step3 = await stepOver(threadFront);
+  equal(step3.frame.where.line, 7);
+  await resume(threadFront);
+}
diff --git a/devtools/server/tests/xpcshell/test_stepping-13.js b/devtools/server/tests/xpcshell/test_stepping-13.js
new file mode 100644
index 0000000000..cbdb78ce2d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-13.js
@@ -0,0 +1,39 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/*
+ * Check that is possible to step into both the inner and outer function
+ * calls.
+ */
+
+add_task(
+  threadFrontTest(async ({ commands, threadFront }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+
+    commands.scriptCommand.execute(
+      `(function () {
+        const a = () => { return 2 };
+        debugger;
+        a(a())
+      })()`
+    );
+
+    await waitForEvent(threadFront, "paused");
+    const step1 = await stepOver(threadFront);
+    Assert.equal(step1.frame.where.line, 4, "step to line 4");
+
+    const step2 = await stepIn(threadFront);
+    Assert.equal(step2.frame.where.line, 2, "step in to line 2");
+
+    const step3 = await stepOut(threadFront);
+    Assert.equal(step3.frame.where.line, 4, "step back to line 4");
+    Assert.equal(step3.frame.where.column, 9, "step out to column 9");
+
+    const step4 = await stepIn(threadFront);
+    Assert.equal(step4.frame.where.line, 2, "step in to line 2");
+
+    await threadFront.resume();
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_stepping-14.js b/devtools/server/tests/xpcshell/test_stepping-14.js
new file mode 100644
index 0000000000..6d64a53a66
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-14.js
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/*
+ * Check that is possible to step into both the inner and outer function
+ * calls.
+ */
+
+add_task(
+  threadFrontTest(async ({ commands, threadFront }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+
+    commands.scriptCommand.execute(`(function () {
+        async function f() {
+          const p = Promise.resolve(43);
+          await p;
+          return p;
+        }
+
+        function call_f() {
+          Promise.resolve(42).then(forty_two => {
+            return forty_two;
+          });
+
+          f().then(v => {
+            return v;
+          });
+        }
+        debugger;
+        call_f();
+      })()`);
+
+    const packet = await waitForEvent(threadFront, "paused");
+    const location = {
+      sourceId: packet.frame.where.actor,
+      line: 4,
+      column: 10,
+    };
+
+    await threadFront.setBreakpoint(location, {});
+
+    const packet2 = await resumeAndWaitForPause(threadFront);
+    Assert.equal(packet2.frame.where.line, 4, "landed at await");
+
+    const packet3 = await stepIn(threadFront);
+    Assert.equal(packet3.frame.where.line, 5, "step to the next line");
+
+    await threadFront.resume();
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_stepping-15.js b/devtools/server/tests/xpcshell/test_stepping-15.js
new file mode 100644
index 0000000000..9e79b93687
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-15.js
@@ -0,0 +1,78 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test stepping from inside a blackboxed function
+ * test-page: https://dbg-blackbox-stepping.glitch.me/
+ */
+
+async function invokeAndPause({ global, threadFront }, expression, url) {
+  return executeOnNextTickAndWaitForPause(
+    () => Cu.evalInSandbox(expression, global, "1.8", url, 1),
+    threadFront
+  );
+}
+add_task(
+  threadFrontTest(async ({ commands, threadFront, debuggee }) => {
+    const dbg = { global: debuggee, threadFront };
+
+    // Test stepping from a blackboxed location
+    async function testStepping(action, expectedLine) {
+      commands.scriptCommand.execute(`outermost()`);
+      await waitForPause(threadFront);
+      await blackBox(blackboxedSourceFront);
+      const packet = await action(threadFront);
+      const { line, actor } = packet.frame.where;
+      equal(actor, unblackboxedActor, "paused in unblackboxed source");
+      equal(line, expectedLine, "paused at correct line");
+      await threadFront.resume();
+      await unBlackBox(blackboxedSourceFront);
+    }
+
+    invokeAndPause(
+      dbg,
+      `function outermost() {
+        const value = blackboxed1();
+        return value + 1;
+      }
+      function innermost() {
+        return 1;
+      }`,
+      "http://example.com/unblackboxed.js"
+    );
+    invokeAndPause(
+      dbg,
+      `function blackboxed1() {
+        return blackboxed2();
+      }
+      function blackboxed2() {
+        return innermost();
+      }`,
+      "http://example.com/blackboxed.js"
+    );
+
+    const { sources } = await getSources(threadFront);
+    const blackboxedSourceFront = threadFront.source(
+      sources.find(source => source.url == "http://example.com/blackboxed.js")
+    );
+    const unblackboxedActor = sources.find(
+      source => source.url == "http://example.com/unblackboxed.js"
+    ).actor;
+
+    await setBreakpoint(threadFront, {
+      sourceUrl: blackboxedSourceFront.url,
+      line: 5,
+    });
+
+    info("Step Out to outermost");
+    await testStepping(stepOut, 3);
+
+    info("Step Over to outermost");
+    await testStepping(stepOver, 3);
+
+    info("Step In to innermost");
+    await testStepping(stepIn, 6);
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_stepping-16.js b/devtools/server/tests/xpcshell/test_stepping-16.js
new file mode 100644
index 0000000000..e3bd94b747
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-16.js
@@ -0,0 +1,81 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test stepping from inside a blackboxed function
+ * test-page: https://dbg-blackbox-stepping2.glitch.me/
+ */
+
+async function invokeAndPause({ global, threadFront }, expression, url) {
+  return executeOnNextTickAndWaitForPause(
+    () => Cu.evalInSandbox(expression, global, "1.8", url, 1),
+    threadFront
+  );
+}
+
+add_task(
+  threadFrontTest(async ({ commands, threadFront, debuggee }) => {
+    const dbg = { global: debuggee, threadFront };
+    invokeAndPause(
+      dbg,
+      `function outermost() {
+        blackboxed(
+          function inner1() {
+            return 1;
+          },
+          function inner2() {
+            return 2;
+          }
+        );
+      }`,
+      "http://example.com/unblackboxed.js"
+    );
+    invokeAndPause(
+      dbg,
+      `function blackboxed(...args) {
+        for (const arg of args) {
+          arg();
+        }
+      }`,
+      "http://example.com/blackboxed.js"
+    );
+
+    const { sources } = await getSources(threadFront);
+    const blackboxedSourceFront = threadFront.source(
+      sources.find(source => source.url == "http://example.com/blackboxed.js")
+    );
+    const unblackboxedSource = sources.find(
+      source => source.url == "http://example.com/unblackboxed.js"
+    );
+    const unblackboxedActor = unblackboxedSource.actor;
+    const unblackboxedSourceFront = threadFront.source(unblackboxedSource);
+
+    await setBreakpoint(threadFront, {
+      sourceUrl: unblackboxedSourceFront.url,
+      line: 4,
+    });
+    blackBox(blackboxedSourceFront);
+
+    async function testStepping(action, expectedLine) {
+      commands.scriptCommand.execute("outermost()");
+      await waitForPause(threadFront);
+      await stepOver(threadFront);
+      const packet = await action(threadFront);
+      const { actor, line } = packet.frame.where;
+      equal(actor, unblackboxedActor, "Paused in unblackboxed source");
+      equal(line, expectedLine, "Paused at correct line");
+      await threadFront.resume();
+    }
+
+    info("Step Out to outermost");
+    await testStepping(stepOut, 10);
+
+    info("Step Over to outermost");
+    await testStepping(stepOver, 10);
+
+    info("Step In to inner2");
+    await testStepping(stepIn, 7);
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_stepping-17.js b/devtools/server/tests/xpcshell/test_stepping-17.js
new file mode 100644
index 0000000000..816946fa4c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-17.js
@@ -0,0 +1,69 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/*
+ * Check that you can step from one script or event to another
+ */
+
+add_task(
+  threadFrontTest(async ({ commands, threadFront, debuggee }) => {
+    Cu.evalInSandbox(
+      `function blackboxed(callback) { return () => callback(); }`,
+      debuggee,
+      "1.8",
+      "http://example.com/blackboxed.js",
+      1
+    );
+
+    const { sources } = await getSources(threadFront);
+    const blackboxedSourceFront = threadFront.source(
+      sources.find(source => source.url == "http://example.com/blackboxed.js")
+    );
+    blackBox(blackboxedSourceFront);
+
+    const testStepping = async function (wrapperName, stepHandler, message) {
+      commands.scriptCommand.execute(`(function () {
+          const p = Promise.resolve();
+          p.then(${wrapperName}(() => { debugger; }))
+          .then(${wrapperName}(() => { }));
+        })();`);
+
+      await waitForEvent(threadFront, "paused");
+      const step = await stepHandler(threadFront);
+      Assert.equal(step.frame.where.line, 4, message);
+      await resume(threadFront);
+    };
+
+    const stepTwice = async function () {
+      await stepOver(threadFront);
+      return stepOver(threadFront);
+    };
+
+    await testStepping("", stepTwice, "Step over on the outermost frame");
+    await testStepping("blackboxed", stepTwice, "Step over with blackboxing");
+    await testStepping("", stepOut, "Step out on the outermost frame");
+    await testStepping("blackboxed", stepOut, "Step out with blackboxing");
+
+    commands.scriptCommand.execute(`(async function () {
+        const p = Promise.resolve();
+        const p2 = p.then(() => {
+          debugger;
+          return "async stepping!";
+        });
+        debugger;
+        await p;
+        const result = await p2;
+        return result;
+      })();
+      `);
+
+    await waitForEvent(threadFront, "paused");
+    await stepOver(threadFront);
+    await stepOver(threadFront);
+    const step = await stepOut(threadFront);
+    await resume(threadFront);
+    Assert.equal(step.frame.where.line, 9, "Step out of promise into async fn");
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_stepping-18.js b/devtools/server/tests/xpcshell/test_stepping-18.js
new file mode 100644
index 0000000000..e8581835d3
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-18.js
@@ -0,0 +1,100 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check scenarios where we're leaving function a and
+ * going to the function b's call-site.
+ */
+
+async function testFinish({ threadFront, devToolsClient }) {
+  await close(devToolsClient);
+
+  do_test_finished();
+}
+
+async function invokeAndPause({ global, threadFront }, expression) {
+  return executeOnNextTickAndWaitForPause(
+    () => Cu.evalInSandbox(expression, global),
+    threadFront
+  );
+}
+
+async function steps(threadFront, sequence) {
+  const locations = [];
+  for (const cmd of sequence) {
+    const packet = await step(threadFront, cmd);
+    locations.push(getPauseLocation(packet));
+  }
+  return locations;
+}
+
+async function step(threadFront, cmd) {
+  return cmd(threadFront);
+}
+
+function getPauseLocation(packet) {
+  const { line, column } = packet.frame.where;
+  return { line, column };
+}
+
+async function stepOutOfA(dbg, func, frameIndex, expectedLocation) {
+  const { threadFront } = dbg;
+
+  info("pause and step into a()");
+  await invokeAndPause(dbg, `${func}()`);
+  await steps(threadFront, [stepOver, stepIn, stepIn]);
+
+  const { frames } = await threadFront.frames(0, 5);
+  const frameActorID = frames[frameIndex].actorID;
+  const packet = await stepOut(threadFront, frameActorID);
+
+  deepEqual(
+    getPauseLocation(packet),
+    expectedLocation,
+    `step over location in ${func}`
+  );
+
+  await dbg.threadFront.resume();
+}
+
+async function stepOverInA(dbg, func, frameIndex, expectedLocation) {
+  const { threadFront } = dbg;
+
+  info("pause and step into a()");
+  await invokeAndPause(dbg, `${func}()`);
+  await steps(threadFront, [stepOver, stepIn]);
+
+  const { frames } = await threadFront.frames(0, 5);
+  const frameActorID = frames[frameIndex].actorID;
+  const packet = await stepOver(threadFront, frameActorID);
+
+  deepEqual(
+    getPauseLocation(packet),
+    expectedLocation,
+    `step over location in ${func}`
+  );
+
+  await dbg.threadFront.resume();
+}
+
+function run_test() {
+  return (async function () {
+    const dbg = await setupTestFromUrl("stepping.js");
+
+    info(`Test step over with the 1st frame`);
+    await stepOverInA(dbg, "arithmetic", 0, { line: 8, column: 0 });
+
+    info(`Test step over with the 2nd frame`);
+    await stepOverInA(dbg, "arithmetic", 1, { line: 17, column: 0 });
+
+    info(`Test step out with the 1st frame`);
+    await stepOutOfA(dbg, "nested", 0, { line: 31, column: 0 });
+
+    info(`Test step out with the 2nd frame`);
+    await stepOutOfA(dbg, "nested", 1, { line: 36, column: 0 });
+
+    await testFinish(dbg);
+  })();
+}
diff --git a/devtools/server/tests/xpcshell/test_stepping-19.js b/devtools/server/tests/xpcshell/test_stepping-19.js
new file mode 100644
index 0000000000..7ab21c7b66
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-19.js
@@ -0,0 +1,93 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that step out stops at the async parent's frame.
+ */
+
+async function testFinish({ threadFront, devToolsClient }) {
+  await close(devToolsClient);
+
+  do_test_finished();
+}
+
+async function invokeAndPause({ global, threadFront }, expression) {
+  return executeOnNextTickAndWaitForPause(
+    () => Cu.evalInSandbox(expression, global),
+    threadFront
+  );
+}
+
+async function steps(threadFront, sequence) {
+  const locations = [];
+  for (const cmd of sequence) {
+    const packet = await step(threadFront, cmd);
+    locations.push(getPauseLocation(packet));
+  }
+  return locations;
+}
+
+async function step(threadFront, cmd) {
+  return cmd(threadFront);
+}
+
+function getPauseLocation(packet) {
+  const { line, column } = packet.frame.where;
+  return { line, column };
+}
+
+async function stepOutBeforeTimer(dbg, func, frameIndex, expectedLocation) {
+  const { threadFront } = dbg;
+
+  await invokeAndPause(dbg, `${func}()`);
+  await steps(threadFront, [stepOver, stepIn]);
+
+  const { frames } = await threadFront.frames(0, 5);
+  const frameActorID = frames[frameIndex].actorID;
+  const packet = await stepOut(threadFront, frameActorID);
+
+  deepEqual(
+    getPauseLocation(packet),
+    expectedLocation,
+    `step out location in ${func}`
+  );
+
+  await resumeAndWaitForPause(threadFront);
+  await resume(threadFront);
+}
+
+async function stepOutAfterTimer(dbg, func, frameIndex, expectedLocation) {
+  const { threadFront } = dbg;
+
+  await invokeAndPause(dbg, `${func}()`);
+  await steps(threadFront, [stepOver, stepIn, stepOver, stepOver]);
+
+  const { frames } = await threadFront.frames(0, 5);
+  const frameActorID = frames[frameIndex].actorID;
+  const packet = await stepOut(threadFront, frameActorID);
+
+  deepEqual(
+    getPauseLocation(packet),
+    expectedLocation,
+    `step out location in ${func}`
+  );
+
+  await resumeAndWaitForPause(threadFront);
+  await dbg.threadFront.resume();
+}
+
+function run_test() {
+  return (async function () {
+    const dbg = await setupTestFromUrl("stepping-async.js");
+
+    info(`Test stepping out before timer;`);
+    await stepOutBeforeTimer(dbg, "stuff", 0, { line: 27, column: 2 });
+
+    info(`Test stepping out after timer;`);
+    await stepOutAfterTimer(dbg, "stuff", 0, { line: 29, column: 2 });
+
+    await testFinish(dbg);
+  })();
+}
diff --git a/devtools/server/tests/xpcshell/test_stepping-with-skip-breakpoints.js b/devtools/server/tests/xpcshell/test_stepping-with-skip-breakpoints.js
new file mode 100644
index 0000000000..3ec4fd994d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_stepping-with-skip-breakpoints.js
@@ -0,0 +1,84 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check basic step-over functionality with pause points
+ * for the first statement and end of the last statement.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+    const dbgStmt = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+    equal(
+      dbgStmt.frame.where.line,
+      2,
+      "Should be at debugger statement on line 2"
+    );
+    equal(debuggee.a, undefined);
+    equal(debuggee.b, undefined);
+
+    const source = await getSource(
+      threadFront,
+      "test_stepping-01-test-code.js"
+    );
+
+    // Add pause points for the first and end of the last statement.
+    // Note: we intentionally ignore the second statement.
+    source.setPausePoints([
+      {
+        location: { line: 3, column: 8 },
+        types: { breakpoint: true, stepOver: true },
+      },
+      {
+        location: { line: 4, column: 14 },
+        types: { breakpoint: true, stepOver: true },
+      },
+    ]);
+
+    dumpn("Step Over to line 3");
+    const step1 = await stepOver(threadFront);
+    equal(step1.why.type, "resumeLimit");
+    equal(step1.frame.where.line, 3);
+    equal(step1.frame.where.column, 12);
+
+    equal(debuggee.a, undefined);
+    equal(debuggee.b, undefined);
+
+    dumpn("Step Over to line 4");
+    const step2 = await stepOver(threadFront);
+    equal(step2.why.type, "resumeLimit");
+    equal(step2.frame.where.line, 4);
+    equal(step2.frame.where.column, 12);
+
+    equal(debuggee.a, 1);
+    equal(debuggee.b, undefined);
+
+    dumpn("Step Over to the end of line 4");
+    const step3 = await stepOver(threadFront);
+    equal(step3.why.type, "resumeLimit");
+    equal(step3.frame.where.line, 4);
+    equal(step3.frame.where.column, 14);
+    equal(debuggee.a, 1);
+    equal(debuggee.b, 2);
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  // prettier-ignore
+  Cu.evalInSandbox(
+    `                                   // 1
+    debugger;                           // 2
+    var a = 1;                          // 3
+    var b = 2;`,                        // 4
+    debuggee,
+    "1.8",
+    "test_stepping-01-test-code.js",
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_symbolactor.js b/devtools/server/tests/xpcshell/test_symbolactor.js
new file mode 100644
index 0000000000..0d04a2bd1d
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_symbolactor.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  SymbolActor,
+} = require("resource://devtools/server/actors/object/symbol.js");
+
+function run_test() {
+  test_SA_destroy();
+  test_SA_form();
+  test_SA_raw();
+}
+
+const SYMBOL_NAME = "abc";
+const TEST_SYMBOL = Symbol(SYMBOL_NAME);
+
+function makeMockSymbolActor() {
+  const symbol = TEST_SYMBOL;
+  const mockConn = null;
+  const actor = new SymbolActor(mockConn, symbol);
+  actor.actorID = "symbol1";
+  const parentPool = {
+    symbolActors: {
+      [symbol]: actor,
+    },
+    unmanage: () => {},
+  };
+  actor.getParent = () => parentPool;
+  return actor;
+}
+
+function test_SA_destroy() {
+  const actor = makeMockSymbolActor();
+  strictEqual(actor.getParent().symbolActors[TEST_SYMBOL], actor);
+
+  actor.destroy();
+  strictEqual(TEST_SYMBOL in actor.getParent().symbolActors, false);
+}
+
+function test_SA_form() {
+  const actor = makeMockSymbolActor();
+  const form = actor.form();
+  strictEqual(form.type, "symbol");
+  strictEqual(form.actor, actor.actorID);
+  strictEqual(form.name, SYMBOL_NAME);
+}
+
+function test_SA_raw() {
+  const actor = makeMockSymbolActor();
+  strictEqual(actor.rawValue(), TEST_SYMBOL);
+}
diff --git a/devtools/server/tests/xpcshell/test_symbols-01.js b/devtools/server/tests/xpcshell/test_symbols-01.js
new file mode 100644
index 0000000000..5352542e83
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_symbols-01.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that we can represent ES6 Symbols over the RDP.
+ */
+
+const URL = "foo.js";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    await testSymbols(threadFront, debuggee);
+  })
+);
+
+async function testSymbols(threadFront, debuggee) {
+  const evalCode = () => {
+    /* eslint-disable mozilla/var-only-at-top-level, no-unused-vars */
+    // prettier-ignore
+    Cu.evalInSandbox(
+      "(" + function () {
+        var symbolWithName = Symbol("Chris");
+        var symbolWithoutName = Symbol();
+        var iteratorSymbol = Symbol.iterator;
+        debugger;
+      } + "())",
+      debuggee,
+      "1.8",
+      URL,
+      1
+    );
+    /* eslint-enable mozilla/var-only-at-top-level, no-unused-vars */
+  };
+
+  const packet = await executeOnNextTickAndWaitForPause(evalCode, threadFront);
+  const environment = await packet.frame.getEnvironment();
+  const { symbolWithName, symbolWithoutName, iteratorSymbol } =
+    environment.bindings.variables;
+
+  equal(symbolWithName.value.type, "symbol");
+  equal(symbolWithName.value.name, "Chris");
+
+  equal(symbolWithoutName.value.type, "symbol");
+  ok(!("name" in symbolWithoutName.value));
+
+  equal(iteratorSymbol.value.type, "symbol");
+  equal(iteratorSymbol.value.name, "Symbol.iterator");
+}
diff --git a/devtools/server/tests/xpcshell/test_symbols-02.js b/devtools/server/tests/xpcshell/test_symbols-02.js
new file mode 100644
index 0000000000..12d4ef80c8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_symbols-02.js
@@ -0,0 +1,44 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that we don't run debuggee code when getting symbol names.
+ */
+
+const URL = "foo.js";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    await testSymbols(threadFront, debuggee);
+  })
+);
+
+async function testSymbols(threadFront, debuggee) {
+  const evalCode = () => {
+    /* eslint-disable mozilla/var-only-at-top-level, no-extend-native, no-unused-vars */
+    // prettier-ignore
+    Cu.evalInSandbox(
+      "(" + function () {
+        Symbol.prototype.toString = () => {
+          throw new Error("lololol");
+        };
+        var sym = Symbol("le troll");
+        debugger;
+      } + "())",
+      debuggee,
+      "1.8",
+      URL,
+      1
+    );
+    /* eslint-enable mozilla/var-only-at-top-level, no-extend-native, no-unused-vars */
+  };
+
+  const packet = await executeOnNextTickAndWaitForPause(evalCode, threadFront);
+  const environment = await packet.frame.getEnvironment();
+  const { sym } = environment.bindings.variables;
+
+  equal(sym.value.type, "symbol");
+  equal(sym.value.name, "le troll");
+}
diff --git a/devtools/server/tests/xpcshell/test_threadlifetime-01.js b/devtools/server/tests/xpcshell/test_threadlifetime-01.js
new file mode 100644
index 0000000000..d2e8234fb9
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_threadlifetime-01.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that thread-lifetime grips last past a resume.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const pauseGrip = packet.frame.arguments[0];
+
+    // Create a thread-lifetime actor for this object.
+    const response = await client.request({
+      to: pauseGrip.actor,
+      type: "threadGrip",
+    });
+    // Successful promotion won't return an error.
+    Assert.equal(response.error, undefined);
+
+    const packet2 = await resumeAndWaitForPause(threadFront);
+
+    // Verify that the promoted actor is returned again.
+    Assert.equal(pauseGrip.actor, packet2.frame.arguments[0].actor);
+    // Now that we've resumed, should get unrecognizePacketType for the
+    // promoted grip.
+    try {
+      await client.request({ to: pauseGrip.actor, type: "bogusRequest" });
+      ok(false, "bogusRequest should throw");
+    } catch (e) {
+      Assert.equal(e.error, "unrecognizedPacketType");
+      ok(true, "bogusRequest thrown");
+    }
+    await threadFront.resume();
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(arg1) {
+          debugger;
+          debugger;
+        }
+        stopMe({ obj: true });
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_threadlifetime-02.js b/devtools/server/tests/xpcshell/test_threadlifetime-02.js
new file mode 100644
index 0000000000..c35350a48c
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_threadlifetime-02.js
@@ -0,0 +1,73 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that thread-lifetime grips last past a resume.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee, client }) => {
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    const pauseGrip = packet.frame.arguments[0];
+
+    // Create a thread-lifetime actor for this object.
+    const response = await client.request({
+      to: pauseGrip.actor,
+      type: "threadGrip",
+    });
+    // Successful promotion won't return an error.
+    Assert.equal(response.error, undefined);
+
+    const packet2 = await resumeAndWaitForPause(threadFront);
+
+    // Verify that the promoted actor is returned again.
+    Assert.equal(pauseGrip.actor, packet2.frame.arguments[0].actor);
+    // Now that we've resumed, release the thread-lifetime grip.
+    const objFront = new ObjectFront(
+      threadFront.conn,
+      threadFront.targetFront,
+      threadFront,
+      pauseGrip
+    );
+    await objFront.release();
+    const objFront2 = new ObjectFront(
+      threadFront.conn,
+      threadFront.targetFront,
+      threadFront,
+      pauseGrip
+    );
+
+    try {
+      await objFront2
+        .request({ to: pauseGrip.actor, type: "bogusRequest" })
+        .catch(function (error) {
+          Assert.ok(!!error.message.match(/noSuchActor/));
+          threadFront.resume();
+          throw new Error();
+        });
+      ok(false, "bogusRequest should throw");
+    } catch (e) {
+      ok(true, "bogusRequest thrown");
+    }
+  })
+);
+
+function evaluateTestCode(debuggee) {
+  debuggee.eval(
+    "(" +
+      function () {
+        function stopMe(arg1) {
+          debugger;
+          debugger;
+        }
+        stopMe({ obj: true });
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_threadlifetime-04.js b/devtools/server/tests/xpcshell/test_threadlifetime-04.js
new file mode 100644
index 0000000000..302985b4a1
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_threadlifetime-04.js
@@ -0,0 +1,63 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Check that requesting a thread-lifetime actor twice for the same
+ * value returns the same actor.
+ */
+
+var gDebuggee;
+var gClient;
+var gThreadFront;
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee, client }) => {
+      gThreadFront = threadFront;
+      gClient = client;
+      gDebuggee = debuggee;
+      test_thread_lifetime();
+    },
+    { waitForFinish: true }
+  )
+);
+
+function test_thread_lifetime() {
+  gThreadFront.once("paused", function (packet) {
+    const pauseGrip = packet.frame.arguments[0];
+
+    gClient.request(
+      { to: pauseGrip.actor, type: "threadGrip" },
+      function (response) {
+        // Successful promotion won't return an error.
+        Assert.equal(response.error, undefined);
+
+        const threadGrip1 = response.from;
+
+        gClient.request(
+          { to: pauseGrip.actor, type: "threadGrip" },
+          function (response) {
+            Assert.equal(threadGrip1, response.from);
+            gThreadFront.resume().then(function () {
+              threadFrontTestFinished();
+            });
+          }
+        );
+      }
+    );
+  });
+
+  gDebuggee.eval(
+    "(" +
+      function () {
+        function stopMe(arg1) {
+          debugger;
+        }
+        stopMe({ obj: true });
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_unsafeDereference.js b/devtools/server/tests/xpcshell/test_unsafeDereference.js
new file mode 100644
index 0000000000..53b70420c6
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_unsafeDereference.js
@@ -0,0 +1,130 @@
+// Any copyright is dedicated to the Public Domain.
+// http://creativecommons.org/publicdomain/zero/1.0/
+
+/* eslint-disable strict */
+
+// Test Debugger.Object.prototype.unsafeDereference in the presence of
+// interesting cross-compartment wrappers.
+//
+// This is not really a devtools server test; it's more of a Debugger test.
+// But we need xpcshell and Components.utils.Sandbox to get
+// cross-compartment wrappers with interesting properties, and this is the
+// xpcshell test directory most closely related to the JS Debugger API.
+
+addDebuggerToGlobal(globalThis);
+
+// Add a method to Debugger.Object for fetching value properties
+// conveniently.
+Debugger.Object.prototype.getProperty = function (name) {
+  const desc = this.getOwnPropertyDescriptor(name);
+  if (!desc) {
+    return undefined;
+  }
+  if (!desc.value) {
+    throw Error(
+      "Debugger.Object.prototype.getProperty: " +
+        "not a value property: " +
+        name
+    );
+  }
+  return desc.value;
+};
+
+function run_test() {
+  // Create a low-privilege sandbox, and a chrome-privilege sandbox.
+  const contentBox = Cu.Sandbox("http://www.example.com");
+  const chromeBox = Cu.Sandbox(this);
+
+  // Create an objects in this compartment, and one in each sandbox. We'll
+  // refer to the objects as "mainObj", "contentObj", and "chromeObj", in
+  // variable and property names.
+  const mainObj = { name: "mainObj" };
+  Cu.evalInSandbox('var contentObj = { name: "contentObj" };', contentBox);
+  Cu.evalInSandbox('var chromeObj = { name: "chromeObj" };', chromeBox);
+
+  // Give each global a pointer to all the other globals' objects.
+  contentBox.mainObj = chromeBox.mainObj = mainObj;
+  const contentObj = (chromeBox.contentObj = contentBox.contentObj);
+  const chromeObj = (contentBox.chromeObj = chromeBox.chromeObj);
+
+  // First, a whole bunch of basic sanity checks, to ensure that JavaScript
+  // evaluated in various scopes really does see the world the way this
+  // test expects it to.
+
+  // The objects appear as global variables in the sandbox, and as
+  // the sandbox object's properties in chrome.
+  Assert.ok(Cu.evalInSandbox("mainObj", contentBox) === contentBox.mainObj);
+  Assert.ok(
+    Cu.evalInSandbox("contentObj", contentBox) === contentBox.contentObj
+  );
+  Assert.ok(Cu.evalInSandbox("chromeObj", contentBox) === contentBox.chromeObj);
+  Assert.ok(Cu.evalInSandbox("mainObj", chromeBox) === chromeBox.mainObj);
+  Assert.ok(Cu.evalInSandbox("contentObj", chromeBox) === chromeBox.contentObj);
+  Assert.ok(Cu.evalInSandbox("chromeObj", chromeBox) === chromeBox.chromeObj);
+
+  // We (the main global) can see properties of all objects in all globals.
+  Assert.ok(contentBox.mainObj.name === "mainObj");
+  Assert.ok(contentBox.contentObj.name === "contentObj");
+  Assert.ok(contentBox.chromeObj.name === "chromeObj");
+
+  // chromeBox can see properties of all objects in all globals.
+  Assert.equal(Cu.evalInSandbox("mainObj.name", chromeBox), "mainObj");
+  Assert.equal(Cu.evalInSandbox("contentObj.name", chromeBox), "contentObj");
+  Assert.equal(Cu.evalInSandbox("chromeObj.name", chromeBox), "chromeObj");
+
+  // contentBox can see properties of the content object, but not of either
+  // chrome object, because by default, content -> chrome wrappers hide all
+  // object properties.
+  Assert.equal(Cu.evalInSandbox("mainObj.name", contentBox), undefined);
+  Assert.equal(Cu.evalInSandbox("contentObj.name", contentBox), "contentObj");
+  Assert.equal(Cu.evalInSandbox("chromeObj.name", contentBox), undefined);
+
+  // When viewing an object in compartment A from the vantage point of
+  // compartment B, Debugger should give the same results as debuggee code
+  // would.
+
+  // Create a debugger, debugging our two sandboxes.
+  const dbg = new Debugger();
+
+  // Create Debugger.Object instances referring to the two sandboxes, as
+  // seen from their own compartments.
+  const contentBoxDO = dbg.addDebuggee(contentBox);
+  const chromeBoxDO = dbg.addDebuggee(chromeBox);
+
+  // Use Debugger to view the objects from contentBox. We should get the
+  // same D.O instance from both getProperty and makeDebuggeeValue, and the
+  // same property visibility we checked for above.
+  const mainFromContentDO = contentBoxDO.getProperty("mainObj");
+  Assert.equal(mainFromContentDO, contentBoxDO.makeDebuggeeValue(mainObj));
+  Assert.equal(mainFromContentDO.getProperty("name"), undefined);
+  Assert.equal(mainFromContentDO.unsafeDereference(), mainObj);
+
+  const contentFromContentDO = contentBoxDO.getProperty("contentObj");
+  Assert.equal(
+    contentFromContentDO,
+    contentBoxDO.makeDebuggeeValue(contentObj)
+  );
+  Assert.equal(contentFromContentDO.getProperty("name"), "contentObj");
+  Assert.equal(contentFromContentDO.unsafeDereference(), contentObj);
+
+  const chromeFromContentDO = contentBoxDO.getProperty("chromeObj");
+  Assert.equal(chromeFromContentDO, contentBoxDO.makeDebuggeeValue(chromeObj));
+  Assert.equal(chromeFromContentDO.getProperty("name"), undefined);
+  Assert.equal(chromeFromContentDO.unsafeDereference(), chromeObj);
+
+  // Similarly, viewing from chromeBox.
+  const mainFromChromeDO = chromeBoxDO.getProperty("mainObj");
+  Assert.equal(mainFromChromeDO, chromeBoxDO.makeDebuggeeValue(mainObj));
+  Assert.equal(mainFromChromeDO.getProperty("name"), "mainObj");
+  Assert.equal(mainFromChromeDO.unsafeDereference(), mainObj);
+
+  const contentFromChromeDO = chromeBoxDO.getProperty("contentObj");
+  Assert.equal(contentFromChromeDO, chromeBoxDO.makeDebuggeeValue(contentObj));
+  Assert.equal(contentFromChromeDO.getProperty("name"), "contentObj");
+  Assert.equal(contentFromChromeDO.unsafeDereference(), contentObj);
+
+  const chromeFromChromeDO = chromeBoxDO.getProperty("chromeObj");
+  Assert.equal(chromeFromChromeDO, chromeBoxDO.makeDebuggeeValue(chromeObj));
+  Assert.equal(chromeFromChromeDO.getProperty("name"), "chromeObj");
+  Assert.equal(chromeFromChromeDO.unsafeDereference(), chromeObj);
+}
diff --git a/devtools/server/tests/xpcshell/test_wasm_source-01.js b/devtools/server/tests/xpcshell/test_wasm_source-01.js
new file mode 100644
index 0000000000..fe8e43e236
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_wasm_source-01.js
@@ -0,0 +1,143 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow, max-nested-callbacks */
+
+"use strict";
+
+/**
+ * Verify if client can receive binary wasm
+ */
+
+var gDebuggee;
+var gThreadFront;
+
+add_task(
+  threadFrontTest(
+    async ({ threadFront, debuggee, client }) => {
+      gThreadFront = threadFront;
+      gDebuggee = debuggee;
+
+      await gThreadFront.reconfigure({
+        observeAsmJS: true,
+        observeWasm: true,
+      });
+
+      test_source();
+    },
+    { waitForFinish: true, doNotRunWorker: true }
+  )
+);
+
+const EXPECTED_CONTENT = String.fromCharCode(
+  0,
+  97,
+  115,
+  109,
+  1,
+  0,
+  0,
+  0,
+  1,
+  132,
+  128,
+  128,
+  128,
+  0,
+  1,
+  96,
+  0,
+  0,
+  3,
+  130,
+  128,
+  128,
+  128,
+  0,
+  1,
+  0,
+  6,
+  129,
+  128,
+  128,
+  128,
+  0,
+  0,
+  7,
+  133,
+  128,
+  128,
+  128,
+  0,
+  1,
+  1,
+  102,
+  0,
+  0,
+  10,
+  136,
+  128,
+  128,
+  128,
+  0,
+  1,
+  130,
+  128,
+  128,
+  128,
+  0,
+  0,
+  11
+);
+
+function test_source() {
+  gThreadFront.once("paused", function (packet) {
+    gThreadFront.getSources().then(function (response) {
+      Assert.ok(!!response);
+      Assert.ok(!!response.sources);
+
+      const source = response.sources.filter(function (s) {
+        return s.introductionType === "wasm";
+      })[0];
+
+      Assert.ok(!!source);
+
+      const sourceFront = gThreadFront.source(source);
+      sourceFront.source().then(function (response) {
+        Assert.ok(!!response);
+        Assert.ok(!!response.contentType);
+        Assert.ok(response.contentType.includes("wasm"));
+
+        const sourceContent = response.source;
+        Assert.ok(!!sourceContent);
+        Assert.equal(typeof sourceContent, "object");
+        Assert.ok("binary" in sourceContent);
+        Assert.equal(EXPECTED_CONTENT, sourceContent.binary);
+
+        gThreadFront.resume().then(function () {
+          threadFrontTestFinished();
+        });
+      });
+    });
+  });
+
+  /* eslint-disable comma-spacing, max-len */
+  gDebuggee.eval(
+    "(" +
+      function () {
+        // WebAssembly bytecode was generated by running:
+        // js -e 'print(wasmTextToBinary("(module(func(export \"f\")))"))'
+        const m = new WebAssembly.Module(
+          new Uint8Array([
+            0, 97, 115, 109, 1, 0, 0, 0, 1, 132, 128, 128, 128, 0, 1, 96, 0, 0,
+            3, 130, 128, 128, 128, 0, 1, 0, 6, 129, 128, 128, 128, 0, 0, 7, 133,
+            128, 128, 128, 0, 1, 1, 102, 0, 0, 10, 136, 128, 128, 128, 0, 1,
+            130, 128, 128, 128, 0, 0, 11,
+          ])
+        );
+        const i = new WebAssembly.Instance(m);
+        debugger;
+        i.exports.f();
+      } +
+      ")()"
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_watchpoint-01.js b/devtools/server/tests/xpcshell/test_watchpoint-01.js
new file mode 100644
index 0000000000..2d1d0e78f4
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_watchpoint-01.js
@@ -0,0 +1,197 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow */
+
+"use strict";
+
+/*
+- Tests adding set and get watchpoints.
+- Tests removing a watchpoint.
+- Tests removing all watchpoints.
+*/
+
+add_task(
+  threadFrontTest(async args => {
+    await testSetWatchpoint(args);
+    await testGetWatchpoint(args);
+    await testRemoveWatchpoint(args);
+    await testRemoveWatchpoints(args);
+  })
+);
+
+async function testSetWatchpoint({ commands, threadFront, debuggee }) {
+  async function evaluateJS(input) {
+    const { result } = await commands.scriptCommand.execute(input, {
+      thread: threadFront.actor,
+      frameActor: packet.frame.actorID,
+    });
+    return result;
+  }
+
+  function evaluateTestCode(debuggee) {
+    /* eslint-disable */
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMe(obj) {              // 2
+        debugger;                         // 3
+        obj.a = 2;                        // 4
+      }                                   //
+      stopMe({a: { b: 1 }})`,
+      debuggee,
+      "1.8",
+      "test_watchpoint-01.js"
+    );
+    /* eslint-disable */
+  }
+
+  const packet = await executeOnNextTickAndWaitForPause(
+    () => evaluateTestCode(debuggee),
+    threadFront
+  );
+
+  info("Test that we paused on the debugger statement");
+  Assert.equal(packet.frame.where.line, 3);
+
+  info("Add set watchpoint");
+  const args = packet.frame.arguments;
+  const obj = args[0];
+  const objClient = threadFront.pauseGrip(obj);
+  await objClient.addWatchpoint("a", "obj.a", "set");
+
+  let result = await evaluateJS("obj.a");
+  Assert.equal(result.getGrip().preview.ownProperties.b.value, 1);
+
+  result = await evaluateJS("obj.a.b");
+  Assert.equal(result, 1);
+
+  info("Test that watchpoint triggers pause on set");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 4);
+  Assert.equal(packet2.why.type, "setWatchpoint");
+  Assert.equal(obj.preview.ownProperties.a.value.ownPropertyLength, 1);
+
+  await resume(threadFront);
+}
+
+async function testGetWatchpoint({ threadFront, debuggee }) {
+  function evaluateTestCode(debuggee) {
+    /* eslint-disable */
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMe(obj) {              // 2
+        debugger;                         // 3
+        obj.a + 4;                        // 4
+      }                                   //
+      stopMe({a: 1})`,
+      debuggee,
+      "1.8",
+      "test_watchpoint-01.js"
+    );
+    /* eslint-disable */
+  }
+
+  const packet = await executeOnNextTickAndWaitForPause(
+    () => evaluateTestCode(debuggee),
+    threadFront
+  );
+
+  info("Test that we paused on the debugger statement");
+  Assert.equal(packet.frame.where.line, 3);
+
+  info("Add get watchpoint.");
+  const args = packet.frame.arguments;
+  const obj = args[0];
+  const objClient = threadFront.pauseGrip(obj);
+  await objClient.addWatchpoint("a", "obj.a", "get");
+
+  info("Test that watchpoint triggers pause on get.");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 4);
+  Assert.equal(packet2.why.type, "getWatchpoint");
+  Assert.equal(obj.preview.ownProperties.a.value, 1);
+
+  await resume(threadFront);
+}
+
+async function testRemoveWatchpoint({ threadFront, debuggee }) {
+  function evaluateTestCode(debuggee) {
+    /* eslint-disable */
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMe(obj) {              // 2
+        debugger;                         // 3
+        obj.a = 2;                        // 4
+        debugger;                         // 5
+      }                                   //
+
+      stopMe({a: 1})`,
+      debuggee,
+      "1.8",
+      "test_watchpoint-01.js"
+    );
+    /* eslint-disable */
+  }
+
+  const packet = await executeOnNextTickAndWaitForPause(
+    () => evaluateTestCode(debuggee),
+    threadFront
+  );
+
+  info(`Test that we paused on the debugger statement`);
+  Assert.equal(packet.frame.where.line, 3);
+
+  info(`Add set watchpoint`);
+  const args = packet.frame.arguments;
+  const obj = args[0];
+  const objClient = threadFront.pauseGrip(obj);
+  await objClient.addWatchpoint("a", "obj.a", "set");
+
+  info(`Remove set watchpoint`);
+  await objClient.removeWatchpoint("a");
+
+  info(`Test that we do not pause on set`);
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 5);
+
+  await resume(threadFront);
+}
+
+async function testRemoveWatchpoints({ threadFront, debuggee }) {
+  function evaluateTestCode(debuggee) {
+    /* eslint-disable */
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMe(obj) {              // 2
+        debugger;                         // 3
+        obj.a = 2;                        // 4
+        debugger;                         // 5
+      }                                   //
+      stopMe({a: 1})`,
+      debuggee,
+      "1.8",
+      "test_watchpoint-01.js"
+    );
+    /* eslint-disable */
+  }
+
+  const packet = await executeOnNextTickAndWaitForPause(
+    () => evaluateTestCode(debuggee),
+    threadFront
+  );
+
+  info("Test that we paused on the debugger statement");
+  Assert.equal(packet.frame.where.line, 3);
+
+  info("Add and then remove set watchpoint");
+  const args = packet.frame.arguments;
+  const obj = args[0];
+  const objClient = threadFront.pauseGrip(obj);
+  await objClient.addWatchpoint("a", "obj.a", "set");
+  await objClient.removeWatchpoints();
+
+  info("Test that we do not pause on set");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 5);
+
+  await resume(threadFront);
+}
diff --git a/devtools/server/tests/xpcshell/test_watchpoint-02.js b/devtools/server/tests/xpcshell/test_watchpoint-02.js
new file mode 100644
index 0000000000..d0739c8a00
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_watchpoint-02.js
@@ -0,0 +1,223 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow */
+
+"use strict";
+
+/*
+Test that debugger advances instead of pausing twice on the
+same line when encountering both a watchpoint and a breakpoint.
+*/
+
+add_task(
+  threadFrontTest(async args => {
+    await testBreakpointAndSetWatchpoint(args);
+    await testBreakpointAndGetWatchpoint(args);
+    await testLoops(args);
+  })
+);
+
+// Test that we advance to the next line when a location
+// has both a breakpoint and set watchpoint.
+async function testBreakpointAndSetWatchpoint({
+  commands,
+  threadFront,
+  debuggee,
+}) {
+  async function evaluateJS(input) {
+    const { result } = await commands.scriptCommand.execute(input, {
+      frameActor: packet.frame.actorID,
+    });
+    return result;
+  }
+
+  function evaluateTestCode(debuggee) {
+    /* eslint-disable */
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMe(obj) {              // 2
+        debugger;                         // 3
+        obj.a = 2;                        // 4
+        debugger;                         // 5
+      }                                   //
+      stopMe({a: 1})`,
+      debuggee,
+      "1.8",
+      "test_watchpoint-02.js"
+    );
+    /* eslint-disable */
+  }
+
+  const packet = await executeOnNextTickAndWaitForPause(
+    () => evaluateTestCode(debuggee),
+    threadFront
+  );
+
+  info("Test that we pause on the debugger statement.");
+  Assert.equal(packet.frame.where.line, 3);
+  Assert.equal(packet.why.type, "debuggerStatement");
+
+  info("Add set watchpoint.");
+  const args = packet.frame.arguments;
+  const obj = args[0];
+  const objClient = threadFront.pauseGrip(obj);
+  await objClient.addWatchpoint("a", "obj.a", "set");
+
+  info("Add breakpoint.");
+  const source = await getSourceById(threadFront, packet.frame.where.actor);
+
+  const location = {
+    sourceUrl: source.url,
+    line: 4,
+  };
+
+  threadFront.setBreakpoint(location, {});
+
+  info("Test that pause occurs on breakpoint.");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 4);
+  Assert.equal(packet2.why.type, "breakpoint");
+
+  const packet3 = await resumeAndWaitForPause(threadFront);
+
+  info("Test that we pause on the second debugger statement.");
+  Assert.equal(packet3.frame.where.line, 5);
+  Assert.equal(packet3.why.type, "debuggerStatement");
+
+  info("Test that the value has updated.");
+  const result = await evaluateJS("obj.a");
+  Assert.equal(result, 2);
+
+  info("Remove breakpoint and finish.");
+  threadFront.removeBreakpoint(location, {});
+
+  await resume(threadFront);
+}
+
+// Test that we advance to the next line when a location
+// has both a breakpoint and get watchpoint.
+async function testBreakpointAndGetWatchpoint({ threadFront, debuggee }) {
+  function evaluateTestCode(debuggee) {
+    /* eslint-disable */
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMe(obj) {              // 2
+        debugger;                         // 3
+        obj.a + 4;                        // 4
+        debugger;                         // 5
+      }                                   //
+      stopMe({a: 1})`,
+      debuggee,
+      "1.8",
+      "test_watchpoint-02.js"
+    );
+    /* eslint-disable */
+  }
+
+  const packet = await executeOnNextTickAndWaitForPause(
+    () => evaluateTestCode(debuggee),
+    threadFront
+  );
+
+  info("Test that we pause on the debugger statement.");
+  Assert.equal(packet.frame.where.line, 3);
+
+  info("Add get watchpoint.");
+  const args = packet.frame.arguments;
+  const obj = args[0];
+  const objClient = threadFront.pauseGrip(obj);
+  await objClient.addWatchpoint("a", "obj.a", "get");
+
+  info("Add breakpoint.");
+  const source = await getSourceById(threadFront, packet.frame.where.actor);
+
+  const location = {
+    sourceUrl: source.url,
+    line: 4,
+  };
+
+  threadFront.setBreakpoint(location, {});
+
+  info("Test that pause occurs on breakpoint.");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 4);
+  Assert.equal(packet2.why.type, "breakpoint");
+
+  const packet3 = await resumeAndWaitForPause(threadFront);
+
+  info("Test that we pause on the second debugger statement.");
+  Assert.equal(packet3.frame.where.line, 5);
+  Assert.equal(packet3.why.type, "debuggerStatement");
+
+  info("Remove breakpoint and finish.");
+  threadFront.removeBreakpoint(location, {});
+
+  await resume(threadFront);
+}
+
+// Test that we can pause multiple times
+// on the same line for a watchpoint.
+async function testLoops({ commands, threadFront, debuggee }) {
+  async function evaluateJS(input) {
+    const { result } = await commands.scriptCommand.execute(input, {
+      frameActor: packet.frame.actorID,
+    });
+    return result;
+  }
+
+  function evaluateTestCode(debuggee) {
+    /* eslint-disable */
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMe(obj) {              // 2
+        let i = 0;                        // 3
+        debugger;                         // 4
+        while (i++ < 2) {                 // 5
+          obj.a = 2;                      // 6
+        }                                 // 7
+        debugger;                         // 8
+      }                                   //
+      stopMe({a: 1})`,
+      debuggee,
+      "1.8",
+      "test_watchpoint-02.js"
+    );
+    /* eslint-disable */
+  }
+
+  const packet = await executeOnNextTickAndWaitForPause(
+    () => evaluateTestCode(debuggee),
+    threadFront
+  );
+
+  info("Test that we pause on the debugger statement.");
+  Assert.equal(packet.frame.where.line, 4);
+  Assert.equal(packet.why.type, "debuggerStatement");
+
+  info("Add set watchpoint.");
+  const args = packet.frame.arguments;
+  const obj = args[0];
+  const objClient = threadFront.pauseGrip(obj);
+  await objClient.addWatchpoint("a", "obj.a", "set");
+
+  info("Test that watchpoint triggers pause on set.");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 6);
+  Assert.equal(packet2.why.type, "setWatchpoint");
+  let result = await evaluateJS("obj.a");
+  Assert.equal(result, 1);
+
+  info("Test that watchpoint triggers pause on set (2nd time).");
+  const packet3 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet3.frame.where.line, 6);
+  Assert.equal(packet3.why.type, "setWatchpoint");
+  let result2 = await evaluateJS("obj.a");
+  Assert.equal(result2, 2);
+
+  info("Test that we pause on second debugger statement.");
+  const packet4 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet4.frame.where.line, 8);
+  Assert.equal(packet4.why.type, "debuggerStatement");
+
+  await resume(threadFront);
+}
diff --git a/devtools/server/tests/xpcshell/test_watchpoint-03.js b/devtools/server/tests/xpcshell/test_watchpoint-03.js
new file mode 100644
index 0000000000..33f4fbd2a2
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_watchpoint-03.js
@@ -0,0 +1,72 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow */
+
+"use strict";
+/*
+See Bug 1601311.
+Tests that removing a watchpoint does not change the value of the property that had the watchpoint.
+*/
+
+add_task(
+  threadFrontTest(async ({ commands, threadFront, debuggee }) => {
+    async function evaluateJS(input) {
+      const { result } = await commands.scriptCommand.execute(input, {
+        frameActor: packet.frame.actorID,
+      });
+      return result;
+    }
+
+    function evaluateTestCode(debuggee) {
+      /* eslint-disable */
+      Cu.evalInSandbox(
+        `                                   // 1
+                  function stopMe(obj) {              // 2
+                    debugger;                         // 3
+                    obj.a = 2;                        // 4
+                    debugger;                         // 5
+                  }                                   //
+
+                  stopMe({a: 1})`,
+        debuggee,
+        "1.8",
+        "test_watchpoint-03.js"
+      );
+      /* eslint-disable */
+    }
+
+    const packet = await executeOnNextTickAndWaitForPause(
+      () => evaluateTestCode(debuggee),
+      threadFront
+    );
+
+    info("Test that we paused on the debugger statement.");
+    Assert.equal(packet.frame.where.line, 3);
+
+    info("Add set watchpoint.");
+    const args = packet.frame.arguments;
+    const obj = args[0];
+    const objClient = threadFront.pauseGrip(obj);
+    await objClient.addWatchpoint("a", "obj.a", "set");
+
+    info("Test that we pause on set.");
+    const packet2 = await resumeAndWaitForPause(threadFront);
+    Assert.equal(packet2.frame.where.line, 4);
+
+    const packet3 = await resumeAndWaitForPause(threadFront);
+
+    info("Test that we pause on the second debugger statement.");
+    Assert.equal(packet3.frame.where.line, 5);
+    Assert.equal(packet3.why.type, "debuggerStatement");
+
+    info("Remove watchpoint.");
+    await objClient.removeWatchpoint("a");
+
+    info("Test that the value has updated.");
+    const result = await evaluateJS("obj.a");
+    Assert.equal(result, 2);
+
+    info("Finish test.");
+    await resume(threadFront);
+  })
+);
diff --git a/devtools/server/tests/xpcshell/test_watchpoint-04.js b/devtools/server/tests/xpcshell/test_watchpoint-04.js
new file mode 100644
index 0000000000..4ee6eadd5a
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_watchpoint-04.js
@@ -0,0 +1,78 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that watchpoints ignore blackboxed sources
+ */
+
+const BLACK_BOXED_URL = "http://example.com/blackboxme.js";
+const SOURCE_URL = "http://example.com/source.js";
+
+add_task(
+  threadFrontTest(async ({ threadFront, debuggee }) => {
+    await executeOnNextTickAndWaitForPause(
+      () => evalCode(debuggee),
+      threadFront
+    );
+
+    info(`blackbox the source`);
+    const { error, sources } = await threadFront.getSources();
+    Assert.ok(!error, "Should not get an error: " + error);
+    const sourceFront = threadFront.source(
+      sources.filter(s => s.url == BLACK_BOXED_URL)[0]
+    );
+
+    await blackBox(sourceFront);
+
+    await threadFront.resume();
+    const packet = await executeOnNextTickAndWaitForPause(
+      debuggee.runTest,
+      threadFront
+    );
+
+    Assert.equal(
+      packet.frame.where.line,
+      3,
+      "Paused at first debugger statement"
+    );
+
+    await addWatchpoint(threadFront, packet.frame, "obj", "a", "set");
+
+    info(`Resume and skip the watchpoint`);
+    const pausePacket = await resumeAndWaitForPause(threadFront);
+
+    Assert.equal(
+      pausePacket.frame.where.line,
+      5,
+      "Paused at second debugger statement"
+    );
+
+    await threadFront.resume();
+  })
+);
+
+function evalCode(debuggee) {
+  Cu.evalInSandbox(
+    `function doStuff(obj) {
+      obj.a = 2;
+    }`,
+    debuggee,
+    "1.8",
+    BLACK_BOXED_URL,
+    1
+  );
+  Cu.evalInSandbox(
+    `function runTest() {
+      const obj = {a: 1}
+      debugger
+      doStuff(obj);
+      debugger
+    }; debugger;`,
+    debuggee,
+    "1.8",
+    SOURCE_URL,
+    1
+  );
+}
diff --git a/devtools/server/tests/xpcshell/test_watchpoint-05.js b/devtools/server/tests/xpcshell/test_watchpoint-05.js
new file mode 100644
index 0000000000..4d25a59399
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_watchpoint-05.js
@@ -0,0 +1,113 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable no-shadow */
+
+"use strict";
+
+/*
+- Adds a 'get or set' watchpoint. Tests that the debugger will pause on both get and set.
+*/
+
+add_task(
+  threadFrontTest(async args => {
+    await testGetPauseWithGetOrSetWatchpoint(args);
+    await testSetPauseWithGetOrSetWatchpoint(args);
+  })
+);
+
+async function testGetPauseWithGetOrSetWatchpoint({ threadFront, debuggee }) {
+  function evaluateTestCode(debuggee) {
+    /* eslint-disable */
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMe(obj) {              // 2
+        debugger;                         // 3
+        obj.a + 4;                        // 4
+      }                                   //
+      stopMe({a: 1})`,
+      debuggee,
+      "1.8",
+      "test_watchpoint-05.js"
+    );
+    /* eslint-disable */
+  }
+
+  const packet = await executeOnNextTickAndWaitForPause(
+    () => evaluateTestCode(debuggee),
+    threadFront
+  );
+
+  info("Test that we paused on the debugger statement");
+  Assert.equal(packet.frame.where.line, 3);
+
+  info("Add get or set watchpoint.");
+  const args = packet.frame.arguments;
+  const obj = args[0];
+  const objClient = threadFront.pauseGrip(obj);
+  await objClient.addWatchpoint("a", "obj.a", "getorset");
+
+  info("Test that watchpoint triggers pause on get.");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 4);
+  Assert.equal(packet2.why.type, "getWatchpoint");
+  Assert.equal(obj.preview.ownProperties.a.value, 1);
+
+  await resume(threadFront);
+}
+
+async function testSetPauseWithGetOrSetWatchpoint({
+  commands,
+  threadFront,
+  debuggee,
+}) {
+  async function evaluateJS(input) {
+    const { result } = await commands.scriptCommand.execute(input, {
+      frameActor: packet.frame.actorID,
+    });
+    return result;
+  }
+
+  function evaluateTestCode(debuggee) {
+    /* eslint-disable */
+    Cu.evalInSandbox(
+      `                                   // 1
+      function stopMe(obj) {              // 2
+        debugger;                         // 3
+        obj.a = 2;                        // 4
+      }                                   //
+      stopMe({a: { b: 1 }})`,
+      debuggee,
+      "1.8",
+      "test_watchpoint-05.js"
+    );
+    /* eslint-disable */
+  }
+
+  const packet = await executeOnNextTickAndWaitForPause(
+    () => evaluateTestCode(debuggee),
+    threadFront
+  );
+
+  info("Test that we paused on the debugger statement");
+  Assert.equal(packet.frame.where.line, 3);
+
+  info("Add get or set watchpoint");
+  const args = packet.frame.arguments;
+  const obj = args[0];
+  const objClient = threadFront.pauseGrip(obj);
+  await objClient.addWatchpoint("a", "obj.a", "getorset");
+
+  let result = await evaluateJS("obj.a");
+  Assert.equal(result.getGrip().preview.ownProperties.b.value, 1);
+
+  result = await evaluateJS("obj.a.b");
+  Assert.equal(result, 1);
+
+  info("Test that watchpoint triggers pause on set");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  Assert.equal(packet2.frame.where.line, 4);
+  Assert.equal(packet2.why.type, "setWatchpoint");
+  Assert.equal(obj.preview.ownProperties.a.value.ownPropertyLength, 1);
+
+  await resume(threadFront);
+}
diff --git a/devtools/server/tests/xpcshell/test_webext_apis.js b/devtools/server/tests/xpcshell/test_webext_apis.js
new file mode 100644
index 0000000000..5a2f2b990a
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_webext_apis.js
@@ -0,0 +1,162 @@
+/* Any copyright is dedicated to the Public Domain.
+http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { AddonManager } = ChromeUtils.importESModule(
+  "resource://gre/modules/AddonManager.sys.mjs"
+);
+const { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+const DistinctDevToolsServer = getDistinctDevToolsServer();
+ExtensionTestUtils.init(this);
+
+add_setup(async () => {
+  Services.prefs.setBoolPref("extensions.blocklist.enabled", false);
+  await startupAddonsManager();
+});
+
+// Basic request wrapper that sends a request and resolves on the next packet.
+// Will only work for very basic scenarios, without events emitted on the server
+// etc...
+async function sendRequest(transport, request) {
+  return new Promise(resolve => {
+    transport.hooks = {
+      onPacket: packet => {
+        dump(`received packet: ${JSON.stringify(packet)}\n`);
+        // Let's resolve only when we get a packet that is related to our
+        // request. It is needed because some methods do not return the correct
+        // response right away. This is the case of the `reload` method, which
+        // receives a `addonListChanged` message first and then a `reload`
+        // message.
+        if (packet.from === request.to) {
+          resolve(packet);
+        }
+      },
+    };
+    transport.send(request);
+  });
+}
+
+// If this test case fails, please reach out to webext peers because
+// https://github.com/mozilla/web-ext relies on the APIs tested here.
+add_task(async function test_webext_run_apis() {
+  DistinctDevToolsServer.init();
+  DistinctDevToolsServer.registerAllActors();
+
+  const transport = DistinctDevToolsServer.connectPipe();
+
+  // After calling connectPipe, the root actor will be created on the server
+  // and a packet will be emitted after a tick. Wait for the initial packet.
+  await new Promise(resolve => {
+    transport.hooks = { onPacket: resolve };
+  });
+
+  const getRootResponse = await sendRequest(transport, {
+    to: "root",
+    type: "getRoot",
+  });
+
+  ok(getRootResponse, "received a response after calling RootActor::getRoot");
+  ok(getRootResponse.addonsActor, "getRoot returned an addonsActor id");
+
+  // installTemporaryAddon
+  const addonId = "test-addons-actor@mozilla.org";
+  const addonPath = getFilePath("addons/web-extension", false, true);
+  const promiseStarted = AddonTestUtils.promiseWebExtensionStartup(addonId);
+  const { addon } = await sendRequest(transport, {
+    to: getRootResponse.addonsActor,
+    type: "installTemporaryAddon",
+    addonPath,
+    // The openDevTools parameter is not always passed by web-ext. This test
+    // omits it, to make sure that the request without the flag is accepted.
+    // openDevTools: false,
+  });
+  await promiseStarted;
+
+  ok(addon, "addonsActor allows to install a temporary add-on");
+  equal(addon.id, addonId, "temporary add-on is the expected one");
+  equal(addon.actor, false, "temporary add-on does not have an actor");
+
+  // listAddons
+  let { addons } = await sendRequest(transport, {
+    to: "root",
+    type: "listAddons",
+  });
+  ok(Array.isArray(addons), "listAddons() returns a list of add-ons");
+  equal(addons.length, 1, "expected an add-on installed");
+
+  const installedAddon = addons[0];
+  equal(installedAddon.id, addonId, "installed add-on is the expected one");
+  ok(installedAddon.actor, "returned add-on has an actor");
+
+  // reload
+  const promiseReloaded = AddonTestUtils.promiseAddonEvent("onInstalled");
+  const promiseRestarted = AddonTestUtils.promiseWebExtensionStartup(addonId);
+  await sendRequest(transport, {
+    to: installedAddon.actor,
+    type: "reload",
+  });
+  await Promise.all([promiseReloaded, promiseRestarted]);
+
+  // uninstallAddon
+  const promiseUninstalled = new Promise(resolve => {
+    const listener = {};
+    listener.onUninstalled = uninstalledAddon => {
+      if (uninstalledAddon.id == addonId) {
+        AddonManager.removeAddonListener(listener);
+        resolve();
+      }
+    };
+    AddonManager.addAddonListener(listener);
+  });
+  await sendRequest(transport, {
+    to: getRootResponse.addonsActor,
+    type: "uninstallAddon",
+    addonId,
+  });
+  await promiseUninstalled;
+
+  ({ addons } = await sendRequest(transport, {
+    to: "root",
+    type: "listAddons",
+  }));
+  equal(addons.length, 0, "expected no add-on installed");
+
+  // Attempt to uninstall an add-on that is (no longer) installed.
+  let error = await sendRequest(transport, {
+    to: getRootResponse.addonsActor,
+    type: "uninstallAddon",
+    addonId,
+  });
+  equal(
+    error?.message,
+    `Could not uninstall add-on "${addonId}"`,
+    "expected error"
+  );
+
+  // Attempt to uninstall a non-temporarily loaded extension, which we do not
+  // allow at the moment. We start by loading an extension, then we call the
+  // `uninstallAddon`.
+  const id = "not-a-temporary@extension";
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      browser_specific_settings: { gecko: { id } },
+    },
+    useAddonManager: "permanent",
+  });
+  await extension.startup();
+
+  error = await sendRequest(transport, {
+    to: getRootResponse.addonsActor,
+    type: "uninstallAddon",
+    addonId: id,
+  });
+  equal(error?.message, `Could not uninstall add-on "${id}"`, "expected error");
+
+  await extension.unload();
+
+  transport.close();
+});
diff --git a/devtools/server/tests/xpcshell/test_webextension_descriptor.js b/devtools/server/tests/xpcshell/test_webextension_descriptor.js
new file mode 100644
index 0000000000..00cdeea605
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_webextension_descriptor.js
@@ -0,0 +1,141 @@
+/* Any copyright is dedicated to the Public Domain.
+http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+const DistinctDevToolsServer = getDistinctDevToolsServer();
+ExtensionTestUtils.init(this);
+
+add_setup(async () => {
+  Services.prefs.setBoolPref("extensions.blocklist.enabled", false);
+  await startupAddonsManager();
+
+  // We intentionally generate install-time manifest warnings, so don't trigger
+  // the special test-only mode of converting them to errors.
+  Services.prefs.setBoolPref(
+    "extensions.webextensions.warnings-as-errors",
+    false
+  );
+
+  DistinctDevToolsServer.init();
+  DistinctDevToolsServer.registerAllActors();
+});
+
+// Verifies:
+// - listAddons
+// - WebExtensionDescriptorActor output
+// Also a regression test for bug 1837185, that AddonManager.sys.mjs and
+// ExtensionParent.sys.mjs are imported from the correct loader.
+add_task(async function test_listAddons_and_WebExtensionDescriptor() {
+  const transport = DistinctDevToolsServer.connectPipe();
+  const client = new DevToolsClient(transport);
+  await client.connect();
+
+  const getRootResponse = await client.mainRoot.getRoot();
+
+  ok(getRootResponse, "received a response after calling RootActor::getRoot");
+  ok(getRootResponse.addonsActor, "getRoot returned an addonsActor id");
+
+  const ADDON_ID = "with@warning";
+  const extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      name: "DummyExtensionWithUnknownManifestKey",
+      unknown_manifest_key: "this is an unknown manifest key",
+      browser_specific_settings: { gecko: { id: ADDON_ID } },
+    },
+    background: `browser.test.sendMessage("background_started");`,
+  });
+  await extension.startup();
+  await extension.awaitMessage("background_started");
+
+  // listAddons: addon after new install.
+  {
+    const listAddonsResponse = await client.mainRoot.listAddons();
+    const addon = listAddonsResponse.find(a => a.id === ADDON_ID);
+    ok(addon, "listAddons() returns a list of add-ons including with@warning");
+
+    // Inspect all raw properties of the message, to make sure that we always
+    // have full coverage for all current and future properties.
+    const { actor, url, warnings, ...addonMinusSomeKeys } = addon._form;
+    const actorPattern = /^server\d+\.conn\d+\.webExtensionDescriptor\d+$/;
+    ok(actorPattern.test(actor), `actor is webExtensionDescriptor: ${actor}`);
+    // We don't care about the exact path, just a dummy check:
+    ok(url.endsWith(".xpi"), `url is path to the xpi file`);
+
+    deepEqual(
+      warnings,
+      [
+        "Reading manifest: Warning processing unknown_manifest_key: An unexpected property was found in the WebExtension manifest.",
+      ],
+      "Can retrieve warnings."
+    );
+
+    // Verify that the other remaining keys have a meaningful value.
+    // This is mainly to have some form of verification on the value of the
+    // properties. If this check ever fails, double-check whether the proposed
+    // change makes sense and if it does just update the test expectation here.
+    deepEqual(
+      addonMinusSomeKeys,
+      {
+        backgroundScriptStatus: undefined,
+        debuggable: true,
+        hidden: false,
+        iconDataURL: undefined,
+        iconURL: null,
+        id: ADDON_ID,
+        isSystem: false,
+        isWebExtension: true,
+        manifestURL: `moz-extension://${extension.uuid}/manifest.json`,
+        name: "DummyExtensionWithUnknownManifestKey",
+        persistentBackgroundScript: true,
+        temporarilyInstalled: false,
+        traits: {
+          supportsReloadDescriptor: true,
+          watcher: true,
+        },
+      },
+      "WebExtensionDescriptorActor content matches the add-on"
+    );
+  }
+
+  await extension.upgrade({
+    manifest: {
+      name: "Updated_extension",
+      new_unknown_manifest_key: "different warning than before",
+      browser_specific_settings: { gecko: { id: ADDON_ID } },
+    },
+    background: `browser.test.sendMessage("updated_done");`,
+  });
+  await extension.awaitMessage("updated_done");
+
+  // listAddons: addon after update.
+  {
+    const listAddonsResponse = await client.mainRoot.listAddons();
+    const addon = listAddonsResponse.find(a => a.id === ADDON_ID);
+    ok(addon, "listAddons() should still list the add-on after update");
+    equal(addon.name, "Updated_extension", "Got updated name");
+    deepEqual(
+      addon.warnings,
+      [
+        "Reading manifest: Warning processing new_unknown_manifest_key: An unexpected property was found in the WebExtension manifest.",
+      ],
+      "Can retrieve new warnings for updated add-on."
+    );
+  }
+
+  await extension.unload();
+
+  // listAddons: addon after removal - gone.
+  {
+    const listAddonsResponse = await client.mainRoot.listAddons();
+    const addon = listAddonsResponse.find(a => a.id === ADDON_ID);
+    deepEqual(addon, null, "Add-on should be gone after removal");
+  }
+
+  await client.close();
+});
diff --git a/devtools/server/tests/xpcshell/test_xpcshell_debugging.js b/devtools/server/tests/xpcshell/test_xpcshell_debugging.js
new file mode 100644
index 0000000000..2f7cf70e42
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_xpcshell_debugging.js
@@ -0,0 +1,90 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test the xpcshell-test debug support.  Ideally we should have this test
+// next to the xpcshell support code, but that's tricky...
+
+// HACK: ServiceWorkerManager requires the "profile-change-teardown" to cleanly
+// shutdown, and setting _profileInitialized to `true` will trigger those
+// notifications (see /testing/xpcshell/head.js).
+// eslint-disable-next-line no-undef
+_profileInitialized = true;
+
+add_task(async function () {
+  const testFile = do_get_file("xpcshell_debugging_script.js");
+
+  // _setupDevToolsServer is from xpcshell-test's head.js
+  /* global _setupDevToolsServer */
+  let testInitialized = false;
+  const { DevToolsServer } = _setupDevToolsServer([testFile.path], () => {
+    testInitialized = true;
+  });
+  const transport = DevToolsServer.connectPipe();
+  const client = new DevToolsClient(transport);
+  await client.connect();
+
+  // Ensure that global actors are available. Just test the device actor.
+  const deviceFront = await client.mainRoot.getFront("device");
+  const desc = await deviceFront.getDescription();
+  equal(
+    desc.geckobuildid,
+    Services.appinfo.platformBuildID,
+    "device actor works"
+  );
+
+  // Even though we have no tabs, getMainProcess gives us the chrome debugger.
+  const targetDescriptor = await client.mainRoot.getMainProcess();
+  const front = await targetDescriptor.getTarget();
+  const watcher = await targetDescriptor.getWatcher();
+
+  const threadFront = await front.attachThread();
+
+  // Checks that the thread actor initializes immediately and that _setupDevToolsServer
+  // callback gets called.
+  ok(testInitialized);
+
+  const onPause = waitForPause(threadFront);
+
+  // Now load our test script,
+  // in another event loop so that the test can keep running!
+  Services.tm.dispatchToMainThread(() => {
+    load(testFile.path);
+  });
+
+  // and our "paused" listener should get hit.
+  info("Wait for first paused event");
+  const packet1 = await onPause;
+  equal(
+    packet1.why.type,
+    "breakpoint",
+    "yay - hit the breakpoint at the first line in our script"
+  );
+
+  // Resume again - next stop should be our "debugger" statement.
+  info("Wait for second pause event");
+  const packet2 = await resumeAndWaitForPause(threadFront);
+  equal(
+    packet2.why.type,
+    "debuggerStatement",
+    "yay - hit the 'debugger' statement in our script"
+  );
+
+  info("Dynamically add a breakpoint after the debugger statement");
+  const breakpointsFront = await watcher.getBreakpointListActor();
+  await breakpointsFront.setBreakpoint(
+    { sourceUrl: testFile.path, line: 11 },
+    {}
+  );
+
+  // Resume again - next stop should be the new breakpoint.
+  info("Wait for third pause event");
+  const packet3 = await resumeAndWaitForPause(threadFront);
+  equal(
+    packet3.why.type,
+    "breakpoint",
+    "yay - hit the breakpoint added after starting the test"
+  );
+  finishClient(client);
+});
diff --git a/devtools/server/tests/xpcshell/testactors.js b/devtools/server/tests/xpcshell/testactors.js
new file mode 100644
index 0000000000..af208fe93e
--- /dev/null
+++ b/devtools/server/tests/xpcshell/testactors.js
@@ -0,0 +1,242 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  LazyPool,
+  createExtraActors,
+} = require("resource://devtools/shared/protocol/lazy-pool.js");
+const { RootActor } = require("resource://devtools/server/actors/root.js");
+const { ThreadActor } = require("resource://devtools/server/actors/thread.js");
+const {
+  DevToolsServer,
+} = require("resource://devtools/server/devtools-server.js");
+const {
+  ActorRegistry,
+} = require("resource://devtools/server/actors/utils/actor-registry.js");
+const {
+  SourcesManager,
+} = require("resource://devtools/server/actors/utils/sources-manager.js");
+const makeDebugger = require("resource://devtools/server/actors/utils/make-debugger.js");
+const protocol = require("resource://devtools/shared/protocol.js");
+const {
+  windowGlobalTargetSpec,
+} = require("resource://devtools/shared/specs/targets/window-global.js");
+const {
+  tabDescriptorSpec,
+} = require("resource://devtools/shared/specs/descriptors/tab.js");
+const Targets = require("resource://devtools/server/actors/targets/index.js");
+const {
+  createContentProcessSessionContext,
+} = require("resource://devtools/server/actors/watcher/session-context.js");
+
+var gTestGlobals = new Set();
+DevToolsServer.addTestGlobal = function (global) {
+  gTestGlobals.add(global);
+};
+DevToolsServer.removeTestGlobal = function (global) {
+  gTestGlobals.delete(global);
+};
+
+DevToolsServer.getTestGlobal = function (name) {
+  for (const g of gTestGlobals) {
+    if (g.__name == name) {
+      return g;
+    }
+  }
+
+  return null;
+};
+
+var gAllowNewThreadGlobals = false;
+DevToolsServer.allowNewThreadGlobals = function () {
+  gAllowNewThreadGlobals = true;
+};
+DevToolsServer.disallowNewThreadGlobals = function () {
+  gAllowNewThreadGlobals = false;
+};
+
+// A mock tab list, for use by tests. This simply presents each global in
+// gTestGlobals as a tab, and the list is fixed: it never calls its
+// onListChanged handler.
+//
+// As implemented now, we consult gTestGlobals when we're constructed, not
+// when we're iterated over, so tests have to add their globals before the
+// root actor is created.
+function TestTabList(connection) {
+  this.conn = connection;
+
+  // An array of actors for each global added with
+  // DevToolsServer.addTestGlobal.
+  this._descriptorActors = [];
+
+  // A pool mapping those actors' names to the actors.
+  this._descriptorActorPool = new LazyPool(connection);
+
+  for (const global of gTestGlobals) {
+    const actor = new TestTargetActor(connection, global);
+    this._descriptorActorPool.manage(actor);
+
+    const descriptorActor = new TestDescriptorActor(connection, actor);
+    this._descriptorActorPool.manage(descriptorActor);
+
+    this._descriptorActors.push(descriptorActor);
+  }
+}
+
+TestTabList.prototype = {
+  constructor: TestTabList,
+  destroy() {},
+  getList() {
+    return Promise.resolve([...this._descriptorActors]);
+  },
+  // Helper method only available for the xpcshell implementation of tablist.
+  getTargetActorForTab(title) {
+    const descriptorActor = this._descriptorActors.find(d => d.title === title);
+    if (!descriptorActor) {
+      return null;
+    }
+    return descriptorActor._targetActor;
+  },
+};
+
+exports.createRootActor = function createRootActor(connection) {
+  ActorRegistry.registerModule("devtools/server/actors/webconsole", {
+    prefix: "console",
+    constructor: "WebConsoleActor",
+    type: { target: true },
+  });
+  const root = new RootActor(connection, {
+    tabList: new TestTabList(connection),
+    globalActorFactories: ActorRegistry.globalActorFactories,
+  });
+
+  root.applicationType = "xpcshell-tests";
+  return root;
+};
+
+class TestDescriptorActor extends protocol.Actor {
+  constructor(conn, targetActor) {
+    super(conn, tabDescriptorSpec);
+    this._targetActor = targetActor;
+  }
+
+  // We don't exercise the selected tab in xpcshell tests.
+  get selected() {
+    return false;
+  }
+
+  get title() {
+    return this._targetActor.title;
+  }
+
+  form() {
+    const form = {
+      actor: this.actorID,
+      traits: {},
+      selected: this.selected,
+      title: this._targetActor.title,
+      url: this._targetActor.url,
+    };
+
+    return form;
+  }
+
+  getFavicon() {
+    return "";
+  }
+
+  getTarget() {
+    return this._targetActor.form();
+  }
+}
+
+class TestTargetActor extends protocol.Actor {
+  constructor(conn, global) {
+    super(conn, windowGlobalTargetSpec);
+
+    this.sessionContext = createContentProcessSessionContext();
+    this._global = global;
+    this._global.wrappedJSObject = global;
+    this.threadActor = new ThreadActor(this, this._global);
+    this.conn.addActor(this.threadActor);
+    this._extraActors = {};
+    // This is a hack in order to enable threadActor to be accessed from getFront
+    this._extraActors.threadActor = this.threadActor;
+    this.makeDebugger = makeDebugger.bind(null, {
+      findDebuggees: () => [this._global],
+      shouldAddNewGlobalAsDebuggee: g => gAllowNewThreadGlobals,
+    });
+    this.dbg = this.makeDebugger();
+    this.notifyResources = this.notifyResources.bind(this);
+  }
+
+  targetType = Targets.TYPES.FRAME;
+
+  get window() {
+    return this._global;
+  }
+
+  // Both title and url point to this._global.__name
+  get title() {
+    return this._global.__name;
+  }
+
+  get url() {
+    return this._global.__name;
+  }
+
+  get sourcesManager() {
+    if (!this._sourcesManager) {
+      this._sourcesManager = new SourcesManager(this.threadActor);
+    }
+    return this._sourcesManager;
+  }
+
+  form() {
+    const response = {
+      actor: this.actorID,
+      title: this.title,
+      threadActor: this.threadActor.actorID,
+    };
+
+    // Walk over target-scoped actors and add them to a new LazyPool.
+    const actorPool = new LazyPool(this.conn);
+    const actors = createExtraActors(
+      ActorRegistry.targetScopedActorFactories,
+      actorPool,
+      this
+    );
+    if (actorPool?._poolMap.size > 0) {
+      this._descriptorActorPool = actorPool;
+      this.conn.addActorPool(this._descriptorActorPool);
+    }
+
+    return { ...response, ...actors };
+  }
+
+  detach(request) {
+    this.threadActor.destroy();
+    return { type: "detached" };
+  }
+
+  reload(request) {
+    this.sourcesManager.reset();
+    this.threadActor.clearDebuggees();
+    this.threadActor.dbg.addDebuggees();
+    return {};
+  }
+
+  removeActorByName(name) {
+    const actor = this._extraActors[name];
+    if (this._descriptorActorPool) {
+      this._descriptorActorPool.removeActor(actor);
+    }
+    delete this._extraActors[name];
+  }
+
+  notifyResources(updateType, resources) {
+    this.emit(`resource-${updateType}-form`, resources);
+  }
+}
diff --git a/devtools/server/tests/xpcshell/webextension-helpers.js b/devtools/server/tests/xpcshell/webextension-helpers.js
new file mode 100644
index 0000000000..46968f09e7
--- /dev/null
+++ b/devtools/server/tests/xpcshell/webextension-helpers.js
@@ -0,0 +1,197 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* globals browser */
+
+"use strict";
+
+/**
+ * Test helpers shared by the devtools server xpcshell tests related to webextensions.
+ */
+
+const { FileUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/FileUtils.sys.mjs"
+);
+const { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+const {
+  CommandsFactory,
+} = require("resource://devtools/shared/commands/commands-factory.js");
+
+/**
+ * Loads and starts up a test extension given the provided extension configuration.
+ *
+ * @param {Object} extConfig - The extension configuration object
+ * @return {ExtensionWrapper} extension - Resolves with an extension object once the
+ * extension has started up.
+ */
+async function startupExtension(extConfig) {
+  const extension = ExtensionTestUtils.loadExtension(extConfig);
+
+  await extension.startup();
+
+  return extension;
+}
+exports.startupExtension = startupExtension;
+
+/**
+ * Initializes the extensionStorage actor for a given extension. This is effectively
+ * what happens when the addon storage panel is opened in the browser.
+ *
+ * @param {String} - id, The addon id
+ * @return {Object} - Resolves with the DevTools "commands" objact and the extensionStorage
+ * resource/front.
+ */
+async function openAddonStoragePanel(id) {
+  const commands = await CommandsFactory.forAddon(id);
+  await commands.targetCommand.startListening();
+
+  // Fetch the EXTENSION_STORAGE resource.
+  // Unfortunately, we can't use resourceCommand.waitForNextResource as it would destroy
+  // the actor by immediately unwatching for the resource type.
+  const extensionStorage = await new Promise(resolve => {
+    commands.resourceCommand.watchResources(
+      [commands.resourceCommand.TYPES.EXTENSION_STORAGE],
+      {
+        onAvailable(resources) {
+          resolve(resources[0]);
+        },
+      }
+    );
+  });
+
+  return { commands, extensionStorage };
+}
+exports.openAddonStoragePanel = openAddonStoragePanel;
+
+/**
+ * Builds the extension configuration object passed into ExtensionTestUtils.loadExtension
+ *
+ * @param {Object} options - Options, if any, to add to the configuration
+ * @param {Function} options.background - A function comprising the test extension's
+ * background script if provided
+ * @param {Object} options.files - An object whose keys correspond to file names and
+ * values map to the file contents
+ * @param {Object} options.manifest - An object representing the extension's manifest
+ * @return {Object} - The extension configuration object
+ */
+function getExtensionConfig(options = {}) {
+  const { manifest, ...otherOptions } = options;
+  const baseConfig = {
+    manifest: {
+      ...manifest,
+      permissions: ["storage"],
+    },
+    useAddonManager: "temporary",
+  };
+  return {
+    ...baseConfig,
+    ...otherOptions,
+  };
+}
+exports.getExtensionConfig = getExtensionConfig;
+
+/**
+ * Shared files for a test extension that has no background page but adds storage
+ * items via a transient extension page in a tab
+ */
+const ext_no_bg = {
+  files: {
+    "extension_page_in_tab.html": `<!DOCTYPE html>
+      <html>
+        <head>
+          <meta charset="utf-8">
+        </head>
+        <body>
+          <h1>Extension Page in a Tab</h1>
+          <script src="extension_page_in_tab.js"></script>
+        </body>
+      </html>`,
+    "extension_page_in_tab.js": extensionScriptWithMessageListener,
+  },
+};
+exports.ext_no_bg = ext_no_bg;
+
+/**
+ * An extension script that can be used in any extension context (e.g. as a background
+ * script or as an extension page script loaded in a tab).
+ */
+async function extensionScriptWithMessageListener() {
+  let fireOnChanged = false;
+  browser.storage.onChanged.addListener(() => {
+    if (fireOnChanged) {
+      // Do not fire it again until explicitly requested again using the "storage-local-fireOnChanged" test message.
+      fireOnChanged = false;
+      browser.test.sendMessage("storage-local-onChanged");
+    }
+  });
+
+  browser.test.onMessage.addListener(async (msg, ...args) => {
+    let item = null;
+    switch (msg) {
+      case "storage-local-set":
+        await browser.storage.local.set(args[0]);
+        break;
+      case "storage-local-get":
+        item = await browser.storage.local.get(args[0]);
+        break;
+      case "storage-local-remove":
+        await browser.storage.local.remove(args[0]);
+        break;
+      case "storage-local-clear":
+        await browser.storage.local.clear();
+        break;
+      case "storage-local-fireOnChanged": {
+        // Allow the storage.onChanged listener to send a test event
+        // message when onChanged is being fired.
+        fireOnChanged = true;
+        // Do not fire fireOnChanged:done.
+        return;
+      }
+      default:
+        browser.test.fail(`Unexpected test message: ${msg}`);
+    }
+
+    browser.test.sendMessage(`${msg}:done`, item);
+  });
+  // window is available in background scripts
+  // eslint-disable-next-line no-undef
+  browser.test.sendMessage("extension-origin", window.location.origin);
+}
+exports.extensionScriptWithMessageListener = extensionScriptWithMessageListener;
+
+/**
+ * Shutdown procedure common to all tasks.
+ *
+ * @param {Object} extension - The test extension
+ * @param {Object} commands - The web extension commands used by the DevTools to interact with the backend
+ */
+async function shutdown(extension, commands) {
+  if (commands) {
+    await commands.destroy();
+  }
+  await extension.unload();
+}
+exports.shutdown = shutdown;
+
+/**
+ * Mocks the missing 'storage/permanent' directory needed by the "indexedDB"
+ * storage actor's 'populateStoresForHosts' method. This
+ * directory exists in a full browser i.e. mochitest.
+ */
+function createMissingIndexedDBDirs() {
+  const dir = Services.dirsvc.get("ProfD", Ci.nsIFile).clone();
+  dir.append("storage");
+  if (!dir.exists()) {
+    dir.create(dir.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  }
+  dir.append("permanent");
+  if (!dir.exists()) {
+    dir.create(dir.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  }
+
+  return dir;
+}
+exports.createMissingIndexedDBDirs = createMissingIndexedDBDirs;
diff --git a/devtools/server/tests/xpcshell/xpcshell.ini b/devtools/server/tests/xpcshell/xpcshell.ini
new file mode 100644
index 0000000000..9bfe8f5e47
--- /dev/null
+++ b/devtools/server/tests/xpcshell/xpcshell.ini
@@ -0,0 +1,249 @@
+[DEFAULT]
+tags = devtools
+head = head_dbg.js
+firefox-appdir = browser
+skip-if = toolkit == 'android'
+# While not every devtools test uses evalInSandbox over 80 do, so it's easier to
+# set allow_parent_unrestricted_js_loads for all the tests here.
+# Similar story for the eval restrictions
+prefs =
+  security.allow_parent_unrestricted_js_loads=true
+  security.allow_eval_with_system_principal=true
+  security.allow_eval_in_parent_process=true
+
+support-files =
+  completions.js
+  webextension-helpers.js
+  source-map-data/sourcemapped.coffee
+  source-map-data/sourcemapped.map
+  post_init_global_actors.js
+  post_init_target_scoped_actors.js
+  pre_init_global_actors.js
+  pre_init_target_scoped_actors.js
+  registertestactors-lazy.js
+  sourcemapped.js
+  testactors.js
+  hello-actor.js
+  stepping.js
+  stepping-async.js
+  source-03.js
+  setBreakpoint-on-column.js
+  setBreakpoint-on-column-minified.js
+  setBreakpoint-on-column-in-gcd-script.js
+  setBreakpoint-on-column-with-no-offsets.js
+  setBreakpoint-on-column-with-no-offsets-in-gcd-script.js
+  setBreakpoint-on-line.js
+  setBreakpoint-on-line-in-gcd-script.js
+  setBreakpoint-on-line-with-multiple-offsets.js
+  setBreakpoint-on-line-with-multiple-statements.js
+  setBreakpoint-on-line-with-no-offsets.js
+  setBreakpoint-on-line-with-no-offsets-in-gcd-script.js
+  addons/web-extension/manifest.json
+  addons/web-extension-upgrade/manifest.json
+  addons/web-extension2/manifest.json
+
+[test_addon_debugging_connect.js]
+[test_addon_events.js]
+[test_addon_reload.js]
+[test_addons_actor.js]
+[test_animation_name.js]
+[test_animation_type.js]
+[test_nesting-03.js]
+[test_nesting-04.js]
+[test_forwardingprefix.js]
+[test_getyoungestframe.js]
+[test_dbgactor.js]
+[test_dbgglobal.js]
+[test_dbgclient_debuggerstatement.js]
+[test_attach.js]
+[test_MemoryActor_saveHeapSnapshot_01.js]
+[test_MemoryActor_saveHeapSnapshot_02.js]
+[test_MemoryActor_saveHeapSnapshot_03.js]
+[test_blackboxing-01.js]
+[test_blackboxing-02.js]
+[test_blackboxing-03.js]
+[test_blackboxing-04.js]
+[test_blackboxing-05.js]
+[test_blackboxing-08.js]
+[test_extension_storage_actor.js]
+skip-if = tsan # Unreasonably slow, bug 1612707
+[test_extension_storage_actor_upgrade.js]
+[test_frameactor-01.js]
+[test_frameactor-02.js]
+[test_frameactor-03.js]
+[test_frameactor-04.js]
+[test_frameactor-05.js]
+[test_frameactor_wasm-01.js]
+[test_framearguments-01.js]
+[test_getRuleText.js]
+[test_getTextAtLineColumn.js]
+[test_pauselifetime-01.js]
+[test_pauselifetime-02.js]
+[test_pauselifetime-03.js]
+[test_pauselifetime-04.js]
+[test_threadlifetime-01.js]
+[test_threadlifetime-02.js]
+[test_threadlifetime-04.js]
+[test_functiongrips-01.js]
+[test_front_destroy.js]
+[test_nativewrappers.js]
+[test_nodelistactor.js]
+[test_format_command.js]
+[test_register_actor.js]
+[test_breakpoint-01.js]
+[test_breakpoint-03.js]
+skip-if = true # breakpoint sliding is not supported bug 1525685
+[test_breakpoint-04.js]
+[test_breakpoint-05.js]
+skip-if = true # breakpoint sliding is not supported bug 1525685
+[test_breakpoint-06.js]
+skip-if = true # breakpoint sliding is not supported bug 1525685
+[test_breakpoint-07.js]
+skip-if = true # breakpoint sliding is not supported bug 1525685
+[test_breakpoint-08.js]
+skip-if = true # breakpoint sliding is not supported bug 1525685
+[test_breakpoint-09.js]
+[test_breakpoint-10.js]
+[test_breakpoint-11.js]
+[test_breakpoint-12.js]
+skip-if = true # breakpoint sliding is not supported bug 1525685
+[test_breakpoint-13.js]
+[test_breakpoint-14.js]
+[test_breakpoint-16.js]
+[test_breakpoint-17.js]
+skip-if = true # tests for breakpoint actors are obsolete bug 1524374
+[test_breakpoint-18.js]
+[test_breakpoint-19.js]
+skip-if = true
+reason = bug 1104838
+[test_breakpoint-20.js]
+[test_breakpoint-21.js]
+[test_breakpoint-22.js]
+skip-if = true # breakpoint sliding is not supported bug 1525685
+[test_breakpoint-23.js]
+[test_breakpoint-24.js]
+[test_breakpoint-25.js]
+[test_breakpoint-26.js]
+[test_conditional_breakpoint-01.js]
+[test_conditional_breakpoint-02.js]
+[test_conditional_breakpoint-03.js]
+[test_conditional_breakpoint-04.js]
+[test_console_eval-01.js]
+[test_console_eval-02.js]
+[test_logpoint-01.js]
+[test_logpoint-02.js]
+[test_logpoint-03.js]
+[test_listsources-01.js]
+[test_listsources-02.js]
+[test_listsources-03.js]
+[test_new_source-01.js]
+[test_new_source-02.js]
+[test_objectgrips-02.js]
+[test_objectgrips-03.js]
+[test_objectgrips-04.js]
+[test_objectgrips-05.js]
+[test_objectgrips-06.js]
+[test_objectgrips-07.js]
+[test_objectgrips-08.js]
+[test_objectgrips-14.js]
+[test_objectgrips-15.js]
+[test_objectgrips-16.js]
+[test_objectgrips-17.js]
+[test_objectgrips-18.js]
+[test_objectgrips-19.js]
+[test_objectgrips-20.js]
+[test_objectgrips-21.js]
+[test_objectgrips-22.js]
+[test_objectgrips-23.js]
+[test_objectgrips-24.js]
+[test_objectgrips-25.js]
+[test_objectgrips-property-value-01.js]
+[test_objectgrips-property-value-02.js]
+[test_objectgrips-property-value-03.js]
+[test_objectgrips-sparse-array.js]
+[test_objectgrips-fn-apply-01.js]
+[test_objectgrips-fn-apply-02.js]
+[test_objectgrips-fn-apply-03.js]
+[test_objectgrips-nested-promise.js]
+[test_objectgrips-nested-proxy.js]
+[test_promise_state-01.js]
+[test_promise_state-02.js]
+[test_promise_state-03.js]
+[test_interrupt.js]
+[test_stepping-01.js]
+[test_stepping-02.js]
+[test_stepping-03.js]
+[test_stepping-04.js]
+[test_stepping-05.js]
+[test_stepping-06.js]
+[test_stepping-07.js]
+[test_stepping-08.js]
+[test_stepping-09.js]
+[test_stepping-10.js]
+[test_stepping-11.js]
+[test_stepping-12.js]
+[test_stepping-13.js]
+[test_stepping-14.js]
+[test_stepping-15.js]
+[test_stepping-16.js]
+[test_stepping-17.js]
+[test_stepping-18.js]
+[test_stepping-19.js]
+[test_stepping-with-skip-breakpoints.js]
+[test_framebindings-01.js]
+[test_framebindings-02.js]
+[test_framebindings-03.js]
+[test_framebindings-04.js]
+[test_framebindings-05.js]
+[test_framebindings-06.js]
+[test_framebindings-07.js]
+[test_pause_exceptions-01.js]
+[test_pause_exceptions-02.js]
+[test_pause_exceptions-03.js]
+[test_pause_exceptions-04.js]
+[test_longstringgrips-01.js]
+[test_source-01.js]
+[test_source-02.js]
+[test_source-03.js]
+[test_source-04.js]
+[test_wasm_source-01.js]
+[test_watchpoint-01.js]
+[test_watchpoint-02.js]
+[test_watchpoint-03.js]
+[test_watchpoint-04.js]
+skip-if = apple_silicon # Disabled due to bleedover with other tests when run in regular suites; passes in "failures" jobs
+[test_watchpoint-05.js]
+[test_breakpoint-actor-map.js]
+skip-if = true # tests for breakpoint actors are obsolete bug 1524374
+[test_unsafeDereference.js]
+[test_add_actors.js]
+[test_ignore_caught_exceptions.js]
+[test_ignore_no_interface_exceptions.js]
+[test_requestTypes.js]
+reason = bug 937197
+[test_layout-reflows-observer.js]
+[test_client_request.js]
+[test_symbols-01.js]
+[test_symbols-02.js]
+[test_xpcshell_debugging.js]
+support-files = xpcshell_debugging_script.js
+[test_setBreakpoint-at-the-beginning-of-a-minified-fn.js]
+[test_setBreakpoint-at-the-end-of-a-minified-fn.js]
+[test_setBreakpoint-on-column.js]
+[test_setBreakpoint-on-column-in-gcd-script.js]
+[test_setBreakpoint-on-line.js]
+[test_setBreakpoint-on-line-in-gcd-script.js]
+[test_setBreakpoint-on-line-with-multiple-offsets.js]
+[test_setBreakpoint-on-line-with-multiple-statements.js]
+[test_setBreakpoint-on-line-with-no-offsets.js]
+skip-if = true # breakpoint sliding is not supported bug 1525685
+[test_setBreakpoint-on-line-with-no-offsets-in-gcd-script.js]
+skip-if = true # breakpoint sliding is not supported bug 1525685
+[test_safe-getter.js]
+[test_shapes_highlighter_helpers.js]
+[test_symbolactor.js]
+[test_webext_apis.js]
+[test_webextension_descriptor.js]
+[test_restartFrame-01.js]
+[test_connection_closes_all_pools.js]
+[test_sessionDataHelpers.js]
diff --git a/devtools/server/tests/xpcshell/xpcshell_debugging_script.js b/devtools/server/tests/xpcshell/xpcshell_debugging_script.js
new file mode 100644
index 0000000000..f762b1c3e8
--- /dev/null
+++ b/devtools/server/tests/xpcshell/xpcshell_debugging_script.js
@@ -0,0 +1,11 @@
+dump("hello from the debugee!\n");
+// We should hit the above dump as we set a breakpoint on the first line
+
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// This is a file that test_xpcshell_debugging.js debugs.
+
+debugger; // and why not check we hit this!?
+
+dump("try to set a breakpoint here");