From 26a029d407be480d791972afb5975cf62c9360a6 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Fri, 19 Apr 2024 02:47:55 +0200
Subject: Adding upstream version 124.0.1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 toolkit/components/windowwatcher/test/browser.toml |  35 +++
 .../test/browser_new_content_window_chromeflags.js | 278 +++++++++++++++++++++
 ...ser_new_content_window_from_chrome_principal.js |  44 ++++
 .../test/browser_new_remote_window_flags.js        |  85 +++++++
 .../windowwatcher/test/browser_new_sized_window.js |  67 +++++
 .../test/browser_non_popup_from_popup.js           |  53 ++++
 .../test/browser_popup_condition_current.js        |  13 +
 .../test/browser_popup_condition_tab.js            |  13 +
 .../test/browser_popup_condition_window.js         |  13 +
 toolkit/components/windowwatcher/test/chrome.toml  |  10 +
 .../windowwatcher/test/file_named_window.html      |   5 +
 .../windowwatcher/test/file_storage_copied.html    |  13 +
 .../windowwatcher/test/file_test_dialog.html       |  14 ++
 toolkit/components/windowwatcher/test/head.js      | 207 +++++++++++++++
 .../components/windowwatcher/test/mochitest.toml   |  11 +
 toolkit/components/windowwatcher/test/moz.build    |  17 ++
 .../test/test_alwaysOnTop_windows.html             |  86 +++++++
 .../test/test_blank_named_window.html              |  40 +++
 .../windowwatcher/test/test_dialog_arguments.html  |  35 +++
 .../windowwatcher/test/test_modal_windows.html     |  52 ++++
 .../windowwatcher/test/test_named_window.html      |  87 +++++++
 .../windowwatcher/test/test_storage_copied.html    |  43 ++++
 22 files changed, 1221 insertions(+)
 create mode 100644 toolkit/components/windowwatcher/test/browser.toml
 create mode 100644 toolkit/components/windowwatcher/test/browser_new_content_window_chromeflags.js
 create mode 100644 toolkit/components/windowwatcher/test/browser_new_content_window_from_chrome_principal.js
 create mode 100644 toolkit/components/windowwatcher/test/browser_new_remote_window_flags.js
 create mode 100644 toolkit/components/windowwatcher/test/browser_new_sized_window.js
 create mode 100644 toolkit/components/windowwatcher/test/browser_non_popup_from_popup.js
 create mode 100644 toolkit/components/windowwatcher/test/browser_popup_condition_current.js
 create mode 100644 toolkit/components/windowwatcher/test/browser_popup_condition_tab.js
 create mode 100644 toolkit/components/windowwatcher/test/browser_popup_condition_window.js
 create mode 100644 toolkit/components/windowwatcher/test/chrome.toml
 create mode 100644 toolkit/components/windowwatcher/test/file_named_window.html
 create mode 100644 toolkit/components/windowwatcher/test/file_storage_copied.html
 create mode 100644 toolkit/components/windowwatcher/test/file_test_dialog.html
 create mode 100644 toolkit/components/windowwatcher/test/head.js
 create mode 100644 toolkit/components/windowwatcher/test/mochitest.toml
 create mode 100644 toolkit/components/windowwatcher/test/moz.build
 create mode 100644 toolkit/components/windowwatcher/test/test_alwaysOnTop_windows.html
 create mode 100644 toolkit/components/windowwatcher/test/test_blank_named_window.html
 create mode 100644 toolkit/components/windowwatcher/test/test_dialog_arguments.html
 create mode 100644 toolkit/components/windowwatcher/test/test_modal_windows.html
 create mode 100644 toolkit/components/windowwatcher/test/test_named_window.html
 create mode 100644 toolkit/components/windowwatcher/test/test_storage_copied.html

(limited to 'toolkit/components/windowwatcher/test')

diff --git a/toolkit/components/windowwatcher/test/browser.toml b/toolkit/components/windowwatcher/test/browser.toml
new file mode 100644
index 0000000000..90882dc378
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/browser.toml
@@ -0,0 +1,35 @@
+[DEFAULT]
+tags = "openwindow"
+support-files = ["head.js"]
+
+["browser_new_content_window_chromeflags.js"]
+
+["browser_new_content_window_from_chrome_principal.js"]
+
+["browser_new_remote_window_flags.js"]
+
+["browser_new_sized_window.js"]
+skip-if = ["os == 'win'"] # Bug 1276802 - Opening windows from content on Windows might not get the size right
+
+["browser_non_popup_from_popup.js"]
+
+["browser_popup_condition_current.js"]
+skip-if = [
+  "debug", # Opening many windows takes a long time on slow builds
+  "tsan", # Opening many windows takes a long time on slow builds
+  "socketprocess_networking",
+]
+
+["browser_popup_condition_tab.js"]
+skip-if = [
+  "debug", # Opening many windows takes a long time on slow builds
+  "tsan", # Opening many windows takes a long time on slow builds
+  "socketprocess_networking",
+]
+
+["browser_popup_condition_window.js"]
+skip-if = [
+  "debug", # Opening many windows takes a long time on slow builds
+  "tsan", # Opening many windows takes a long time on slow builds
+  "socketprocess_networking",
+]
diff --git a/toolkit/components/windowwatcher/test/browser_new_content_window_chromeflags.js b/toolkit/components/windowwatcher/test/browser_new_content_window_chromeflags.js
new file mode 100644
index 0000000000..4eff3b46f0
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/browser_new_content_window_chromeflags.js
@@ -0,0 +1,278 @@
+/**
+ * Tests that chromeFlags are set properly on windows that are
+ * being opened from content.
+ */
+
+// The following are not allowed from web content.
+//
+// <feature string>: {
+//   flag: <associated nsIWebBrowserChrome flag>,
+//   defaults_to: <what this feature defaults to normally>
+// }
+const DISALLOWED = {
+  location: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_LOCATIONBAR,
+    defaults_to: true,
+  },
+  chrome: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_OPENAS_CHROME,
+    defaults_to: false,
+  },
+  dialog: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_OPENAS_DIALOG,
+    defaults_to: false,
+  },
+  private: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_PRIVATE_WINDOW,
+    defaults_to: false,
+  },
+  "non-private": {
+    flag: Ci.nsIWebBrowserChrome.CHROME_NON_PRIVATE_WINDOW,
+    defaults_to: false,
+  },
+  // "all":
+  //   checked manually, since this is an aggregate
+  //   flag.
+  //
+  // "remote":
+  //   checked manually, since its default value will
+  //   depend on whether or not e10s is enabled by default.
+  alwaysLowered: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_WINDOW_LOWERED,
+    defaults_to: false,
+  },
+  "z-lock": {
+    flag: Ci.nsIWebBrowserChrome.CHROME_WINDOW_LOWERED, // Renamed to alwaysLowered
+    defaults_to: false,
+  },
+  alwaysRaised: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_WINDOW_RAISED,
+    defaults_to: false,
+  },
+  alwaysOnTop: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_ALWAYS_ON_TOP,
+    defaults_to: false,
+  },
+  suppressanimation: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_SUPPRESS_ANIMATION,
+    defaults_to: false,
+  },
+  extrachrome: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_EXTRA,
+    defaults_to: false,
+  },
+  centerscreen: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_CENTER_SCREEN,
+    defaults_to: false,
+  },
+  dependent: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_DEPENDENT,
+    defaults_to: false,
+  },
+  modal: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_MODAL,
+    defaults_to: false,
+  },
+  titlebar: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_TITLEBAR,
+    defaults_to: true,
+  },
+  close: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_WINDOW_CLOSE,
+    defaults_to: true,
+  },
+  resizable: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_WINDOW_RESIZE,
+    defaults_to: true,
+  },
+  status: {
+    flag: Ci.nsIWebBrowserChrome.CHROME_STATUSBAR,
+    defaults_to: true,
+  },
+};
+
+// This magic value of 2 means that by default, when content tries
+// to open a new window, it'll actually open in a new window instead
+// of a new tab.
+Services.prefs.setIntPref("browser.link.open_newwindow", 2);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("browser.link.open_newwindow");
+});
+
+/**
+ * Given some nsIDOMWindow for a window running in the parent process,
+ * asynchronously return the nsIWebBrowserChrome chrome flags for the
+ * associated content window.
+ *
+ * @param win (nsIDOMWindow)
+ * @returns int
+ */
+function getContentChromeFlags(win) {
+  let b = win.gBrowser.selectedBrowser;
+  return SpecialPowers.spawn(b, [], async function () {
+    // Content scripts provide docShell as a global.
+    /* global docShell */
+    docShell.QueryInterface(Ci.nsIInterfaceRequestor);
+    try {
+      // This will throw if we're not a remote browser.
+      return docShell
+        .getInterface(Ci.nsIBrowserChild)
+        .QueryInterface(Ci.nsIWebBrowserChrome).chromeFlags;
+    } catch (e) {
+      // This must be a non-remote browser...
+      return docShell.treeOwner.QueryInterface(
+        Ci.nsIWebBrowserChrome
+      ).chromeFlags;
+    }
+  });
+}
+
+/**
+ * For some chromeFlags, ensures that flags in the DISALLOWED
+ * group were not modified.
+ *
+ * @param chromeFlags (int)
+ *        Some chromeFlags to check.
+ */
+function assertContentFlags(chromeFlags, isPopup) {
+  for (let feature in DISALLOWED) {
+    let flag = DISALLOWED[feature].flag;
+    Assert.ok(flag, "Expected flag to be a non-zeroish value");
+    if (DISALLOWED[feature].defaults_to) {
+      // The feature is supposed to default to true, so it should
+      // stay true.
+      Assert.ok(
+        chromeFlags & flag,
+        `Expected feature ${feature} to be unchanged`
+      );
+    } else {
+      // The feature is supposed to default to false, so it should
+      // stay false.
+      Assert.ok(
+        !(chromeFlags & flag),
+        `Expected feature ${feature} to be unchanged`
+      );
+    }
+  }
+}
+
+/**
+ * Opens a window from content using window.open with the
+ * features computed from DISALLOWED. The computed feature string attempts to
+ * flip every feature away from their default.
+ */
+add_task(async function test_disallowed_flags() {
+  // Construct a features string that flips all DISALLOWED features
+  // to not be their defaults.
+  const DISALLOWED_STRING = Object.keys(DISALLOWED)
+    .map(feature => {
+      let toValue = DISALLOWED[feature].defaults_to ? "no" : "yes";
+      return `${feature}=${toValue}`;
+    })
+    .join(",");
+
+  const FEATURES = [DISALLOWED_STRING].join(",");
+
+  const SCRIPT_PAGE = `data:text/html,<script>window.open("about:blank", "_blank", "${FEATURES}");</script>`;
+  const SCRIPT_PAGE_FOR_CHROME_ALL = `data:text/html,<script>window.open("about:blank", "_blank", "all");</script>`;
+
+  let newWinPromise = BrowserTestUtils.waitForNewWindow();
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: SCRIPT_PAGE,
+    },
+    async function (browser) {
+      let win = await newWinPromise;
+      let parentChromeFlags = getParentChromeFlags(win);
+      assertContentFlags(parentChromeFlags);
+
+      if (win.gMultiProcessBrowser) {
+        Assert.ok(
+          parentChromeFlags & Ci.nsIWebBrowserChrome.CHROME_REMOTE_WINDOW,
+          "Should be remote by default"
+        );
+      } else {
+        Assert.ok(
+          !(parentChromeFlags & Ci.nsIWebBrowserChrome.CHROME_REMOTE_WINDOW),
+          "Should not be remote by default"
+        );
+      }
+
+      // Confusingly, chromeFlags also exist in the content process
+      // as part of the BrowserChild, so we have to check those too.
+      let contentChromeFlags = await getContentChromeFlags(win);
+      assertContentFlags(contentChromeFlags);
+
+      Assert.equal(
+        parentChromeFlags & Ci.nsIWebBrowserChrome.CHROME_REMOTE_WINDOW,
+        contentChromeFlags & Ci.nsIWebBrowserChrome.CHROME_REMOTE_WINDOW,
+        "Should have matching remote value in parent and content"
+      );
+
+      Assert.equal(
+        parentChromeFlags & Ci.nsIWebBrowserChrome.CHROME_FISSION_WINDOW,
+        contentChromeFlags & Ci.nsIWebBrowserChrome.CHROME_FISSION_WINDOW,
+        "Should have matching fission value in parent and content"
+      );
+
+      await BrowserTestUtils.closeWindow(win);
+    }
+  );
+
+  // We check "all" manually, since that's an aggregate flag
+  // and doesn't fit nicely into the ALLOWED / DISALLOWED scheme
+  newWinPromise = BrowserTestUtils.waitForNewWindow();
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: SCRIPT_PAGE_FOR_CHROME_ALL,
+    },
+    async function (browser) {
+      let win = await newWinPromise;
+      let parentChromeFlags = getParentChromeFlags(win);
+      Assert.notEqual(
+        parentChromeFlags & Ci.nsIWebBrowserChrome.CHROME_ALL,
+        Ci.nsIWebBrowserChrome.CHROME_ALL,
+        "Should not have been able to set CHROME_ALL"
+      );
+      await BrowserTestUtils.closeWindow(win);
+    }
+  );
+});
+
+/**
+ * Opens a window with some chrome flags specified, which should not affect
+ * scrollbars flag which defaults to true when not disabled explicitly.
+ */
+add_task(async function test_scrollbars_flag() {
+  const SCRIPT = 'window.open("about:blank", "_blank", "toolbar=0");';
+  const SCRIPT_PAGE = `data:text/html,<script>${SCRIPT}</script>`;
+
+  let newWinPromise = BrowserTestUtils.waitForNewWindow();
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: SCRIPT_PAGE,
+    },
+    async function (browser) {
+      let win = await newWinPromise;
+
+      let parentChromeFlags = getParentChromeFlags(win);
+      Assert.ok(
+        parentChromeFlags & Ci.nsIWebBrowserChrome.CHROME_SCROLLBARS,
+        "Should have scrollbars when not disabled explicitly"
+      );
+
+      let contentChromeFlags = await getContentChromeFlags(win);
+      Assert.ok(
+        contentChromeFlags & Ci.nsIWebBrowserChrome.CHROME_SCROLLBARS,
+        "Should have scrollbars when not disabled explicitly"
+      );
+
+      await BrowserTestUtils.closeWindow(win);
+    }
+  );
+});
diff --git a/toolkit/components/windowwatcher/test/browser_new_content_window_from_chrome_principal.js b/toolkit/components/windowwatcher/test/browser_new_content_window_from_chrome_principal.js
new file mode 100644
index 0000000000..28c1c23e60
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/browser_new_content_window_from_chrome_principal.js
@@ -0,0 +1,44 @@
+"use strict";
+
+/**
+ * Tests that if chrome-privileged code calls .open() on an
+ * unprivileged window, that the principal in the newly
+ * opened window is appropriately set.
+ */
+add_task(async function test_chrome_opens_window() {
+  // This magic value of 2 means that by default, when content tries
+  // to open a new window, it'll actually open in a new window instead
+  // of a new tab.
+  await SpecialPowers.pushPrefEnv({
+    set: [["browser.link.open_newwindow", 2]],
+  });
+
+  let newWinPromise = BrowserTestUtils.waitForNewWindow({
+    url: "https://example.com/",
+  });
+
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], async function () {
+    content.open("https://example.com/", "_blank");
+  });
+
+  let win = await newWinPromise;
+  let browser = win.gBrowser.selectedBrowser;
+  Assert.ok(
+    E10SUtils.isWebRemoteType(browser.remoteType),
+    "Should have the default content remote type."
+  );
+
+  await SpecialPowers.spawn(browser, [], async function () {
+    Assert.ok(
+      !content.document.nodePrincipal.isSystemPrincipal,
+      "We should not have a system principal."
+    );
+    Assert.equal(
+      content.document.nodePrincipal.origin,
+      "https://example.com",
+      "Should have the example.com principal"
+    );
+  });
+
+  await BrowserTestUtils.closeWindow(win);
+});
diff --git a/toolkit/components/windowwatcher/test/browser_new_remote_window_flags.js b/toolkit/components/windowwatcher/test/browser_new_remote_window_flags.js
new file mode 100644
index 0000000000..06a15d123c
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/browser_new_remote_window_flags.js
@@ -0,0 +1,85 @@
+/**
+ * Tests that when a remote browser opens a new window that the
+ * newly opened window is also remote.
+ */
+
+const ANCHOR_PAGE = `data:text/html,<a href="about:blank" target="_blank">Click me!</a>`;
+const SCRIPT_PAGE = `data:text/html,<script>window.open("about:blank", "_blank");</script>`;
+
+// This magic value of 2 means that by default, when content tries
+// to open a new window, it'll actually open in a new window instead
+// of a new tab.
+add_setup(async function () {
+  await SpecialPowers.pushPrefEnv({
+    set: [["browser.link.open_newwindow", 2]],
+  });
+});
+
+function assertFlags(win) {
+  let docShell = win.docShell;
+  let loadContext = docShell.QueryInterface(Ci.nsILoadContext);
+  let chromeFlags = docShell.treeOwner
+    .QueryInterface(Ci.nsIInterfaceRequestor)
+    .getInterface(Ci.nsIAppWindow).chromeFlags;
+  Assert.ok(
+    loadContext.useRemoteTabs,
+    "Should be using remote tabs on the load context"
+  );
+  Assert.ok(
+    chromeFlags & Ci.nsIWebBrowserChrome.CHROME_REMOTE_WINDOW,
+    "Should have the remoteness chrome flag on the window"
+  );
+}
+
+/**
+ * Content can open a window using a target="_blank" link
+ */
+add_task(async function test_new_remote_window_flags_target_blank() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: ANCHOR_PAGE,
+    },
+    async function (browser) {
+      let newWinPromise = BrowserTestUtils.waitForNewWindow();
+      await BrowserTestUtils.synthesizeMouseAtCenter("a", {}, browser);
+      let win = await newWinPromise;
+      assertFlags(win);
+      await BrowserTestUtils.closeWindow(win);
+    }
+  );
+});
+
+/**
+ * Content can open a window using window.open
+ */
+add_task(async function test_new_remote_window_flags_window_open() {
+  let newWinPromise = BrowserTestUtils.waitForNewWindow();
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: SCRIPT_PAGE,
+    },
+    async function (browser) {
+      let win = await newWinPromise;
+      assertFlags(win);
+      await BrowserTestUtils.closeWindow(win);
+    }
+  );
+});
+
+/**
+ * Privileged content scripts can also open new windows
+ * using content.open.
+ */
+add_task(async function test_new_remote_window_flags_content_open() {
+  let newWinPromise = BrowserTestUtils.waitForNewWindow();
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], async function () {
+    content.open("about:blank", "_blank");
+  });
+
+  let win = await newWinPromise;
+  assertFlags(win);
+  await BrowserTestUtils.closeWindow(win);
+});
diff --git a/toolkit/components/windowwatcher/test/browser_new_sized_window.js b/toolkit/components/windowwatcher/test/browser_new_sized_window.js
new file mode 100644
index 0000000000..0a1e63a8c8
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/browser_new_sized_window.js
@@ -0,0 +1,67 @@
+"use strict";
+
+/**
+ * Tests that content can open windows at requested dimensions
+ * of height and width.
+ */
+
+/**
+ * This utility function does most of the actual testing. We
+ * construct a feature string suitable for the passed in width
+ * and height, and then run that script in content to open the
+ * new window. When the new window comes up, this function tests
+ * to ensure that the content area of the initial browser is the
+ * requested dimensions. Finally, we also ensure that we're not
+ * persisting the position, size or sizemode of the new browser
+ * window.
+ */
+function test_dimensions({ width, height }) {
+  let features = [];
+  if (width) {
+    features.push(`width=${width}`);
+  }
+  if (height) {
+    features.push(`height=${height}`);
+  }
+  const FEATURE_STR = features.join(",");
+  const SCRIPT_PAGE = `data:text/html,<script>window.open("about:blank", "_blank", "${FEATURE_STR}");</script>`;
+
+  let newWinPromise = BrowserTestUtils.waitForNewWindow();
+
+  return BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: SCRIPT_PAGE,
+    },
+    async function (browser) {
+      let win = await newWinPromise;
+      let rect = win.gBrowser.selectedBrowser.getBoundingClientRect();
+
+      if (width) {
+        Assert.equal(rect.width, width, "Should have the requested width");
+      }
+
+      if (height) {
+        Assert.equal(rect.height, height, "Should have the requested height");
+      }
+
+      let treeOwner = win.docShell.treeOwner;
+      let persistPosition = {};
+      let persistSize = {};
+      let persistSizeMode = {};
+      treeOwner.getPersistence(persistPosition, persistSize, persistSizeMode);
+
+      Assert.ok(!persistPosition.value, "Should not persist position");
+      Assert.ok(!persistSize.value, "Should not persist size");
+      Assert.ok(!persistSizeMode.value, "Should not persist size mode");
+
+      await BrowserTestUtils.closeWindow(win);
+    }
+  );
+}
+
+add_task(async function test_new_sized_window() {
+  await test_dimensions({ width: 100 });
+  await test_dimensions({ height: 150 });
+  await test_dimensions({ width: 300, height: 200 });
+});
diff --git a/toolkit/components/windowwatcher/test/browser_non_popup_from_popup.js b/toolkit/components/windowwatcher/test/browser_non_popup_from_popup.js
new file mode 100644
index 0000000000..9c905bacc1
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/browser_non_popup_from_popup.js
@@ -0,0 +1,53 @@
+"use strict";
+
+// Opening non-popup from a popup should open a new tab in the most recent
+// non-popup window.
+add_task(async function test_non_popup_from_popup() {
+  const BLANK_PAGE = "data:text/html,";
+
+  // A page opened in a new tab.
+  const OPEN_PAGE = "data:text/plain,hello";
+
+  // A page opened in a new popup.
+  // This opens a new non-popup page with OPEN_PAGE,
+  // tha should be opened in a new tab in most recent window.
+  const NON_POPUP_OPENER = btoa(
+    `data:text/html,<script>window.open('${OPEN_PAGE}', '', '')</script>`
+  );
+
+  // A page opened in a new tab.
+  // This opens a popup with NON_POPUP_OPENER.
+  const POPUP_OPENER = `data:text/html,<script>window.open(atob("${NON_POPUP_OPENER}"), "", "width=500");</script>`;
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["browser.link.open_newwindow", 3]],
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: BLANK_PAGE,
+    },
+    async function (browser) {
+      // Wait for a popup opened by POPUP_OPENER.
+      const newPopupPromise = BrowserTestUtils.waitForNewWindow();
+
+      // Wait for a new tab opened by NON_POPUP_OPENER.
+      const newTabPromise = BrowserTestUtils.waitForNewTab(gBrowser, OPEN_PAGE);
+
+      // Open a new tab that opens a popup with NON_POPUP_OPENER.
+      BrowserTestUtils.startLoadingURIString(gBrowser, POPUP_OPENER);
+
+      let win = await newPopupPromise;
+      Assert.ok(true, "popup is opened");
+
+      let tab = await newTabPromise;
+      Assert.ok(true, "new tab is opened in the recent window");
+
+      BrowserTestUtils.removeTab(tab);
+      await BrowserTestUtils.closeWindow(win);
+    }
+  );
+
+  await SpecialPowers.popPrefEnv();
+});
diff --git a/toolkit/components/windowwatcher/test/browser_popup_condition_current.js b/toolkit/components/windowwatcher/test/browser_popup_condition_current.js
new file mode 100644
index 0000000000..a033c6738a
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/browser_popup_condition_current.js
@@ -0,0 +1,13 @@
+"use strict";
+
+/**
+ * Opens windows from content using window.open with several features patterns.
+ */
+add_task(async function test_popup_conditions_current() {
+  // Non-popup is opened in a current tab.
+  await SpecialPowers.pushPrefEnv({
+    set: [["browser.link.open_newwindow", 1]],
+  });
+  await testPopupPatterns("current");
+  await SpecialPowers.popPrefEnv();
+});
diff --git a/toolkit/components/windowwatcher/test/browser_popup_condition_tab.js b/toolkit/components/windowwatcher/test/browser_popup_condition_tab.js
new file mode 100644
index 0000000000..36a98fd511
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/browser_popup_condition_tab.js
@@ -0,0 +1,13 @@
+"use strict";
+
+/**
+ * Opens windows from content using window.open with several features patterns.
+ */
+add_task(async function test_popup_conditions_tab() {
+  // Non-popup is opened in a new tab (default behavior).
+  await SpecialPowers.pushPrefEnv({
+    set: [["browser.link.open_newwindow", 3]],
+  });
+  await testPopupPatterns("tab");
+  await SpecialPowers.popPrefEnv();
+});
diff --git a/toolkit/components/windowwatcher/test/browser_popup_condition_window.js b/toolkit/components/windowwatcher/test/browser_popup_condition_window.js
new file mode 100644
index 0000000000..6f66124a1a
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/browser_popup_condition_window.js
@@ -0,0 +1,13 @@
+"use strict";
+
+/**
+ * Opens windows from content using window.open with several features patterns.
+ */
+add_task(async function test_popup_conditions_window() {
+  // Non-popup is opened in a new window.
+  await SpecialPowers.pushPrefEnv({
+    set: [["browser.link.open_newwindow", 2]],
+  });
+  await testPopupPatterns("window");
+  await SpecialPowers.popPrefEnv();
+});
diff --git a/toolkit/components/windowwatcher/test/chrome.toml b/toolkit/components/windowwatcher/test/chrome.toml
new file mode 100644
index 0000000000..24dd1019d7
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/chrome.toml
@@ -0,0 +1,10 @@
+[DEFAULT]
+tags = "openwindow"
+
+["test_alwaysOnTop_windows.html"]
+skip-if = ["os != 'win'"]
+
+["test_dialog_arguments.html"]
+support-files = ["file_test_dialog.html"]
+
+["test_modal_windows.html"]
diff --git a/toolkit/components/windowwatcher/test/file_named_window.html b/toolkit/components/windowwatcher/test/file_named_window.html
new file mode 100644
index 0000000000..c66d89cd34
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/file_named_window.html
@@ -0,0 +1,5 @@
+<html>
+<body>
+test_named_window.html new window
+</body>
+</html>
diff --git a/toolkit/components/windowwatcher/test/file_storage_copied.html b/toolkit/components/windowwatcher/test/file_storage_copied.html
new file mode 100644
index 0000000000..e32709315a
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/file_storage_copied.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+This page is opened in a new window by test_storage_copied.html.
+We need to return the sessionStorage value for the item "test-item",
+by way of postMessage.
+-->
+<head>
+<body>Opened!</body>
+<script>
+  window.postMessage(window.sessionStorage.getItem("test-item"), "*");
+</script>
+</html>
diff --git a/toolkit/components/windowwatcher/test/file_test_dialog.html b/toolkit/components/windowwatcher/test/file_test_dialog.html
new file mode 100644
index 0000000000..efb11d0077
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/file_test_dialog.html
@@ -0,0 +1,14 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+This page is opened in a new window by test_dialog_arguments. It is
+a dialog which expects a Symbol to be passed in the dialog arguments.
+Once we load, we call back into the opener with the argument we were
+passed.
+-->
+<head>
+<body>Opened!</body>
+<script>
+  window.arguments[1].done(window.arguments[0]);
+</script>
+</html>
diff --git a/toolkit/components/windowwatcher/test/head.js b/toolkit/components/windowwatcher/test/head.js
new file mode 100644
index 0000000000..f72344bcd0
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/head.js
@@ -0,0 +1,207 @@
+/**
+ * Given some nsIDOMWindow for a window running in the parent
+ * process, return the nsIWebBrowserChrome chrome flags for
+ * the associated XUL window.
+ *
+ * @param win (nsIDOMWindow)
+ *        Some window in the parent process.
+ * @returns int
+ */
+function getParentChromeFlags(win) {
+  return win.docShell.treeOwner
+    .QueryInterface(Ci.nsIInterfaceRequestor)
+    .getInterface(Ci.nsIAppWindow).chromeFlags;
+}
+
+const WINDOW_OPEN_FEATURES_PATTERNS = [
+  { features: "", popup: false },
+
+  // If features isn't empty, the following should be true to open tab/window:
+  //   * location or toolbar (defaults to false)
+  //   * menubar (defaults to false)
+  //   * resizable (defaults to true)
+  //   * scrollbars (defaults to false)
+  //   * status (defaults to false)
+  { features: "location,menubar,resizable,scrollbars,status", popup: false },
+  { features: "toolbar,menubar,resizable,scrollbars,status", popup: false },
+
+  // resizable defaults to true.
+  { features: "location,menubar,scrollbars,status", popup: false },
+
+  // The following testcases use "location,menubar,scrollbars,status"
+  // as the base non-popup case, and test the boundary between popup
+  // vs non-popup.
+
+  // If either location or toolbar is true, not popup.
+  {
+    features: "toolbar,menubar,resizable,scrollbars,status",
+    popup: false,
+  },
+  {
+    features: "location,menubar,resizable,scrollbars,status",
+    popup: false,
+  },
+
+  // If both location and toolbar are false, popup.
+  { features: "menubar,scrollbars,status", popup: true },
+
+  // If menubar is false, popup.
+  { features: "location,resizable,scrollbars,status", popup: true },
+
+  // If resizable is true, not popup.
+  {
+    features: "location,menubar,resizable=yes,scrollbars,status",
+    popup: false,
+  },
+
+  // If resizable is false, popup.
+  { features: "location,menubar,resizable=0,scrollbars,status", popup: true },
+
+  // If scrollbars is false, popup.
+  { features: "location,menubar,resizable,status", popup: true },
+
+  // If status is false, popup.
+  { features: "location,menubar,resizable,scrollbars", popup: true },
+
+  // position and size have no effect.
+  {
+    features:
+      "location,menubar,scrollbars,status," +
+      "left=100,screenX=100,top=100,screenY=100," +
+      "width=100,innerWidth=100,outerWidth=100," +
+      "height=100,innerHeight=100,outerHeight=100",
+    popup: false,
+  },
+
+  // Most feature defaults to false if the feature is not empty.
+  // Specifying only some of them opens a popup.
+  { features: "location,toolbar,menubar", popup: true },
+  { features: "resizable,scrollbars,status", popup: true },
+
+  // Specifying unknown feature makes the feature not empty.
+  { features: "someunknownfeature", popup: true },
+
+  // noopener and noreferrer are removed before testing if feature is empty.
+  { features: "noopener,noreferrer", popup: false },
+];
+
+const WINDOW_CHROME_FLAGS = {
+  CHROME_WINDOW_BORDERS: true,
+  CHROME_WINDOW_CLOSE: true,
+  CHROME_WINDOW_RESIZE: true,
+  CHROME_LOCATIONBAR: true,
+  CHROME_STATUSBAR: true,
+  CHROME_SCROLLBARS: true,
+  CHROME_TITLEBAR: true,
+
+  CHROME_MENUBAR: true,
+  CHROME_TOOLBAR: true,
+  CHROME_PERSONAL_TOOLBAR: true,
+};
+
+const POPUP_CHROME_FLAGS = {
+  CHROME_WINDOW_BORDERS: true,
+  CHROME_WINDOW_CLOSE: true,
+  CHROME_WINDOW_RESIZE: true,
+  CHROME_LOCATIONBAR: true,
+  CHROME_STATUSBAR: true,
+  CHROME_SCROLLBARS: true,
+  CHROME_TITLEBAR: true,
+
+  CHROME_MENUBAR: false,
+  CHROME_TOOLBAR: false,
+  CHROME_PERSONAL_TOOLBAR: false,
+};
+
+async function testPopupPatterns(nonPopup) {
+  for (const { features, popup } of WINDOW_OPEN_FEATURES_PATTERNS) {
+    const BLANK_PAGE = "data:text/html,";
+    const OPEN_PAGE = "data:text/plain,hello";
+    const SCRIPT_PAGE = `data:text/html,<script>window.open("${OPEN_PAGE}", "", "${features}");</script>`;
+
+    async function testNewWindow(flags) {
+      await BrowserTestUtils.withNewTab(
+        {
+          gBrowser,
+          url: BLANK_PAGE,
+        },
+        async function (browser) {
+          const newWinPromise = BrowserTestUtils.waitForNewWindow();
+          BrowserTestUtils.startLoadingURIString(gBrowser, SCRIPT_PAGE);
+
+          const win = await newWinPromise;
+          const parentChromeFlags = getParentChromeFlags(win);
+
+          for (const [name, visible] of Object.entries(flags)) {
+            if (visible) {
+              Assert.equal(
+                !!(parentChromeFlags & Ci.nsIWebBrowserChrome[name]),
+                true,
+                `${name} should be present for features "${features}"`
+              );
+            } else {
+              Assert.equal(
+                !!(parentChromeFlags & Ci.nsIWebBrowserChrome[name]),
+                false,
+                `${name} should not be present for features "${features}"`
+              );
+            }
+          }
+
+          await BrowserTestUtils.closeWindow(win);
+        }
+      );
+    }
+
+    async function testNewTab() {
+      await BrowserTestUtils.withNewTab(
+        {
+          gBrowser,
+          url: BLANK_PAGE,
+        },
+        async function (browser) {
+          const newTabPromise = BrowserTestUtils.waitForNewTab(
+            gBrowser,
+            OPEN_PAGE
+          );
+          BrowserTestUtils.startLoadingURIString(gBrowser, SCRIPT_PAGE);
+
+          let tab = await newTabPromise;
+          BrowserTestUtils.removeTab(tab);
+        }
+      );
+    }
+
+    async function testCurrentTab() {
+      await BrowserTestUtils.withNewTab(
+        {
+          gBrowser,
+          url: BLANK_PAGE,
+        },
+        async function (browser) {
+          const pagePromise = BrowserTestUtils.browserLoaded(
+            browser,
+            false,
+            OPEN_PAGE
+          );
+          BrowserTestUtils.startLoadingURIString(gBrowser, SCRIPT_PAGE);
+
+          await pagePromise;
+        }
+      );
+    }
+
+    if (!popup) {
+      if (nonPopup == "window") {
+        await testNewWindow(WINDOW_CHROME_FLAGS);
+      } else if (nonPopup == "tab") {
+        await testNewTab();
+      } else {
+        // current tab
+        await testCurrentTab();
+      }
+    } else {
+      await testNewWindow(POPUP_CHROME_FLAGS);
+    }
+  }
+}
diff --git a/toolkit/components/windowwatcher/test/mochitest.toml b/toolkit/components/windowwatcher/test/mochitest.toml
new file mode 100644
index 0000000000..67b0f80eb8
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/mochitest.toml
@@ -0,0 +1,11 @@
+[DEFAULT]
+tags = "openwindow"
+skip-if = ["os == 'android'"] # Fennec doesn't support web content opening new windows (See bug 1277544 for details)
+
+["test_blank_named_window.html"]
+
+["test_named_window.html"]
+support-files = ["file_named_window.html"]
+
+["test_storage_copied.html"]
+support-files = ["file_storage_copied.html"]
diff --git a/toolkit/components/windowwatcher/test/moz.build b/toolkit/components/windowwatcher/test/moz.build
new file mode 100644
index 0000000000..0333f1deda
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/moz.build
@@ -0,0 +1,17 @@
+# -*- 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/.
+
+BROWSER_CHROME_MANIFESTS += [
+    "browser.toml",
+]
+
+MOCHITEST_MANIFESTS += [
+    "mochitest.toml",
+]
+
+MOCHITEST_CHROME_MANIFESTS += [
+    "chrome.toml",
+]
diff --git a/toolkit/components/windowwatcher/test/test_alwaysOnTop_windows.html b/toolkit/components/windowwatcher/test/test_alwaysOnTop_windows.html
new file mode 100644
index 0000000000..05c768c93f
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/test_alwaysOnTop_windows.html
@@ -0,0 +1,86 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+Tests the alwaysOnTop window feature for the Windows OS.
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test an alwaysOnTop window on Windows</title>
+
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css">
+
+  <script type="application/javascript">
+
+  const {BrowserTestUtils} = ChromeUtils.importESModule(
+    "resource://testing-common/BrowserTestUtils.sys.mjs"
+  );
+  const {ctypes} = ChromeUtils.importESModule(
+    "resource://gre/modules/ctypes.sys.mjs"
+  );
+
+  function assertAlwaysOnTop(win, expected) {
+    let docShell = win.docShell;
+    let chromeFlags = docShell.treeOwner
+                              .QueryInterface(Ci.nsIInterfaceRequestor)
+                              .getInterface(Ci.nsIAppWindow)
+                              .chromeFlags;
+    let hasFlag = !!(chromeFlags & Ci.nsIWebBrowserChrome.CHROME_ALWAYS_ON_TOP);
+    is(hasFlag, expected, "Window should have CHROME_ALWAYS_ON_TOP flag.");
+
+    const hWND = Number(win.docShell.treeOwner.nsIBaseWindow.nativeHandle);
+    const WS_EX_TOPMOST = 0x00000008;
+    const GWL_EXSTYLE = -20;
+
+    let lib = ctypes.open("user32.dll");
+    // On 32-bit systems, the function we need to call is GetWindowLongW. On
+    // 64-bit systems, the function is GetWindowLongPtrW. Interestingly,
+    // the MSDN page[1] for GetWindowLongPtrW claims that calling it should work
+    // on both 32-bit and 64-bit, but that didn't appear to be the case here
+    // with local testing, hence the conditional.
+    //
+    // [1]: https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-getwindowlongptrw
+    let GetWindowFuncSymbol = Services.appinfo.is64Bit ? "GetWindowLongPtrW"
+                                                       : "GetWindowLongW";
+    let GetWindowFunc = lib.declare(GetWindowFuncSymbol, ctypes.winapi_abi,
+                                    ctypes.intptr_t, ctypes.uintptr_t,
+                                    ctypes.int);
+
+    let styles = GetWindowFunc(hWND, GWL_EXSTYLE);
+    let isAlwaysOnTop = !!(styles & WS_EX_TOPMOST);
+    is(isAlwaysOnTop, expected, "Window should be always on top.");
+    lib.close();
+  }
+
+  if (Services.appinfo.OS != "WINNT") {
+    ok(false, "This test is only designed to run on Windows.");
+  } else {
+    add_task(async function() {
+      let normalWinOpened = BrowserTestUtils.domWindowOpenedAndLoaded();
+      window.openDialog("about:blank",
+                        "_blank", "chrome,width=100,height=100,noopener", null);
+      let normalWin = await normalWinOpened;
+      ok(normalWin, "Normal window opened");
+      assertAlwaysOnTop(normalWin, false);
+      await BrowserTestUtils.closeWindow(normalWin);
+
+      let alwaysOnTopWinOpened = BrowserTestUtils.domWindowOpenedAndLoaded();
+      window.openDialog("about:blank",
+                        "_blank", "chrome,width=100,height=100,alwaysOnTop,noopener", null);
+      let alwaysOnTopWin = await alwaysOnTopWinOpened;
+      ok(alwaysOnTopWin, "AlwaysOnTop window opened");
+      assertAlwaysOnTop(alwaysOnTopWin, true);
+      await BrowserTestUtils.closeWindow(alwaysOnTopWin);
+    });
+  }
+
+  </script>
+</head>
+<body>
+<p id="display"></p>
+<div id="content" style="display: none">
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/toolkit/components/windowwatcher/test/test_blank_named_window.html b/toolkit/components/windowwatcher/test/test_blank_named_window.html
new file mode 100644
index 0000000000..f8472d216a
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/test_blank_named_window.html
@@ -0,0 +1,40 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+Test that when opening a window with the reserved name _blank that the new
+window does not get that name, and that subsequent window openings with that
+name result in new windows being opened.
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test named windows</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="head.js" type="application/javascript"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+  <script type="application/javascript">
+    "use strict";
+    add_task(async function() {
+      // This magic value of 2 means that by default, when content tries
+      // to open a new window, it'll actually open in a new window instead
+      // of a new tab.
+      await SpecialPowers.pushPrefEnv({"set": [
+        ["browser.link.open_newwindow", 2],
+      ]});
+
+      let win1 = window.open("data:text/html,<p>This is window 1 for test_blank_named_window.html</p>", "_blank");
+
+      let name = SpecialPowers.wrap(win1).docShell.name;
+
+      is(name, "", "Should have no name");
+
+      let win2 = window.open("data:text/html,<p>This is window 2 for test_blank_named_window.html</p>", "_blank");
+      isnot(win1, win2, "Should not have gotten back the same window");
+
+      win1.close();
+      win2.close();
+    });
+  </script>
+</body>
+</html>
diff --git a/toolkit/components/windowwatcher/test/test_dialog_arguments.html b/toolkit/components/windowwatcher/test/test_dialog_arguments.html
new file mode 100644
index 0000000000..6e937c6d01
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/test_dialog_arguments.html
@@ -0,0 +1,35 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+Test that arguments can be passed to dialogs.
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test a modal window</title>
+
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css">
+
+  <script type="application/javascript">
+
+  const TEST_ITEM = Symbol("test-item");
+
+  function done(returnedItem) {
+    is(returnedItem, TEST_ITEM,
+       "Dialog should have received test item");
+    win.close();
+    SimpleTest.finish();
+  }
+
+  SimpleTest.waitForExplicitFinish();
+  let win = window.browsingContext.topChromeWindow.openDialog("file_test_dialog.html", "_blank", "width=100,height=100", TEST_ITEM, window);
+  </script>
+</head>
+<body>
+<p id="display"></p>
+<div id="content" style="display: none">
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/toolkit/components/windowwatcher/test/test_modal_windows.html b/toolkit/components/windowwatcher/test/test_modal_windows.html
new file mode 100644
index 0000000000..3c0aa6ebb5
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/test_modal_windows.html
@@ -0,0 +1,52 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+Test that the parent can open modal windows, and that the modal window
+that is opened reports itself as being modal.
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test a modal window</title>
+
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css">
+
+  <script type="application/javascript">
+
+  const {BrowserTestUtils} = ChromeUtils.importESModule(
+    "resource://testing-common/BrowserTestUtils.sys.mjs"
+  );
+
+  add_task(async function() {
+    BrowserTestUtils.domWindowOpened().then((win) => {
+      let treeOwner = win.docShell.treeOwner;
+      let chromeFlags = treeOwner.QueryInterface(Ci.nsIInterfaceRequestor)
+                                 .getInterface(Ci.nsIAppWindow)
+                                 .chromeFlags;
+      ok(chromeFlags & Ci.nsIWebBrowserChrome.CHROME_MODAL,
+         "Should have the modal chrome flag");
+
+      let wbc = treeOwner.QueryInterface(Ci.nsIInterfaceRequestor)
+                         .getInterface(Ci.nsIWebBrowserChrome);
+      ok(wbc.isWindowModal(), "Should report as modal");
+
+      win.close();
+    });
+
+    window.openDialog("data:text/html,<p>This is a modal window for test_modal_windows.html</p>",
+                      "_blank", "modal,noopener", null);
+    // Since the modal runs a nested event loop, just to be on the safe side,
+    // we'll wait a tick of the main event loop before resolving the task.
+    await new Promise(resolve => setTimeout(resolve, 0));
+  });
+
+  </script>
+</head>
+<body>
+<p id="display"></p>
+<div id="content" style="display: none">
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/toolkit/components/windowwatcher/test/test_named_window.html b/toolkit/components/windowwatcher/test/test_named_window.html
new file mode 100644
index 0000000000..af3536dd5e
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/test_named_window.html
@@ -0,0 +1,87 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+Test that when content opens a new window with a name, that the
+newly opened window actually gets that name, and that subsequent
+attempts to open a window with that name will target the same
+window.
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test named windows</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="head.js" type="application/javascript"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+  <a href="#" id="link">Click me</a>
+
+  <script type="application/javascript">
+    "use strict";
+
+    const NAME = "my_window";
+    const TARGET_URL = location.href.replace("test_named_window.html",
+                                             "file_named_window.html");
+    const TARGET_URL_2 = TARGET_URL + "#2";
+    const TARGET_URL_3 = TARGET_URL + "#3";
+
+    /**
+     * Returns a Promise that resolves once some target has had
+     * some event dispatched on it.
+     *
+     * @param target
+     *        The thing to wait for the event to be dispatched
+     *        through.
+     * @param eventName
+     *        The name of the event to wait for.
+     * @returns Promise
+     */
+    function promiseEvent(target, eventName) {
+      return new Promise(resolve => {
+        target.addEventListener(eventName, function(e) {
+          resolve(e);
+        }, {capture: true, once: true});
+      });
+    }
+
+    add_task(async function() {
+      // This magic value of 2 means that by default, when content tries
+      // to open a new window, it'll actually open in a new window instead
+      // of a new tab.
+      await SpecialPowers.pushPrefEnv({"set": [
+        ["browser.link.open_newwindow", 2],
+      ]});
+
+      let win1 = window.open(TARGET_URL, "my_window");
+      await promiseEvent(win1, "load");
+
+      let name = SpecialPowers.wrap(win1).docShell.name;
+
+      is(name, NAME, "Should have the expected name");
+      is(win1.location.href, new URL(TARGET_URL).href,
+         "Should have loaded target TARGET_URL in the original window");
+
+      let hashChange = promiseEvent(win1, "hashchange");
+      let win2 = window.open(TARGET_URL_2, "my_window");
+      await hashChange;
+
+      is(win1, win2, "Should have gotten back the same window");
+      is(win1.location.href, new URL(TARGET_URL_2).href,
+         "Should have re-targeted pre-existing window");
+
+      hashChange = promiseEvent(win1, "hashchange");
+      let link = document.getElementById("link");
+      link.setAttribute("target", NAME);
+      link.setAttribute("href", TARGET_URL_3);
+      link.click();
+
+      await hashChange;
+
+      is(win1.location.href, new URL(TARGET_URL_3).href,
+         "Should have re-targeted pre-existing window");
+
+      win1.close();
+    });
+  </script>
+</body>
+</html>
diff --git a/toolkit/components/windowwatcher/test/test_storage_copied.html b/toolkit/components/windowwatcher/test/test_storage_copied.html
new file mode 100644
index 0000000000..de05cd6855
--- /dev/null
+++ b/toolkit/components/windowwatcher/test/test_storage_copied.html
@@ -0,0 +1,43 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+Test sessionStorage is copied over when a new window opens to the
+same domain as the opener.
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test storage copied</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="head.js" type="application/javascript"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+  <script type="application/javascript">
+    "use strict";
+
+    function waitForMessage(win) {
+      return new Promise(resolve => {
+        win.addEventListener("message", function(event) {
+          resolve(event.data);
+        }, {once: true});
+      });
+    }
+
+    add_task(async function() {
+      const TEST_VALUE = "test-value";
+      // This magic value of 2 means that by default, when content tries
+      // to open a new window, it'll actually open in a new window instead
+      // of a new tab.
+      await SpecialPowers.pushPrefEnv({"set": [
+        ["browser.link.open_newwindow", 2],
+      ]});
+
+      window.sessionStorage.setItem("test-item", TEST_VALUE);
+      let win = window.open("file_storage_copied.html", "my_window");
+      let data = await waitForMessage(win);
+      is(data, TEST_VALUE, "Should have cloned the test value");
+      win.close();
+    });
+  </script>
+</body>
+</html>
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