13 files changed, 2553 insertions, 0 deletions
diff --git a/remote/shared/test/xpcshell/head.js b/remote/shared/test/xpcshell/head.js
new file mode 100644
index 0000000000..2e7cf578d3
--- /dev/null
+++ b/remote/shared/test/xpcshell/head.js
@@ -0,0 +1,3 @@
+const SVG_NS = "http://www.w3.org/2000/svg";
+const XHTML_NS = "http://www.w3.org/1999/xhtml";
+const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
diff --git a/remote/shared/test/xpcshell/test_AppInfo.js b/remote/shared/test/xpcshell/test_AppInfo.js
new file mode 100644
index 0000000000..9149564aa1
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_AppInfo.js
@@ -0,0 +1,53 @@
+/* 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/. */
+
+"use strict";
+
+const { AppConstants } = ChromeUtils.importESModule(
+  "resource://gre/modules/AppConstants.sys.mjs"
+);
+
+const { AppInfo, getTimeoutMultiplier } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/AppInfo.sys.mjs"
+);
+
+// Minimal xpcshell tests for AppInfo; Services.appinfo.* is not available
+
+add_task(function test_custom_properties() {
+  const properties = [
+    // platforms
+    "isAndroid",
+    "isLinux",
+    "isMac",
+    "isWindows",
+    // applications
+    "isFirefox",
+    "isThunderbird",
+  ];
+
+  for (const prop of properties) {
+    equal(
+      typeof AppInfo[prop],
+      "boolean",
+      `Custom property ${prop} has expected type`
+    );
+  }
+});
+
+add_task(function test_getTimeoutMultiplier() {
+  const message = "Timeout multiplier has expected value";
+  const timeoutMultiplier = getTimeoutMultiplier();
+
+  if (
+    AppConstants.DEBUG ||
+    AppConstants.MOZ_CODE_COVERAGE ||
+    AppConstants.ASAN
+  ) {
+    equal(timeoutMultiplier, 4, message);
+  } else if (AppConstants.TSAN) {
+    equal(timeoutMultiplier, 8, message);
+  } else {
+    equal(timeoutMultiplier, 1, message);
+  }
+});
diff --git a/remote/shared/test/xpcshell/test_ChallengeHeaderParser.js b/remote/shared/test/xpcshell/test_ChallengeHeaderParser.js
new file mode 100644
index 0000000000..fa624e9c20
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_ChallengeHeaderParser.js
@@ -0,0 +1,140 @@
+/* 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/. */
+
+const { parseChallengeHeader } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/ChallengeHeaderParser.sys.mjs"
+);
+
+add_task(async function test_single_scheme() {
+  const TEST_HEADERS = [
+    {
+      // double quotes
+      header: 'Basic realm="test"',
+      params: [{ name: "realm", value: "test" }],
+    },
+    {
+      // single quote
+      header: "Basic realm='test'",
+      params: [{ name: "realm", value: "test" }],
+    },
+    {
+      // multiline
+      header: `Basic
+       realm='test'`,
+      params: [{ name: "realm", value: "test" }],
+    },
+    {
+      // with additional parameter.
+      header: 'Basic realm="test", charset="UTF-8"',
+      params: [
+        { name: "realm", value: "test" },
+        { name: "charset", value: "UTF-8" },
+      ],
+    },
+  ];
+  for (const { header, params } of TEST_HEADERS) {
+    const challenges = parseChallengeHeader(header);
+    equal(challenges.length, 1);
+    equal(challenges[0].scheme, "Basic");
+    deepEqual(challenges[0].params, params);
+  }
+});
+
+add_task(async function test_realmless_scheme() {
+  const TEST_HEADERS = [
+    {
+      // no parameter
+      header: "Custom",
+      params: [],
+    },
+    {
+      // one non-realm parameter
+      header: "Custom charset='UTF-8'",
+      params: [{ name: "charset", value: "UTF-8" }],
+    },
+  ];
+
+  for (const { header, params } of TEST_HEADERS) {
+    const challenges = parseChallengeHeader(header);
+    equal(challenges.length, 1);
+    equal(challenges[0].scheme, "Custom");
+    deepEqual(challenges[0].params, params);
+  }
+});
+
+add_task(async function test_multiple_schemes() {
+  const TEST_HEADERS = [
+    {
+      header: 'Scheme1 realm="foo", Scheme2 realm="bar"',
+      params: [
+        [{ name: "realm", value: "foo" }],
+        [{ name: "realm", value: "bar" }],
+      ],
+    },
+    {
+      header: 'Scheme1 realm="foo", charset="UTF-8", Scheme2 realm="bar"',
+      params: [
+        [
+          { name: "realm", value: "foo" },
+          { name: "charset", value: "UTF-8" },
+        ],
+        [{ name: "realm", value: "bar" }],
+      ],
+    },
+    {
+      header: `Scheme1 realm="foo",
+                       charset="UTF-8",
+               Scheme2 realm="bar"`,
+      params: [
+        [
+          { name: "realm", value: "foo" },
+          { name: "charset", value: "UTF-8" },
+        ],
+        [{ name: "realm", value: "bar" }],
+      ],
+    },
+  ];
+  for (const { header, params } of TEST_HEADERS) {
+    const challenges = parseChallengeHeader(header);
+    equal(challenges.length, 2);
+    equal(challenges[0].scheme, "Scheme1");
+    deepEqual(challenges[0].params, params[0]);
+    equal(challenges[1].scheme, "Scheme2");
+    deepEqual(challenges[1].params, params[1]);
+  }
+});
+
+add_task(async function test_digest_scheme() {
+  const header = `Digest
+    realm="http-auth@example.org",
+    qop="auth, auth-int",
+    algorithm=SHA-256,
+    nonce="7ypf/xlj9XXwfDPEoM4URrv/xwf94BcCAzFZH4GiTo0v",
+    opaque="FQhe/qaU925kfnzjCev0ciny7QMkPqMAFRtzCUYo5tdS"`;
+
+  const challenges = parseChallengeHeader(header);
+  equal(challenges.length, 1);
+  equal(challenges[0].scheme, "Digest");
+
+  // Note: we are not doing a deepEqual check here, because one of the params
+  // actually contains a `,` inside quotes for its value, which will not be
+  // handled properly by the current ChallengeHeaderParser. See Bug 1857847.
+  const realmParam = challenges[0].params.find(param => param.name === "realm");
+  ok(realmParam);
+  equal(realmParam.value, "http-auth@example.org");
+
+  // Once Bug 1857847 is addressed, this should start failing and can be
+  // switched to deepEqual.
+  notDeepEqual(
+    challenges[0].params,
+    [
+      { name: "realm", value: "http-auth@example.org" },
+      { name: "qop", value: "auth, auth-int" },
+      { name: "algorithm", value: "SHA-256" },
+      { name: "nonce", value: "7ypf/xlj9XXwfDPEoM4URrv/xwf94BcCAzFZH4GiTo0v" },
+      { name: "opaque", value: "FQhe/qaU925kfnzjCev0ciny7QMkPqMAFRtzCUYo5tdS" },
+    ],
+    "notDeepEqual should be changed to deepEqual when Bug 1857847 is fixed"
+  );
+});
diff --git a/remote/shared/test/xpcshell/test_DOM.js b/remote/shared/test/xpcshell/test_DOM.js
new file mode 100644
index 0000000000..19844659b9
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_DOM.js
@@ -0,0 +1,479 @@
+/* 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/. */
+
+const { dom } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/DOM.sys.mjs"
+);
+const { NodeCache } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/webdriver/NodeCache.sys.mjs"
+);
+
+class MockElement {
+  constructor(tagName, attrs = {}) {
+    this.tagName = tagName;
+    this.localName = tagName;
+
+    this.isConnected = false;
+    this.ownerGlobal = {
+      document: {
+        isActive() {
+          return true;
+        },
+      },
+    };
+
+    for (let attr in attrs) {
+      this[attr] = attrs[attr];
+    }
+  }
+
+  get nodeType() {
+    return 1;
+  }
+
+  get ELEMENT_NODE() {
+    return 1;
+  }
+
+  // this is a severely limited CSS selector
+  // that only supports lists of tag names
+  matches(selector) {
+    let tags = selector.split(",");
+    return tags.includes(this.localName);
+  }
+}
+
+class MockXULElement extends MockElement {
+  constructor(tagName, attrs = {}) {
+    super(tagName, attrs);
+    this.namespaceURI = XUL_NS;
+
+    if (typeof this.ownerDocument == "undefined") {
+      this.ownerDocument = {};
+    }
+    if (typeof this.ownerDocument.documentElement == "undefined") {
+      this.ownerDocument.documentElement = { namespaceURI: XUL_NS };
+    }
+  }
+}
+
+const xulEl = new MockXULElement("text");
+
+const domElInPrivilegedDocument = new MockElement("input", {
+  nodePrincipal: { isSystemPrincipal: true },
+});
+const xulElInPrivilegedDocument = new MockXULElement("text", {
+  nodePrincipal: { isSystemPrincipal: true },
+});
+
+function setupTest() {
+  const browser = Services.appShell.createWindowlessBrowser(false);
+
+  browser.document.body.innerHTML = `
+    <div id="foo" style="margin: 50px">
+      <iframe></iframe>
+      <video></video>
+      <svg xmlns="http://www.w3.org/2000/svg"></svg>
+      <textarea></textarea>
+    </div>
+  `;
+
+  const divEl = browser.document.querySelector("div");
+  const svgEl = browser.document.querySelector("svg");
+  const textareaEl = browser.document.querySelector("textarea");
+  const videoEl = browser.document.querySelector("video");
+
+  const iframeEl = browser.document.querySelector("iframe");
+  const childEl = iframeEl.contentDocument.createElement("div");
+  iframeEl.contentDocument.body.appendChild(childEl);
+
+  const shadowRoot = videoEl.openOrClosedShadowRoot;
+
+  return {
+    browser,
+    nodeCache: new NodeCache(),
+    childEl,
+    divEl,
+    iframeEl,
+    shadowRoot,
+    svgEl,
+    textareaEl,
+    videoEl,
+  };
+}
+
+add_task(function test_findClosest() {
+  const { divEl, videoEl } = setupTest();
+
+  equal(dom.findClosest(divEl, "foo"), null);
+  equal(dom.findClosest(videoEl, "div"), divEl);
+});
+
+add_task(function test_isSelected() {
+  const { browser, divEl } = setupTest();
+
+  const checkbox = browser.document.createElement("input");
+  checkbox.setAttribute("type", "checkbox");
+
+  ok(!dom.isSelected(checkbox));
+  checkbox.checked = true;
+  ok(dom.isSelected(checkbox));
+
+  // selected is not a property of <input type=checkbox>
+  checkbox.selected = true;
+  checkbox.checked = false;
+  ok(!dom.isSelected(checkbox));
+
+  const option = browser.document.createElement("option");
+
+  ok(!dom.isSelected(option));
+  option.selected = true;
+  ok(dom.isSelected(option));
+
+  // checked is not a property of <option>
+  option.checked = true;
+  option.selected = false;
+  ok(!dom.isSelected(option));
+
+  // anything else should not be selected
+  for (const type of [undefined, null, "foo", true, [], {}, divEl]) {
+    ok(!dom.isSelected(type));
+  }
+});
+
+add_task(function test_isElement() {
+  const { divEl, iframeEl, shadowRoot, svgEl } = setupTest();
+
+  ok(dom.isElement(divEl));
+  ok(dom.isElement(svgEl));
+  ok(dom.isElement(xulEl));
+  ok(dom.isElement(domElInPrivilegedDocument));
+  ok(dom.isElement(xulElInPrivilegedDocument));
+
+  ok(!dom.isElement(shadowRoot));
+  ok(!dom.isElement(divEl.ownerGlobal));
+  ok(!dom.isElement(iframeEl.contentWindow));
+
+  for (const type of [true, 42, {}, [], undefined, null]) {
+    ok(!dom.isElement(type));
+  }
+});
+
+add_task(function test_isDOMElement() {
+  const { divEl, iframeEl, shadowRoot, svgEl } = setupTest();
+
+  ok(dom.isDOMElement(divEl));
+  ok(dom.isDOMElement(svgEl));
+  ok(dom.isDOMElement(domElInPrivilegedDocument));
+
+  ok(!dom.isDOMElement(shadowRoot));
+  ok(!dom.isDOMElement(divEl.ownerGlobal));
+  ok(!dom.isDOMElement(iframeEl.contentWindow));
+  ok(!dom.isDOMElement(xulEl));
+  ok(!dom.isDOMElement(xulElInPrivilegedDocument));
+
+  for (const type of [true, 42, "foo", {}, [], undefined, null]) {
+    ok(!dom.isDOMElement(type));
+  }
+});
+
+add_task(function test_isXULElement() {
+  const { divEl, iframeEl, shadowRoot, svgEl } = setupTest();
+
+  ok(dom.isXULElement(xulEl));
+  ok(dom.isXULElement(xulElInPrivilegedDocument));
+
+  ok(!dom.isXULElement(divEl));
+  ok(!dom.isXULElement(domElInPrivilegedDocument));
+  ok(!dom.isXULElement(svgEl));
+  ok(!dom.isXULElement(shadowRoot));
+  ok(!dom.isXULElement(divEl.ownerGlobal));
+  ok(!dom.isXULElement(iframeEl.contentWindow));
+
+  for (const type of [true, 42, "foo", {}, [], undefined, null]) {
+    ok(!dom.isXULElement(type));
+  }
+});
+
+add_task(function test_isDOMWindow() {
+  const { divEl, iframeEl, shadowRoot, svgEl } = setupTest();
+
+  ok(dom.isDOMWindow(divEl.ownerGlobal));
+  ok(dom.isDOMWindow(iframeEl.contentWindow));
+
+  ok(!dom.isDOMWindow(divEl));
+  ok(!dom.isDOMWindow(svgEl));
+  ok(!dom.isDOMWindow(shadowRoot));
+  ok(!dom.isDOMWindow(domElInPrivilegedDocument));
+  ok(!dom.isDOMWindow(xulEl));
+  ok(!dom.isDOMWindow(xulElInPrivilegedDocument));
+
+  for (const type of [true, 42, {}, [], undefined, null]) {
+    ok(!dom.isDOMWindow(type));
+  }
+});
+
+add_task(function test_isShadowRoot() {
+  const { browser, divEl, iframeEl, shadowRoot, svgEl } = setupTest();
+
+  ok(dom.isShadowRoot(shadowRoot));
+
+  ok(!dom.isShadowRoot(divEl));
+  ok(!dom.isShadowRoot(svgEl));
+  ok(!dom.isShadowRoot(divEl.ownerGlobal));
+  ok(!dom.isShadowRoot(iframeEl.contentWindow));
+  ok(!dom.isShadowRoot(xulEl));
+  ok(!dom.isShadowRoot(domElInPrivilegedDocument));
+  ok(!dom.isShadowRoot(xulElInPrivilegedDocument));
+
+  for (const type of [true, 42, "foo", {}, [], undefined, null]) {
+    ok(!dom.isShadowRoot(type));
+  }
+
+  const documentFragment = browser.document.createDocumentFragment();
+  ok(!dom.isShadowRoot(documentFragment));
+});
+
+add_task(function test_isReadOnly() {
+  const { browser, divEl, textareaEl } = setupTest();
+
+  const input = browser.document.createElement("input");
+  input.readOnly = true;
+  ok(dom.isReadOnly(input));
+
+  textareaEl.readOnly = true;
+  ok(dom.isReadOnly(textareaEl));
+
+  ok(!dom.isReadOnly(divEl));
+  divEl.readOnly = true;
+  ok(!dom.isReadOnly(divEl));
+
+  ok(!dom.isReadOnly(null));
+});
+
+add_task(function test_isDisabled() {
+  const { browser, divEl, svgEl } = setupTest();
+
+  const select = browser.document.createElement("select");
+  const option = browser.document.createElement("option");
+  select.appendChild(option);
+  select.disabled = true;
+  ok(dom.isDisabled(option));
+
+  const optgroup = browser.document.createElement("optgroup");
+  option.parentNode = optgroup;
+  ok(dom.isDisabled(option));
+
+  optgroup.parentNode = select;
+  ok(dom.isDisabled(option));
+
+  select.disabled = false;
+  ok(!dom.isDisabled(option));
+
+  for (const type of ["button", "input", "select", "textarea"]) {
+    const elem = browser.document.createElement(type);
+    ok(!dom.isDisabled(elem));
+    elem.disabled = true;
+    ok(dom.isDisabled(elem));
+  }
+
+  ok(!dom.isDisabled(divEl));
+
+  svgEl.disabled = true;
+  ok(!dom.isDisabled(svgEl));
+
+  ok(!dom.isDisabled(new MockXULElement("browser", { disabled: true })));
+});
+
+add_task(function test_isEditingHost() {
+  const { browser, divEl, svgEl } = setupTest();
+
+  ok(!dom.isEditingHost(null));
+
+  ok(!dom.isEditingHost(divEl));
+  divEl.contentEditable = true;
+  ok(dom.isEditingHost(divEl));
+
+  ok(!dom.isEditingHost(svgEl));
+  browser.document.designMode = "on";
+  ok(dom.isEditingHost(svgEl));
+});
+
+add_task(function test_isEditable() {
+  const { browser, divEl, svgEl, textareaEl } = setupTest();
+
+  ok(!dom.isEditable(null));
+
+  for (let type of [
+    "checkbox",
+    "radio",
+    "hidden",
+    "submit",
+    "button",
+    "image",
+  ]) {
+    const input = browser.document.createElement("input");
+    input.setAttribute("type", type);
+
+    ok(!dom.isEditable(input));
+  }
+
+  const input = browser.document.createElement("input");
+  ok(dom.isEditable(input));
+  input.setAttribute("type", "text");
+  ok(dom.isEditable(input));
+
+  ok(dom.isEditable(textareaEl));
+
+  const textareaDisabled = browser.document.createElement("textarea");
+  textareaDisabled.disabled = true;
+  ok(!dom.isEditable(textareaDisabled));
+
+  const textareaReadOnly = browser.document.createElement("textarea");
+  textareaReadOnly.readOnly = true;
+  ok(!dom.isEditable(textareaReadOnly));
+
+  ok(!dom.isEditable(divEl));
+  divEl.contentEditable = true;
+  ok(dom.isEditable(divEl));
+
+  ok(!dom.isEditable(svgEl));
+  browser.document.designMode = "on";
+  ok(dom.isEditable(svgEl));
+});
+
+add_task(function test_isMutableFormControlElement() {
+  const { browser, divEl, textareaEl } = setupTest();
+
+  ok(!dom.isMutableFormControl(null));
+
+  ok(dom.isMutableFormControl(textareaEl));
+
+  const textareaDisabled = browser.document.createElement("textarea");
+  textareaDisabled.disabled = true;
+  ok(!dom.isMutableFormControl(textareaDisabled));
+
+  const textareaReadOnly = browser.document.createElement("textarea");
+  textareaReadOnly.readOnly = true;
+  ok(!dom.isMutableFormControl(textareaReadOnly));
+
+  const mutableStates = new Set([
+    "color",
+    "date",
+    "datetime-local",
+    "email",
+    "file",
+    "month",
+    "number",
+    "password",
+    "range",
+    "search",
+    "tel",
+    "text",
+    "url",
+    "week",
+  ]);
+  for (const type of mutableStates) {
+    const input = browser.document.createElement("input");
+    input.setAttribute("type", type);
+    ok(dom.isMutableFormControl(input));
+  }
+
+  const inputHidden = browser.document.createElement("input");
+  inputHidden.setAttribute("type", "hidden");
+  ok(!dom.isMutableFormControl(inputHidden));
+
+  ok(!dom.isMutableFormControl(divEl));
+  divEl.contentEditable = true;
+  ok(!dom.isMutableFormControl(divEl));
+  browser.document.designMode = "on";
+  ok(!dom.isMutableFormControl(divEl));
+});
+
+add_task(function test_coordinates() {
+  const { divEl } = setupTest();
+
+  let coords = dom.coordinates(divEl);
+  ok(coords.hasOwnProperty("x"));
+  ok(coords.hasOwnProperty("y"));
+  equal(typeof coords.x, "number");
+  equal(typeof coords.y, "number");
+
+  deepEqual(dom.coordinates(divEl), { x: 0, y: 0 });
+  deepEqual(dom.coordinates(divEl, 10, 10), { x: 10, y: 10 });
+  deepEqual(dom.coordinates(divEl, -5, -5), { x: -5, y: -5 });
+
+  Assert.throws(() => dom.coordinates(null), /node is null/);
+
+  Assert.throws(
+    () => dom.coordinates(divEl, "string", undefined),
+    /Offset must be a number/
+  );
+  Assert.throws(
+    () => dom.coordinates(divEl, undefined, "string"),
+    /Offset must be a number/
+  );
+  Assert.throws(
+    () => dom.coordinates(divEl, "string", "string"),
+    /Offset must be a number/
+  );
+  Assert.throws(
+    () => dom.coordinates(divEl, {}, undefined),
+    /Offset must be a number/
+  );
+  Assert.throws(
+    () => dom.coordinates(divEl, undefined, {}),
+    /Offset must be a number/
+  );
+  Assert.throws(
+    () => dom.coordinates(divEl, {}, {}),
+    /Offset must be a number/
+  );
+  Assert.throws(
+    () => dom.coordinates(divEl, [], undefined),
+    /Offset must be a number/
+  );
+  Assert.throws(
+    () => dom.coordinates(divEl, undefined, []),
+    /Offset must be a number/
+  );
+  Assert.throws(
+    () => dom.coordinates(divEl, [], []),
+    /Offset must be a number/
+  );
+});
+
+add_task(function test_isDetached() {
+  const { childEl, iframeEl } = setupTest();
+
+  let detachedShadowRoot = childEl.attachShadow({ mode: "open" });
+  detachedShadowRoot.innerHTML = "<input></input>";
+
+  // Connected to the DOM
+  ok(!dom.isDetached(detachedShadowRoot));
+
+  // Node document (ownerDocument) is not the active document
+  iframeEl.remove();
+  ok(dom.isDetached(detachedShadowRoot));
+
+  // host element is stale (eg. not connected)
+  detachedShadowRoot.host.remove();
+  equal(childEl.isConnected, false);
+  ok(dom.isDetached(detachedShadowRoot));
+});
+
+add_task(function test_isStale() {
+  const { childEl, iframeEl } = setupTest();
+
+  // Connected to the DOM
+  ok(!dom.isStale(childEl));
+
+  // Not part of the active document
+  iframeEl.remove();
+  ok(dom.isStale(childEl));
+
+  // Not connected to the DOM
+  childEl.remove();
+  ok(dom.isStale(childEl));
+});
diff --git a/remote/shared/test/xpcshell/test_Format.js b/remote/shared/test/xpcshell/test_Format.js
new file mode 100644
index 0000000000..cfdd35be08
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_Format.js
@@ -0,0 +1,108 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { truncate, pprint } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/Format.sys.mjs"
+);
+
+const MAX_STRING_LENGTH = 250;
+const HALF = "x".repeat(MAX_STRING_LENGTH / 2);
+
+add_task(function test_pprint() {
+  equal('[object Object] {"foo":"bar"}', pprint`${{ foo: "bar" }}`);
+
+  equal("[object Number] 42", pprint`${42}`);
+  equal("[object Boolean] true", pprint`${true}`);
+  equal("[object Undefined] undefined", pprint`${undefined}`);
+  equal("[object Null] null", pprint`${null}`);
+
+  let complexObj = { toJSON: () => "foo" };
+  equal('[object Object] "foo"', pprint`${complexObj}`);
+
+  let cyclic = {};
+  cyclic.me = cyclic;
+  equal("[object Object] <cyclic object value>", pprint`${cyclic}`);
+
+  let el = {
+    hasAttribute: attr => attr in el,
+    getAttribute: attr => (attr in el ? el[attr] : null),
+    nodeType: 1,
+    localName: "input",
+    id: "foo",
+    class: "a b",
+    href: "#",
+    name: "bar",
+    src: "s",
+    type: "t",
+  };
+  equal(
+    '<input id="foo" class="a b" href="#" name="bar" src="s" type="t">',
+    pprint`${el}`
+  );
+});
+
+add_task(function test_truncate_empty() {
+  equal(truncate``, "");
+});
+
+add_task(function test_truncate_noFields() {
+  equal(truncate`foo bar`, "foo bar");
+});
+
+add_task(function test_truncate_multipleFields() {
+  equal(truncate`${0}`, "0");
+  equal(truncate`${1}${2}${3}`, "123");
+  equal(truncate`a${1}b${2}c${3}`, "a1b2c3");
+});
+
+add_task(function test_truncate_primitiveFields() {
+  equal(truncate`${123}`, "123");
+  equal(truncate`${true}`, "true");
+  equal(truncate`${null}`, "");
+  equal(truncate`${undefined}`, "");
+});
+
+add_task(function test_truncate_string() {
+  equal(truncate`${"foo"}`, "foo");
+  equal(truncate`${"x".repeat(250)}`, "x".repeat(250));
+  equal(truncate`${"x".repeat(260)}`, `${HALF} ... ${HALF}`);
+});
+
+add_task(function test_truncate_array() {
+  equal(truncate`${["foo"]}`, JSON.stringify(["foo"]));
+  equal(truncate`${"foo"} ${["bar"]}`, `foo ${JSON.stringify(["bar"])}`);
+  equal(
+    truncate`${["x".repeat(260)]}`,
+    JSON.stringify([`${HALF} ... ${HALF}`])
+  );
+});
+
+add_task(function test_truncate_object() {
+  equal(truncate`${{}}`, JSON.stringify({}));
+  equal(truncate`${{ foo: "bar" }}`, JSON.stringify({ foo: "bar" }));
+  equal(
+    truncate`${{ foo: "x".repeat(260) }}`,
+    JSON.stringify({ foo: `${HALF} ... ${HALF}` })
+  );
+  equal(truncate`${{ foo: ["bar"] }}`, JSON.stringify({ foo: ["bar"] }));
+  equal(
+    truncate`${{ foo: ["bar", { baz: 42 }] }}`,
+    JSON.stringify({ foo: ["bar", { baz: 42 }] })
+  );
+
+  let complex = {
+    toString() {
+      return "hello world";
+    },
+  };
+  equal(truncate`${complex}`, "hello world");
+
+  let longComplex = {
+    toString() {
+      return "x".repeat(260);
+    },
+  };
+  equal(truncate`${longComplex}`, `${HALF} ... ${HALF}`);
+});
diff --git a/remote/shared/test/xpcshell/test_Navigate.js b/remote/shared/test/xpcshell/test_Navigate.js
new file mode 100644
index 0000000000..e41508189a
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_Navigate.js
@@ -0,0 +1,879 @@
+/* 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/. */
+
+const { setTimeout } = ChromeUtils.importESModule(
+  "resource://gre/modules/Timer.sys.mjs"
+);
+
+const {
+  DEFAULT_UNLOAD_TIMEOUT,
+  getUnloadTimeoutMultiplier,
+  ProgressListener,
+  waitForInitialNavigationCompleted,
+} = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/Navigate.sys.mjs"
+);
+
+const CURRENT_URI = Services.io.newURI("http://foo.bar/");
+const INITIAL_URI = Services.io.newURI("about:blank");
+const TARGET_URI = Services.io.newURI("http://foo.cheese/");
+const TARGET_URI_IS_ERROR_PAGE = Services.io.newURI("doesnotexist://");
+const TARGET_URI_WITH_HASH = Services.io.newURI("http://foo.cheese/#foo");
+
+function wait(time) {
+  // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+  return new Promise(resolve => setTimeout(resolve, time));
+}
+
+class MockRequest {
+  constructor(uri) {
+    this.originalURI = uri;
+  }
+
+  get QueryInterface() {
+    return ChromeUtils.generateQI(["nsIRequest", "nsIChannel"]);
+  }
+}
+
+class MockWebProgress {
+  constructor(browsingContext) {
+    this.browsingContext = browsingContext;
+
+    this.documentRequest = null;
+    this.isLoadingDocument = false;
+    this.listener = null;
+    this.progressListenerRemoved = false;
+  }
+
+  addProgressListener(listener) {
+    if (this.listener) {
+      throw new Error("Cannot register listener twice");
+    }
+
+    this.listener = listener;
+  }
+
+  removeProgressListener(listener) {
+    if (listener === this.listener) {
+      this.listener = null;
+      this.progressListenerRemoved = true;
+    } else {
+      throw new Error("Unknown listener");
+    }
+  }
+
+  sendLocationChange(options = {}) {
+    const { flag = 0 } = options;
+
+    this.documentRequest = null;
+
+    if (flag & Ci.nsIWebProgressListener.LOCATION_CHANGE_SAME_DOCUMENT) {
+      this.browsingContext.currentURI = TARGET_URI_WITH_HASH;
+    } else if (flag & Ci.nsIWebProgressListener.LOCATION_CHANGE_ERROR_PAGE) {
+      this.browsingContext.currentURI = TARGET_URI_IS_ERROR_PAGE;
+    }
+
+    this.listener?.onLocationChange(
+      this,
+      this.documentRequest,
+      TARGET_URI_WITH_HASH,
+      flag
+    );
+
+    return new Promise(executeSoon);
+  }
+
+  sendStartState(options = {}) {
+    const { coop = false, isInitial = false } = options;
+
+    if (coop) {
+      this.browsingContext = new MockTopContext(this);
+    }
+
+    if (!this.browsingContext.currentWindowGlobal) {
+      this.browsingContext.currentWindowGlobal = {};
+    }
+
+    this.browsingContext.currentWindowGlobal.isInitialDocument = isInitial;
+
+    this.isLoadingDocument = true;
+    const uri = isInitial ? INITIAL_URI : TARGET_URI;
+    this.documentRequest = new MockRequest(uri);
+
+    this.listener?.onStateChange(
+      this,
+      this.documentRequest,
+      Ci.nsIWebProgressListener.STATE_START,
+      null
+    );
+
+    return new Promise(executeSoon);
+  }
+
+  sendStopState(options = {}) {
+    const { errorFlag = 0 } = options;
+
+    this.browsingContext.currentURI = this.documentRequest.originalURI;
+
+    this.isLoadingDocument = false;
+    this.documentRequest = null;
+
+    this.listener?.onStateChange(
+      this,
+      this.documentRequest,
+      Ci.nsIWebProgressListener.STATE_STOP,
+      errorFlag
+    );
+
+    return new Promise(executeSoon);
+  }
+}
+
+class MockTopContext {
+  constructor(webProgress = null) {
+    this.currentURI = CURRENT_URI;
+    this.currentWindowGlobal = { isInitialDocument: true };
+    this.id = 7;
+    this.top = this;
+    this.webProgress = webProgress || new MockWebProgress(this);
+  }
+}
+
+const hasPromiseResolved = async function (promise) {
+  let resolved = false;
+  promise.finally(() => (resolved = true));
+  // Make sure microtasks have time to run.
+  await new Promise(resolve => Services.tm.dispatchToMainThread(resolve));
+  return resolved;
+};
+
+const hasPromiseRejected = async function (promise) {
+  let rejected = false;
+  promise.catch(() => (rejected = true));
+  // Make sure microtasks have time to run.
+  await new Promise(resolve => Services.tm.dispatchToMainThread(resolve));
+  return rejected;
+};
+
+add_task(
+  async function test_waitForInitialNavigation_initialDocumentNoWindowGlobal() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    // In some cases there might be no window global yet.
+    delete browsingContext.currentWindowGlobal;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+
+    const navigated = waitForInitialNavigationCompleted(webProgress);
+    await webProgress.sendStartState({ isInitial: true });
+
+    ok(
+      !(await hasPromiseResolved(navigated)),
+      "waitForInitialNavigationCompleted has not resolved yet"
+    );
+
+    await webProgress.sendStopState();
+    const { currentURI, targetURI } = await navigated;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+    ok(
+      webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+      "Is initial document"
+    );
+    equal(
+      currentURI.spec,
+      INITIAL_URI.spec,
+      "Expected current URI has been set"
+    );
+    equal(targetURI.spec, INITIAL_URI.spec, "Expected target URI has been set");
+  }
+);
+
+add_task(
+  async function test_waitForInitialNavigation_initialDocumentNotLoaded() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+
+    const navigated = waitForInitialNavigationCompleted(webProgress);
+
+    await webProgress.sendStartState({ isInitial: true });
+
+    ok(
+      !(await hasPromiseResolved(navigated)),
+      "waitForInitialNavigationCompleted has not resolved yet"
+    );
+
+    await webProgress.sendStopState();
+    const { currentURI, targetURI } = await navigated;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+    ok(
+      webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+      "Is initial document"
+    );
+    equal(
+      currentURI.spec,
+      INITIAL_URI.spec,
+      "Expected current URI has been set"
+    );
+    equal(targetURI.spec, INITIAL_URI.spec, "Expected target URI has been set");
+  }
+);
+
+add_task(
+  async function test_waitForInitialNavigation_initialDocumentLoadingAndNoAdditionalLoad() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    await webProgress.sendStartState({ isInitial: true });
+    ok(webProgress.isLoadingDocument, "Document is loading");
+
+    const navigated = waitForInitialNavigationCompleted(webProgress);
+
+    ok(
+      !(await hasPromiseResolved(navigated)),
+      "waitForInitialNavigationCompleted has not resolved yet"
+    );
+
+    await webProgress.sendStopState();
+    const { currentURI, targetURI } = await navigated;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+    ok(
+      webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+      "Is initial document"
+    );
+    equal(
+      currentURI.spec,
+      INITIAL_URI.spec,
+      "Expected current URI has been set"
+    );
+    equal(targetURI.spec, INITIAL_URI.spec, "Expected target URI has been set");
+  }
+);
+
+add_task(
+  async function test_waitForInitialNavigation_initialDocumentFinishedLoadingNoAdditionalLoad() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    await webProgress.sendStartState({ isInitial: true });
+    await webProgress.sendStopState();
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+
+    const navigated = waitForInitialNavigationCompleted(webProgress);
+
+    ok(
+      !(await hasPromiseResolved(navigated)),
+      "waitForInitialNavigationCompleted has not resolved yet"
+    );
+
+    const { currentURI, targetURI } = await navigated;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+    ok(
+      webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+      "Is initial document"
+    );
+    equal(
+      currentURI.spec,
+      INITIAL_URI.spec,
+      "Expected current URI has been set"
+    );
+    equal(targetURI.spec, INITIAL_URI.spec, "Expected target URI has been set");
+  }
+);
+
+add_task(
+  async function test_waitForInitialNavigation_initialDocumentLoadingAndAdditionalLoad() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    await webProgress.sendStartState({ isInitial: true });
+
+    ok(webProgress.isLoadingDocument, "Document is loading");
+
+    const navigated = waitForInitialNavigationCompleted(webProgress);
+
+    ok(
+      !(await hasPromiseResolved(navigated)),
+      "waitForInitialNavigationCompleted has not resolved yet"
+    );
+
+    await webProgress.sendStopState();
+
+    await wait(100);
+
+    await webProgress.sendStartState({ isInitial: false });
+    await webProgress.sendStopState();
+
+    const { currentURI, targetURI } = await navigated;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+    ok(
+      !webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+      "Is not initial document"
+    );
+    equal(
+      currentURI.spec,
+      TARGET_URI.spec,
+      "Expected current URI has been set"
+    );
+    equal(targetURI.spec, TARGET_URI.spec, "Expected target URI has been set");
+  }
+);
+
+add_task(
+  async function test_waitForInitialNavigation_initialDocumentFinishedLoadingAndAdditionalLoad() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    await webProgress.sendStartState({ isInitial: true });
+    await webProgress.sendStopState();
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+
+    const navigated = waitForInitialNavigationCompleted(webProgress);
+
+    ok(
+      !(await hasPromiseResolved(navigated)),
+      "waitForInitialNavigationCompleted has not resolved yet"
+    );
+
+    await wait(100);
+
+    await webProgress.sendStartState({ isInitial: false });
+    await webProgress.sendStopState();
+
+    const { currentURI, targetURI } = await navigated;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+    ok(
+      !webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+      "Is not initial document"
+    );
+    equal(
+      currentURI.spec,
+      TARGET_URI.spec,
+      "Expected current URI has been set"
+    );
+    equal(targetURI.spec, TARGET_URI.spec, "Expected target URI has been set");
+  }
+);
+
+add_task(
+  async function test_waitForInitialNavigation_notInitialDocumentNotLoading() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+
+    const navigated = waitForInitialNavigationCompleted(webProgress);
+    await webProgress.sendStartState({ isInitial: false });
+
+    ok(
+      !(await hasPromiseResolved(navigated)),
+      "waitForInitialNavigationCompleted has not resolved yet"
+    );
+
+    await webProgress.sendStopState();
+    const { currentURI, targetURI } = await navigated;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+    ok(
+      !browsingContext.currentWindowGlobal.isInitialDocument,
+      "Is not initial document"
+    );
+    equal(
+      currentURI.spec,
+      TARGET_URI.spec,
+      "Expected current URI has been set"
+    );
+    equal(targetURI.spec, TARGET_URI.spec, "Expected target URI has been set");
+  }
+);
+
+add_task(
+  async function test_waitForInitialNavigation_notInitialDocumentAlreadyLoading() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    await webProgress.sendStartState({ isInitial: false });
+    ok(webProgress.isLoadingDocument, "Document is loading");
+
+    const navigated = waitForInitialNavigationCompleted(webProgress);
+
+    ok(
+      !(await hasPromiseResolved(navigated)),
+      "waitForInitialNavigationCompleted has not resolved yet"
+    );
+
+    await webProgress.sendStopState();
+    const { currentURI, targetURI } = await navigated;
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+    ok(
+      !browsingContext.currentWindowGlobal.isInitialDocument,
+      "Is not initial document"
+    );
+    equal(
+      currentURI.spec,
+      TARGET_URI.spec,
+      "Expected current URI has been set"
+    );
+    equal(targetURI.spec, TARGET_URI.spec, "Expected target URI has been set");
+  }
+);
+
+add_task(
+  async function test_waitForInitialNavigation_notInitialDocumentFinishedLoading() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    await webProgress.sendStartState({ isInitial: false });
+    await webProgress.sendStopState();
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+
+    const { currentURI, targetURI } = await waitForInitialNavigationCompleted(
+      webProgress
+    );
+
+    ok(!webProgress.isLoadingDocument, "Document is not loading");
+    ok(
+      !webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+      "Is not initial document"
+    );
+    equal(
+      currentURI.spec,
+      TARGET_URI.spec,
+      "Expected current URI has been set"
+    );
+    equal(targetURI.spec, TARGET_URI.spec, "Expected target URI has been set");
+  }
+);
+
+add_task(async function test_waitForInitialNavigation_resolveWhenStarted() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  await webProgress.sendStartState({ isInitial: true });
+  ok(webProgress.isLoadingDocument, "Document is already loading");
+
+  const { currentURI, targetURI } = await waitForInitialNavigationCompleted(
+    webProgress,
+    {
+      resolveWhenStarted: true,
+    }
+  );
+
+  ok(webProgress.isLoadingDocument, "Document is still loading");
+  ok(
+    webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+    "Is initial document"
+  );
+  equal(currentURI.spec, CURRENT_URI.spec, "Expected current URI has been set");
+  equal(targetURI.spec, INITIAL_URI.spec, "Expected target URI has been set");
+});
+
+add_task(async function test_waitForInitialNavigation_crossOrigin() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  ok(!webProgress.isLoadingDocument, "Document is not loading");
+
+  const navigated = waitForInitialNavigationCompleted(webProgress);
+  await webProgress.sendStartState({ coop: true });
+
+  ok(
+    !(await hasPromiseResolved(navigated)),
+    "waitForInitialNavigationCompleted has not resolved yet"
+  );
+
+  await webProgress.sendStopState();
+  const { currentURI, targetURI } = await navigated;
+
+  notEqual(
+    browsingContext,
+    webProgress.browsingContext,
+    "Got new browsing context"
+  );
+  ok(!webProgress.isLoadingDocument, "Document is not loading");
+  ok(
+    !webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+    "Is not initial document"
+  );
+  equal(currentURI.spec, TARGET_URI.spec, "Expected current URI has been set");
+  equal(targetURI.spec, TARGET_URI.spec, "Expected target URI has been set");
+});
+
+add_task(async function test_waitForInitialNavigation_unloadTimeout_default() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  // Stop the navigation on an initial page which is not loading anymore.
+  // This situation happens with new tabs on Android, even though they are on
+  // the initial document, they will not start another navigation on their own.
+  await webProgress.sendStartState({ isInitial: true });
+  await webProgress.sendStopState();
+
+  ok(!webProgress.isLoadingDocument, "Document is not loading");
+
+  const navigated = waitForInitialNavigationCompleted(webProgress);
+
+  // Start a timer longer than the timeout which will be used by
+  // waitForInitialNavigationCompleted, and check that navigated resolves first.
+  const waitForMoreThanDefaultTimeout = wait(
+    DEFAULT_UNLOAD_TIMEOUT * 1.5 * getUnloadTimeoutMultiplier()
+  );
+  await Promise.race([navigated, waitForMoreThanDefaultTimeout]);
+
+  ok(
+    await hasPromiseResolved(navigated),
+    "waitForInitialNavigationCompleted has resolved"
+  );
+
+  ok(!webProgress.isLoadingDocument, "Document is not loading");
+  ok(
+    webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+    "Document is still on the initial document"
+  );
+});
+
+add_task(async function test_waitForInitialNavigation_unloadTimeout_longer() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  // Stop the navigation on an initial page which is not loading anymore.
+  // This situation happens with new tabs on Android, even though they are on
+  // the initial document, they will not start another navigation on their own.
+  await webProgress.sendStartState({ isInitial: true });
+  await webProgress.sendStopState();
+
+  ok(!webProgress.isLoadingDocument, "Document is not loading");
+
+  const navigated = waitForInitialNavigationCompleted(webProgress, {
+    unloadTimeout: DEFAULT_UNLOAD_TIMEOUT * 3,
+  });
+
+  // Start a timer longer than the default timeout of the Navigate module.
+  // However here we used a custom timeout, so we expect that the navigation
+  // will not be done yet by the time this timer is done.
+  const waitForMoreThanDefaultTimeout = wait(
+    DEFAULT_UNLOAD_TIMEOUT * 1.5 * getUnloadTimeoutMultiplier()
+  );
+  await Promise.race([navigated, waitForMoreThanDefaultTimeout]);
+
+  // The promise should not have resolved because we didn't reached the custom
+  // timeout which is 3 times the default one.
+  ok(
+    !(await hasPromiseResolved(navigated)),
+    "waitForInitialNavigationCompleted has not resolved yet"
+  );
+
+  // The navigation should eventually resolve once we reach the custom timeout.
+  await navigated;
+
+  ok(!webProgress.isLoadingDocument, "Document is not loading");
+  ok(
+    webProgress.browsingContext.currentWindowGlobal.isInitialDocument,
+    "Document is still on the initial document"
+  );
+});
+
+add_task(async function test_ProgressListener_expectNavigation() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  const progressListener = new ProgressListener(webProgress, {
+    expectNavigation: true,
+    unloadTimeout: 10,
+  });
+  const navigated = progressListener.start();
+
+  // Wait for unloadTimeout to finish in case it started
+  await wait(30);
+
+  ok(!(await hasPromiseResolved(navigated)), "Listener has not resolved yet");
+
+  await webProgress.sendStartState();
+  await webProgress.sendStopState();
+
+  ok(await hasPromiseResolved(navigated), "Listener has resolved");
+});
+
+add_task(
+  async function test_ProgressListener_expectNavigation_initialDocumentFinishedLoading() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    const progressListener = new ProgressListener(webProgress, {
+      expectNavigation: true,
+      unloadTimeout: 10,
+    });
+    const navigated = progressListener.start();
+
+    ok(!(await hasPromiseResolved(navigated)), "Listener has not resolved yet");
+
+    await webProgress.sendStartState({ isInitial: true });
+    await webProgress.sendStopState();
+
+    // Wait for unloadTimeout to finish in case it started
+    await wait(30);
+
+    ok(!(await hasPromiseResolved(navigated)), "Listener has not resolved yet");
+
+    await webProgress.sendStartState();
+    await webProgress.sendStopState();
+
+    ok(await hasPromiseResolved(navigated), "Listener has resolved");
+  }
+);
+
+add_task(async function test_ProgressListener_isStarted() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  const progressListener = new ProgressListener(webProgress);
+  ok(!progressListener.isStarted);
+
+  progressListener.start();
+  ok(progressListener.isStarted);
+
+  progressListener.stop();
+  ok(!progressListener.isStarted);
+});
+
+add_task(async function test_ProgressListener_notWaitForExplicitStart() {
+  // Create a webprogress and start it before creating the progress listener.
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+  await webProgress.sendStartState();
+
+  // Create the progress listener for a webprogress already in a navigation.
+  const progressListener = new ProgressListener(webProgress, {
+    waitForExplicitStart: false,
+  });
+  const navigated = progressListener.start();
+
+  // Send stop state to complete the initial navigation
+  await webProgress.sendStopState();
+  ok(
+    await hasPromiseResolved(navigated),
+    "Listener has resolved after initial navigation"
+  );
+});
+
+add_task(async function test_ProgressListener_waitForExplicitStart() {
+  // Create a webprogress and start it before creating the progress listener.
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+  await webProgress.sendStartState();
+
+  // Create the progress listener for a webprogress already in a navigation.
+  const progressListener = new ProgressListener(webProgress, {
+    waitForExplicitStart: true,
+  });
+  const navigated = progressListener.start();
+
+  // Send stop state to complete the initial navigation
+  await webProgress.sendStopState();
+  ok(
+    !(await hasPromiseResolved(navigated)),
+    "Listener has not resolved after initial navigation"
+  );
+
+  // Start a new navigation
+  await webProgress.sendStartState();
+  ok(
+    !(await hasPromiseResolved(navigated)),
+    "Listener has not resolved after starting new navigation"
+  );
+
+  // Finish the new navigation
+  await webProgress.sendStopState();
+  ok(
+    await hasPromiseResolved(navigated),
+    "Listener resolved after finishing the new navigation"
+  );
+});
+
+add_task(
+  async function test_ProgressListener_waitForExplicitStartAndResolveWhenStarted() {
+    // Create a webprogress and start it before creating the progress listener.
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+    await webProgress.sendStartState();
+
+    // Create the progress listener for a webprogress already in a navigation.
+    const progressListener = new ProgressListener(webProgress, {
+      resolveWhenStarted: true,
+      waitForExplicitStart: true,
+    });
+    const navigated = progressListener.start();
+
+    // Send stop state to complete the initial navigation
+    await webProgress.sendStopState();
+    ok(
+      !(await hasPromiseResolved(navigated)),
+      "Listener has not resolved after initial navigation"
+    );
+
+    // Start a new navigation
+    await webProgress.sendStartState();
+    ok(
+      await hasPromiseResolved(navigated),
+      "Listener resolved after starting the new navigation"
+    );
+  }
+);
+
+add_task(
+  async function test_ProgressListener_resolveWhenNavigatingInsideDocument() {
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+
+    const progressListener = new ProgressListener(webProgress);
+    const navigated = progressListener.start();
+
+    ok(!(await hasPromiseResolved(navigated)), "Listener has not resolved");
+
+    // Send hash change location change notification to complete the navigation
+    await webProgress.sendLocationChange({
+      flag: Ci.nsIWebProgressListener.LOCATION_CHANGE_SAME_DOCUMENT,
+    });
+
+    ok(await hasPromiseResolved(navigated), "Listener has resolved");
+
+    const { currentURI, targetURI } = progressListener;
+    equal(
+      currentURI.spec,
+      TARGET_URI_WITH_HASH.spec,
+      "Expected current URI has been set"
+    );
+    equal(
+      targetURI.spec,
+      TARGET_URI_WITH_HASH.spec,
+      "Expected target URI has been set"
+    );
+  }
+);
+
+add_task(async function test_ProgressListener_ignoreCacheError() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  const progressListener = new ProgressListener(webProgress);
+  const navigated = progressListener.start();
+
+  ok(!(await hasPromiseResolved(navigated)), "Listener has not resolved");
+
+  await webProgress.sendStartState();
+  await webProgress.sendStopState({
+    errorFlag: Cr.NS_ERROR_PARSED_DATA_CACHED,
+  });
+
+  ok(await hasPromiseResolved(navigated), "Listener has resolved");
+});
+
+add_task(async function test_ProgressListener_navigationRejectedOnErrorPage() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  const progressListener = new ProgressListener(webProgress, {
+    waitForExplicitStart: false,
+  });
+  const navigated = progressListener.start();
+
+  await webProgress.sendStartState();
+  await webProgress.sendLocationChange({
+    flag:
+      Ci.nsIWebProgressListener.LOCATION_CHANGE_SAME_DOCUMENT |
+      Ci.nsIWebProgressListener.LOCATION_CHANGE_ERROR_PAGE,
+  });
+
+  ok(
+    await hasPromiseRejected(navigated),
+    "Listener has rejected in location change for error page"
+  );
+});
+
+add_task(async function test_ProgressListener_navigationRejectedOnStopState() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  const progressListener = new ProgressListener(webProgress, {
+    waitForExplicitStart: false,
+  });
+  const navigated = progressListener.start();
+
+  await webProgress.sendStartState();
+  await webProgress.sendStopState({ errorFlag: Cr.NS_BINDING_ABORTED });
+
+  ok(
+    await hasPromiseRejected(navigated),
+    "Listener has rejected in stop state for erroneous navigation"
+  );
+});
+
+add_task(async function test_ProgressListener_stopIfStarted() {
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+
+  const progressListener = new ProgressListener(webProgress);
+  const navigated = progressListener.start();
+
+  progressListener.stopIfStarted();
+  ok(!(await hasPromiseResolved(navigated)), "Listener has not resolved");
+
+  await webProgress.sendStartState();
+  progressListener.stopIfStarted();
+  ok(await hasPromiseResolved(navigated), "Listener has resolved");
+});
+
+add_task(async function test_ProgressListener_stopIfStarted_alreadyStarted() {
+  // Create an already navigating browsing context.
+  const browsingContext = new MockTopContext();
+  const webProgress = browsingContext.webProgress;
+  await webProgress.sendStartState();
+
+  // Create a progress listener which accepts already ongoing navigations.
+  const progressListener = new ProgressListener(webProgress, {
+    waitForExplicitStart: false,
+  });
+  const navigated = progressListener.start();
+
+  // stopIfStarted should stop the listener because of the ongoing navigation.
+  progressListener.stopIfStarted();
+  ok(await hasPromiseResolved(navigated), "Listener has resolved");
+});
+
+add_task(
+  async function test_ProgressListener_stopIfStarted_alreadyStarted_waitForExplicitStart() {
+    // Create an already navigating browsing context.
+    const browsingContext = new MockTopContext();
+    const webProgress = browsingContext.webProgress;
+    await webProgress.sendStartState();
+
+    // Create a progress listener which rejects already ongoing navigations.
+    const progressListener = new ProgressListener(webProgress, {
+      waitForExplicitStart: true,
+    });
+    const navigated = progressListener.start();
+
+    // stopIfStarted will not stop the listener for the existing navigation.
+    progressListener.stopIfStarted();
+    ok(!(await hasPromiseResolved(navigated)), "Listener has not resolved");
+
+    // stopIfStarted will stop the listener when called after starting a new
+    // navigation.
+    await webProgress.sendStartState();
+    progressListener.stopIfStarted();
+    ok(await hasPromiseResolved(navigated), "Listener has resolved");
+  }
+);
diff --git a/remote/shared/test/xpcshell/test_Realm.js b/remote/shared/test/xpcshell/test_Realm.js
new file mode 100644
index 0000000000..3990cce482
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_Realm.js
@@ -0,0 +1,116 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { Realm, WindowRealm } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/Realm.sys.mjs"
+);
+
+add_task(function test_id() {
+  const realm1 = new Realm();
+  const id1 = realm1.id;
+  Assert.equal(typeof id1, "string");
+
+  const realm2 = new Realm();
+  const id2 = realm2.id;
+  Assert.equal(typeof id2, "string");
+
+  Assert.notEqual(id1, id2, "Ids for different realms are different");
+});
+
+add_task(function test_handleObjectMap() {
+  const realm = new Realm();
+
+  // Test an unknown handle.
+  Assert.equal(
+    realm.getObjectForHandle("unknown"),
+    undefined,
+    "Unknown handles return undefined"
+  );
+
+  // Test creating a simple handle.
+  const object = {};
+  const handle = realm.getHandleForObject(object);
+  Assert.equal(typeof handle, "string", "Created a valid handle");
+  Assert.equal(
+    realm.getObjectForHandle(handle),
+    object,
+    "Using the handle returned the original object"
+  );
+
+  // Test another handle for the same object.
+  const secondHandle = realm.getHandleForObject(object);
+  Assert.equal(typeof secondHandle, "string", "Created a valid handle");
+  Assert.notEqual(secondHandle, handle, "A different handle was generated");
+  Assert.equal(
+    realm.getObjectForHandle(secondHandle),
+    object,
+    "Using the second handle also returned the original object"
+  );
+
+  // Test using the handles in another realm.
+  const otherRealm = new Realm();
+  Assert.equal(
+    otherRealm.getObjectForHandle(handle),
+    undefined,
+    "A realm returns undefined for handles from another realm"
+  );
+
+  // Removing an unknown handle should not throw or have any side effect on
+  // existing handles.
+  realm.removeObjectHandle("unknown");
+  Assert.equal(realm.getObjectForHandle(handle), object);
+  Assert.equal(realm.getObjectForHandle(secondHandle), object);
+
+  // Remove the second handle
+  realm.removeObjectHandle(secondHandle);
+  Assert.equal(
+    realm.getObjectForHandle(handle),
+    object,
+    "The first handle is still resolving the object"
+  );
+  Assert.equal(
+    realm.getObjectForHandle(secondHandle),
+    undefined,
+    "The second handle returns undefined after calling removeObjectHandle"
+  );
+
+  // Remove the original handle
+  realm.removeObjectHandle(handle);
+  Assert.equal(
+    realm.getObjectForHandle(handle),
+    undefined,
+    "The first handle returns undefined as well"
+  );
+});
+
+add_task(async function test_windowRealm_isSandbox() {
+  const windowlessBrowser = Services.appShell.createWindowlessBrowser(false);
+  const contentWindow = windowlessBrowser.docShell.domWindow;
+
+  const realm1 = new WindowRealm(contentWindow);
+  Assert.equal(realm1.isSandbox, false);
+
+  const realm2 = new WindowRealm(contentWindow, { sandboxName: "test" });
+  Assert.equal(realm2.isSandbox, true);
+});
+
+add_task(async function test_windowRealm_userActivationEnabled() {
+  const windowlessBrowser = Services.appShell.createWindowlessBrowser(false);
+  const contentWindow = windowlessBrowser.docShell.domWindow;
+  const userActivation = contentWindow.navigator.userActivation;
+
+  const realm = new WindowRealm(contentWindow);
+
+  Assert.equal(realm.userActivationEnabled, false);
+  Assert.equal(userActivation.isActive && userActivation.hasBeenActive, false);
+
+  realm.userActivationEnabled = true;
+  Assert.equal(realm.userActivationEnabled, true);
+  Assert.equal(userActivation.isActive && userActivation.hasBeenActive, true);
+
+  realm.userActivationEnabled = false;
+  Assert.equal(realm.userActivationEnabled, false);
+  Assert.equal(userActivation.isActive && userActivation.hasBeenActive, false);
+});
diff --git a/remote/shared/test/xpcshell/test_RecommendedPreferences.js b/remote/shared/test/xpcshell/test_RecommendedPreferences.js
new file mode 100644
index 0000000000..20de07a528
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_RecommendedPreferences.js
@@ -0,0 +1,118 @@
+/* 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/. */
+
+const { RecommendedPreferences } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/RecommendedPreferences.sys.mjs"
+);
+
+const COMMON_PREF = "toolkit.startup.max_resumed_crashes";
+
+const PROTOCOL_1_PREF = "dom.disable_beforeunload";
+const PROTOCOL_1_RECOMMENDED_PREFS = new Map([[PROTOCOL_1_PREF, true]]);
+
+const PROTOCOL_2_PREF = "browser.contentblocking.features.standard";
+const PROTOCOL_2_RECOMMENDED_PREFS = new Map([
+  [PROTOCOL_2_PREF, "-tp,tpPrivate,cookieBehavior0,-cm,-fp"],
+]);
+
+function cleanup() {
+  info("Restore recommended preferences and test preferences");
+  Services.prefs.clearUserPref("remote.prefs.recommended");
+  RecommendedPreferences.restoreAllPreferences();
+}
+
+// cleanup() should be called:
+// - explicitly after each test to avoid side effects
+// - via registerCleanupFunction in case a test crashes/times out
+registerCleanupFunction(cleanup);
+
+add_task(async function test_multipleClients() {
+  info("Check initial values for the test preferences");
+  checkPreferences({ common: false, protocol_1: false, protocol_2: false });
+
+  checkPreferences({ common: false, protocol_1: false, protocol_2: false });
+
+  info("Apply recommended preferences for a protocol_1 client");
+  RecommendedPreferences.applyPreferences(PROTOCOL_1_RECOMMENDED_PREFS);
+  checkPreferences({ common: true, protocol_1: true, protocol_2: false });
+
+  info("Apply recommended preferences for a protocol_2 client");
+  RecommendedPreferences.applyPreferences(PROTOCOL_2_RECOMMENDED_PREFS);
+  checkPreferences({ common: true, protocol_1: true, protocol_2: true });
+
+  info("Restore protocol_1 preferences");
+  RecommendedPreferences.restorePreferences(PROTOCOL_1_RECOMMENDED_PREFS);
+  checkPreferences({ common: true, protocol_1: false, protocol_2: true });
+
+  info("Restore protocol_2 preferences");
+  RecommendedPreferences.restorePreferences(PROTOCOL_2_RECOMMENDED_PREFS);
+  checkPreferences({ common: true, protocol_1: false, protocol_2: false });
+
+  info("Restore all the altered preferences");
+  RecommendedPreferences.restoreAllPreferences();
+  checkPreferences({ common: false, protocol_1: false, protocol_2: false });
+
+  info("Attemps to restore again");
+  RecommendedPreferences.restoreAllPreferences();
+  checkPreferences({ common: false, protocol_1: false, protocol_2: false });
+
+  cleanup();
+});
+
+add_task(async function test_disabled() {
+  info("Disable RecommendedPreferences");
+  Services.prefs.setBoolPref("remote.prefs.recommended", false);
+
+  info("Check initial values for the test preferences");
+  checkPreferences({ common: false, protocol_1: false, protocol_2: false });
+
+  info("Recommended preferences are not applied, applyPreferences is a no-op");
+  RecommendedPreferences.applyPreferences(PROTOCOL_1_RECOMMENDED_PREFS);
+  checkPreferences({ common: false, protocol_1: false, protocol_2: false });
+
+  cleanup();
+});
+
+add_task(async function test_noCustomPreferences() {
+  info("Applying preferences without any custom preference should not throw");
+  RecommendedPreferences.applyPreferences();
+
+  cleanup();
+});
+
+// Check that protocols can override common preferences.
+add_task(async function test_override() {
+  info("Make sure the common preference has no user value");
+  Services.prefs.clearUserPref(COMMON_PREF);
+
+  const OVERRIDE_VALUE = 42;
+  const OVERRIDE_COMMON_PREF = new Map([[COMMON_PREF, OVERRIDE_VALUE]]);
+
+  info("Apply a map of preferences overriding a common preference");
+  RecommendedPreferences.applyPreferences(OVERRIDE_COMMON_PREF);
+
+  equal(
+    Services.prefs.getIntPref(COMMON_PREF),
+    OVERRIDE_VALUE,
+    "The common preference was set to the expected value"
+  );
+
+  cleanup();
+});
+
+function checkPreferences({ common, protocol_1, protocol_2 }) {
+  checkPreference(COMMON_PREF, { hasValue: common });
+  checkPreference(PROTOCOL_1_PREF, { hasValue: protocol_1 });
+  checkPreference(PROTOCOL_2_PREF, { hasValue: protocol_2 });
+}
+
+function checkPreference(pref, { hasValue }) {
+  equal(
+    Services.prefs.prefHasUserValue(pref),
+    hasValue,
+    hasValue
+      ? `The preference ${pref} has a user value`
+      : `The preference ${pref} has no user value`
+  );
+}
diff --git a/remote/shared/test/xpcshell/test_Stack.js b/remote/shared/test/xpcshell/test_Stack.js
new file mode 100644
index 0000000000..c41c5f0240
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_Stack.js
@@ -0,0 +1,120 @@
+/* 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/. */
+
+const { getFramesFromStack, isChromeFrame } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/Stack.sys.mjs"
+);
+
+const sourceFrames = [
+  {
+    column: 1,
+    functionDisplayName: "foo",
+    line: 2,
+    source: "cheese",
+    sourceId: 1,
+  },
+  {
+    column: 3,
+    functionDisplayName: null,
+    line: 4,
+    source: "cake",
+    sourceId: 2,
+  },
+  {
+    column: 5,
+    functionDisplayName: "chrome",
+    line: 6,
+    source: "chrome://foo",
+    sourceId: 3,
+  },
+];
+
+const targetFrames = [
+  {
+    columnNumber: 1,
+    functionName: "foo",
+    lineNumber: 2,
+    filename: "cheese",
+    sourceId: 1,
+  },
+  {
+    columnNumber: 3,
+    functionName: "",
+    lineNumber: 4,
+    filename: "cake",
+    sourceId: 2,
+  },
+  {
+    columnNumber: 5,
+    functionName: "chrome",
+    lineNumber: 6,
+    filename: "chrome://foo",
+    sourceId: 3,
+  },
+];
+
+add_task(async function test_getFramesFromStack() {
+  const stack = buildStack(sourceFrames);
+  const frames = getFramesFromStack(stack, { includeChrome: false });
+
+  ok(Array.isArray(frames), "frames is of expected type Array");
+  equal(frames.length, 3, "Got expected amount of frames");
+  checkFrame(frames.at(0), targetFrames.at(0));
+  checkFrame(frames.at(1), targetFrames.at(1));
+  checkFrame(frames.at(2), targetFrames.at(2));
+});
+
+add_task(async function test_getFramesFromStack_asyncStack() {
+  const stack = buildStack(sourceFrames, true);
+  const frames = getFramesFromStack(stack);
+
+  ok(Array.isArray(frames), "frames is of expected type Array");
+  equal(frames.length, 3, "Got expected amount of frames");
+  checkFrame(frames.at(0), targetFrames.at(0));
+  checkFrame(frames.at(1), targetFrames.at(1));
+  checkFrame(frames.at(2), targetFrames.at(2));
+});
+
+add_task(async function test_isChromeFrame() {
+  for (const filename of ["chrome://foo/bar", "resource://foo/bar"]) {
+    ok(isChromeFrame({ filename }), "Frame is of expected chrome scope");
+  }
+
+  for (const filename of ["http://foo.bar", "about:blank"]) {
+    ok(!isChromeFrame({ filename }), "Frame is of expected content scope");
+  }
+});
+
+function buildStack(frames, async = false) {
+  const parent = async ? "asyncParent" : "parent";
+
+  let currentFrame, stack;
+  for (const frame of frames) {
+    if (currentFrame) {
+      currentFrame[parent] = Object.assign({}, frame);
+      currentFrame = currentFrame[parent];
+    } else {
+      stack = Object.assign({}, frame);
+      currentFrame = stack;
+    }
+  }
+
+  return stack;
+}
+
+function checkFrame(frame, expectedFrame) {
+  equal(
+    frame.columnNumber,
+    expectedFrame.columnNumber,
+    "Got expected column number"
+  );
+  equal(
+    frame.functionName,
+    expectedFrame.functionName,
+    "Got expected function name"
+  );
+  equal(frame.lineNumber, expectedFrame.lineNumber, "Got expected line number");
+  equal(frame.filename, expectedFrame.filename, "Got expected filename");
+  equal(frame.sourceId, expectedFrame.sourceId, "Got expected source id");
+}
diff --git a/remote/shared/test/xpcshell/test_Sync.js b/remote/shared/test/xpcshell/test_Sync.js
new file mode 100644
index 0000000000..de4a4d30fe
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_Sync.js
@@ -0,0 +1,436 @@
+/* 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/. */
+
+const { setTimeout } = ChromeUtils.importESModule(
+  "resource://gre/modules/Timer.sys.mjs"
+);
+
+const { AnimationFramePromise, Deferred, EventPromise, PollPromise } =
+  ChromeUtils.importESModule("chrome://remote/content/shared/Sync.sys.mjs");
+
+const { Log } = ChromeUtils.importESModule(
+  "resource://gre/modules/Log.sys.mjs"
+);
+
+/**
+ * Mimic a DOM node for listening for events.
+ */
+class MockElement {
+  constructor() {
+    this.capture = false;
+    this.eventName = null;
+    this.func = null;
+    this.mozSystemGroup = false;
+    this.wantUntrusted = false;
+    this.untrusted = false;
+  }
+
+  addEventListener(name, func, options = {}) {
+    const { capture, mozSystemGroup, wantUntrusted } = options;
+
+    this.eventName = name;
+    this.func = func;
+    this.capture = capture ?? false;
+    this.mozSystemGroup = mozSystemGroup ?? false;
+    this.wantUntrusted = wantUntrusted ?? false;
+  }
+
+  click() {
+    if (this.func) {
+      const event = {
+        capture: this.capture,
+        mozSystemGroup: this.mozSystemGroup,
+        target: this,
+        type: this.eventName,
+        untrusted: this.untrusted,
+        wantUntrusted: this.wantUntrusted,
+      };
+      this.func(event);
+    }
+  }
+
+  dispatchEvent(event) {
+    if (this.wantUntrusted) {
+      this.untrusted = true;
+    }
+    this.click();
+  }
+
+  removeEventListener(name, func) {
+    this.capture = false;
+    this.eventName = null;
+    this.func = null;
+    this.mozSystemGroup = false;
+    this.untrusted = false;
+    this.wantUntrusted = false;
+  }
+}
+
+class MockAppender extends Log.Appender {
+  constructor(formatter) {
+    super(formatter);
+    this.messages = [];
+  }
+
+  append(message) {
+    this.doAppend(message);
+  }
+
+  doAppend(message) {
+    this.messages.push(message);
+  }
+}
+
+add_task(async function test_AnimationFramePromise() {
+  let called = false;
+  let win = {
+    requestAnimationFrame(callback) {
+      called = true;
+      callback();
+    },
+  };
+  await AnimationFramePromise(win);
+  ok(called);
+});
+
+add_task(async function test_AnimationFramePromiseAbortWhenWindowClosed() {
+  let win = {
+    closed: true,
+    requestAnimationFrame() {},
+  };
+  await AnimationFramePromise(win);
+});
+
+add_task(async function test_DeferredPending() {
+  const deferred = Deferred();
+  ok(deferred.pending);
+
+  deferred.resolve();
+  await deferred.promise;
+  ok(!deferred.pending);
+});
+
+add_task(async function test_DeferredRejected() {
+  const deferred = Deferred();
+
+  // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+  setTimeout(() => deferred.reject(new Error("foo")), 100);
+
+  try {
+    await deferred.promise;
+    ok(false);
+  } catch (e) {
+    ok(!deferred.pending);
+
+    ok(!deferred.fulfilled);
+    ok(deferred.rejected);
+    equal(e.message, "foo");
+  }
+});
+
+add_task(async function test_DeferredResolved() {
+  const deferred = Deferred();
+  ok(deferred.pending);
+
+  // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+  setTimeout(() => deferred.resolve("foo"), 100);
+
+  const result = await deferred.promise;
+  ok(!deferred.pending);
+
+  ok(deferred.fulfilled);
+  ok(!deferred.rejected);
+  equal(result, "foo");
+});
+
+add_task(async function test_EventPromise_subjectTypes() {
+  for (const subject of ["foo", 42, null, undefined, true, [], {}]) {
+    Assert.throws(() => new EventPromise(subject, "click"), /TypeError/);
+  }
+});
+
+add_task(async function test_EventPromise_eventNameTypes() {
+  const element = new MockElement();
+
+  for (const eventName of [42, null, undefined, true, [], {}]) {
+    Assert.throws(() => new EventPromise(element, eventName), /TypeError/);
+  }
+});
+
+add_task(async function test_EventPromise_subjectAndEventNameEvent() {
+  const element = new MockElement();
+
+  const clicked = new EventPromise(element, "click");
+  element.click();
+  const event = await clicked;
+
+  equal(element, event.target);
+});
+
+add_task(async function test_EventPromise_captureTypes() {
+  const element = new MockElement();
+
+  for (const capture of [null, "foo", 42, [], {}]) {
+    Assert.throws(
+      () => new EventPromise(element, "click", { capture }),
+      /TypeError/
+    );
+  }
+});
+
+add_task(async function test_EventPromise_captureEvent() {
+  const element = new MockElement();
+
+  for (const capture of [undefined, false, true]) {
+    const expectedCapture = capture ?? false;
+
+    const clicked = new EventPromise(element, "click", { capture });
+    element.click();
+    const event = await clicked;
+
+    equal(element, event.target);
+    equal(expectedCapture, event.capture);
+  }
+});
+
+add_task(async function test_EventPromise_checkFnTypes() {
+  const element = new MockElement();
+
+  for (const checkFn of ["foo", 42, true, [], {}]) {
+    Assert.throws(
+      () => new EventPromise(element, "click", { checkFn }),
+      /TypeError/
+    );
+  }
+});
+
+add_task(async function test_EventPromise_checkFnCallback() {
+  const element = new MockElement();
+
+  let count;
+  const data = [
+    { checkFn: null, expected_count: 0 },
+    { checkFn: undefined, expected_count: 0 },
+    {
+      checkFn: event => {
+        throw new Error("foo");
+      },
+      expected_count: 0,
+    },
+    { checkFn: event => count++ > 0, expected_count: 2 },
+  ];
+
+  for (const { checkFn, expected_count } of data) {
+    count = 0;
+
+    const clicked = new EventPromise(element, "click", { checkFn });
+    element.click();
+    element.click();
+    const event = await clicked;
+
+    equal(element, event.target);
+    equal(expected_count, count);
+  }
+});
+
+add_task(async function test_EventPromise_mozSystemGroupTypes() {
+  const element = new MockElement();
+
+  for (const mozSystemGroup of [null, "foo", 42, [], {}]) {
+    Assert.throws(
+      () => new EventPromise(element, "click", { mozSystemGroup }),
+      /TypeError/
+    );
+  }
+});
+
+add_task(async function test_EventPromise_mozSystemGroupEvent() {
+  const element = new MockElement();
+
+  for (const mozSystemGroup of [undefined, false, true]) {
+    const expectedMozSystemGroup = mozSystemGroup ?? false;
+
+    const clicked = new EventPromise(element, "click", { mozSystemGroup });
+    element.click();
+    const event = await clicked;
+
+    equal(element, event.target);
+    equal(expectedMozSystemGroup, event.mozSystemGroup);
+  }
+});
+
+add_task(async function test_EventPromise_wantUntrustedTypes() {
+  const element = new MockElement();
+
+  for (let wantUntrusted of [null, "foo", 42, [], {}]) {
+    Assert.throws(
+      () => new EventPromise(element, "click", { wantUntrusted }),
+      /TypeError/
+    );
+  }
+});
+
+add_task(async function test_EventPromise_wantUntrustedEvent() {
+  for (const wantUntrusted of [undefined, false, true]) {
+    let expected_untrusted = wantUntrusted ?? false;
+
+    const element = new MockElement();
+
+    const clicked = new EventPromise(element, "click", { wantUntrusted });
+    element.dispatchEvent(new CustomEvent("click", {}));
+    const event = await clicked;
+
+    equal(element, event.target);
+    equal(expected_untrusted, event.untrusted);
+  }
+});
+
+add_task(function test_executeSoon_callback() {
+  // executeSoon() is already defined for xpcshell in head.js. As such import
+  // our implementation into a custom namespace.
+  let sync = ChromeUtils.importESModule(
+    "chrome://remote/content/shared/Sync.sys.mjs"
+  );
+
+  for (let func of ["foo", null, true, [], {}]) {
+    Assert.throws(() => sync.executeSoon(func), /TypeError/);
+  }
+
+  let a;
+  sync.executeSoon(() => {
+    a = 1;
+  });
+  executeSoon(() => equal(1, a));
+});
+
+add_task(function test_PollPromise_funcTypes() {
+  for (let type of ["foo", 42, null, undefined, true, [], {}]) {
+    Assert.throws(() => new PollPromise(type), /TypeError/);
+  }
+  new PollPromise(() => {});
+  new PollPromise(function () {});
+});
+
+add_task(function test_PollPromise_timeoutTypes() {
+  for (let timeout of ["foo", true, [], {}]) {
+    Assert.throws(() => new PollPromise(() => {}, { timeout }), /TypeError/);
+  }
+  for (let timeout of [1.2, -1]) {
+    Assert.throws(() => new PollPromise(() => {}, { timeout }), /RangeError/);
+  }
+  for (let timeout of [null, undefined, 42]) {
+    new PollPromise(resolve => resolve(1), { timeout });
+  }
+});
+
+add_task(function test_PollPromise_intervalTypes() {
+  for (let interval of ["foo", null, true, [], {}]) {
+    Assert.throws(() => new PollPromise(() => {}, { interval }), /TypeError/);
+  }
+  for (let interval of [1.2, -1]) {
+    Assert.throws(() => new PollPromise(() => {}, { interval }), /RangeError/);
+  }
+  new PollPromise(() => {}, { interval: 42 });
+});
+
+add_task(async function test_PollPromise_retvalTypes() {
+  for (let typ of [true, false, "foo", 42, [], {}]) {
+    strictEqual(typ, await new PollPromise(resolve => resolve(typ)));
+  }
+});
+
+add_task(async function test_PollPromise_rethrowError() {
+  let nevals = 0;
+  let err;
+  try {
+    await PollPromise(() => {
+      ++nevals;
+      throw new Error();
+    });
+  } catch (e) {
+    err = e;
+  }
+  equal(1, nevals);
+  ok(err instanceof Error);
+});
+
+add_task(async function test_PollPromise_noTimeout() {
+  let nevals = 0;
+  await new PollPromise((resolve, reject) => {
+    ++nevals;
+    nevals < 100 ? reject() : resolve();
+  });
+  equal(100, nevals);
+});
+
+add_task(async function test_PollPromise_zeroTimeout() {
+  // run at least once when timeout is 0
+  let nevals = 0;
+  let start = new Date().getTime();
+  await new PollPromise(
+    (resolve, reject) => {
+      ++nevals;
+      reject();
+    },
+    { timeout: 0 }
+  );
+  let end = new Date().getTime();
+  equal(1, nevals);
+  less(end - start, 500);
+});
+
+add_task(async function test_PollPromise_timeoutElapse() {
+  let nevals = 0;
+  let start = new Date().getTime();
+  await new PollPromise(
+    (resolve, reject) => {
+      ++nevals;
+      reject();
+    },
+    { timeout: 100 }
+  );
+  let end = new Date().getTime();
+  lessOrEqual(nevals, 11);
+  greaterOrEqual(end - start, 100);
+});
+
+add_task(async function test_PollPromise_interval() {
+  let nevals = 0;
+  await new PollPromise(
+    (resolve, reject) => {
+      ++nevals;
+      reject();
+    },
+    { timeout: 100, interval: 100 }
+  );
+  equal(2, nevals);
+});
+
+add_task(async function test_PollPromise_resolve() {
+  const log = Log.repository.getLogger("RemoteAgent");
+  const appender = new MockAppender(new Log.BasicFormatter());
+  appender.level = Log.Level.Info;
+  log.addAppender(appender);
+
+  const errorMessage = "PollingFailed";
+  const timeout = 100;
+
+  await new PollPromise(
+    (resolve, reject) => {
+      resolve();
+    },
+    { timeout, errorMessage }
+  );
+  Assert.equal(appender.messages.length, 0);
+
+  await new PollPromise(
+    (resolve, reject) => {
+      reject();
+    },
+    { timeout, errorMessage: "PollingFailed" }
+  );
+  Assert.equal(appender.messages.length, 1);
+  Assert.equal(appender.messages[0].level, Log.Level.Warn);
+  Assert.equal(appender.messages[0].message, "PollingFailed after 100 ms");
+});
diff --git a/remote/shared/test/xpcshell/test_TabManager.js b/remote/shared/test/xpcshell/test_TabManager.js
new file mode 100644
index 0000000000..e9da02c861
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_TabManager.js
@@ -0,0 +1,56 @@
+/* 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/. */
+
+const { TabManager } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/TabManager.sys.mjs"
+);
+
+class MockTopBrowsingContext {
+  constructor() {
+    this.embedderElement = { permanentKey: {} };
+    this.id = 1;
+    this.top = this;
+  }
+}
+
+class MockBrowsingContext {
+  constructor() {
+    this.id = 2;
+
+    const topContext = new MockTopBrowsingContext();
+    this.parent = topContext;
+    this.top = topContext;
+  }
+}
+
+const mockTopBrowsingContext = new MockTopBrowsingContext();
+const mockBrowsingContext = new MockBrowsingContext();
+
+add_task(async function test_getIdForBrowsingContext() {
+  // Browsing context not set.
+  equal(TabManager.getIdForBrowsingContext(null), null);
+  equal(TabManager.getIdForBrowsingContext(undefined), null);
+
+  // Child browsing context.
+  equal(
+    TabManager.getIdForBrowsingContext(mockBrowsingContext),
+    mockBrowsingContext.id
+  );
+
+  const browser = mockTopBrowsingContext.embedderElement;
+  equal(
+    TabManager.getIdForBrowsingContext(mockTopBrowsingContext),
+    TabManager.getIdForBrowser(browser)
+  );
+});
+
+add_task(async function test_removeTab() {
+  // Tab not defined.
+  await TabManager.removeTab(null);
+});
+
+add_task(async function test_selectTab() {
+  // Tab not defined.
+  await TabManager.selectTab(null);
+});
diff --git a/remote/shared/test/xpcshell/test_UUID.js b/remote/shared/test/xpcshell/test_UUID.js
new file mode 100644
index 0000000000..e929a9e0a8
--- /dev/null
+++ b/remote/shared/test/xpcshell/test_UUID.js
@@ -0,0 +1,21 @@
+/* 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/. */
+
+const { generateUUID } = ChromeUtils.importESModule(
+  "chrome://remote/content/shared/UUID.sys.mjs"
+);
+
+add_task(function test_UUID_valid() {
+  const uuid = generateUUID();
+  const regExp = new RegExp(
+    /^[a-f|0-9]{8}-[a-f|0-9]{4}-[a-f|0-9]{4}-[a-f|0-9]{4}-[a-f|0-9]{12}$/g
+  );
+  ok(regExp.test(uuid));
+});
+
+add_task(function test_UUID_unique() {
+  const uuid1 = generateUUID();
+  const uuid2 = generateUUID();
+  notEqual(uuid1, uuid2);
+});
diff --git a/remote/shared/test/xpcshell/xpcshell.toml b/remote/shared/test/xpcshell/xpcshell.toml
new file mode 100644
index 0000000000..ebb6c77950
--- /dev/null
+++ b/remote/shared/test/xpcshell/xpcshell.toml
@@ -0,0 +1,24 @@
+[DEFAULT]
+head = "head.js"
+
+["test_AppInfo.js"]
+
+["test_ChallengeHeaderParser.js"]
+
+["test_DOM.js"]
+
+["test_Format.js"]
+
+["test_Navigate.js"]
+
+["test_Realm.js"]
+
+["test_RecommendedPreferences.js"]
+
+["test_Stack.js"]
+
+["test_Sync.js"]
+
+["test_TabManager.js"]
+
+["test_UUID.js"]