Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

14 files changed, 631 insertions, 0 deletions

diff --git a/devtools/platform/IJSDebugger.idl b/devtools/platform/IJSDebugger.idl
new file mode 100644
index 0000000000..ec309a315f
--- /dev/null
+++ b/devtools/platform/IJSDebugger.idl
@@ -0,0 +1,22 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Do not use this interface. Instead, write:
+ *     const { addDebuggerToGlobal } = ChromeUtils.importESModule(
+ *       "resource://gre/modules/jsdebugger.sys.mjs"
+ *     );
+ *     addDebuggerToGlobal(global);
+ */
+[scriptable, uuid(a36fa816-31da-4b23-bc97-6412771f0867)]
+interface IJSDebugger : nsISupports
+{
+  /**
+   * Define the global Debugger constructor on a given global.
+   */
+  [implicit_jscontext]
+  void addClass(in jsval global);
+};
diff --git a/devtools/platform/JSDebugger.cpp b/devtools/platform/JSDebugger.cpp
new file mode 100644
index 0000000000..54fde46a54
--- /dev/null
+++ b/devtools/platform/JSDebugger.cpp
@@ -0,0 +1,55 @@
+/* -*-  Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*-
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "JSDebugger.h"
+#include "nsThreadUtils.h"
+#include "jsapi.h"
+#include "jsfriendapi.h"
+#include "js/Wrapper.h"
+#include "nsServiceManagerUtils.h"
+
+#define JSDEBUGGER_CONTRACTID "@mozilla.org/jsdebugger;1"
+
+#define JSDEBUGGER_CID                               \
+  {                                                  \
+    0x0365cbd5, 0xd46e, 0x4e94, {                    \
+      0xa3, 0x9f, 0x83, 0xb6, 0x3c, 0xd1, 0xa9, 0x63 \
+    }                                                \
+  }
+
+namespace mozilla::jsdebugger {
+
+NS_IMPL_ISUPPORTS(JSDebugger, IJSDebugger)
+
+JSDebugger::JSDebugger() = default;
+
+JSDebugger::~JSDebugger() = default;
+
+NS_IMETHODIMP
+JSDebugger::AddClass(JS::Handle<JS::Value> global, JSContext* cx) {
+  if (!global.isObject()) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  JS::Rooted<JSObject*> obj(cx, &global.toObject());
+  obj = js::UncheckedUnwrap(obj, /* stopAtWindowProxy = */ false);
+  if (!obj) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!JS_IsGlobalObject(obj)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  JSAutoRealm ar(cx, obj);
+  if (!JS_DefineDebuggerObject(cx, obj)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+}  // namespace mozilla::jsdebugger
diff --git a/devtools/platform/JSDebugger.h b/devtools/platform/JSDebugger.h
new file mode 100644
index 0000000000..830daa3a43
--- /dev/null
+++ b/devtools/platform/JSDebugger.h
@@ -0,0 +1,30 @@
+/* -*-  Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*-
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef JSDebugger_h
+#define JSDebugger_h
+
+#include "IJSDebugger.h"
+#include "mozilla/Attributes.h"
+
+namespace mozilla {
+namespace jsdebugger {
+
+class JSDebugger final : public IJSDebugger {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_IJSDEBUGGER
+
+  JSDebugger();
+
+ private:
+  ~JSDebugger();
+};
+
+}  // namespace jsdebugger
+}  // namespace mozilla
+
+#endif /* JSDebugger_h */
diff --git a/devtools/platform/components.conf b/devtools/platform/components.conf
new file mode 100644
index 0000000000..8e37217dd3
--- /dev/null
+++ b/devtools/platform/components.conf
@@ -0,0 +1,20 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+Classes = [
+    {
+        'cid': '{ec5aa99c-7abb-4142-ac5f-aab2419e38e2}',
+        'contract_ids': ['@mozilla.org/jsinspector;1'],
+        'type': 'mozilla::jsinspector::nsJSInspector',
+        'headers': ['/devtools/platform/nsJSInspector.h'],
+    },
+    {
+        'cid': '{0365cbd5-d46e-4e94-a39f-83b63cd1a963}',
+        'contract_ids': ['@mozilla.org/jsdebugger;1'],
+        'type': 'mozilla::jsdebugger::JSDebugger',
+        'headers': ['/devtools/platform/JSDebugger.h'],
+    },
+]
diff --git a/devtools/platform/jsdebugger.sys.mjs b/devtools/platform/jsdebugger.sys.mjs
new file mode 100644
index 0000000000..a4af1fdbc3
--- /dev/null
+++ b/devtools/platform/jsdebugger.sys.mjs
@@ -0,0 +1,94 @@
+/* -*-  indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * This is the js module for Debugger. Import it like so:
+ *   const { addDebuggerToGlobal } = ChromeUtils.importESModule(
+ *     "resource://gre/modules/jsdebugger.sys.mjs"
+ *   );
+ *   addDebuggerToGlobal(globalThis);
+ *
+ * This will create a 'Debugger' object, which provides an interface to debug
+ * JavaScript code running in other compartments in the same process, on the
+ * same thread.
+ *
+ * For documentation on the API, see:
+ *   https://developer.mozilla.org/en-US/docs/Tools/Debugger-API
+ */
+
+const init = Cc["@mozilla.org/jsdebugger;1"].createInstance(Ci.IJSDebugger);
+
+export function addDebuggerToGlobal(global) {
+  init.addClass(global);
+  initPromiseDebugging(global);
+}
+
+// Defines the Debugger in a sandbox global in a separate compartment. This
+// ensures the debugger and debuggee are in different compartments.
+export function addSandboxedDebuggerToGlobal(global) {
+  const sb = Cu.Sandbox(global, { freshCompartment: true });
+  addDebuggerToGlobal(sb);
+  global.Debugger = sb.Debugger;
+}
+
+function initPromiseDebugging(global) {
+  if (global.Debugger.Object.prototype.PromiseDebugging) {
+    return;
+  }
+
+  // If the PromiseDebugging object doesn't have all legacy functions, we're
+  // using the new accessors on Debugger.Object already.
+  if (!PromiseDebugging.getDependentPromises) {
+    return;
+  }
+
+  // Otherwise, polyfill them using PromiseDebugging.
+  global.Debugger.Object.prototype.PromiseDebugging = PromiseDebugging;
+  global.eval(polyfillSource);
+}
+
+const polyfillSource = `
+  Object.defineProperty(Debugger.Object.prototype, "promiseState", {
+    get() {
+      const state = this.PromiseDebugging.getState(this.unsafeDereference());
+      return {
+        state: state.state,
+        value: this.makeDebuggeeValue(state.value),
+        reason: this.makeDebuggeeValue(state.reason)
+      };
+    }
+  });
+  Object.defineProperty(Debugger.Object.prototype, "promiseLifetime", {
+    get() {
+      return this.PromiseDebugging.getPromiseLifetime(this.unsafeDereference());
+    }
+  });
+  Object.defineProperty(Debugger.Object.prototype, "promiseTimeToResolution", {
+    get() {
+      return this.PromiseDebugging.getTimeToSettle(this.unsafeDereference());
+    }
+  });
+  Object.defineProperty(Debugger.Object.prototype, "promiseDependentPromises", {
+    get() {
+      let promises = this.PromiseDebugging.getDependentPromises(this.unsafeDereference());
+      return promises.map(p => this.makeDebuggeeValue(p));
+    }
+  });
+  Object.defineProperty(Debugger.Object.prototype, "promiseAllocationSite", {
+    get() {
+      return this.PromiseDebugging.getAllocationStack(this.unsafeDereference());
+    }
+  });
+  Object.defineProperty(Debugger.Object.prototype, "promiseResolutionSite", {
+    get() {
+      let state = this.promiseState.state;
+      if (state === "fulfilled") {
+        return this.PromiseDebugging.getFullfillmentStack(this.unsafeDereference());
+      } else {
+        return this.PromiseDebugging.getRejectionStack(this.unsafeDereference());
+      }
+    }
+  });
+`;
diff --git a/devtools/platform/moz.build b/devtools/platform/moz.build
new file mode 100644
index 0000000000..33be638e5b
--- /dev/null
+++ b/devtools/platform/moz.build
@@ -0,0 +1,33 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPCSHELL_TESTS_MANIFESTS += ["tests/xpcshell/xpcshell.ini"]
+
+XPIDL_SOURCES += [
+    "IJSDebugger.idl",
+    "nsIJSInspector.idl",
+]
+
+XPIDL_MODULE = "jsdevtools"
+
+SOURCES += [
+    "JSDebugger.cpp",
+    "nsJSInspector.cpp",
+]
+
+XPCOM_MANIFESTS += [
+    "components.conf",
+]
+
+EXTRA_JS_MODULES += [
+    "jsdebugger.sys.mjs",
+]
+
+# The /devtools/moz.build opted in to treatment of devtools as a browser
+# component, but for this platform integration code it is simpler not too.
+DIST_SUBDIR = ""
+
+FINAL_LIBRARY = "xul"
diff --git a/devtools/platform/nsIJSInspector.idl b/devtools/platform/nsIJSInspector.idl
new file mode 100644
index 0000000000..40ad495234
--- /dev/null
+++ b/devtools/platform/nsIJSInspector.idl
@@ -0,0 +1,75 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Utilities for running nested event loops, asking them to return, and
+ * keeping track of which ones are still running.
+ */
+[scriptable, uuid(6758d0d7-e96a-4c5c-bca8-3bcbe5a15943)]
+interface nsIJSInspector : nsISupports
+{
+  /**
+   * Process the current thread's event queue, calling event handlers until
+   * a call to exitNestedEventLoop, below, asks us to return.
+   *
+   * The name 'enterNestedEventLoop' may be misleading if read too literally.
+   * This method loops calling event handlers until one asks it to stop, and
+   * then returns. So by that point, the nested event loop has been not only
+   * entered, but also run and exited.
+   *
+   * When enterNestedEventLoop calls an event handler, that handler may itself
+   * call enterNestedEventLoop, and so on, so that there may be arbitrarily
+   * many such calls on the stack at the same time.
+   *
+   * We say an enterNestedEventLoop call is "running" if it has not yet been
+   * asked to return, or "stopped" if it has been asked to return once it has
+   * finished processing the current event.
+   *
+   * @param requestor   A token of the caller's choice to identify this event
+   *                    loop.
+   *
+   * @return depth      The number of running enterNestedEventLoop calls
+   *                    remaining, now that this one has returned.
+   *
+   *                    (Note that not all calls still on the stack are
+   *                    necessary running; exitNestedEventLoop can ask any
+   *                    number of enterNestedEventLoop calls to return.)
+   */
+  unsigned long enterNestedEventLoop(in jsval requestor);
+
+  /**
+   * Stop the youngest running enterNestedEventLoop call, asking it to return
+   * once it has finished processing the current event.
+   *
+   * The name 'exitNestedEventLoop' may be misleading if read too literally.
+   * The affected event loop does not return immediately when this method is
+   * called. Rather, this method simply returns to its caller; the affected
+   * loop's current event handler is allowed to run to completion; and then
+   * that loop returns without processing any more events.
+   *
+   * This method ignores loops that have already been stopped, and operates on
+   * the youngest loop that is still running. Each call to this method stops
+   * another running loop.
+   *
+   * @return depth      The number of running enterNestedEventLoop calls
+   *                    remaining, now that one has been stopped.
+   *
+   * @throws NS_ERROR_FAILURE if there are no running enterNestedEventLoop calls.
+   */
+  unsigned long exitNestedEventLoop();
+
+  /**
+    * The number of running enterNestedEventLoop calls on the stack.
+    * This count does not include stopped enterNestedEventLoop calls.
+    */
+  readonly attribute unsigned long eventLoopNestLevel;
+
+  /**
+   * The |requestor| value that was passed to the youngest running
+   * enterNestedEventLoop call.
+   */
+  readonly attribute jsval lastNestRequestor;
+};
diff --git a/devtools/platform/nsJSInspector.cpp b/devtools/platform/nsJSInspector.cpp
new file mode 100644
index 0000000000..944cd9d943
--- /dev/null
+++ b/devtools/platform/nsJSInspector.cpp
@@ -0,0 +1,116 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsJSInspector.h"
+#include "mozilla/HoldDropJSObjects.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "nsTArray.h"
+
+#define JSINSPECTOR_CONTRACTID "@mozilla.org/jsinspector;1"
+
+#define JSINSPECTOR_CID                              \
+  {                                                  \
+    0xec5aa99c, 0x7abb, 0x4142, {                    \
+      0xac, 0x5f, 0xaa, 0xb2, 0x41, 0x9e, 0x38, 0xe2 \
+    }                                                \
+  }
+
+namespace mozilla {
+namespace jsinspector {
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsJSInspector)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+  NS_INTERFACE_MAP_ENTRY(nsIJSInspector)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(nsJSInspector)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsJSInspector)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsJSInspector)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsJSInspector)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsJSInspector)
+  tmp->mRequestors.Clear();
+  tmp->mLastRequestor = JS::NullValue();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(nsJSInspector)
+  for (uint32_t i = 0; i < tmp->mRequestors.Length(); ++i) {
+    NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mRequestors[i])
+  }
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mLastRequestor)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+nsJSInspector::nsJSInspector()
+    : mNestedLoopLevel(0), mRequestors(1), mLastRequestor(JS::NullValue()) {}
+
+nsJSInspector::~nsJSInspector() {
+  MOZ_ASSERT(mRequestors.Length() == 0);
+  MOZ_ASSERT(mLastRequestor.isNull());
+  mozilla::DropJSObjects(this);
+}
+
+NS_IMETHODIMP
+nsJSInspector::EnterNestedEventLoop(JS::Handle<JS::Value> requestor,
+                                    uint32_t* out) {
+  nsresult rv = NS_OK;
+
+  mLastRequestor = requestor;
+  mRequestors.AppendElement(requestor);
+  mozilla::HoldJSObjects(this);
+
+  mozilla::dom::AutoNoJSAPI nojsapi;
+
+  uint32_t nestLevel = ++mNestedLoopLevel;
+  if (!SpinEventLoopUntil("nsJSInspector::EnterNestedEventLoop"_ns,
+                          [&]() { return mNestedLoopLevel < nestLevel; })) {
+    rv = NS_ERROR_UNEXPECTED;
+  }
+
+  NS_ASSERTION(mNestedLoopLevel <= nestLevel,
+               "nested event didn't unwind properly");
+
+  if (mNestedLoopLevel == nestLevel) {
+    mLastRequestor = mRequestors.ElementAt(--mNestedLoopLevel);
+  }
+
+  *out = mNestedLoopLevel;
+  return rv;
+}
+
+NS_IMETHODIMP
+nsJSInspector::ExitNestedEventLoop(uint32_t* out) {
+  if (mNestedLoopLevel > 0) {
+    mRequestors.RemoveElementAt(--mNestedLoopLevel);
+    if (mNestedLoopLevel > 0)
+      mLastRequestor = mRequestors.ElementAt(mNestedLoopLevel - 1);
+    else
+      mLastRequestor = JS::NullValue();
+  } else {
+    return NS_ERROR_FAILURE;
+  }
+
+  *out = mNestedLoopLevel;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSInspector::GetEventLoopNestLevel(uint32_t* out) {
+  *out = mNestedLoopLevel;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJSInspector::GetLastNestRequestor(JS::MutableHandle<JS::Value> out) {
+  out.set(mLastRequestor);
+  return NS_OK;
+}
+
+}  // namespace jsinspector
+}  // namespace mozilla
diff --git a/devtools/platform/nsJSInspector.h b/devtools/platform/nsJSInspector.h
new file mode 100644
index 0000000000..c4292fb88f
--- /dev/null
+++ b/devtools/platform/nsJSInspector.h
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef COMPONENTS_JSINSPECTOR_H
+#define COMPONENTS_JSINSPECTOR_H
+
+#include "nsIJSInspector.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsTArray.h"
+#include "js/Value.h"
+#include "js/RootingAPI.h"
+
+namespace mozilla {
+namespace jsinspector {
+
+class nsJSInspector final : public nsIJSInspector {
+ public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(nsJSInspector)
+  NS_DECL_NSIJSINSPECTOR
+
+  nsJSInspector();
+
+ private:
+  ~nsJSInspector();
+
+  uint32_t mNestedLoopLevel;
+  nsTArray<JS::Heap<JS::Value> > mRequestors;
+  JS::Heap<JS::Value> mLastRequestor;
+};
+
+}  // namespace jsinspector
+}  // namespace mozilla
+
+#endif
diff --git a/devtools/platform/tests/xpcshell/.eslintrc.js b/devtools/platform/tests/xpcshell/.eslintrc.js
new file mode 100644
index 0000000000..dc7f2c85c4
--- /dev/null
+++ b/devtools/platform/tests/xpcshell/.eslintrc.js
@@ -0,0 +1,19 @@
+"use strict";
+
+// Parent config file for all devtools xpcshell files.
+module.exports = {
+  extends: ["plugin:mozilla/xpcshell-test"],
+  rules: {
+    // Allow non-camelcase so that run_test doesn't produce a warning.
+    camelcase: "off",
+    // Allow using undefined variables so that tests can refer to functions
+    // and variables defined in head.js files, without having to maintain a
+    // list of globals in each .eslintrc file.
+    // Note that bug 1168340 will eventually help auto-registering globals
+    // from head.js files.
+    "no-undef": "off",
+    "block-scoped-var": "off",
+    // Tests can always import anything.
+    "mozilla/reject-some-requires": "off",
+  },
+};
diff --git a/devtools/platform/tests/xpcshell/head_dbg.js b/devtools/platform/tests/xpcshell/head_dbg.js
new file mode 100644
index 0000000000..48942bdb7a
--- /dev/null
+++ b/devtools/platform/tests/xpcshell/head_dbg.js
@@ -0,0 +1,14 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function testGlobal(name) {
+  const systemPrincipal = Cc["@mozilla.org/systemprincipal;1"].createInstance(
+    Ci.nsIPrincipal
+  );
+
+  const sandbox = Cu.Sandbox(systemPrincipal);
+  Cu.evalInSandbox("this.__name = '" + name + "'", sandbox);
+  return sandbox;
+}
diff --git a/devtools/platform/tests/xpcshell/test_nativewrappers.js b/devtools/platform/tests/xpcshell/test_nativewrappers.js
new file mode 100644
index 0000000000..a7ea81adaf
--- /dev/null
+++ b/devtools/platform/tests/xpcshell/test_nativewrappers.js
@@ -0,0 +1,45 @@
+"use strict";
+
+function run_test() {
+  const { addDebuggerToGlobal } = ChromeUtils.importESModule(
+    "resource://gre/modules/jsdebugger.sys.mjs"
+  );
+
+  Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+  });
+
+  addDebuggerToGlobal(globalThis);
+  const g = testGlobal("test1");
+
+  const dbg = new Debugger();
+  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 = testGlobal("test2");
+  g2.g = g;
+  g2.eval(
+    "(" +
+      function createBadEvent() {
+        // eslint-disable-next-line mozilla/reject-importGlobalProperties
+        Cu.importGlobalProperties(["DOMParser"]);
+        const parser = new DOMParser();
+        const doc = parser.parseFromString("<foo></foo>", "text/xml");
+        g.stopMe(doc.createEvent("MouseEvent"));
+      } +
+      ")()"
+  );
+
+  dbg.removeAllDebuggees();
+}
diff --git a/devtools/platform/tests/xpcshell/test_nsjsinspector.js b/devtools/platform/tests/xpcshell/test_nsjsinspector.js
new file mode 100644
index 0000000000..74d18b7689
--- /dev/null
+++ b/devtools/platform/tests/xpcshell/test_nsjsinspector.js
@@ -0,0 +1,65 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test the basic functionality of the nsIJSInspector component.
+var gCount = 0;
+const MAX = 10;
+
+var inspector = Cc["@mozilla.org/jsinspector;1"].getService(Ci.nsIJSInspector);
+
+// Emulate 10 simultaneously-debugged windows from 3 separate client connections.
+var requestor = count => ({
+  url: "http://foo/bar/" + count,
+  connection: "conn" + (count % 3),
+});
+
+function run_test() {
+  test_nesting();
+}
+
+function test_nesting() {
+  Assert.equal(inspector.eventLoopNestLevel, 0);
+
+  Services.tm.dispatchToMainThread({ run: enterEventLoop });
+
+  Assert.equal(inspector.enterNestedEventLoop(requestor(gCount)), 0);
+  Assert.equal(inspector.eventLoopNestLevel, 0);
+  Assert.equal(inspector.lastNestRequestor, null);
+}
+
+function enterEventLoop() {
+  if (gCount++ < MAX) {
+    Services.tm.dispatchToMainThread({ run: enterEventLoop });
+
+    Object.create(requestor(gCount));
+
+    Assert.equal(inspector.eventLoopNestLevel, gCount);
+    Assert.equal(inspector.lastNestRequestor.url, requestor(gCount - 1).url);
+    Assert.equal(
+      inspector.lastNestRequestor.connection,
+      requestor(gCount - 1).connection
+    );
+    Assert.equal(inspector.enterNestedEventLoop(requestor(gCount)), gCount);
+  } else {
+    Assert.equal(gCount, MAX + 1);
+    Services.tm.dispatchToMainThread({ run: exitEventLoop });
+  }
+}
+
+function exitEventLoop() {
+  if (inspector.lastNestRequestor != null) {
+    Assert.equal(inspector.lastNestRequestor.url, requestor(gCount - 1).url);
+    Assert.equal(
+      inspector.lastNestRequestor.connection,
+      requestor(gCount - 1).connection
+    );
+    if (gCount-- > 1) {
+      Services.tm.dispatchToMainThread({ run: exitEventLoop });
+    }
+
+    Assert.equal(inspector.exitNestedEventLoop(), gCount);
+    Assert.equal(inspector.eventLoopNestLevel, gCount);
+  }
+}
diff --git a/devtools/platform/tests/xpcshell/xpcshell.ini b/devtools/platform/tests/xpcshell/xpcshell.ini
new file mode 100644
index 0000000000..c87cd5302c
--- /dev/null
+++ b/devtools/platform/tests/xpcshell/xpcshell.ini
@@ -0,0 +1,6 @@
+[DEFAULT]
+tags = devtools
+head = head_dbg.js
+
+[test_nsjsinspector.js]
+[test_nativewrappers.js]