Adding upstream version 124.0.1.upstream/124.0.1

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

131 files changed, 11310 insertions, 0 deletions

diff --git a/devtools/client/aboutdebugging/test/browser/browser.toml b/devtools/client/aboutdebugging/test/browser/browser.toml
new file mode 100644
index 0000000000..771f58b7e3
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser.toml
@@ -0,0 +1,273 @@
+[DEFAULT]
+tags = "devtools"
+subsuite = "devtools"
+prefs = ["devtools.aboutdebugging.showHiddenAddons=false"] # showHiddenAddons has different values depending on the build flags, ensure consistent test behavior by always setting it to false.
+support-files = [
+  "empty.html",
+  "head.js",
+  "helper-adb.js",
+  "helper-addons.js",
+  "helper-collapsibilities.js",
+  "helper-mocks.js",
+  "helper-real-usb.js",
+  "helper-serviceworker.js",
+  "helper-telemetry.js",
+  "mocks/*",
+  "resources/bad-extensions/*",
+  "resources/packaged-extension/*",
+  "resources/service-workers/*",
+  "resources/test-adb-extension/*",
+  "resources/test-temporary-extension/*",
+  "resources/doc_aboutdebugging_devtoolstoolbox_breakpoint.html",
+  "resources/script_aboutdebugging_devtoolstoolbox_breakpoint.js",
+  "test-tab-favicons.html",
+  "!/devtools/client/debugger/test/mochitest/shared-head.js",
+  "!/devtools/client/shared/test/shared-head.js",
+  "!/devtools/client/shared/test/telemetry-test-helpers.js",
+  "!/devtools/client/webconsole/test/browser/shared-head.js",
+]
+
+["browser_aboutdebugging_addons_debug_console.js"]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_debug_debugger.js"]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_debug_inspector.js"]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_debug_nobg.js"]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_debug_popup.js"]
+skip-if = [
+  "verify && debug", # verify: crashes on shutdown, timeouts
+  "os == 'linux' && debug", # linux debug Bug 1299001
+]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_debug_reload.js"]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_debug_storage.js"]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_debug_toolbox.js"]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_eventpage_actions_and_status.js"]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_eventpage_terminate_on_idle.js"]
+tags = "webextensions"
+
+["browser_aboutdebugging_addons_manifest_url.js"]
+skip-if = ["os == 'mac' && debug"] # ADB start() fails on linux 32, see Bug 1499638, macosx1014 debug due to 1514751
+
+["browser_aboutdebugging_addons_popup_picker.js"]
+
+["browser_aboutdebugging_addons_remote_runtime.js"]
+
+["browser_aboutdebugging_addons_temporary_addon_buttons.js"]
+skip-if = ["os == 'win'"] # On windows the AddonManager locks the XPI file loaded as a temporary extension and we can not test the reload of the extension.
+
+["browser_aboutdebugging_addons_temporary_id_message.js"]
+
+["browser_aboutdebugging_addons_temporary_install_error.js"]
+
+["browser_aboutdebugging_addons_temporary_install_path.js"]
+
+["browser_aboutdebugging_addons_temporary_reload_error.js"]
+skip-if = ["os == 'win'"] # On windows the AddonManager locks the XPI file loaded as a temporary extension and we can not test the reload of the extension.
+
+["browser_aboutdebugging_addons_warnings.js"]
+
+["browser_aboutdebugging_connect_networklocations.js"]
+
+["browser_aboutdebugging_connect_toggle_usb_devices.js"]
+
+["browser_aboutdebugging_connection_prompt_setting.js"]
+
+["browser_aboutdebugging_debug-target-pane_collapsibilities_interaction.js"]
+fail-if = ["a11y_checks"] # Bug 1849028 clicked element may not be focusable and/or labeled
+
+["browser_aboutdebugging_debug-target-pane_collapsibilities_preference.js"]
+fail-if = ["a11y_checks"] # Bug 1849028 clicked element may not be focusable and/or labeled
+
+["browser_aboutdebugging_debug-target-pane_empty.js"]
+
+["browser_aboutdebugging_debug-target-pane_usb_runtime.js"]
+
+["browser_aboutdebugging_devtools.js"]
+
+["browser_aboutdebugging_devtoolstoolbox_breakpoint.js"]
+
+["browser_aboutdebugging_devtoolstoolbox_contextmenu.js"]
+
+["browser_aboutdebugging_devtoolstoolbox_contextmenu_markupview.js"]
+
+["browser_aboutdebugging_devtoolstoolbox_focus.js"]
+
+["browser_aboutdebugging_devtoolstoolbox_menubar.js"]
+
+["browser_aboutdebugging_devtoolstoolbox_navigate_back_forward.js"]
+
+["browser_aboutdebugging_devtoolstoolbox_navigate_reload_button.js"]
+
+["browser_aboutdebugging_devtoolstoolbox_navigate_to_url.js"]
+skip-if = ["a11y_checks"] # Bug 1849028 and 1849179 for causing crashes
+
+["browser_aboutdebugging_devtoolstoolbox_reload.js"]
+skip-if = [
+  "verify",
+  "ccov",
+  "os == 'linux' && debug", #bug 1544828, test loads the toolbox 2 times for each panel, might timeout or OOM
+]
+
+["browser_aboutdebugging_devtoolstoolbox_shortcuts.js"]
+skip-if = [
+  "ccov",
+  "os == 'linux'", # Bug 1521349, Bug 1548015, Bug 1544828
+]
+
+["browser_aboutdebugging_devtoolstoolbox_splitconsole_key.js"]
+
+["browser_aboutdebugging_devtoolstoolbox_target_destroyed.js"]
+skip-if = [
+  "debug",
+  "asan", # This test leaks. See bug 1529005
+]
+
+["browser_aboutdebugging_devtoolstoolbox_tooltip_markupview.js"]
+fail-if = ["a11y_checks"] # Bug 1849028 clicked element may not be focusable and/or labeled
+
+["browser_aboutdebugging_devtoolstoolbox_zoom.js"]
+
+["browser_aboutdebugging_fenix_runtime_display.js"]
+skip-if = ["a11y_checks"] # Bug 1849028 and 1849179 for causing crashes
+
+["browser_aboutdebugging_fenix_runtime_node_picker.js"]
+skip-if = ["a11y_checks"] # Bug 1849028, 1858041, and 1849179 for causing crashes
+
+["browser_aboutdebugging_hidden_addons.js"]
+
+["browser_aboutdebugging_message_close.js"]
+
+["browser_aboutdebugging_navigate.js"]
+
+["browser_aboutdebugging_persist_connection.js"]
+
+["browser_aboutdebugging_process_category.js"]
+
+["browser_aboutdebugging_process_main.js"]
+
+["browser_aboutdebugging_process_main_local.js"]
+skip-if = ["debug"]
+
+["browser_aboutdebugging_profiler_dialog.js"]
+support-files = ["!/devtools/client/performance-new/test/browser/helpers.js"]
+fail-if = ["a11y_checks"] # Bug 1849028 clicked element may not be focusable and/or labeled
+
+["browser_aboutdebugging_real_usb_runtime_page_runtime_info.js"]
+
+["browser_aboutdebugging_real_usb_sidebar.js"]
+
+["browser_aboutdebugging_routes.js"]
+
+["browser_aboutdebugging_rtl.js"]
+
+["browser_aboutdebugging_runtime_compatibility_warning.js"]
+
+["browser_aboutdebugging_runtime_disconnect_remote_runtime.js"]
+
+["browser_aboutdebugging_runtime_remote_runtime_buttons.js"]
+
+["browser_aboutdebugging_runtime_usbclient_closed.js"]
+
+["browser_aboutdebugging_select_network_runtime.js"]
+
+["browser_aboutdebugging_select_page_with_serviceworker.js"]
+
+["browser_aboutdebugging_serviceworker_console.js"]
+
+["browser_aboutdebugging_serviceworker_fetch_flag.js"]
+skip-if = [
+  "os == 'win' && debug",
+  "os == 'mac'",
+  "os == 'linux'", #Bug 1529824
+]
+
+["browser_aboutdebugging_serviceworker_not_compatible.js"]
+
+["browser_aboutdebugging_serviceworker_push.js"]
+
+["browser_aboutdebugging_serviceworker_pushservice_url.js"]
+
+["browser_aboutdebugging_serviceworker_runtime-page.js"]
+
+["browser_aboutdebugging_serviceworker_start.js"]
+
+["browser_aboutdebugging_serviceworker_status.js"]
+
+["browser_aboutdebugging_serviceworker_timeout.js"]
+skip-if = [
+  "debug",
+  "asan", # Frequent intermittent failures, Bug 1522800
+]
+
+["browser_aboutdebugging_serviceworker_unregister.js"]
+
+["browser_aboutdebugging_sidebar_connection_state.js"]
+skip-if = ["a11y_checks"] # Bug 1849028 and 1849179 for causing crashes
+
+["browser_aboutdebugging_sidebar_network_runtimes.js"]
+
+["browser_aboutdebugging_sidebar_usb_runtime.js"]
+
+["browser_aboutdebugging_sidebar_usb_runtime_connect.js"]
+
+["browser_aboutdebugging_sidebar_usb_runtime_refresh.js"]
+
+["browser_aboutdebugging_sidebar_usb_runtime_select.js"]
+
+["browser_aboutdebugging_sidebar_usb_status.js"]
+
+["browser_aboutdebugging_sidebar_usb_unavailable_runtime.js"]
+
+["browser_aboutdebugging_sidebar_usb_unplugged_device.js"]
+
+["browser_aboutdebugging_tab_favicons.js"]
+
+["browser_aboutdebugging_tab_navigate.js"]
+
+["browser_aboutdebugging_tab_zombietab.js"]
+
+["browser_aboutdebugging_targets_sorted.js"]
+
+["browser_aboutdebugging_telemetry_basic.js"]
+
+["browser_aboutdebugging_telemetry_connection_attempt.js"]
+skip-if = ["a11y_checks"] # Bug 1849028 and 1849179 for causing crashes
+
+["browser_aboutdebugging_telemetry_inspect.js"]
+skip-if = ["a11y_checks"] # Bug 1849028 and 1849179 for causing crashes
+
+["browser_aboutdebugging_telemetry_navigate.js"]
+
+["browser_aboutdebugging_telemetry_runtime_actions.js"]
+
+["browser_aboutdebugging_telemetry_runtime_connected_details.js"]
+
+["browser_aboutdebugging_telemetry_runtime_updates.js"]
+
+["browser_aboutdebugging_telemetry_runtime_updates_multi.js"]
+
+["browser_aboutdebugging_telemetry_runtime_updates_network.js"]
+
+["browser_aboutdebugging_thisfirefox.js"]
+
+["browser_aboutdebugging_thisfirefox_runtime_info.js"]
+
+["browser_aboutdebugging_thisfirefox_worker_inspection.js"]
+
+["browser_aboutdebugging_workers_remote_runtime.js"]
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_console.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_console.js
new file mode 100644
index 0000000000..1612cd545f
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_console.js
@@ -0,0 +1,440 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// There are shutdown issues for which multiple rejections are left uncaught.
+// See bug 1018184 for resolving these issues.
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(/File closed/);
+
+// Avoid test timeouts that can occur while waiting for the "addon-console-works" message.
+requestLongerTimeout(2);
+
+const ADDON_ID = "test-devtools-webextension@mozilla.org";
+const ADDON_NAME = "base-test-devtools-webextension";
+
+const OTHER_ADDON_ID = "other-test-devtools-webextension@mozilla.org";
+const OTHER_ADDON_NAME = "other-test-devtools-webextension";
+
+const POPUPONLY_ADDON_ID = "popuponly-test-devtools-webextension@mozilla.org";
+const POPUPONLY_ADDON_NAME = "popuponly-test-devtools-webextension";
+
+const BACKGROUND_ADDON_ID = "background-test-devtools-webextension@mozilla.org";
+const BACKGROUND_ADDON_NAME = "background-test-devtools-webextension";
+
+/**
+ * This test file ensures that the webextension addon developer toolbox:
+ * - when the debug button is clicked on a webextension, the opened toolbox
+ *   has a working webconsole with the background page as default target;
+ */
+add_task(async function testWebExtensionsToolboxWebConsole() {
+  await pushPref("devtools.webconsole.filter.css", true);
+  await enableExtensionDebugging();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtensionFromXPI(
+    {
+      background() {
+        window.myWebExtensionAddonFunction = function () {
+          console.log(
+            "Background page function called",
+            this.browser.runtime.getManifest()
+          );
+        };
+
+        const style = document.createElement("style");
+        style.textContent = "* { color: error; }";
+        document.documentElement.appendChild(style);
+
+        throw new Error("Background page exception");
+      },
+      extraProperties: {
+        browser_action: {
+          default_title: "WebExtension Popup Debugging",
+          default_popup: "popup.html",
+          default_area: "navbar",
+        },
+      },
+      files: {
+        "popup.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="popup.js"></script>
+          </head>
+          <body>
+            Popup
+          </body>
+        </html>
+      `,
+        "popup.js": function () {
+          console.log("Popup log");
+
+          const style = document.createElement("style");
+          style.textContent = "* { color: popup-error; }";
+          document.documentElement.appendChild(style);
+
+          throw new Error("Popup exception");
+        },
+      },
+      id: ADDON_ID,
+      name: ADDON_NAME,
+    },
+    document
+  );
+
+  // Install another addon in order to ensure we don't get its logs
+  await installTemporaryExtensionFromXPI(
+    {
+      background() {
+        console.log("Other addon log");
+
+        const style = document.createElement("style");
+        style.textContent = "* { background-color: error; }";
+        document.documentElement.appendChild(style);
+
+        throw new Error("Other addon exception");
+      },
+      extraProperties: {
+        browser_action: {
+          default_title: "Other addon popup",
+          default_popup: "other-popup.html",
+          default_area: "navbar",
+        },
+      },
+      files: {
+        "other-popup.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="other-popup.js"></script>
+          </head>
+          <body>
+            Other popup
+          </body>
+        </html>
+      `,
+        "other-popup.js": function () {
+          console.log("Other popup log");
+
+          const style = document.createElement("style");
+          style.textContent = "* { background-color: popup-error; }";
+          document.documentElement.appendChild(style);
+
+          throw new Error("Other popup exception");
+        },
+      },
+      id: OTHER_ADDON_ID,
+      name: OTHER_ADDON_NAME,
+    },
+    document
+  );
+
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    ADDON_NAME
+  );
+  const toolbox = getToolbox(devtoolsWindow);
+  const webconsole = await toolbox.selectTool("webconsole");
+  const { hud } = webconsole;
+
+  info("Trigger some code in the background page logging some stuff");
+  const onMessage = waitUntil(() => {
+    return !!findMessagesByType(hud, "Background page exception", ".error")
+      .length;
+  });
+  hud.ui.wrapper.dispatchEvaluateExpression("myWebExtensionAddonFunction()");
+  await onMessage;
+
+  info("Open the two add-ons popups to cover popups messages");
+  const onPopupMessage = waitUntil(() => {
+    return !!findMessagesByType(hud, "Popup exception", ".error").length;
+  });
+  clickOnAddonWidget(OTHER_ADDON_ID);
+  clickOnAddonWidget(ADDON_ID);
+  await onPopupMessage;
+
+  info("Wait a bit to catch unexpected duplicates or mixed up messages");
+  await wait(1000);
+
+  is(
+    findMessagesByType(hud, "Background page exception", ".error").length,
+    1,
+    "We get the background page exception"
+  );
+  is(
+    findMessagesByType(hud, "Popup exception", ".error").length,
+    1,
+    "We get the popup exception"
+  );
+  is(
+    findMessagesByType(
+      hud,
+      "Expected color but found ‘error’.  Error in parsing value for ‘color’.  Declaration dropped.",
+      ".warn"
+    ).length,
+    1,
+    "We get the addon's background page CSS error message"
+  );
+  is(
+    findMessagesByType(
+      hud,
+      "Expected color but found ‘popup-error’.  Error in parsing value for ‘color’.  Declaration dropped.",
+      ".warn"
+    ).length,
+    1,
+    "We get the addon's popup CSS error message"
+  );
+
+  // Verify that we don't get the other addon log and errors
+  ok(
+    !findMessageByType(hud, "Other addon log", ".console-api"),
+    "We don't get the other addon log"
+  );
+  ok(
+    !findMessageByType(hud, "Other addon exception", ".console-api"),
+    "We don't get the other addon exception"
+  );
+  ok(
+    !findMessageByType(hud, "Other popup log", ".console-api"),
+    "We don't get the other addon popup log"
+  );
+  ok(
+    !findMessageByType(hud, "Other popup exception", ".error"),
+    "We don't get the other addon popup exception"
+  );
+  ok(
+    !findMessageByType(
+      hud,
+      "Expected color but found ‘error’.  Error in parsing value for ‘background-color’.  Declaration dropped.",
+      ".warn"
+    ),
+    "We don't get the other addon's background page CSS error message"
+  );
+  ok(
+    !findMessageByType(
+      hud,
+      "Expected color but found ‘popup-error’.  Error in parsing value for ‘background-color’.  Declaration dropped.",
+      ".warn"
+    ),
+    "We don't get the other addon's popup CSS error message"
+  );
+
+  // Verify that console evaluations still work after reloading the page
+  info("Reload the webextension document");
+  const { onDomCompleteResource } =
+    await waitForNextTopLevelDomCompleteResource(toolbox.commands);
+  hud.ui.wrapper.dispatchEvaluateExpression("location.reload()");
+  await onDomCompleteResource;
+
+  info("Try to evaluate something after reload");
+
+  const onEvaluationResultAfterReload = waitUntil(() =>
+    findMessageByType(hud, "result:2", ".result")
+  );
+  const onMessageAfterReload = waitUntil(() =>
+    findMessageByType(hud, "message after reload", ".console-api")
+  );
+  hud.ui.wrapper.dispatchEvaluateExpression(
+    "console.log('message after reload'); 'result:' + (1 + 1)"
+  );
+  // Both cover that the console.log worked
+  await onMessageAfterReload;
+  // And we received the evaluation result
+  await onEvaluationResultAfterReload;
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+
+  // Note that it seems to be important to remove the addons in the reverse order
+  // from which they were installed...
+  await removeTemporaryExtension(OTHER_ADDON_NAME, document);
+  await removeTemporaryExtension(ADDON_NAME, document);
+  await removeTab(tab);
+});
+
+add_task(async function testWebExtensionNoBgScript() {
+  await pushPref("devtools.webconsole.filter.css", true);
+  await enableExtensionDebugging();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtensionFromXPI(
+    {
+      extraProperties: {
+        browser_action: {
+          default_title: "WebExtension Popup Only",
+          default_popup: "popup.html",
+          default_area: "navbar",
+        },
+      },
+      files: {
+        "popup.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="popup.js"></script>
+          </head>
+          <body>
+            Popup
+          </body>
+        </html>
+      `,
+        "popup.js": function () {
+          console.log("Popup-only log");
+
+          const style = document.createElement("style");
+          style.textContent = "* { color: popup-only-error; }";
+          document.documentElement.appendChild(style);
+
+          throw new Error("Popup-only exception");
+        },
+      },
+      id: POPUPONLY_ADDON_ID,
+      name: POPUPONLY_ADDON_NAME,
+    },
+    document
+  );
+
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    POPUPONLY_ADDON_NAME
+  );
+  const toolbox = getToolbox(devtoolsWindow);
+  const webconsole = await toolbox.selectTool("webconsole");
+  const { hud } = webconsole;
+
+  info("Open the add-on popup");
+  const onPopupMessage = waitUntil(() => {
+    return !!findMessagesByType(hud, "Popup-only exception", ".error").length;
+  });
+  clickOnAddonWidget(POPUPONLY_ADDON_ID);
+  await onPopupMessage;
+
+  info("Wait a bit to catch unexpected duplicates or mixed up messages");
+  await wait(1000);
+  is(
+    findMessagesByType(hud, "Popup-only exception", ".error").length,
+    1,
+    "We get the popup exception"
+  );
+  is(
+    findMessagesByType(hud, "Popup-only log", ".console-api").length,
+    1,
+    "We get the addon's popup log"
+  );
+  is(
+    findMessagesByType(
+      hud,
+      "Expected color but found ‘popup-only-error’.  Error in parsing value for ‘color’.  Declaration dropped.",
+      ".warn"
+    ).length,
+    1,
+    "We get the addon's popup CSS error message"
+  );
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+  await removeTemporaryExtension(POPUPONLY_ADDON_NAME, document);
+  await removeTab(tab);
+});
+
+// Check that reloading the addon several times does not break the console,
+// see Bug 1778951.
+add_task(async function testWebExtensionTwoReloads() {
+  await enableExtensionDebugging();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtensionFromXPI(
+    {
+      background() {
+        console.log("Background page log");
+      },
+      extraProperties: {
+        browser_action: {
+          default_title: "WebExtension with background script",
+          default_popup: "popup.html",
+          default_area: "navbar",
+        },
+      },
+      files: {
+        "popup.html": `<!DOCTYPE html>
+        <html>
+          <body>
+            Popup
+          </body>
+        </html>
+      `,
+      },
+      id: BACKGROUND_ADDON_ID,
+      name: BACKGROUND_ADDON_NAME,
+    },
+    document
+  );
+
+  // Retrieve the addonTarget element before calling `openAboutDevtoolsToolbox`,
+  // otherwise it will pick the about:devtools-toolbox tab with the same name
+  // instead.
+  const addonTarget = findDebugTargetByText(BACKGROUND_ADDON_NAME, document);
+
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    BACKGROUND_ADDON_NAME
+  );
+  const toolbox = getToolbox(devtoolsWindow);
+  const webconsole = await toolbox.selectTool("webconsole");
+  const { hud } = webconsole;
+
+  // Verify that console evaluations still work after reloading the addon
+  info("Reload the webextension itself");
+  let { onDomCompleteResource } = await waitForNextTopLevelDomCompleteResource(
+    toolbox.commands
+  );
+  const reloadButton = addonTarget.querySelector(
+    ".qa-temporary-extension-reload-button"
+  );
+  reloadButton.click();
+  await onDomCompleteResource;
+
+  info("Try to evaluate something after 1st addon reload");
+  // Wait before evaluating the message, otherwise they might be cleaned up by
+  // the console UI.
+  info("Wait until the background script log is visible");
+  await waitUntil(() =>
+    findMessageByType(hud, "Background page log", ".message")
+  );
+
+  hud.ui.wrapper.dispatchEvaluateExpression("40+1");
+  await waitUntil(() => findMessageByType(hud, "41", ".result"));
+
+  info("Reload the extension a second time");
+  ({ onDomCompleteResource } = await waitForNextTopLevelDomCompleteResource(
+    toolbox.commands
+  ));
+  reloadButton.click();
+  await onDomCompleteResource;
+
+  info("Wait until the background script log is visible - after reload");
+  await waitUntil(() =>
+    findMessageByType(hud, "Background page log", ".message")
+  );
+
+  info("Try to evaluate something after 2nd addon reload");
+  hud.ui.wrapper.dispatchEvaluateExpression("40+2");
+  await waitUntil(() => findMessageByType(hud, "42", ".result"));
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+  await removeTemporaryExtension(BACKGROUND_ADDON_NAME, document);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_debugger.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_debugger.js
new file mode 100644
index 0000000000..123d3ccdf1
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_debugger.js
@@ -0,0 +1,86 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+const L10N = new LocalizationHelper(
+  "devtools/client/locales/toolbox.properties"
+);
+
+add_task(async () => {
+  const EXTENSION_NAME = "temporary-web-extension";
+  const EXTENSION_ID = "test-devtools@mozilla.org";
+
+  await enableExtensionDebugging();
+
+  info(
+    "The debugger should show the source codes of extension even if " +
+      "devtools.chrome.enabled and devtools.debugger.remote-enabled are off"
+  );
+  await pushPref("devtools.chrome.enabled", false);
+  await pushPref("devtools.debugger.remote-enabled", false);
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtensionFromXPI(
+    {
+      background() {
+        window.someRandomMethodName = () => {
+          // This will not be referred from anywhere.
+          // However this is necessary to show as the source code in the debugger.
+        };
+      },
+      id: EXTENSION_ID,
+      name: EXTENSION_NAME,
+    },
+    document
+  );
+
+  // Select the debugger right away to avoid any noise coming from the inspector.
+  await pushPref("devtools.toolbox.selectedTool", "jsdebugger");
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    EXTENSION_NAME
+  );
+  const toolbox = getToolbox(devtoolsWindow);
+  const { panelWin } = toolbox.getCurrentPanel();
+
+  info("Check the state of redux");
+  ok(
+    panelWin.dbg.store.getState().sourcesTree.isWebExtension,
+    "isWebExtension flag in sourcesTree is true"
+  );
+
+  info("Check whether the element displays correctly");
+  let sourceList = panelWin.document.querySelector(".sources-list");
+  ok(sourceList, "Source list element displays correctly");
+  ok(
+    sourceList.textContent.includes("temporary-web-extension"),
+    "Extension name displays correctly"
+  );
+
+  const waitForLoadedPanelsReload = await watchForLoadedPanelsReload(toolbox);
+
+  info("Reload the addon using a toolbox reload shortcut");
+  toolbox.win.focus();
+  synthesizeKeyShortcut(L10N.getStr("toolbox.reload.key"), toolbox.win);
+
+  await waitForLoadedPanelsReload();
+
+  info("Wait until a new background log message is logged");
+  await waitFor(() => {
+    // As React may re-create a new sources-list element,
+    // fetch the latest instance
+    sourceList = panelWin.document.querySelector(".sources-list");
+    return sourceList?.textContent.includes("temporary-web-extension");
+  }, "Wait for the source to re-appear");
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+  await removeTemporaryExtension(EXTENSION_NAME, document);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_inspector.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_inspector.js
new file mode 100644
index 0000000000..a652ab41a8
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_inspector.js
@@ -0,0 +1,86 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// There are shutdown issues for which multiple rejections are left uncaught.
+// See bug 1018184 for resolving these issues.
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(/File closed/);
+
+// Avoid test timeouts that can occur while waiting for the "addon-console-works" message.
+requestLongerTimeout(2);
+
+const ADDON_ID = "test-devtools-webextension@mozilla.org";
+const ADDON_NAME = "test-devtools-webextension";
+
+/**
+ * This test file ensures that the webextension addon developer toolbox:
+ * - the webextension developer toolbox has a working Inspector panel, with the
+ *   background page as default target;
+ */
+add_task(async function testWebExtensionsToolboxWebConsole() {
+  await enableExtensionDebugging();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtensionFromXPI(
+    {
+      background() {
+        document.body.innerText = "Background Page Body Test Content";
+      },
+      id: ADDON_ID,
+      name: ADDON_NAME,
+    },
+    document
+  );
+
+  info("Open a toolbox to debug the addon");
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    ADDON_NAME
+  );
+  const toolbox = getToolbox(devtoolsWindow);
+
+  const inspector = await toolbox.selectTool("inspector");
+  const nodeActor = await inspector.walker.querySelector(
+    inspector.walker.rootNode,
+    "body"
+  );
+  ok(nodeActor, "Got a nodeActor");
+  ok(nodeActor.inlineTextChild, "Got a nodeActor with an inline text child");
+
+  const actualValue = nodeActor.inlineTextChild._form.nodeValue;
+
+  is(
+    String(actualValue).trim(),
+    "Background Page Body Test Content",
+    "nodeActor has the expected inlineTextChild value"
+  );
+
+  info("Check that the color scheme simulation buttons are hidden");
+  const lightButtonIsHidden = inspector.panelDoc
+    .querySelector("#color-scheme-simulation-light-toggle")
+    ?.hasAttribute("hidden");
+  const darkButtonIsHidded = inspector.panelDoc
+    .querySelector("#color-scheme-simulation-dark-toggle")
+    ?.hasAttribute("hidden");
+  ok(
+    lightButtonIsHidden,
+    "The light color scheme simulation button exists and is hidden"
+  );
+  ok(
+    darkButtonIsHidded,
+    "The dark color scheme simulation button exists and is hidden"
+  );
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+  await removeTemporaryExtension(ADDON_NAME, document);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_nobg.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_nobg.js
new file mode 100644
index 0000000000..4f8f35acd2
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_nobg.js
@@ -0,0 +1,78 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// There are shutdown issues for which multiple rejections are left uncaught.
+// See bug 1018184 for resolving these issues.
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(/File closed/);
+
+const ADDON_NOBG_ID = "test-devtools-webextension-nobg@mozilla.org";
+const ADDON_NOBG_NAME = "test-devtools-webextension-nobg";
+
+/**
+ * This test file ensures that the webextension addon developer toolbox:
+ * - the webextension developer toolbox is connected to a fallback page when the
+ *   background page is not available (and in the fallback page document body contains
+ *   the expected message, which warns the user that the current page is not a real
+ *   webextension context);
+ */
+add_task(async function testWebExtensionsToolboxNoBackgroundPage() {
+  await enableExtensionDebugging();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtensionFromXPI(
+    {
+      // Do not pass any `background` script.
+      id: ADDON_NOBG_ID,
+      name: ADDON_NOBG_NAME,
+    },
+    document
+  );
+
+  info("Open a toolbox to debug the addon");
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    ADDON_NOBG_NAME
+  );
+  const toolbox = getToolbox(devtoolsWindow);
+
+  ok(
+    toolbox.commands.descriptorFront.isWebExtensionDescriptor,
+    "Toolbox is debugging an addon"
+  );
+  const targetName = toolbox.target.name;
+  is(targetName, ADDON_NOBG_NAME, "Toolbox has the expected target");
+
+  const inspector = await toolbox.selectTool("inspector");
+
+  let nodeActor;
+  info(`Wait the fallback window to be fully loaded`);
+  await asyncWaitUntil(async () => {
+    nodeActor = await inspector.walker.querySelector(
+      inspector.walker.rootNode,
+      "h1"
+    );
+    return nodeActor && nodeActor.inlineTextChild;
+  });
+
+  info("Got a nodeActor with an inline text child");
+  const actualValue = nodeActor.inlineTextChild._form.nodeValue;
+  is(
+    actualValue,
+    "Your addon does not have any document opened yet.",
+    "nodeActor has the expected inlineTextChild value"
+  );
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+  await removeTemporaryExtension(ADDON_NOBG_NAME, document);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_popup.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_popup.js
new file mode 100644
index 0000000000..c205ecbfe3
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_popup.js
@@ -0,0 +1,246 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// There are shutdown issues for which multiple rejections are left uncaught.
+// See bug 1018184 for resolving these issues.
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(/File closed/);
+
+// Avoid test timeouts that can occur while waiting for the "addon-console-works" message.
+requestLongerTimeout(2);
+
+const ADDON_ID = "test-devtools-webextension@mozilla.org";
+const ADDON_NAME = "test-devtools-webextension";
+
+/**
+ * This test file ensures that the webextension addon developer toolbox:
+ * - has a frame list menu and the noautohide toolbar toggle button, and they
+ *   can be used to switch the current target to the extension popup page.
+ */
+add_task(async function testWebExtensionsToolboxWebConsole() {
+  await enableExtensionDebugging();
+
+  // Bug 1686922: Disable the error count button to avoid intermittent failures.
+  await pushPref("devtools.command-button-errorcount.enabled", false);
+
+  is(
+    Services.prefs.getBoolPref("ui.popup.disable_autohide"),
+    false,
+    "disable_autohide should be initially false"
+  );
+
+  const {
+    document,
+    tab,
+    window: aboutDebuggingWindow,
+  } = await openAboutDebugging();
+  await selectThisFirefoxPage(
+    document,
+    aboutDebuggingWindow.AboutDebugging.store
+  );
+
+  const extension = await installTestAddon(document);
+
+  const onBackgroundFunctionCalled = waitForExtensionTestMessage(
+    extension,
+    "onBackgroundFunctionCalled"
+  );
+  const onPopupPageFunctionCalled = waitForExtensionTestMessage(
+    extension,
+    "onPopupPageFunctionCalled"
+  );
+
+  info("Open a toolbox to debug the addon");
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    aboutDebuggingWindow,
+    ADDON_NAME
+  );
+
+  const toolbox = getToolbox(devtoolsWindow);
+  const webconsole = await toolbox.selectTool("webconsole");
+
+  info("Clicking the menu button to disable autohide");
+  await disablePopupAutohide(toolbox);
+
+  info("Check that console messages are evaluated in the background context");
+  const consoleWrapper = webconsole.hud.ui.wrapper;
+  consoleWrapper.dispatchEvaluateExpression("backgroundFunction()");
+  await onBackgroundFunctionCalled;
+
+  clickOnAddonWidget(ADDON_ID);
+
+  info("Wait until the frames list button is displayed");
+  const btn = await waitFor(() =>
+    toolbox.doc.getElementById("command-button-frames")
+  );
+
+  info("Clicking the frame list button");
+  btn.click();
+
+  const menuList = toolbox.doc.getElementById("toolbox-frame-menu");
+  const frames = Array.from(menuList.querySelectorAll(".command"));
+  is(frames.length, 2, "Has the expected number of frames");
+
+  const popupFrameBtn = frames
+    .filter(frame => {
+      return frame.querySelector(".label").textContent.endsWith("popup.html");
+    })
+    .pop();
+
+  ok(popupFrameBtn, "Extension Popup frame found in the listed frames");
+
+  info(
+    "Click on the extension popup frame and wait for a `dom-complete` resource"
+  );
+  const { onDomCompleteResource } =
+    await waitForNextTopLevelDomCompleteResource(toolbox.commands);
+  popupFrameBtn.click();
+  await onDomCompleteResource;
+
+  info("Execute `popupPageFunction()`");
+  consoleWrapper.dispatchEvaluateExpression("popupPageFunction()");
+
+  const args = await onPopupPageFunctionCalled;
+  ok(true, "Received console message from the popup page function as expected");
+  is(args[0], "onPopupPageFunctionCalled", "Got the expected console message");
+  is(
+    args[1] && args[1].name,
+    ADDON_NAME,
+    "Got the expected manifest from WebExtension API"
+  );
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, aboutDebuggingWindow);
+
+  is(
+    Services.prefs.getBoolPref("ui.popup.disable_autohide"),
+    false,
+    "disable_autohide should be reset to false when the toolbox is closed"
+  );
+
+  await removeTemporaryExtension(ADDON_NAME, document);
+  await removeTab(tab);
+});
+
+/**
+ * Helper to wait for a specific message on an Extension instance.
+ */
+function waitForExtensionTestMessage(extension, expectedMessage) {
+  return new Promise(done => {
+    extension.on("test-message", function testLogListener(evt, ...args) {
+      const [message] = args;
+
+      if (message !== expectedMessage) {
+        return;
+      }
+
+      extension.off("test-message", testLogListener);
+      done(args);
+    });
+  });
+}
+
+/**
+ * Install the addon used for this test.
+ * Returns a Promise that resolve the Extension instance that was just
+ * installed.
+ */
+async function installTestAddon(doc) {
+  // Start watching for the extension on the Extension Management before we
+  // install it.
+  const onExtensionReady = waitForExtension(ADDON_NAME);
+
+  // Install the extension.
+  await installTemporaryExtensionFromXPI(
+    {
+      background() {
+        const { browser } = this;
+        window.backgroundFunction = function () {
+          browser.test.sendMessage("onBackgroundFunctionCalled");
+        };
+      },
+      extraProperties: {
+        browser_action: {
+          default_title: "WebExtension Popup Debugging",
+          default_popup: "popup.html",
+        },
+      },
+      files: {
+        "popup.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="popup.js"></script>
+          </head>
+          <body>
+            Background Page Body Test Content
+          </body>
+        </html>
+      `,
+        "popup.js": function () {
+          const { browser } = this;
+          window.popupPageFunction = function () {
+            browser.test.sendMessage(
+              "onPopupPageFunctionCalled",
+              browser.runtime.getManifest()
+            );
+          };
+        },
+      },
+      id: ADDON_ID,
+      name: ADDON_NAME,
+    },
+    doc
+  );
+
+  // The onExtensionReady promise will resolve the extension instance.
+  return onExtensionReady;
+}
+
+/**
+ * Helper to retrieve the Extension instance.
+ */
+async function waitForExtension(addonName) {
+  const { Management } = ChromeUtils.importESModule(
+    "resource://gre/modules/Extension.sys.mjs"
+  );
+
+  return new Promise(resolve => {
+    Management.on("startup", function listener(event, extension) {
+      if (extension.name != addonName) {
+        return;
+      }
+
+      Management.off("startup", listener);
+      resolve(extension);
+    });
+  });
+}
+
+/**
+ * Disables the popup autohide feature, which is mandatory to debug webextension
+ * popups.
+ */
+function disablePopupAutohide(toolbox) {
+  return new Promise(resolve => {
+    toolbox.doc.addEventListener(
+      "popupshown",
+      () => {
+        const menuItem = toolbox.doc.getElementById(
+          "toolbox-meatball-menu-noautohide"
+        );
+        menuItem.click();
+        resolve();
+      },
+      { once: true }
+    );
+    toolbox.doc.getElementById("toolbox-meatball-menu-button").click();
+  });
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_reload.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_reload.js
new file mode 100644
index 0000000000..d6caca64d6
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_reload.js
@@ -0,0 +1,135 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// There are shutdown issues for which multiple rejections are left uncaught.
+// See bug 1018184 for resolving these issues.
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(/File closed/);
+
+// Avoid test timeouts that can occur while waiting for the "addon-console-works" message.
+requestLongerTimeout(2);
+
+const ADDON_ID = "test-devtools-webextension@mozilla.org";
+const ADDON_NAME = "test-devtools-webextension";
+
+const L10N = new LocalizationHelper(
+  "devtools/client/locales/toolbox.properties"
+);
+
+// Check that addon browsers can be reloaded via the toolbox reload shortcuts
+add_task(async function testWebExtensionToolboxReload() {
+  await enableExtensionDebugging();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtensionFromXPI(
+    {
+      background() {
+        console.log("background script executed " + Math.random());
+      },
+      id: ADDON_ID,
+      name: ADDON_NAME,
+    },
+    document
+  );
+
+  // Select the debugger right away to avoid any noise coming from the inspector.
+  await pushPref("devtools.toolbox.selectedTool", "webconsole");
+  const { devtoolsDocument, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    ADDON_NAME
+  );
+  const toolbox = getToolbox(devtoolsWindow);
+
+  ok(
+    devtoolsDocument.querySelector(".qa-reload-button"),
+    "Reload button is visible"
+  );
+  ok(
+    !devtoolsDocument.querySelector(".qa-back-button"),
+    "Back button is hidden"
+  );
+  ok(
+    !devtoolsDocument.querySelector(".qa-forward-button"),
+    "Forward button is hidden"
+  );
+  ok(
+    !devtoolsDocument.querySelector(".debug-target-url-form"),
+    "URL form is hidden"
+  );
+  ok(
+    devtoolsDocument.getElementById("toolbox-meatball-menu-noautohide"),
+    "Disable popup autohide button is displayed"
+  );
+  ok(
+    !devtoolsDocument.getElementById(
+      "toolbox-meatball-menu-pseudo-locale-accented"
+    ),
+    "Accented locale is not displayed (only on browser toolbox)"
+  );
+
+  const webconsole = await toolbox.selectTool("webconsole");
+  const { hud } = webconsole;
+
+  info("Wait for the initial background message to appear in the console");
+  const initialMessage = await waitFor(() =>
+    findMessagesByType(hud, "background script executed", ".console-api")
+  );
+  ok(initialMessage, "Found the expected message from the background script");
+
+  const waitForLoadedPanelsReload = await watchForLoadedPanelsReload(toolbox);
+
+  info("Reload the addon using a toolbox reload shortcut");
+  toolbox.win.focus();
+  synthesizeKeyShortcut(L10N.getStr("toolbox.reload.key"), toolbox.win);
+
+  info("Wait until a new background log message is logged");
+  const secondMessage = await waitFor(() => {
+    const newMessage = findMessagesByType(
+      hud,
+      "background script executed",
+      ".console-api"
+    );
+    if (newMessage && newMessage !== initialMessage) {
+      return newMessage;
+    }
+    return false;
+  });
+
+  await waitForLoadedPanelsReload();
+
+  info("Reload via the debug target info bar button");
+  clickReload(devtoolsDocument);
+
+  info("Wait until yet another background log message is logged");
+  await waitFor(() => {
+    const newMessage = findMessagesByType(
+      hud,
+      "background script executed",
+      ".console-api"
+    );
+    return (
+      newMessage &&
+      newMessage !== initialMessage &&
+      newMessage !== secondMessage
+    );
+  });
+
+  await waitForLoadedPanelsReload();
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+  await removeTemporaryExtension(ADDON_NAME, document);
+  await removeTab(tab);
+});
+
+function clickReload(devtoolsDocument) {
+  devtoolsDocument.querySelector(".qa-reload-button").click();
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_storage.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_storage.js
new file mode 100644
index 0000000000..56f1b0befb
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_storage.js
@@ -0,0 +1,90 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+add_task(async () => {
+  const EXTENSION_NAME = "temporary-web-extension";
+  const EXTENSION_ID = "test-devtools@mozilla.org";
+
+  await enableExtensionDebugging();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const { extension } = await installTemporaryExtensionFromXPI(
+    {
+      background() {
+        const open = indexedDB.open("TestDatabase", 1);
+
+        open.onupgradeneeded = function () {
+          const db = open.result;
+          db.createObjectStore("TestStore", { keyPath: "id" });
+        };
+
+        open.onsuccess = function () {
+          const db = open.result;
+          const tx = db.transaction("TestStore", "readwrite");
+          const store = tx.objectStore("TestStore");
+
+          store.put({ id: 1, name: "John", age: 12 });
+          store.put({ id: 2, name: "Bob", age: 24 });
+          tx.oncomplete = () => db.close();
+        };
+      },
+      id: EXTENSION_ID,
+      name: EXTENSION_NAME,
+    },
+    document
+  );
+
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    EXTENSION_NAME
+  );
+
+  info("Select the storage panel");
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.selectTool("storage");
+  const storage = toolbox.getCurrentPanel();
+
+  info("Check the content of the storage panel treeview");
+  const ids = [
+    "indexedDB",
+    `moz-extension://${extension.uuid}`,
+    "TestDatabase (default)",
+    "TestStore",
+  ];
+  ok(
+    !!storage.panelWindow.document.querySelector(
+      `[data-id='${JSON.stringify(ids)}']`
+    ),
+    "The indexedDB database for the extension is visible"
+  );
+
+  info("Select the indexedDB database for the extension");
+  const updated = storage.UI.once("store-objects-updated");
+  storage.UI.tree.selectedItem = ids;
+  await updated;
+
+  info("Wait until table populated");
+  await waitUntil(() => storage.UI.table.items.size === 2);
+  const items = storage.UI.table.items;
+
+  info("Check the content of the storage panel table");
+  is(items.size, 2);
+  const user1 = JSON.parse(items.get(1).value);
+  const user2 = JSON.parse(items.get(2).value);
+  is(user1.name, "John", "user 1 has the expected name");
+  is(user1.age, 12, "user 1 has the expected age");
+  is(user2.name, "Bob", "user 2 has the expected name");
+  is(user2.age, 24, "user 2 has the expected age");
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+  await removeTemporaryExtension(EXTENSION_NAME, document);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_toolbox.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_toolbox.js
new file mode 100644
index 0000000000..f21e7d9c4a
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_debug_toolbox.js
@@ -0,0 +1,122 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// There are shutdown issues for which multiple rejections are left uncaught.
+// See bug 1018184 for resolving these issues.
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(/File closed/);
+
+const ADDON_ID = "test-devtools-webextension@mozilla.org";
+const ADDON_NAME = "test-devtools-webextension";
+
+/**
+ * This test file ensures that the webextension addon developer toolbox:
+ * - always on top is enabled by default and can be toggled off
+ */
+add_task(async function testWebExtensionsToolbox() {
+  await enableExtensionDebugging();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtensionFromXPI(
+    {
+      background() {
+        document.body.innerText = "Background Page Body Test Content";
+      },
+      id: ADDON_ID,
+      name: ADDON_NAME,
+    },
+    document
+  );
+
+  info("Open a toolbox to debug the addon");
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    ADDON_NAME
+  );
+
+  const toolbox = getToolbox(devtoolsWindow);
+
+  ok(
+    isWindowAlwaysOnTop(devtoolsWindow),
+    "The toolbox window is always on top"
+  );
+  const toggleButton = toolbox.doc.querySelector(".toolbox-always-on-top");
+  ok(!!toggleButton, "The always on top toggle button is visible");
+  ok(
+    toggleButton.classList.contains("checked"),
+    "The button is highlighted to report that always on top is enabled"
+  );
+
+  // When running the test, the devtools window might not be focused, while it does IRL.
+  // Force it to be focused to better reflect the default behavior.
+  info("Force focusing the devtools window");
+  devtoolsWindow.focus();
+
+  // As we update the button with a debounce, we have to wait for it to updates
+  await waitFor(
+    () => toggleButton.classList.contains("toolbox-is-focused"),
+    "Wait for the button to be highlighting that the toolbox is focused (the button isn't highlighted)"
+  );
+  ok(true, "Expected class is added when toolbox is focused");
+
+  info("Focus the browser window");
+  window.focus();
+
+  await waitFor(
+    () => !toggleButton.classList.contains("toolbox-is-focused"),
+    "Wait for the button to be highlighting that the toolbox is no longer focused (the button is highlighted)"
+  );
+  ok(true, "Focused class is removed when browser window gets focused");
+
+  info("Re-focus the DevTools window");
+  devtoolsWindow.focus();
+
+  await waitFor(
+    () => toggleButton.classList.contains("toolbox-is-focused"),
+    "Wait for the button to be re-highlighting that the toolbox is focused"
+  );
+
+  const onToolboxReady = gDevTools.once("toolbox-ready");
+  info("Click on the button");
+  toggleButton.click();
+
+  info("Wait for a new toolbox to be created");
+  const secondToolbox = await onToolboxReady;
+
+  ok(
+    !isWindowAlwaysOnTop(secondToolbox.win),
+    "The toolbox window is no longer always on top"
+  );
+  const secondToggleButton = secondToolbox.doc.querySelector(
+    ".toolbox-always-on-top"
+  );
+  ok(!!secondToggleButton, "The always on top toggle button is still visible");
+
+  ok(
+    !secondToggleButton.classList.contains("checked"),
+    "The button is no longer highlighted to report that always on top is disabled"
+  );
+
+  await closeWebExtAboutDevtoolsToolbox(secondToolbox.win, window);
+  await removeTemporaryExtension(ADDON_NAME, document);
+  await removeTab(tab);
+});
+
+// Check if the window has the "alwaysontop" chrome flag
+function isWindowAlwaysOnTop(window) {
+  return (
+    window.docShell.treeOwner
+      .QueryInterface(Ci.nsIInterfaceRequestor)
+      .getInterface(Ci.nsIAppWindow).chromeFlags &
+    Ci.nsIWebBrowserChrome.CHROME_ALWAYS_ON_TOP
+  );
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_eventpage_actions_and_status.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_eventpage_actions_and_status.js
new file mode 100644
index 0000000000..0e395704f2
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_eventpage_actions_and_status.js
@@ -0,0 +1,153 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+add_setup(async function () {
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.eventPages.enabled", true]],
+  });
+});
+
+// Test that the terminate button is shutting down the background script as expected
+// and the background script status is updated occordingly.
+add_task(async function test_eventpage_terminate_and_status_updates() {
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const EXTENSION_ID = "test-devtools-eventpage@mozilla.org";
+  const EXTENSION_NAME = "Temporary EventPage-based web extension";
+
+  const EXTENSION2_ID = "test-devtools-persistentbg@mozilla.org";
+  const EXTENSION2_NAME =
+    "Temporary PersistentBackgroundPage-based web extension";
+
+  const promiseBackgroundLoaded = promiseBackgroundContextLoaded(EXTENSION_ID);
+  const promiseBackgroundUnloaded =
+    promiseBackgroundContextUnloaded(EXTENSION_ID);
+
+  let waitForBGStatusUpdate = promiseBackgroundStatusUpdate(window);
+
+  // Install the extension using an event page (non persistent background page).
+  await installTemporaryExtensionFromXPI(
+    {
+      id: EXTENSION_ID,
+      name: EXTENSION_NAME,
+      // The extension is expected to have a non persistent background script.
+      extraProperties: {
+        background: {
+          scripts: ["bgpage.js"],
+          persistent: false,
+        },
+      },
+      files: {
+        "bgpage.js": function () {
+          // Emit a dump when the script is loaded to make it easier
+          // to investigate intermittents.
+          dump(`Background script loaded: ${window.location}\n`);
+        },
+      },
+    },
+    document
+  );
+
+  // Install the extension using a persistent background page.
+  await installTemporaryExtensionFromXPI(
+    {
+      id: EXTENSION2_ID,
+      name: EXTENSION2_NAME,
+      // The extension is expected to have a persistent background script.
+      extraProperties: {
+        background: {
+          page: "bppage.html",
+          persistent: true,
+        },
+      },
+      files: { "bgpage.html": "" },
+    },
+    document
+  );
+
+  const target = findDebugTargetByText(EXTENSION_NAME, document);
+  ok(
+    !!target,
+    "The EventPage-based extension is installed with the expected name"
+  );
+
+  const target2 = findDebugTargetByText(EXTENSION2_NAME, document);
+  ok(
+    !!target2,
+    "The PersistentBackgroundScript-based extension is installed with the expected name"
+  );
+
+  const terminateButton = target.querySelector(
+    ".qa-temporary-extension-terminate-bgscript-button"
+  );
+  ok(
+    !!terminateButton,
+    `${EXTENSION_NAME} is expected to have a terminate button`
+  );
+
+  const terminateButton2 = target2.querySelector(
+    ".qa-temporary-extension-terminate-bgscript-button"
+  );
+  ok(
+    !terminateButton2,
+    `${EXTENSION2_NAME} is expected to not have a terminate button`
+  );
+
+  info("Wait for the test extension background script to be loaded");
+  await promiseBackgroundLoaded;
+
+  info("Wait for the test extension background script status update");
+  await waitForBGStatusUpdate;
+
+  await assertBackgroundStatus(EXTENSION_NAME, {
+    document,
+    expectedStatus: "running",
+  });
+
+  // Verify in the card related to extensions with a persistent background page
+  // the background script status is not being rendered at all.
+  const backgroundStatus2 = target2.querySelector(
+    ".extension-backgroundscript__status"
+  );
+  ok(
+    !backgroundStatus2,
+    `${EXTENSION2_NAME} should not be showing background script status`
+  );
+
+  info(`Click on the terminate button for ${EXTENSION_NAME}`);
+  const waitForTerminateSuccess = waitForDispatch(
+    window.AboutDebugging.store,
+    "TERMINATE_EXTENSION_BGSCRIPT_SUCCESS"
+  );
+  waitForBGStatusUpdate = promiseBackgroundStatusUpdate(window);
+  terminateButton.click();
+  await waitForTerminateSuccess;
+
+  info("Wait for the extension background script to be unloaded");
+  await promiseBackgroundUnloaded;
+  await waitForBGStatusUpdate;
+  await assertBackgroundStatus(EXTENSION_NAME, {
+    document,
+    expectedStatus: "stopped",
+  });
+
+  // Uninstall the test extensions.
+  await Promise.all([
+    AddonManager.getAddonByID(EXTENSION_ID).then(addon => addon.uninstall()),
+    AddonManager.getAddonByID(EXTENSION2_ID).then(addon => addon.uninstall()),
+  ]);
+
+  info("Wait until the debug targets with test extensions disappears");
+  await waitUntil(
+    () =>
+      !findDebugTargetByText(EXTENSION_NAME, document) &&
+      !findDebugTargetByText(EXTENSION2_NAME, document)
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_eventpage_terminate_on_idle.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_eventpage_terminate_on_idle.js
new file mode 100644
index 0000000000..1b43808fa2
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_eventpage_terminate_on_idle.js
@@ -0,0 +1,200 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+add_setup(async function () {
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.eventPages.enabled", true]],
+  });
+});
+
+// Test that an extension event page isn't terminated on idle when a DevTools
+// Toolbox is attached to the extension.
+add_task(
+  async function test_eventpage_no_idle_shutdown_with_toolbox_attached() {
+    const { document, tab, window } = await openAboutDebugging();
+    await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+    const EXTENSION_ID = "test-devtools-eventpage@mozilla.org";
+    const EXTENSION_NAME = "Temporary EventPage-based web extension";
+
+    const promiseBackgroundLoaded =
+      promiseBackgroundContextLoaded(EXTENSION_ID);
+
+    let waitForBGStatusUpdate = promiseBackgroundStatusUpdate(window);
+
+    // Install the extension using an event page (non persistent background page).
+    await installTemporaryExtensionFromXPI(
+      {
+        id: EXTENSION_ID,
+        name: EXTENSION_NAME,
+        // The extension is expected to have a non persistent background script.
+        extraProperties: {
+          background: {
+            scripts: ["bgpage.js"],
+            persistent: false,
+          },
+        },
+        files: {
+          "bgpage.js": function () {
+            // Emit a dump when the script is loaded to make it easier
+            // to investigate intermittents.
+            dump(`Background script loaded: ${window.location}\n`);
+          },
+        },
+      },
+      document
+    );
+
+    const target = findDebugTargetByText(EXTENSION_NAME, document);
+    ok(
+      !!target,
+      "The EventPage-based extension is installed with the expected name"
+    );
+
+    info("Wait for the test extension background script to be loaded");
+    await promiseBackgroundLoaded;
+
+    info("Wait for the test extension background script status update");
+    await waitForBGStatusUpdate;
+    await assertBackgroundStatus(EXTENSION_NAME, {
+      document,
+      expectedStatus: "running",
+    });
+
+    waitForBGStatusUpdate = promiseBackgroundStatusUpdate(window);
+    await triggerExtensionEventPageIdleTimeout(EXTENSION_ID);
+    await waitForBGStatusUpdate;
+    await assertBackgroundStatus(EXTENSION_NAME, {
+      document,
+      expectedStatus: "stopped",
+    });
+
+    info(
+      "Respawn the extension background script on new WebExtension API event"
+    );
+    waitForBGStatusUpdate = promiseBackgroundStatusUpdate(window);
+    await wakeupExtensionEventPage(EXTENSION_ID);
+    await waitForBGStatusUpdate;
+    await assertBackgroundStatus(EXTENSION_NAME, {
+      document,
+      expectedStatus: "running",
+    });
+
+    info("Open a DevTools toolbox on the target extension");
+    const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+      document,
+      tab,
+      window,
+      EXTENSION_NAME
+    );
+
+    info(
+      "Verify event page terminated on terminate button clicked while the DevTools toolbox is open"
+    );
+    const terminateButton = target.querySelector(
+      ".qa-temporary-extension-terminate-bgscript-button"
+    );
+    ok(
+      !!terminateButton,
+      `${EXTENSION_NAME} is expected to have a terminate button`
+    );
+
+    info(`Click on the terminate button for ${EXTENSION_NAME}`);
+    const promiseBackgroundUnloaded =
+      promiseBackgroundContextUnloaded(EXTENSION_ID);
+    const waitForTerminateSuccess = waitForDispatch(
+      window.AboutDebugging.store,
+      "TERMINATE_EXTENSION_BGSCRIPT_SUCCESS"
+    );
+    waitForBGStatusUpdate = promiseBackgroundStatusUpdate(window);
+    terminateButton.click();
+    await waitForTerminateSuccess;
+
+    info("Wait for the extension background script to be unloaded");
+    await promiseBackgroundUnloaded;
+    await waitForBGStatusUpdate;
+    await assertBackgroundStatus(EXTENSION_NAME, {
+      document,
+      expectedStatus: "stopped",
+      targetElement: target,
+    });
+
+    info(
+      "Verify event page isn't terminated on idle while the DevTools toolbox is open"
+    );
+
+    // Make sure the event page is running again.
+    waitForBGStatusUpdate = promiseBackgroundStatusUpdate(window);
+    await wakeupExtensionEventPage(EXTENSION_ID);
+    await waitForBGStatusUpdate;
+    await assertBackgroundStatus(EXTENSION_NAME, {
+      document,
+      expectedStatus: "running",
+      targetElement: target,
+    });
+
+    const waitForBGSuspendIgnored =
+      promiseTerminateBackgroundScriptIgnored(EXTENSION_ID);
+    waitForBGStatusUpdate = promiseBackgroundStatusUpdate(window);
+    await triggerExtensionEventPageIdleTimeout(EXTENSION_ID);
+    await Promise.race([waitForBGStatusUpdate, waitForBGSuspendIgnored]);
+
+    await assertBackgroundStatus(EXTENSION_NAME, {
+      document,
+      expectedStatus: "running",
+      // After opening the toolbox there will be an additional target listed
+      // for the devtools toolbox tab, its card includes the extension name
+      // and so while the toolbox is open we should make sure to look for
+      // the background status inside the extension target card instead of
+      // the one associated to the devtools toolbox tab.
+      targetElement: target,
+    });
+
+    info(
+      "Wait for warning message expected to be logged for the event page not terminated on idle"
+    );
+    const toolbox = getToolbox(devtoolsWindow);
+    const webconsole = await toolbox.selectTool("webconsole");
+    const { hud } = webconsole;
+    const expectedWarning =
+      "Background event page was not terminated on idle because a DevTools toolbox is attached to the extension.";
+    let consoleElements;
+    await waitUntil(() => {
+      consoleElements = findMessagesByType(hud, expectedWarning, ".warn");
+      return !!consoleElements.length;
+    });
+
+    const locationElement = consoleElements[0].querySelector(
+      ".frame-link-filename"
+    );
+    ok(
+      locationElement.textContent.endsWith("_generated_background_page.html"),
+      "The warning message is associated to the event page url"
+    );
+
+    info(
+      "Verify event page is terminated on idle after closing the DevTools toolbox"
+    );
+
+    await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+    await triggerExtensionEventPageIdleTimeout(EXTENSION_ID);
+    await waitForBGStatusUpdate;
+    await assertBackgroundStatus(EXTENSION_NAME, {
+      document,
+      expectedStatus: "stopped",
+    });
+
+    // Uninstall the test extensions.
+    info("Unload extension and remove about:debugging tab");
+    await AddonManager.getAddonByID(EXTENSION_ID).then(addon =>
+      addon.uninstall()
+    );
+    info("Wait until the debug targets with test extensions disappears");
+    await waitUntil(() => !findDebugTargetByText(EXTENSION_NAME, document));
+    await removeTab(tab);
+  }
+);
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_manifest_url.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_manifest_url.js
new file mode 100644
index 0000000000..6420a076b0
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_manifest_url.js
@@ -0,0 +1,73 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  adbAddon,
+} = require("resource://devtools/client/shared/remote-debugging/adb/adb-addon.js");
+
+const ABD_ADDON_NAME = "ADB binary provider";
+
+/* import-globals-from helper-adb.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-adb.js", this);
+
+// Test that manifest URLs for addon targets show the manifest correctly in a new tab.
+// This test reuses the ADB extension to be sure to have a valid manifest URL to open.
+add_task(async function () {
+  await pushPref(
+    "devtools.remote.adb.extensionURL",
+    CHROME_URL_ROOT + "resources/test-adb-extension/adb-extension-#OS#.xpi"
+  );
+  await checkAdbNotRunning();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const usbStatusElement = document.querySelector(".qa-sidebar-usb-status");
+
+  info("Install ADB");
+  adbAddon.install("internal");
+  await waitUntil(() => usbStatusElement.textContent.includes("USB enabled"));
+  await waitForAdbStart();
+
+  info("Wait until the debug target for ADB appears");
+  await waitUntil(() => findDebugTargetByText(ABD_ADDON_NAME, document));
+  const adbExtensionItem = findDebugTargetByText(ABD_ADDON_NAME, document);
+
+  const manifestUrlElement = adbExtensionItem.querySelector(".qa-manifest-url");
+  ok(manifestUrlElement, "A link to the manifest is displayed");
+
+  info("Click on the manifest URL and wait for the new tab to open");
+  const onTabOpened = once(gBrowser.tabContainer, "TabOpen");
+  manifestUrlElement.click();
+  const { target } = await onTabOpened;
+  await BrowserTestUtils.browserLoaded(target.linkedBrowser);
+
+  info("Retrieve the text content of the new tab");
+  const textContent = await SpecialPowers.spawn(
+    target.linkedBrowser,
+    [],
+    function () {
+      return content.wrappedJSObject.document.body.textContent;
+    }
+  );
+
+  const manifestObject = JSON.parse(textContent);
+  ok(manifestObject, "The displayed content is a valid JSON object");
+  is(
+    manifestObject.name,
+    ABD_ADDON_NAME,
+    "Manifest tab shows the expected content"
+  );
+
+  info("Close the manifest.json tab");
+  await removeTab(target);
+
+  info("Uninstall the adb extension and wait for the message to udpate");
+  adbAddon.uninstall();
+  await waitUntil(() => usbStatusElement.textContent.includes("USB disabled"));
+  await stopAdbProcess();
+
+  await waitForAboutDebuggingRequests(window.AboutDebugging.store);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_popup_picker.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_popup_picker.js
new file mode 100644
index 0000000000..fc67bc7f7c
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_popup_picker.js
@@ -0,0 +1,99 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// There are shutdown issues for which multiple rejections are left uncaught.
+// See bug 1018184 for resolving these issues.
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(/File closed/);
+
+const ADDON_ID = "test-devtools-webextension@mozilla.org";
+const ADDON_NAME = "test-devtools-webextension";
+
+/**
+ * Check that the node picker can be used when dynamically navigating to a
+ * webextension popup.
+ */
+add_task(async function testNodePickerInExtensionPopup() {
+  await enableExtensionDebugging();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Note that this extension should not define a background script in order to
+  // reproduce the issue. Otherwise opening the popup does not trigger an auto
+  // navigation from DevTools and you have to use the "Disable Popup Auto Hide"
+  // feature which works around the bug tested here.
+  await installTemporaryExtensionFromXPI(
+    {
+      extraProperties: {
+        browser_action: {
+          default_title: "WebExtension with popup",
+          default_popup: "popup.html",
+        },
+      },
+      files: {
+        "popup.html": `<!DOCTYPE html>
+        <html>
+          <body>
+            <div id="pick-me"
+                 style="width:100px; height: 60px; background-color: #f5e8fc">
+              Pick me!
+            </div>
+          </body>
+        </html>
+      `,
+      },
+      id: ADDON_ID,
+      name: ADDON_NAME,
+    },
+    document
+  );
+
+  const { devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    ADDON_NAME
+  );
+  const toolbox = getToolbox(devtoolsWindow);
+  const inspector = await toolbox.getPanel("inspector");
+
+  info("Start the node picker");
+  await toolbox.nodePicker.start();
+
+  info("Open the webextension popup");
+  // Clicking on the addon popup will trigger a navigation between the DevTools
+  // fallback document and the popup document.
+  // Wait until the inspector was fully reloaded and for the node-picker to be
+  // restarted.
+  const nodePickerRestarted = toolbox.nodePicker.once(
+    "node-picker-webextension-target-restarted"
+  );
+  const reloaded = inspector.once("reloaded");
+  clickOnAddonWidget(ADDON_ID);
+  await reloaded;
+  await nodePickerRestarted;
+
+  const popup = await waitFor(() =>
+    gBrowser.ownerDocument.querySelector(".webextension-popup-browser")
+  );
+
+  info("Pick an element inside the webextension popup");
+  const onNewNodeFront = inspector.selection.once("new-node-front");
+  BrowserTestUtils.synthesizeMouseAtCenter(
+    "#pick-me",
+    {},
+    popup.browsingContext
+  );
+  const nodeFront = await onNewNodeFront;
+  is(nodeFront.id, "pick-me", "The expected node front was selected");
+
+  await closeWebExtAboutDevtoolsToolbox(devtoolsWindow, window);
+  await removeTemporaryExtension(ADDON_NAME, document);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_remote_runtime.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_remote_runtime.js
new file mode 100644
index 0000000000..607b8e15b4
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_remote_runtime.js
@@ -0,0 +1,145 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const NETWORK_RUNTIME_HOST = "localhost:6080";
+const NETWORK_RUNTIME_APP_NAME = "TestNetworkApp";
+const USB_RUNTIME_ID = "test-runtime-id";
+const USB_RUNTIME_DEVICE_NAME = "test device name";
+const USB_RUNTIME_APP_NAME = "TestUsbApp";
+
+// Test that addons are displayed and updated for USB runtimes when expected.
+add_task(async function () {
+  const mocks = new Mocks();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Prepare USB client mock");
+  const usbClient = mocks.createUSBRuntime(USB_RUNTIME_ID, {
+    deviceName: USB_RUNTIME_DEVICE_NAME,
+    name: USB_RUNTIME_APP_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Test addons in runtime page for USB client");
+  await connectToRuntime(USB_RUNTIME_DEVICE_NAME, document);
+  await selectRuntime(USB_RUNTIME_DEVICE_NAME, USB_RUNTIME_APP_NAME, document);
+  await testAddonsOnMockedRemoteClient(
+    usbClient,
+    mocks.thisFirefoxClient,
+    document
+  );
+
+  info("Prepare Network client mock");
+  const networkClient = mocks.createNetworkRuntime(NETWORK_RUNTIME_HOST, {
+    name: NETWORK_RUNTIME_APP_NAME,
+  });
+
+  info("Test addons in runtime page for Network client");
+  await connectToRuntime(NETWORK_RUNTIME_HOST, document);
+  await selectRuntime(NETWORK_RUNTIME_HOST, NETWORK_RUNTIME_APP_NAME, document);
+  await testAddonsOnMockedRemoteClient(
+    networkClient,
+    mocks.thisFirefoxClient,
+    document
+  );
+
+  await removeTab(tab);
+});
+
+/**
+ * Check that addons are visible in the runtime page for a remote client (USB or network).
+ */
+async function testAddonsOnMockedRemoteClient(
+  remoteClient,
+  firefoxClient,
+  document
+) {
+  const extensionPane = getDebugTargetPane("Extensions", document);
+  info("Check an empty target pane message is displayed");
+  ok(
+    extensionPane.querySelector(".qa-debug-target-list-empty"),
+    "Extensions list is empty"
+  );
+
+  info("Add an extension to the remote client");
+  const addon = { name: "Test extension name", debuggable: true };
+  const temporaryAddon = {
+    name: "Test temporary extension",
+    debuggable: true,
+    temporarilyInstalled: true,
+  };
+  remoteClient.listAddons = () => [addon, temporaryAddon];
+  remoteClient._eventEmitter.emit("addonListChanged");
+
+  info("Wait until the extension appears");
+  await waitUntil(
+    () => !extensionPane.querySelector(".qa-debug-target-list-empty")
+  );
+
+  const extensionTarget = findDebugTargetByText(
+    "Test extension name",
+    document
+  );
+  ok(extensionTarget, "Extension target appeared for the remote runtime");
+
+  const temporaryExtensionTarget = findDebugTargetByText(
+    "Test temporary extension",
+    document
+  );
+  ok(
+    temporaryExtensionTarget,
+    "Temporary Extension target appeared for the remote runtime"
+  );
+
+  const removeButton = temporaryExtensionTarget.querySelector(
+    ".qa-temporary-extension-remove-button"
+  );
+  ok(removeButton, "Remove button expected for the temporary extension");
+
+  const reloadButton = temporaryExtensionTarget.querySelector(
+    ".qa-temporary-extension-reload-button"
+  );
+  ok(reloadButton, "Reload button expected for the temporary extension");
+
+  // The goal here is to check that runtimes addons are only updated when the remote
+  // runtime is sending addonListChanged events. The reason for this test is because the
+  // previous implementation was updating the remote runtime extensions list when the
+  // _local_ AddonManager was updated.
+  info("Remove the extension from the remote client WITHOUT sending an event");
+  remoteClient.listAddons = () => [];
+
+  info("Simulate an addon update on the ThisFirefox client");
+  firefoxClient._eventEmitter.emit("addonListChanged");
+
+  // To avoid wait for a set period of time we trigger another async update, adding a new
+  // tab. We assume that if the addon update mechanism had started, it would also be done
+  // when the new tab was processed.
+  info("Wait until the tab target for 'http://some.random/url.com' appears");
+  const testTab = {
+    retrieveFavicon: () => {},
+    outerWindowID: 0,
+    traits: {},
+    url: "http://some.random/url.com",
+  };
+  remoteClient.listTabs = () => [testTab];
+  remoteClient._eventEmitter.emit("tabListChanged");
+  await waitUntil(() =>
+    findDebugTargetByText("http://some.random/url.com", document)
+  );
+
+  ok(
+    findDebugTargetByText("Test extension name", document),
+    "The test extension is still visible"
+  );
+
+  info(
+    "Emit `addonListChanged` on remoteClient and wait for the target list to update"
+  );
+  remoteClient._eventEmitter.emit("addonListChanged");
+  await waitUntil(
+    () => !findDebugTargetByText("Test extension name", document)
+  );
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_addon_buttons.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_addon_buttons.js
new file mode 100644
index 0000000000..26b558ff37
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_addon_buttons.js
@@ -0,0 +1,116 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// Test that the reload button updates the addon list with the correct metadata.
+add_task(async function () {
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const ORIGINAL_EXTENSION_NAME = "Temporary web extension (original)";
+  const UPDATED_EXTENSION_NAME = "Temporary web extension (updated)";
+  const EXTENSION_ID = "test-devtools@mozilla.org";
+
+  const { xpiFile: addonFile } = await installTemporaryExtensionFromXPI(
+    {
+      id: EXTENSION_ID,
+      name: ORIGINAL_EXTENSION_NAME,
+    },
+    document
+  );
+
+  const originalTarget = findDebugTargetByText(
+    ORIGINAL_EXTENSION_NAME,
+    document
+  );
+  ok(
+    !!originalTarget,
+    "The temporary extension isinstalled with the expected name"
+  );
+
+  info("Update the name of the temporary extension in the manifest");
+  updateTemporaryXPI(
+    { id: EXTENSION_ID, name: UPDATED_EXTENSION_NAME },
+    addonFile
+  );
+
+  info("Click on the reload button for the temporary extension");
+  const reloadButton = originalTarget.querySelector(
+    ".qa-temporary-extension-reload-button"
+  );
+  reloadButton.click();
+
+  info(
+    "Wait until the debug target with the original extension name disappears"
+  );
+  await waitUntil(
+    () => !findDebugTargetByText(ORIGINAL_EXTENSION_NAME, document)
+  );
+
+  info("Wait until the debug target with the updated extension name appears");
+  await waitUntil(() =>
+    findDebugTargetByText(UPDATED_EXTENSION_NAME, document)
+  );
+
+  const updatedTarget = findDebugTargetByText(UPDATED_EXTENSION_NAME, document);
+  ok(!!updatedTarget, "The temporary extension name has been updated");
+
+  info("Click on the remove button for the temporary extension");
+  const removeButton = updatedTarget.querySelector(
+    ".qa-temporary-extension-remove-button"
+  );
+  removeButton.click();
+
+  info(
+    "Wait until the debug target with the updated extension name disappears"
+  );
+  await waitUntil(
+    () => !findDebugTargetByText(UPDATED_EXTENSION_NAME, document)
+  );
+
+  await removeTab(tab);
+});
+
+add_task(async function () {
+  const PACKAGED_EXTENSION_ID = "packaged-extension@tests";
+  const PACKAGED_EXTENSION_NAME = "Packaged extension";
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installRegularExtension(
+    "resources/packaged-extension/packaged-extension.xpi"
+  );
+
+  info("Wait until extension appears in about:debugging");
+  await waitUntil(() =>
+    findDebugTargetByText(PACKAGED_EXTENSION_NAME, document)
+  );
+  const target = findDebugTargetByText(PACKAGED_EXTENSION_NAME, document);
+
+  const reloadButton = target.querySelector(
+    ".qa-temporary-extension-reload-button"
+  );
+  ok(
+    !reloadButton,
+    "No reload button displayed for a regularly installed extension"
+  );
+
+  const removeButton = target.querySelector(
+    ".qa-temporary-extension-remove-button"
+  );
+  ok(
+    !removeButton,
+    "No remove button displayed for a regularly installed extension"
+  );
+
+  await removeExtension(
+    PACKAGED_EXTENSION_ID,
+    PACKAGED_EXTENSION_NAME,
+    document
+  );
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_id_message.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_id_message.js
new file mode 100644
index 0000000000..6e0b21fb20
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_id_message.js
@@ -0,0 +1,70 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// Test that temporary extensions show a message about temporary ids, with a learn more
+// link.
+add_task(async function () {
+  const EXTENSION_NAME = "Temporary web extension";
+  const EXTENSION_ID = "test-devtools@mozilla.org";
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtensionFromXPI(
+    {
+      id: EXTENSION_ID,
+      name: EXTENSION_NAME,
+    },
+    document
+  );
+
+  info("Wait until a debug target item appears");
+  await waitUntil(() => findDebugTargetByText(EXTENSION_NAME, document));
+
+  const target = findDebugTargetByText(EXTENSION_NAME, document);
+
+  const message = target.querySelector(".qa-temporary-id-message");
+  ok(!!message, "Temporary id message is displayed for temporary extensions");
+
+  const link = target.querySelector(".qa-temporary-id-link");
+  ok(!!link, "Temporary id link is displayed for temporary extensions");
+
+  await removeTemporaryExtension(EXTENSION_NAME, document);
+  await removeTab(tab);
+});
+
+// Test that the message and the link are not displayed for a regular extension.
+add_task(async function () {
+  const PACKAGED_EXTENSION_ID = "packaged-extension@tests";
+  const PACKAGED_EXTENSION_NAME = "Packaged extension";
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installRegularExtension(
+    "resources/packaged-extension/packaged-extension.xpi"
+  );
+
+  info("Wait until extension appears in about:debugging");
+  await waitUntil(() =>
+    findDebugTargetByText(PACKAGED_EXTENSION_NAME, document)
+  );
+  const target = findDebugTargetByText(PACKAGED_EXTENSION_NAME, document);
+
+  const tmpIdMessage = target.querySelector(".qa-temporary-id-message");
+  ok(
+    !tmpIdMessage,
+    "No temporary id message is displayed for a regular extension"
+  );
+
+  await removeExtension(
+    PACKAGED_EXTENSION_ID,
+    PACKAGED_EXTENSION_NAME,
+    document
+  );
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_install_error.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_install_error.js
new file mode 100644
index 0000000000..21a30ab3bf
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_install_error.js
@@ -0,0 +1,89 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+/**
+ * Test that the installation error messages are displayed when installing temporary
+ * extensions.
+ */
+
+const INVALID_JSON_EXTENSION_PATH =
+  "resources/bad-extensions/invalid-json/manifest.json";
+const INVALID_PROP_EXTENSION_PATH =
+  "resources/bad-extensions/invalid-property/manifest.json";
+const EXTENSION_PATH = "resources/test-temporary-extension/manifest.json";
+const EXTENSION_NAME = "test-temporary-extension";
+
+// Extension with an invalid JSON manifest will not be parsed. We check the expected
+// error message is displayed
+add_task(async function testInvalidJsonExtension() {
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const installError = await installBadExtension(
+    INVALID_JSON_EXTENSION_PATH,
+    document
+  );
+  ok(
+    installError.textContent.includes("JSON.parse: unexpected keyword"),
+    "The expected installation error is displayed: " + installError.textContent
+  );
+
+  info("Install a valid extension to make the message disappear");
+  await installTemporaryExtension(EXTENSION_PATH, EXTENSION_NAME, document);
+
+  info("Wait until the error message disappears");
+  await waitUntil(
+    () => !document.querySelector(".qa-tmp-extension-install-error")
+  );
+
+  info("Wait for the temporary addon to be displayed as a debug target");
+  await waitUntil(() => findDebugTargetByText(EXTENSION_NAME, document));
+
+  await removeTemporaryExtension(EXTENSION_NAME, document);
+
+  await removeTab(tab);
+});
+
+// Extension with a valid JSON manifest but containing an invalid property should display
+// a detailed error message coming from the Addon Manager.
+add_task(async function testInvalidPropertyExtension() {
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const installError = await installBadExtension(
+    INVALID_PROP_EXTENSION_PATH,
+    document
+  );
+
+  ok(
+    installError.textContent.includes("Extension is invalid"),
+    "The basic installation error is displayed: " + installError.textContent
+  );
+  ok(
+    installError.textContent.includes(
+      "Reading manifest: Error processing content_scripts.0.matches"
+    ),
+    "The detailed installation error is also displayed: " +
+      installError.textContent
+  );
+
+  await removeTab(tab);
+});
+
+async function installBadExtension(path, document) {
+  info("Install a bad extension at path: " + path);
+  // Do not use installTemporaryAddon here since the install will fail.
+  prepareMockFilePicker(path);
+  document.querySelector(".qa-temporary-extension-install-button").click();
+
+  info("Wait until the install error message appears");
+  await waitUntil(() =>
+    document.querySelector(".qa-tmp-extension-install-error")
+  );
+  return document.querySelector(".qa-tmp-extension-install-error");
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_install_path.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_install_path.js
new file mode 100644
index 0000000000..a6f9fde0c1
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_install_path.js
@@ -0,0 +1,65 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+/**
+ * Test the the path used to install a temporary addon is saved in a preference and reused
+ * next time the feature is used.
+ */
+
+const EXTENSION_PATH = "resources/test-temporary-extension/manifest.json";
+const EXTENSION_NAME = "test-temporary-extension";
+const LAST_DIR_PREF = "devtools.aboutdebugging.tmpExtDirPath";
+
+// Check that the preference is updated when trying to install a temporary extension.
+add_task(async function testPreferenceUpdatedAfterInstallingExtension() {
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref(LAST_DIR_PREF);
+  });
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await installTemporaryExtension(EXTENSION_PATH, EXTENSION_NAME, document);
+
+  info("Check whether the selected dir sets into the pref");
+  const lastDirPath = Services.prefs.getCharPref(LAST_DIR_PREF, "");
+  const expectedPath = getTestFilePath("resources/test-temporary-extension");
+  is(lastDirPath, expectedPath, "The selected dir should set into the pref");
+
+  await waitUntil(() => findDebugTargetByText(EXTENSION_NAME, document));
+  await removeTemporaryExtension(EXTENSION_NAME, document);
+  await removeTab(tab);
+});
+
+// Check that the preference is updated when trying to install a temporary extension.
+add_task(async function testPreferenceRetrievedWhenInstallingExtension() {
+  const selectedDir = getTestFilePath("resources/packaged-extension");
+
+  await pushPref(LAST_DIR_PREF, selectedDir);
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const MockFilePicker = SpecialPowers.MockFilePicker;
+  MockFilePicker.init(window);
+  const onFilePickerShown = new Promise(resolve => {
+    MockFilePicker.showCallback = fp => {
+      resolve(fp);
+    };
+  });
+  document.querySelector(".qa-temporary-extension-install-button").click();
+
+  info("Check whether the shown dir is same as the pref");
+  const fp = await onFilePickerShown;
+  is(
+    fp.displayDirectory.path,
+    selectedDir,
+    "Shown directory sets as same as the pref"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_reload_error.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_reload_error.js
new file mode 100644
index 0000000000..da09727d9e
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_temporary_reload_error.js
@@ -0,0 +1,68 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// Test that the reload button updates the addon list with the correct metadata.
+add_task(async function () {
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const EXTENSION_ID = "test-devtools@mozilla.org";
+  const EXTENSION_NAME = "Temporary web extension";
+
+  let { xpiFile: addonFile } = await installTemporaryExtensionFromXPI(
+    {
+      id: EXTENSION_ID,
+      name: EXTENSION_NAME,
+    },
+    document
+  );
+
+  const target = findDebugTargetByText(EXTENSION_NAME, document);
+  ok(!!target, "The temporary extension is installed with the expected name");
+
+  info("Update the name of the temporary extension in the manifest");
+  addonFile = updateTemporaryXPI({ id: EXTENSION_ID }, addonFile);
+
+  info("Click on the reload button for the invalid temporary extension");
+  const waitForError = waitForDispatch(
+    window.AboutDebugging.store,
+    "TEMPORARY_EXTENSION_RELOAD_FAILURE"
+  );
+  const reloadButton = target.querySelector(
+    ".qa-temporary-extension-reload-button"
+  );
+  reloadButton.click();
+  await waitForError;
+  ok(
+    target.querySelector(".qa-temporary-extension-reload-error"),
+    "The error message of reloading appears"
+  );
+
+  info("Click on the reload button for the valid temporary extension");
+  const waitForSuccess = waitForDispatch(
+    window.AboutDebugging.store,
+    "TEMPORARY_EXTENSION_RELOAD_SUCCESS"
+  );
+  updateTemporaryXPI({ id: EXTENSION_ID, name: EXTENSION_NAME }, addonFile);
+  reloadButton.click();
+  await waitForSuccess;
+  ok(
+    !target.querySelector(".qa-temporary-extension-reload-error"),
+    "The error message of reloading disappears"
+  );
+
+  info("Click on the remove button for the temporary extension");
+  const removeButton = target.querySelector(
+    ".qa-temporary-extension-remove-button"
+  );
+  removeButton.click();
+
+  info("Wait until the debug target with the extension disappears");
+  await waitUntil(() => !findDebugTargetByText(EXTENSION_NAME, document));
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_warnings.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_warnings.js
new file mode 100644
index 0000000000..db46754caa
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_addons_warnings.js
@@ -0,0 +1,49 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+// Test that extension warnings are displayed in about:debugging.
+add_task(async function () {
+  const EXTENSION_NAME = "Temporary web extension";
+  const EXTENSION_ID = "test-devtools@mozilla.org";
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await pushPref("extensions.webextensions.warnings-as-errors", false);
+  await installTemporaryExtensionFromXPI(
+    {
+      id: EXTENSION_ID,
+      name: EXTENSION_NAME,
+      extraProperties: {
+        // This property is not expected in the manifest and should trigger a warning!
+        wrongProperty: {},
+      },
+    },
+    document
+  );
+  await SpecialPowers.popPrefEnv();
+
+  info("Wait until a debug target item appears");
+  await waitUntil(() => findDebugTargetByText(EXTENSION_NAME, document));
+  const target = findDebugTargetByText(EXTENSION_NAME, document);
+
+  const warningMessage = target.querySelector(".qa-message");
+  ok(
+    !!warningMessage,
+    "A warning message is displayed for the installed addon"
+  );
+
+  const warningText = warningMessage.textContent;
+  ok(
+    warningText.includes("wrongProperty"),
+    "The warning message mentions wrongProperty"
+  );
+
+  await removeTemporaryExtension(EXTENSION_NAME, document);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_connect_networklocations.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_connect_networklocations.js
new file mode 100644
index 0000000000..92096703ac
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_connect_networklocations.js
@@ -0,0 +1,103 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test the network locations form of the Connect page.
+ * Check that a network location can be added and removed.
+ */
+
+const TEST_NETWORK_LOCATION = "localhost:1111";
+const TEST_NETWORK_LOCATION_INVALID = "testnetwork";
+
+add_task(async function () {
+  const { document, tab } = await openAboutDebugging();
+
+  await selectConnectPage(document);
+
+  let networkLocations = document.querySelectorAll(".qa-network-location");
+  is(
+    networkLocations.length,
+    0,
+    "By default, no network locations are displayed"
+  );
+
+  info("Check whether error message should show if the input value is invalid");
+  addNetworkLocation(TEST_NETWORK_LOCATION_INVALID, document);
+  await waitUntil(() =>
+    document.querySelector(".qa-connect-page__network-form__error-message")
+  );
+
+  info("Wait until the new network location is visible in the list");
+  addNetworkLocation(TEST_NETWORK_LOCATION, document);
+  await waitUntil(
+    () => document.querySelectorAll(".qa-network-location").length === 1
+  );
+  await waitUntil(
+    () =>
+      !document.querySelector(".qa-connect-page__network-form__error-message")
+  );
+
+  networkLocations = document.querySelectorAll(".qa-network-location");
+  const networkLocationValue = networkLocations[0].querySelector(
+    ".qa-network-location-value"
+  );
+  is(
+    networkLocationValue.textContent,
+    TEST_NETWORK_LOCATION,
+    "Added network location has the expected value"
+  );
+
+  info(
+    "Check whether error message should show if the input value was duplicate"
+  );
+  addNetworkLocation(TEST_NETWORK_LOCATION, document);
+  await waitUntil(() =>
+    document.querySelector(".qa-connect-page__network-form__error-message")
+  );
+
+  info("Wait until the new network location is removed from the list");
+  removeNetworkLocation(TEST_NETWORK_LOCATION, document);
+  await waitUntil(
+    () => document.querySelectorAll(".qa-network-location").length === 0
+  );
+
+  await removeTab(tab);
+});
+
+function addNetworkLocation(location, document) {
+  info("Setting a value in the network form input");
+  const networkLocationInput = document.querySelector(".qa-network-form-input");
+  networkLocationInput.value = "";
+  networkLocationInput.focus();
+  EventUtils.sendString(location, networkLocationInput.ownerGlobal);
+
+  info("Click on network form submit button");
+  const networkLocationSubmitButton = document.querySelector(
+    ".qa-network-form-submit-button"
+  );
+  networkLocationSubmitButton.click();
+}
+
+function removeNetworkLocation(location, document) {
+  const networkLocation = getNetworkLocation(location, document);
+  ok(networkLocation, "Network location container found.");
+
+  info("Click on the remove button for the provided network location");
+  const removeButton = networkLocation.querySelector(
+    ".qa-network-location-remove-button"
+  );
+  removeButton.click();
+}
+
+function getNetworkLocation(location, document) {
+  info("Find the container for network location: " + location);
+  const networkLocations = document.querySelectorAll(".qa-network-location");
+  return [...networkLocations].find(element => {
+    return (
+      element.querySelector(".qa-network-location-value").textContent ===
+      location
+    );
+  });
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_connect_toggle_usb_devices.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_connect_toggle_usb_devices.js
new file mode 100644
index 0000000000..e0d7303669
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_connect_toggle_usb_devices.js
@@ -0,0 +1,81 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-adb.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-adb.js", this);
+
+/**
+ * Check that USB Devices scanning can be enabled and disabled from the connect page.
+ */
+add_task(async function () {
+  await pushPref(
+    "devtools.remote.adb.extensionURL",
+    CHROME_URL_ROOT + "resources/test-adb-extension/adb-extension-#OS#.xpi"
+  );
+  await checkAdbNotRunning();
+
+  const { document, tab } = await openAboutDebugging();
+
+  await selectConnectPage(document);
+
+  info("Wait until Connect page is displayed");
+  await waitUntil(() => document.querySelector(".qa-connect-page"));
+
+  info("Check that by default USB devices are disabled");
+  const usbDisabledMessage = document.querySelector(
+    ".qa-connect-usb-disabled-message"
+  );
+  ok(usbDisabledMessage, "A message about enabling USB devices is rendered");
+
+  const usbToggleButton = document.querySelector(
+    ".qa-connect-usb-toggle-button"
+  );
+  ok(usbToggleButton, "The button to toggle USB devices debugging is rendered");
+  ok(
+    usbToggleButton.textContent.includes("Enable"),
+    "The text of the toggle USB button is correct"
+  );
+
+  info("Click on the toggle button");
+  usbToggleButton.click();
+
+  info("Wait until the toggle button text is updated");
+  await waitUntil(() => usbToggleButton.textContent.includes("Disable"));
+  ok(
+    !document.querySelector(".qa-connect-usb-disabled-message"),
+    "The message about enabling USB devices is no longer rendered"
+  );
+
+  info("Check that the addon was installed with the proper source");
+  const adbExtensionId = Services.prefs.getCharPref(
+    "devtools.remote.adb.extensionID"
+  );
+  const addon = await AddonManager.getAddonByID(adbExtensionId);
+  Assert.deepEqual(
+    addon.installTelemetryInfo,
+    { source: "about:debugging" },
+    "Got the expected addon.installTelemetryInfo"
+  );
+
+  // Right now we are resuming as soon as "USB enabled" is displayed, but ADB
+  // might still be starting up. If we move to uninstall directly, the ADB startup will
+  // fail and we will have an unhandled promise rejection.
+  // See Bug 1498469.
+  await waitForAdbStart();
+
+  info("Click on the toggle button");
+  usbToggleButton.click();
+
+  info("Wait until the toggle button text is updated");
+  await waitUntil(() => usbToggleButton.textContent.includes("Enable"));
+  ok(
+    document.querySelector(".qa-connect-usb-disabled-message"),
+    "The message about enabling USB devices is rendered again"
+  );
+
+  await stopAdbProcess();
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_connection_prompt_setting.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_connection_prompt_setting.js
new file mode 100644
index 0000000000..dfee0c1ba0
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_connection_prompt_setting.js
@@ -0,0 +1,70 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const USB_RUNTIME_ID = "1337id";
+const USB_DEVICE_NAME = "Fancy Phone";
+const USB_APP_NAME = "Lorem ipsum";
+
+/**
+ * Check whether can toggle enable/disable connection prompt setting.
+ */
+add_task(async function () {
+  // enable USB devices mocks
+  const mocks = new Mocks();
+  const runtime = mocks.createUSBRuntime(USB_RUNTIME_ID, {
+    deviceName: USB_DEVICE_NAME,
+    name: USB_APP_NAME,
+  });
+
+  info("Set initial state for test");
+  await pushPref("devtools.debugger.prompt-connection", true);
+
+  // open a remote runtime page
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  mocks.emitUSBUpdate();
+  await connectToRuntime(USB_DEVICE_NAME, document);
+  await selectRuntime(USB_DEVICE_NAME, USB_APP_NAME, document);
+
+  info("Check whether connection prompt toggle button exists");
+  let connectionPromptToggleButton = document.querySelector(
+    ".qa-connection-prompt-toggle-button"
+  );
+  ok(connectionPromptToggleButton, "Toggle button existed");
+  ok(
+    connectionPromptToggleButton.textContent.includes("Disable"),
+    "Toggle button shows 'Disable'"
+  );
+
+  info("Click on the toggle button");
+  connectionPromptToggleButton = document.querySelector(
+    ".qa-connection-prompt-toggle-button"
+  );
+  connectionPromptToggleButton.click();
+  info("Wait until the toggle button text is updated");
+  await waitUntil(() =>
+    connectionPromptToggleButton.textContent.includes("Enable")
+  );
+  info("Check the preference");
+  const disabledPref = runtime.getPreference(
+    "devtools.debugger.prompt-connection"
+  );
+  is(disabledPref, false, "The preference should be updated");
+
+  info("Click on the toggle button again");
+  connectionPromptToggleButton.click();
+  info("Wait until the toggle button text is updated");
+  await waitUntil(() =>
+    connectionPromptToggleButton.textContent.includes("Disable")
+  );
+  info("Check the preference");
+  const enabledPref = runtime.getPreference(
+    "devtools.debugger.prompt-connection"
+  );
+  is(enabledPref, true, "The preference should be updated");
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_collapsibilities_interaction.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_collapsibilities_interaction.js
new file mode 100644
index 0000000000..7b25e02a9b
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_collapsibilities_interaction.js
@@ -0,0 +1,62 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test that collapsibilities of DebugTargetPane on RuntimePage by mouse clicking.
+ */
+
+add_task(async function () {
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  for (const { title } of TARGET_PANES) {
+    info("Check whether this pane is collapsed after clicking the title");
+    await toggleCollapsibility(getDebugTargetPane(title, document));
+    assertDebugTargetCollapsed(getDebugTargetPane(title, document), title);
+
+    info("Check whether this pane is expanded after clicking the title again");
+    await toggleCollapsibility(getDebugTargetPane(title, document));
+    await assertDebugTargetExpanded(getDebugTargetPane(title, document), title);
+  }
+
+  await removeTab(tab);
+});
+
+async function assertDebugTargetCollapsed(paneEl, title) {
+  info("Check debug target is collapsed");
+
+  // check list height
+  const targetEl = paneEl.querySelector(".qa-debug-target-pane__collapsable");
+  is(targetEl.clientHeight, 0, "Height of list element is zero");
+  // check title
+  const titleEl = paneEl.querySelector(".qa-debug-target-pane-title");
+  const expectedTitle = `${title} (${
+    targetEl.querySelectorAll(".qa-debug-target-item").length
+  })`;
+  is(titleEl.textContent, expectedTitle, "Collapsed title is correct");
+}
+
+async function assertDebugTargetExpanded(paneEl, title) {
+  info("Check debug target is expanded");
+
+  // check list height
+  const targetEl = paneEl.querySelector(".qa-debug-target-pane__collapsable");
+  await waitUntil(() => targetEl.clientHeight > 0);
+  ok(true, "Height of list element is greater than zero");
+  // check title
+  const titleEl = paneEl.querySelector(".qa-debug-target-pane-title");
+  const expectedTitle = `${title} (${
+    targetEl.querySelectorAll(".qa-debug-target-item").length
+  })`;
+  is(titleEl.textContent, expectedTitle, "Expanded title is correct");
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_collapsibilities_preference.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_collapsibilities_preference.js
new file mode 100644
index 0000000000..50857ee617
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_collapsibilities_preference.js
@@ -0,0 +1,40 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test for preference of DebugTargetPane collapsibilities.
+ */
+
+add_task(async function () {
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Collapse all pane");
+  for (const { title } of TARGET_PANES) {
+    const debugTargetPaneEl = getDebugTargetPane(title, document);
+    await toggleCollapsibility(debugTargetPaneEl);
+  }
+
+  info("Check preference of collapsibility after closing about:debugging page");
+  await removeTab(tab);
+  // Wait until unmount.
+  await waitUntil(() => document.querySelector(".app") === null);
+
+  for (const { pref } of TARGET_PANES) {
+    is(
+      Services.prefs.getBoolPref(pref),
+      true,
+      `${pref} preference should be true`
+    );
+  }
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_empty.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_empty.js
new file mode 100644
index 0000000000..301be26a32
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_empty.js
@@ -0,0 +1,83 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test that an "empty" message is displayed when there are no debug targets in a debug
+ * target pane.
+ */
+
+const EXTENSION_PATH = "resources/test-temporary-extension/manifest.json";
+const EXTENSION_NAME = "test-temporary-extension";
+
+add_task(async function () {
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Check that the temporary extensions pane is empty");
+  const temporaryExtensionPane = getDebugTargetPane(
+    "Temporary Extensions",
+    document
+  );
+  ok(
+    !temporaryExtensionPane.querySelector(".qa-debug-target-item"),
+    "Temporary Extensions pane contains no debug target"
+  );
+
+  info("Check an empty target pane message is displayed");
+  ok(
+    temporaryExtensionPane.querySelector(".qa-debug-target-list-empty"),
+    "An empty target list message is displayed"
+  );
+
+  info("Install a temporary extension");
+  await installTemporaryExtension(EXTENSION_PATH, EXTENSION_NAME, document);
+
+  info("Wait until a debug target item appears");
+  await waitUntil(() =>
+    temporaryExtensionPane.querySelector(".qa-debug-target-item")
+  );
+
+  info("Check the empty target pane message is no longer displayed");
+  ok(
+    !temporaryExtensionPane.querySelector(".qa-debug-target-list-empty"),
+    "The empty target list message is no longer displayed"
+  );
+
+  const temporaryExtensionItem = temporaryExtensionPane.querySelector(
+    ".qa-debug-target-item"
+  );
+  ok(
+    temporaryExtensionItem,
+    "Temporary Extensions pane now shows debug target"
+  );
+
+  info("Remove the temporary extension");
+  temporaryExtensionItem
+    .querySelector(".qa-temporary-extension-remove-button")
+    .click();
+
+  info("Wait until the debug target item disappears");
+  await waitUntil(
+    () => !temporaryExtensionPane.querySelector(".qa-debug-target-item")
+  );
+
+  info("Check the empty target pane message is displayed again");
+  ok(
+    temporaryExtensionPane.querySelector(".qa-debug-target-list-empty"),
+    "An empty target list message is displayed again"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_usb_runtime.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_usb_runtime.js
new file mode 100644
index 0000000000..0f50b9454b
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_debug-target-pane_usb_runtime.js
@@ -0,0 +1,72 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+const RUNTIME_ID = "test-runtime-id";
+const RUNTIME_DEVICE_NAME = "test device name";
+const RUNTIME_APP_NAME = "TestApp";
+
+// Test that the expected supported categories are displayed for USB runtimes.
+add_task(async function () {
+  const mocks = new Mocks();
+  await checkTargetPanes({ enableLocalTabs: false }, mocks);
+
+  info(
+    "Check that enableLocalTabs has no impact on the categories displayed for remote" +
+      " runtimes."
+  );
+  await checkTargetPanes({ enableLocalTabs: true }, mocks);
+});
+
+async function checkTargetPanes({ enableLocalTabs }, mocks) {
+  const { document, tab, window } = await openAboutDebugging({
+    enableLocalTabs,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceName: RUNTIME_DEVICE_NAME,
+    name: RUNTIME_APP_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  await connectToRuntime(RUNTIME_DEVICE_NAME, document);
+  await selectRuntime(RUNTIME_DEVICE_NAME, RUNTIME_APP_NAME, document);
+
+  const SUPPORTED_TARGET_PANES = [
+    "Temporary Extensions",
+    "Extensions",
+    "Other Workers",
+    "Shared Workers",
+    "Service Workers",
+    "Tabs",
+  ];
+
+  for (const { title } of TARGET_PANES) {
+    const debugTargetPaneEl = getDebugTargetPane(title, document);
+    if (SUPPORTED_TARGET_PANES.includes(title)) {
+      ok(debugTargetPaneEl, `Supported target pane [${title}] is displayed`);
+    } else {
+      ok(!debugTargetPaneEl, `Unsupported target pane [${title}] is hidden`);
+    }
+  }
+
+  const installButton = document.querySelector(
+    ".qa-temporary-extension-install-button"
+  );
+  ok(!installButton, "Temporary Extensions install button is hidden");
+
+  info("Remove USB runtime");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(RUNTIME_DEVICE_NAME, document);
+
+  await removeTab(tab);
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtools.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtools.js
new file mode 100644
index 0000000000..4ea3238ea3
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtools.js
@@ -0,0 +1,51 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Check that DevTools are not closed when leaving This Firefox runtime page.
+ */
+
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const connectSidebarItem = findSidebarItemByText("Setup", document);
+  const connectLink = connectSidebarItem.querySelector(".qa-sidebar-link");
+  ok(connectSidebarItem, "Found the Connect sidebar item");
+
+  info("Open devtools on the current about:debugging tab");
+  const toolbox = await openToolboxForTab(tab, "inspector");
+  const inspector = toolbox.getPanel("inspector");
+
+  info("DevTools starts workers, wait for requests to settle");
+  const store = window.AboutDebugging.store;
+  await waitForAboutDebuggingRequests(store);
+
+  info("Click on the Connect item in the sidebar");
+  connectLink.click();
+  await waitForDispatch(store, "UNWATCH_RUNTIME_SUCCESS");
+
+  info("Wait until Connect page is displayed");
+  await waitUntil(() => document.querySelector(".qa-connect-page"));
+
+  const markupViewElement = inspector.panelDoc.getElementById("markup-box");
+  ok(markupViewElement, "Inspector is still rendered");
+
+  // We explicitely destroy the toolbox in order to ensure waiting for its full destruction
+  // and avoid leak / pending requests
+  info("Destroy the opened toolbox");
+  await toolbox.destroy();
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_breakpoint.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_breakpoint.js
new file mode 100644
index 0000000000..925d40b643
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_breakpoint.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.scriptloader.loadSubScript(
+  "chrome://mochitests/content/browser/devtools/client/debugger/test/mochitest/shared-head.js",
+  this
+);
+
+const SCRIPT_FILE = "script_aboutdebugging_devtoolstoolbox_breakpoint.js";
+const TAB_URL =
+  "https://example.com/browser/devtools/client/aboutdebugging/" +
+  "test/browser/resources/doc_aboutdebugging_devtoolstoolbox_breakpoint.html";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test breakpoints in about:devtools-toolbox tabs (ie non localTab tab target).
+ */
+add_task(async function () {
+  const testTab = await addTab(TAB_URL);
+
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsTab, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    TAB_URL
+  );
+  info("Select performance panel");
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.selectTool("jsdebugger");
+
+  info("Add a breakpoint at line 10 in the test script");
+  const debuggerContext = createDebuggerContext(toolbox);
+  await selectSource(debuggerContext, SCRIPT_FILE);
+  await addBreakpoint(debuggerContext, SCRIPT_FILE, 10);
+
+  info("Invoke testMethod, expect the script to pause on line 10");
+  const onContentTaskDone = ContentTask.spawn(
+    testTab.linkedBrowser,
+    {},
+    function () {
+      content.wrappedJSObject.testMethod();
+    }
+  );
+
+  info("Wait for the debugger to pause");
+  await waitForPaused(debuggerContext);
+  const script = findSource(debuggerContext, SCRIPT_FILE);
+  assertPausedAtSourceAndLine(debuggerContext, script.id, 10);
+
+  info("Resume");
+  await resume(debuggerContext);
+
+  info("Wait for the paused content task to also resolve");
+  await onContentTaskDone;
+
+  info("Remove breakpoint");
+  await removeBreakpoint(debuggerContext, script.id, 10);
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(testTab);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_contextmenu.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_contextmenu.js
new file mode 100644
index 0000000000..eb8f233d12
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_contextmenu.js
@@ -0,0 +1,102 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test context menu on about:devtools-toolbox page.
+ */
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsBrowser, devtoolsTab } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window
+  );
+
+  info("Check whether the menu item which opens devtools is disabled");
+  const rootDocument = devtoolsTab.ownerDocument;
+  await assertContextMenu(
+    rootDocument,
+    devtoolsBrowser,
+    ".debug-target-info",
+    false
+  );
+
+  info("Force to select about:debugging page");
+  await updateSelectedTab(gBrowser, tab, window.AboutDebugging.store);
+
+  info("Check whether the menu item which opens devtools is enabled");
+  await assertContextMenu(rootDocument, devtoolsBrowser, "#mount", true);
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(tab);
+});
+
+async function assertContextMenu(
+  rootDocument,
+  browser,
+  targetSelector,
+  shouldBeEnabled
+) {
+  if (shouldBeEnabled) {
+    await assertContextMenuEnabled(rootDocument, browser, targetSelector);
+  } else {
+    await assertContextMenuDisabled(rootDocument, browser, targetSelector);
+  }
+}
+
+async function assertContextMenuDisabled(
+  rootDocument,
+  browser,
+  targetSelector
+) {
+  const contextMenu = rootDocument.getElementById("contentAreaContextMenu");
+  let isPopupShown = false;
+  const listener = () => {
+    isPopupShown = true;
+  };
+  contextMenu.addEventListener("popupshown", listener);
+  BrowserTestUtils.synthesizeMouseAtCenter(
+    targetSelector,
+    { type: "contextmenu" },
+    browser
+  );
+  await wait(1000);
+  ok(!isPopupShown, `Context menu should not be shown`);
+  contextMenu.removeEventListener("popupshown", listener);
+}
+
+async function assertContextMenuEnabled(rootDocument, browser, targetSelector) {
+  // Show content context menu.
+  const contextMenu = rootDocument.getElementById("contentAreaContextMenu");
+  const popupShownPromise = BrowserTestUtils.waitForEvent(
+    contextMenu,
+    "popupshown"
+  );
+  BrowserTestUtils.synthesizeMouseAtCenter(
+    targetSelector,
+    { type: "contextmenu" },
+    browser
+  );
+  await popupShownPromise;
+  ok(true, `Context menu should be shown`);
+
+  // Hide content context menu.
+  const popupHiddenPromise = BrowserTestUtils.waitForEvent(
+    contextMenu,
+    "popuphidden"
+  );
+  contextMenu.hidePopup();
+  await popupHiddenPromise;
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_contextmenu_markupview.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_contextmenu_markupview.js
new file mode 100644
index 0000000000..bc46b828fd
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_contextmenu_markupview.js
@@ -0,0 +1,45 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test context menu of markup view on about:devtools-toolbox page.
+ */
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsTab, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window
+  );
+
+  info("Select inspector tool");
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.selectTool("inspector");
+
+  info("Show context menu of markup view");
+  const markupDocument = toolbox.getPanel("inspector").markup.doc;
+  EventUtils.synthesizeMouseAtCenter(
+    markupDocument.body,
+    { type: "contextmenu" },
+    markupDocument.ownerGlobal
+  );
+
+  info("Check whether proper context menu of markup view will be shown");
+  await waitUntil(() => toolbox.topDoc.querySelector("#node-menu-edithtml"));
+  ok(true, "Context menu of markup view should be shown");
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_focus.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_focus.js
new file mode 100644
index 0000000000..a3fa63c340
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_focus.js
@@ -0,0 +1,122 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test whether the focus transfers to a tab which is already inspected .
+ */
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  info(
+    "Select 'performance' panel as the initial tool since the tool does not listen " +
+      "any changes of the document without user action"
+  );
+  await pushPref("devtools.toolbox.selectedTool", "performance");
+
+  const { document, tab, window } = await openAboutDebugging();
+  const { store } = window.AboutDebugging;
+  await selectThisFirefoxPage(document, store);
+
+  const inspectionTarget = "about:debugging";
+  info(`Open ${inspectionTarget} as inspection target`);
+  await waitUntil(() => findDebugTargetByText(inspectionTarget, document));
+  info(`Inspect ${inspectionTarget} page in about:devtools-toolbox`);
+  const { devtoolsTab, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    inspectionTarget
+  );
+
+  info(
+    "Check the tab state after clicking inspect button " +
+      "when another tab was selected"
+  );
+  await updateSelectedTab(gBrowser, tab, store);
+  clickInspectButton(inspectionTarget, document);
+  const devtoolsURL = devtoolsWindow.location.href;
+  assertDevtoolsToolboxTabState(devtoolsURL);
+
+  info(
+    "Check the tab state after clicking inspect button " +
+      "when the toolbox tab is in another window"
+  );
+  const newNavigator = gBrowser.replaceTabWithWindow(devtoolsTab);
+  await waitUntil(
+    () =>
+      newNavigator.gBrowser &&
+      newNavigator.gBrowser.selectedTab.linkedBrowser.contentWindow.location
+        .href === devtoolsURL
+  );
+
+  info(
+    "Create a tab in the window and select the tab " +
+      "so that the about:devtools-toolbox tab loses focus"
+  );
+  const newTestTab = newNavigator.gBrowser.addTab(
+    "data:text/html,<title>TEST_TAB</title>",
+    {
+      triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
+    }
+  );
+  await waitUntil(() => findDebugTargetByText("TEST_TAB", document));
+
+  await updateSelectedTab(newNavigator.gBrowser, newTestTab, store);
+
+  let onTabsSuccess = waitForDispatch(store, "REQUEST_TABS_SUCCESS");
+  clickInspectButton(inspectionTarget, document);
+  assertDevtoolsToolboxTabState(devtoolsURL);
+  await onTabsSuccess;
+
+  info("Close new navigator and wait until the debug target disappears");
+  onTabsSuccess = waitForDispatch(store, "REQUEST_TABS_SUCCESS");
+  const onToolboxDestroyed = gDevTools.once("toolbox-destroyed");
+  newNavigator.close();
+  await onToolboxDestroyed;
+  await onTabsSuccess;
+
+  await waitUntil(() => !findDebugTargetByText("Toolbox - ", document));
+
+  info("Remove test tab");
+  await removeTab(tab);
+});
+
+function clickInspectButton(inspectionTarget, doc) {
+  const target = findDebugTargetByText(inspectionTarget, doc);
+  const button = target.querySelector(".qa-debug-target-inspect-button");
+  button.click();
+}
+
+// Check that only one tab is currently opened for the provided URL.
+// Also check that this tab and the tab's window are focused.
+function assertDevtoolsToolboxTabState(devtoolsURL) {
+  const existingTabs = [];
+
+  for (const navigator of Services.wm.getEnumerator("navigator:browser")) {
+    for (const browser of navigator.gBrowser.browsers) {
+      if (
+        browser.contentWindow &&
+        browser.contentWindow.location.href === devtoolsURL
+      ) {
+        const tab = navigator.gBrowser.getTabForBrowser(browser);
+        existingTabs.push(tab);
+      }
+    }
+  }
+
+  is(existingTabs.length, 1, `Only one tab is opened for ${devtoolsURL}`);
+  const tab = existingTabs[0];
+  const navigator = tab.ownerGlobal;
+  is(navigator.gBrowser.selectedTab, tab, "The tab is selected");
+  const focusedNavigator = Services.wm.getMostRecentWindow("navigator:browser");
+  is(navigator, focusedNavigator, "The navigator is focused");
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_menubar.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_menubar.js
new file mode 100644
index 0000000000..c2f0c5e362
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_menubar.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test the status of menu items when open about:devtools-toolbox.
+ */
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsTab, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window
+  );
+
+  info("Check whether the menu items are disabled");
+  const rootDocument = devtoolsTab.ownerDocument;
+  await assertMenusItems(rootDocument, false);
+
+  info("Select the inspector");
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.selectTool("inspector");
+
+  info("Force to select about:debugging page");
+  await updateSelectedTab(gBrowser, tab, window.AboutDebugging.store);
+
+  info("Check whether the menu items are enabled");
+  await assertMenusItems(rootDocument, true);
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(tab);
+});
+
+async function assertMenusItems(rootDocument, shouldBeEnabled) {
+  info("Wait for the Toggle Tools menu-item hidden attribute to change");
+  const menuItem = rootDocument.getElementById("menu_devToolbox");
+  await waitUntil(() => menuItem.hidden === !shouldBeEnabled);
+
+  info(
+    "Check that the state of the Toggle Tools menu-item depends on the page"
+  );
+  assertMenuItem(rootDocument, "menu_devToolbox", shouldBeEnabled);
+
+  info(
+    "Check that the tools menu-items are always enabled regardless of the page"
+  );
+  for (const toolDefinition of gDevTools.getToolDefinitionArray()) {
+    if (!toolDefinition.inMenu) {
+      continue;
+    }
+
+    assertMenuItem(rootDocument, "menuitem_" + toolDefinition.id, true);
+  }
+}
+
+function assertMenuItem(rootDocument, menuItemId, shouldBeEnabled) {
+  const menuItem = rootDocument.getElementById(menuItemId);
+  is(
+    menuItem.hidden,
+    !shouldBeEnabled,
+    `"hidden" attribute of menu item(${menuItemId}) should be correct`
+  );
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_navigate_back_forward.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_navigate_back_forward.js
new file mode 100644
index 0000000000..79428ae8da
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_navigate_back_forward.js
@@ -0,0 +1,63 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const ORIGINAL_URL = "https://example.com/document-builder.sjs?html=page1";
+const OTHER_URL = "https://example.org/document-builder.sjs?html=page2";
+
+async function waitForUrl(url, toolbox, browserTab, win) {
+  const { onDomCompleteResource } =
+    await waitForNextTopLevelDomCompleteResource(toolbox.commands);
+
+  return Promise.all([
+    waitUntil(
+      () =>
+        toolbox.target.url === url &&
+        browserTab.linkedBrowser.currentURI.spec === url
+    ),
+    onDomCompleteResource,
+    toolbox.commands.client.waitForRequestsToSettle(),
+    waitForAboutDebuggingRequests(win.AboutDebugging.store),
+  ]);
+}
+
+// Test that ensures the remote page can go forward and back via UI buttons
+add_task(async function () {
+  const browserTab = await addTab(ORIGINAL_URL);
+
+  const { document, tab, window } = await openAboutDebugging();
+
+  // go to This Firefox and inspect the new tab
+  info("Inspecting a new tab in This Firefox");
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const devToolsToolbox = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    ORIGINAL_URL
+  );
+  const { devtoolsDocument, devtoolsWindow } = devToolsToolbox;
+  const toolbox = getToolbox(devtoolsWindow);
+
+  info("Navigating to another URL");
+  let onTargetSwitched = toolbox.commands.targetCommand.once("switched-target");
+  const urlInput = devtoolsDocument.querySelector(".devtools-textinput");
+  await synthesizeUrlKeyInput(devToolsToolbox, urlInput, OTHER_URL);
+  await waitForUrl(OTHER_URL, toolbox, browserTab, window);
+  await onTargetSwitched;
+
+  info("Clicking back button");
+  onTargetSwitched = toolbox.commands.targetCommand.once("switched-target");
+  devtoolsDocument.querySelector(".qa-back-button").click();
+  await waitForUrl(ORIGINAL_URL, toolbox, browserTab, window);
+  await onTargetSwitched;
+
+  info("Clicking the forward button");
+  onTargetSwitched = toolbox.commands.targetCommand.once("switched-target");
+  devtoolsDocument.querySelector(".qa-forward-button").click();
+  await waitForUrl(OTHER_URL, toolbox, browserTab, window);
+  await onTargetSwitched;
+
+  ok(true, "Clicking back and forward works!");
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_navigate_reload_button.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_navigate_reload_button.js
new file mode 100644
index 0000000000..fbd46101a2
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_navigate_reload_button.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function clickReload(devtoolsDocument) {
+  devtoolsDocument.querySelector(".qa-reload-button").click();
+}
+
+// Test that ensures the remote page is reloaded when the button is clicked
+add_task(async function () {
+  const debug_tab = await addTab("about:home");
+
+  const { document, tab, window } = await openAboutDebugging();
+
+  // go to This Firefox and inspect the new tab
+  info("Inspecting a new tab in This Firefox");
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsDocument, devtoolsTab, devtoolsWindow } =
+    await openAboutDevtoolsToolbox(document, tab, window, "about:home");
+
+  info("Clicking reload button and waiting for requests to complete");
+  const toolbox = getToolbox(devtoolsWindow);
+  const { onDomCompleteResource } =
+    await waitForNextTopLevelDomCompleteResource(toolbox.commands);
+
+  // Watch for navigation promises.
+  const refreshes = Promise.all([
+    onDomCompleteResource,
+    toolbox.commands.client.waitForRequestsToSettle(),
+    waitForAboutDebuggingRequests(window.AboutDebugging.store),
+  ]);
+
+  // We cannot include this one in the Promise.all array, as it needs to be
+  // explicitly called after navigation started.
+  const waitForLoadedPanelsReload = await watchForLoadedPanelsReload(toolbox);
+
+  clickReload(devtoolsDocument);
+  await refreshes;
+  await waitForLoadedPanelsReload();
+
+  ok(true, "Clicked refresh; both page and devtools reloaded");
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+
+  info("Remove the debugged tab");
+  await removeTab(debug_tab);
+  await waitUntil(() => !findDebugTargetByText("about:home", document));
+  await waitForAboutDebuggingRequests(window.AboutDebugging.store);
+
+  info("Remove the about:debugging tab.");
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_navigate_to_url.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_navigate_to_url.js
new file mode 100644
index 0000000000..055db0586c
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_navigate_to_url.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const NEW_TAB_TITLE = "PAGE 2";
+const TAB_URL = "data:text/html,<title>PAGE</title>";
+const NEW_TAB_URL = `data:text/html,<title>${NEW_TAB_TITLE}</title>`;
+
+/**
+ * This test file ensures that the URL input for DebugTargetInfo navigates the target to
+ * the specified URL.
+ */
+add_task(async function () {
+  const { document, tab, window } = await openAboutDebugging();
+
+  info("Open a new background tab.");
+  const debug_tab = await addTab(TAB_URL, { background: true });
+
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const devToolsToolbox = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    "PAGE"
+  );
+  const { devtoolsDocument, devtoolsTab, devtoolsWindow } = devToolsToolbox;
+  const toolbox = getToolbox(devtoolsWindow);
+
+  const urlInput = devtoolsDocument.querySelector(".devtools-textinput");
+  const waitForLoadedPanelsReload = await watchForLoadedPanelsReload(toolbox);
+
+  await synthesizeUrlKeyInput(devToolsToolbox, urlInput, NEW_TAB_URL);
+
+  await waitForLoadedPanelsReload();
+
+  info("Test that the debug target navigated to the specified URL.");
+  await waitUntil(
+    () =>
+      toolbox.target.url === NEW_TAB_URL &&
+      debug_tab.linkedBrowser.currentURI.spec === NEW_TAB_URL
+  );
+  ok(true, "Target navigated.");
+  ok(toolbox.target.title.includes(NEW_TAB_TITLE), "Target's title updated.");
+  is(urlInput.value, NEW_TAB_URL, "Input url updated.");
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+
+  info("Remove the background tab");
+  await removeTab(debug_tab);
+  await waitUntil(() => !findDebugTargetByText("NEW_TAB_TITLE", document));
+  await waitForAboutDebuggingRequests(window.AboutDebugging.store);
+
+  info("Remove the about:debugging tab.");
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_reload.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_reload.js
new file mode 100644
index 0000000000..3eba6bcd7e
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_reload.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test can run for a long time on debug platforms.
+requestLongerTimeout(5);
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+const TOOLS = [
+  "inspector",
+  "webconsole",
+  "jsdebugger",
+  "styleeditor",
+  "memory",
+  "netmonitor",
+  "storage",
+  "accessibility",
+];
+
+/**
+ * Test whether about:devtools-toolbox display correctly after reloading.
+ */
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  for (const toolId of TOOLS) {
+    await testReloadAboutDevToolsToolbox(toolId);
+  }
+});
+
+async function testReloadAboutDevToolsToolbox(toolId) {
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  // We set the options panel to be the default one because slower panels might lead to
+  // race conditions which create leaks in debug mode.
+  await pushPref("devtools.toolbox.selectedTool", "options");
+  const { devtoolsBrowser, devtoolsTab, devtoolsWindow } =
+    await openAboutDevtoolsToolbox(document, tab, window);
+
+  info(`Select tool: ${toolId}`);
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.selectTool(toolId);
+
+  info("Wait for requests to settle before reloading");
+  await toolbox.commands.client.waitForRequestsToSettle();
+
+  info("Reload about:devtools-toolbox page");
+  devtoolsBrowser.reload();
+  await gDevTools.once("toolbox-ready");
+  ok(true, "Toolbox is re-created again");
+
+  // Check that about:devtools-toolbox is still selected tab. See Bug 1570692.
+  is(
+    devtoolsBrowser,
+    gBrowser.selectedBrowser,
+    "about:devtools-toolbox is still selected"
+  );
+
+  info("Check whether about:devtools-toolbox page displays correctly");
+  ok(
+    devtoolsBrowser.contentDocument.querySelector(".debug-target-info"),
+    "about:devtools-toolbox page displays correctly"
+  );
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(tab);
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_shortcuts.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_shortcuts.js
new file mode 100644
index 0000000000..b03a206350
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_shortcuts.js
@@ -0,0 +1,106 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test shortcut keys on about:devtools-toolbox page.
+ */
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsBrowser, devtoolsTab, devtoolsWindow } =
+    await openAboutDevtoolsToolbox(document, tab, window);
+
+  info("Check whether the shortcut keys which opens devtools is disabled");
+  await assertShortcutKeys(devtoolsBrowser, false);
+
+  info("Switch to the inspector programmatically");
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.selectTool("inspector");
+
+  info(
+    "Use the Webconsole keyboard shortcut and wait for the panel to be selected"
+  );
+  const onToolReady = toolbox.once("webconsole-ready");
+  EventUtils.synthesizeKey(
+    "K",
+    {
+      accelKey: true,
+      shiftKey: !navigator.userAgent.match(/Mac/),
+      altKey: navigator.userAgent.match(/Mac/),
+    },
+    devtoolsWindow
+  );
+  await onToolReady;
+
+  info("Force to select about:debugging page");
+  await updateSelectedTab(gBrowser, tab, window.AboutDebugging.store);
+
+  info("Check whether the shortcut keys which opens devtools is enabled");
+  await assertShortcutKeys(tab.linkedBrowser, true);
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(tab);
+});
+
+async function assertShortcutKeys(browser, shouldBeEnabled) {
+  await assertShortcutKey(browser.contentWindow, "VK_F12", {}, shouldBeEnabled);
+  await assertShortcutKey(
+    browser.contentWindow,
+    "I",
+    {
+      accelKey: true,
+      shiftKey: !navigator.userAgent.match(/Mac/),
+      altKey: navigator.userAgent.match(/Mac/),
+    },
+    shouldBeEnabled
+  );
+}
+
+async function assertShortcutKey(win, key, modifiers, shouldBeEnabled) {
+  info(`Assert shortcut key [${key}]`);
+
+  if (shouldBeEnabled) {
+    await assertShortcutKeyEnabled(win, key, modifiers);
+  } else {
+    await assertShortcutKeyDisabled(win, key, modifiers);
+  }
+}
+
+async function assertShortcutKeyDisabled(win, key, modifiers) {
+  let isReadyCalled = false;
+  const toolboxListener = () => {
+    isReadyCalled = true;
+  };
+  gDevTools.on("toolbox-ready", toolboxListener);
+
+  EventUtils.synthesizeKey(key, modifiers, win);
+  await wait(1000);
+  ok(!isReadyCalled, `Devtools should not be opened by ${key}`);
+
+  gDevTools.off("toolbox-ready", toolboxListener);
+}
+
+async function assertShortcutKeyEnabled(win, key, modifiers) {
+  // Open devtools
+  const onToolboxReady = gDevTools.once("toolbox-ready");
+  EventUtils.synthesizeKey(key, modifiers, win);
+  await onToolboxReady;
+  ok(true, `Devtools should be opened by ${key}`);
+
+  // Close devtools
+  const onToolboxDestroyed = gDevTools.once("toolbox-destroyed");
+  EventUtils.synthesizeKey(key, modifiers, win);
+  await onToolboxDestroyed;
+  ok(true, `Devtopls should be closed by ${key}`);
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_splitconsole_key.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_splitconsole_key.js
new file mode 100644
index 0000000000..44e83b8c43
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_splitconsole_key.js
@@ -0,0 +1,46 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test that the split console key shortcut works on about:devtools-toolbox.
+ */
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsTab, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window
+  );
+
+  // Select any tool that is not the Webconsole, since we will assert the split-console.
+  info("Select inspector tool");
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.selectTool("inspector");
+
+  info("Press Escape and wait for the split console to be opened");
+  const onSplitConsole = toolbox.once("split-console");
+  EventUtils.synthesizeKey("VK_ESCAPE", {}, devtoolsWindow);
+  await onSplitConsole;
+  await waitUntil(() => toolbox.isSplitConsoleFocused());
+  ok(true, "Split console is opened and focused");
+
+  info("Press Escape again and wait for the split console to be closed");
+  EventUtils.synthesizeKey("VK_ESCAPE", {}, devtoolsWindow);
+  await waitUntil(() => !toolbox.isSplitConsoleFocused());
+  ok(true, "Split console is closed and no longer focused");
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_target_destroyed.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_target_destroyed.js
new file mode 100644
index 0000000000..d0001d1c03
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_target_destroyed.js
@@ -0,0 +1,36 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that the expected supported categories are displayed for USB runtimes.
+add_task(async function () {
+  const targetTab = await addTab("about:home");
+
+  const { document, tab, window } = await openAboutDebugging();
+
+  // go to This Firefox and inspect the new tab
+  info("Inspecting a new tab in This Firefox");
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsDocument, devtoolsTab, devtoolsWindow } =
+    await openAboutDevtoolsToolbox(document, tab, window, "about:home");
+  const targetUrl = devtoolsDocument.querySelector(".devtools-textinput");
+  ok(
+    targetUrl.value.includes("about:home"),
+    "about:devtools-toolbox is open for the target"
+  );
+
+  // close the inspected tab and check that error page is shown
+  info("removing the inspected tab");
+  await removeTab(targetTab);
+  await waitUntil(() =>
+    devtoolsWindow.document.querySelector(".qa-error-page")
+  );
+
+  info("closing the toolbox");
+  await removeTab(devtoolsTab);
+  await waitUntil(() => !findDebugTargetByText("Toolbox -", document));
+
+  info("removing about:debugging tab");
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_tooltip_markupview.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_tooltip_markupview.js
new file mode 100644
index 0000000000..047b309740
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_tooltip_markupview.js
@@ -0,0 +1,102 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test can run for a long time on asan or debug platforms.
+requestLongerTimeout(3);
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Test tooltip of markup view on about:devtools-toolbox page.
+ */
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  info("Turn on devtools.chrome.enabled to show event badges");
+  await pushPref("devtools.chrome.enabled", true);
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsDocument, devtoolsTab, devtoolsWindow } =
+    await openAboutDevtoolsToolbox(document, tab, window);
+
+  info("Select inspector tool");
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.selectTool("inspector");
+
+  const inspector = toolbox.getPanel("inspector");
+  const markupDocument = inspector.markup.doc;
+  const eventBadge = markupDocument.querySelector(
+    ".inspector-badge.interactive"
+  );
+
+  info(
+    "Check tooltip visibility after clicking on an element in the markup view"
+  );
+  await checkTooltipVisibility(inspector, eventBadge, markupDocument.body);
+
+  info(
+    "Check tooltip visibility after clicking on an element in the DevTools document"
+  );
+  await checkTooltipVisibility(
+    inspector,
+    eventBadge,
+    devtoolsDocument.querySelector(".debug-target-info")
+  );
+
+  info(
+    "Check tooltip visibility after clicking on an element in the root document"
+  );
+  const rootDocument = devtoolsWindow.windowRoot.ownerGlobal.document;
+  await checkTooltipVisibility(
+    inspector,
+    eventBadge,
+    rootDocument.querySelector("#titlebar")
+  );
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(tab);
+});
+
+async function checkTooltipVisibility(
+  inspector,
+  elementForShowing,
+  elementForHiding
+) {
+  info("Show event tooltip");
+  elementForShowing.click();
+  const tooltip = inspector.markup.eventDetailsTooltip;
+  await tooltip.once("shown");
+  is(
+    tooltip.container.classList.contains("tooltip-visible"),
+    true,
+    "The tooltip should be shown"
+  );
+
+  info("Hide event tooltip");
+  EventUtils.synthesizeMouse(
+    elementForHiding,
+    1,
+    1,
+    {},
+    elementForHiding.ownerGlobal
+  );
+  await tooltip.once("hidden");
+  is(
+    tooltip.container.classList.contains("tooltip-visible"),
+    false,
+    "Tooltip should be hidden"
+  );
+
+  if (inspector._updateProgress) {
+    info("Need to wait for the inspector to update");
+    await inspector.once("inspector-updated");
+  }
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_zoom.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_zoom.js
new file mode 100644
index 0000000000..816e2594e1
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_zoom.js
@@ -0,0 +1,64 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+const L10N = new LocalizationHelper(
+  "devtools/client/locales/toolbox.properties"
+);
+
+// Check that the about:devtools-toolbox tab can be zoomed in and that the zoom
+// persists after switching tabs.
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+  const { devtoolsTab, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window
+  );
+
+  is(getZoom(devtoolsWindow), 1, "default zoom level correct");
+
+  info("Increase the zoom level");
+
+  // Note that we read the shortcut from the toolbox properties, but that should
+  // match the default browser shortcut `full-zoom-enlarge-shortcut`.
+  synthesizeKeyShortcut(L10N.getStr("toolbox.zoomIn.key"));
+  await waitFor(() => getZoom(devtoolsWindow) > 1);
+  is(getZoom(devtoolsWindow).toFixed(2), "1.10", "zoom level increased");
+
+  info("Switch tabs between about:debugging and the toolbox tab");
+  gBrowser.selectedTab = tab;
+  gBrowser.selectedTab = devtoolsTab;
+
+  info("Wait for the browser to reapply the zoom");
+  await wait(500);
+
+  is(
+    getZoom(devtoolsWindow).toFixed(2),
+    "1.10",
+    "zoom level was restored after switching tabs"
+  );
+
+  info("Restore the default zoom level");
+  synthesizeKeyShortcut(L10N.getStr("toolbox.zoomReset.key"));
+  await waitFor(() => getZoom(devtoolsWindow) === 1);
+  is(getZoom(devtoolsWindow), 1, "default zoom level restored");
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(tab);
+});
+
+function getZoom(win) {
+  return win.browsingContext.fullZoom;
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_fenix_runtime_display.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_fenix_runtime_display.js
new file mode 100644
index 0000000000..778b1bb967
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_fenix_runtime_display.js
@@ -0,0 +1,141 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const RUNTIME_ID = "1337id";
+const DEVICE_NAME = "Fancy Phone";
+const SERVER_RUNTIME_NAME = "Mozilla Firefox";
+const ADB_RUNTIME_NAME = "Firefox Preview";
+const SERVER_VERSION = "v7.3.31";
+const ADB_VERSION = "v1.3.37";
+
+const FENIX_RELEASE_ICON_SRC =
+  "chrome://devtools/skin/images/aboutdebugging-fenix.svg";
+const FENIX_NIGHTLY_ICON_SRC =
+  "chrome://devtools/skin/images/aboutdebugging-fenix-nightly.svg";
+
+/**
+ * Check that Fenix runtime information is correctly displayed in about:debugging.
+ */
+add_task(async function () {
+  const mocks = new Mocks();
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceName: DEVICE_NAME,
+    isFenix: true,
+    name: SERVER_RUNTIME_NAME,
+    shortName: ADB_RUNTIME_NAME,
+    versionName: ADB_VERSION,
+    version: SERVER_VERSION,
+  });
+
+  // open a remote runtime page
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  mocks.emitUSBUpdate();
+  await connectToRuntime(DEVICE_NAME, document);
+  await selectRuntime(DEVICE_NAME, ADB_RUNTIME_NAME, document);
+
+  info("Check that the runtime information is displayed as expected");
+  const runtimeInfo = document.querySelector(".qa-runtime-name");
+  ok(runtimeInfo, "Runtime info for the Fenix runtime is displayed");
+  const runtimeInfoText = runtimeInfo.textContent;
+
+  ok(runtimeInfoText.includes(ADB_RUNTIME_NAME), "Name is the ADB name");
+  ok(
+    !runtimeInfoText.includes(SERVER_RUNTIME_NAME),
+    "Name does not include the server name"
+  );
+
+  ok(runtimeInfoText.includes(ADB_VERSION), "Version contains the ADB version");
+  ok(
+    !runtimeInfoText.includes(SERVER_VERSION),
+    "Version does not contain the server version"
+  );
+
+  const runtimeIcon = document.querySelector(".qa-runtime-icon");
+  is(
+    runtimeIcon.src,
+    FENIX_RELEASE_ICON_SRC,
+    "The runtime icon is the Fenix icon"
+  );
+
+  info("Remove USB runtime");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(DEVICE_NAME, document);
+
+  await removeTab(tab);
+});
+
+/**
+ * Check that Fenix runtime information is correctly displayed in about:devtools-toolbox.
+ */
+add_task(async function () {
+  // We use a real local client combined with a mocked USB runtime to be able to open
+  // about:devtools-toolbox on a real target.
+  const clientWrapper = await createLocalClientWrapper();
+
+  const mocks = new Mocks();
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    channel: "nightly",
+    clientWrapper,
+    deviceName: DEVICE_NAME,
+    isFenix: true,
+    name: SERVER_RUNTIME_NAME,
+    shortName: ADB_RUNTIME_NAME,
+    versionName: ADB_VERSION,
+    version: SERVER_VERSION,
+  });
+
+  // open a remote runtime page
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  mocks.emitUSBUpdate();
+  info("Select the runtime page for the USB runtime");
+  const onRequestSuccess = waitForRequestsSuccess(window.AboutDebugging.store);
+  await connectToRuntime(DEVICE_NAME, document);
+  await selectRuntime(DEVICE_NAME, ADB_RUNTIME_NAME, document);
+  info(
+    "Wait for requests to finish the USB runtime is backed by a real local client"
+  );
+  await onRequestSuccess;
+
+  info("Wait for the about:debugging target to be available");
+  await waitUntil(() => findDebugTargetByText("about:debugging", document));
+  const { devtoolsDocument, devtoolsTab } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window
+  );
+
+  const runtimeInfo = devtoolsDocument.querySelector(".qa-runtime-info");
+  const runtimeInfoText = runtimeInfo.textContent;
+  ok(
+    runtimeInfoText.includes(ADB_RUNTIME_NAME),
+    "Name is the ADB runtime name"
+  );
+  ok(runtimeInfoText.includes(ADB_VERSION), "Version is the ADB version");
+
+  const runtimeIcon = devtoolsDocument.querySelector(".qa-runtime-icon");
+  is(
+    runtimeIcon.src,
+    FENIX_NIGHTLY_ICON_SRC,
+    "The runtime icon is the Fenix icon"
+  );
+
+  info("Wait for all pending requests to settle on the DevToolsClient");
+  await clientWrapper.client.waitForRequestsToSettle();
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+
+  info("Remove USB runtime");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(DEVICE_NAME, document);
+
+  await removeTab(tab);
+  await clientWrapper.close();
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_fenix_runtime_node_picker.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_fenix_runtime_node_picker.js
new file mode 100644
index 0000000000..59bdbd765d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_fenix_runtime_node_picker.js
@@ -0,0 +1,83 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const RUNTIME_ID = "1337id";
+const DEVICE_NAME = "Fancy Phone";
+const SERVER_RUNTIME_NAME = "Mozilla Firefox";
+const ADB_RUNTIME_NAME = "Firefox Preview";
+const SERVER_VERSION = "v7.3.31";
+const ADB_VERSION = "v1.3.37";
+
+/**
+ * Check that the node picker button in about:devtools-toolbox has the expected class when
+ * connecting to an Android phone.
+ */
+add_task(async function () {
+  // We use a real local client combined with a mocked USB runtime to be able to open
+  // about:devtools-toolbox on a real target.
+  const clientWrapper = await createLocalClientWrapper();
+
+  const mocks = new Mocks();
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    channel: "nightly",
+    clientWrapper,
+    deviceName: DEVICE_NAME,
+    isFenix: true,
+    name: SERVER_RUNTIME_NAME,
+    shortName: ADB_RUNTIME_NAME,
+    versionName: ADB_VERSION,
+    version: SERVER_VERSION,
+  });
+
+  // open a remote runtime page
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  mocks.emitUSBUpdate();
+  info("Select the runtime page for the USB runtime");
+  const onRequestSuccess = waitForRequestsSuccess(window.AboutDebugging.store);
+  await connectToRuntime(DEVICE_NAME, document);
+  await selectRuntime(DEVICE_NAME, ADB_RUNTIME_NAME, document);
+  info(
+    "Wait for requests to finish the USB runtime is backed by a real local client"
+  );
+  await onRequestSuccess;
+
+  info("Wait for the about:debugging target to be available");
+  await waitUntil(() => findDebugTargetByText("about:debugging", document));
+  const { devtoolsDocument, devtoolsTab } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window
+  );
+
+  const pickerButton = devtoolsDocument.querySelector("#command-button-pick");
+  ok(
+    pickerButton.classList.contains("remote-fenix"),
+    "The node picker does have the expected additional className when debugging an android phone"
+  );
+  const pickerButtonTitle = pickerButton.getAttribute("title");
+  const expectedKeyboardShortcut =
+    Services.appinfo.OS === "Darwin"
+      ? `Cmd+Shift+C or Cmd+Opt+C`
+      : `Ctrl+Shift+C`;
+  is(
+    pickerButtonTitle,
+    `Pick an element from the Android phone (${expectedKeyboardShortcut})`,
+    `The node picker does have the expected tooltip when debugging an android phone`
+  );
+
+  info("Wait for all pending requests to settle on the DevToolsClient");
+  await clientWrapper.client.waitForRequestsToSettle();
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+
+  info("Remove USB runtime");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(DEVICE_NAME, document);
+
+  await removeTab(tab);
+  await clientWrapper.close();
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_hidden_addons.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_hidden_addons.js
new file mode 100644
index 0000000000..5d28752c93
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_hidden_addons.js
@@ -0,0 +1,66 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that system and hidden addons are only displayed when the showSystemAddons
+// preferences is true.
+
+const SYSTEM_ADDON = createAddonData({
+  id: "system",
+  name: "System Addon",
+  isSystem: true,
+  hidden: true,
+});
+const HIDDEN_ADDON = createAddonData({
+  id: "hidden",
+  name: "Hidden Addon",
+  isSystem: false,
+  hidden: true,
+});
+const NORMAL_ADDON = createAddonData({
+  id: "normal",
+  name: "Normal Addon",
+  isSystem: false,
+  hidden: false,
+});
+
+add_task(async function testShowSystemAddonsTrue() {
+  info("Test with showHiddenAddons set to true");
+  await testAddonsDisplay(true);
+
+  info("Test with showHiddenAddons set to false");
+  await testAddonsDisplay(false);
+});
+
+async function testAddonsDisplay(showHidden) {
+  const thisFirefoxClient = setupThisFirefoxMock();
+  thisFirefoxClient.listAddons = () => [
+    SYSTEM_ADDON,
+    HIDDEN_ADDON,
+    NORMAL_ADDON,
+  ];
+
+  info("Set showHiddenAddons to " + showHidden);
+  await pushPref("devtools.aboutdebugging.showHiddenAddons", showHidden);
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const hasSystemAddon = !!findDebugTargetByText("System Addon", document);
+  const hasHiddenAddon = !!findDebugTargetByText("Hidden Addon", document);
+  const hasInstalledAddon = !!findDebugTargetByText("Normal Addon", document);
+  is(
+    hasSystemAddon,
+    showHidden,
+    "System addon display is correct when showHiddenAddons is " + showHidden
+  );
+  is(
+    hasHiddenAddon,
+    showHidden,
+    "Hidden addon display is correct when showHiddenAddons is " + showHidden
+  );
+  ok(hasInstalledAddon, "Installed addon is always displayed");
+
+  await removeTab(tab);
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_message_close.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_message_close.js
new file mode 100644
index 0000000000..58ae2db6a3
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_message_close.js
@@ -0,0 +1,82 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-addons.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-addons.js", this);
+
+const EXTENSION_NAME = "Temporary web extension";
+const EXTENSION_ID = "test-devtools@mozilla.org";
+
+// Test that Message component can be closed with the X button
+add_task(async function () {
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Check that the message can be closed with icon");
+  let warningMessage = await installExtensionWithWarning(document);
+  await testCloseMessageWithIcon(warningMessage, document);
+  await removeTemporaryExtension(EXTENSION_NAME, document);
+
+  info("Check that the message can be closed with the button around the icon");
+  warningMessage = await installExtensionWithWarning(document);
+  await testCloseMessageWithButton(warningMessage, document);
+  await removeTemporaryExtension(EXTENSION_NAME, document);
+
+  await removeTab(tab);
+});
+
+async function testCloseMessageWithIcon(warningMessage, doc) {
+  const closeIcon = warningMessage.querySelector(
+    ".qa-message-button-close-icon"
+  );
+  ok(!!closeIcon, "The warning message has a close icon");
+
+  info("Closing the message and waiting for it to disappear");
+  closeIcon.click();
+
+  const target = findDebugTargetByText(EXTENSION_NAME, doc);
+  await waitUntil(() => target.querySelector(".qa-message") === null);
+}
+
+async function testCloseMessageWithButton(warningMessage, doc) {
+  const closeButton = warningMessage.querySelector(
+    ".qa-message-button-close-button"
+  );
+  ok(!!closeButton, "The warning message has a close button");
+
+  info("Click on the button and wait for the message to disappear");
+  EventUtils.synthesizeMouse(closeButton, 1, 1, {}, doc.defaultView);
+
+  const target = findDebugTargetByText(EXTENSION_NAME, doc);
+  await waitUntil(() => target.querySelector(".qa-message") === null);
+}
+
+async function installExtensionWithWarning(doc) {
+  await pushPref("extensions.webextensions.warnings-as-errors", false);
+  await installTemporaryExtensionFromXPI(
+    {
+      id: EXTENSION_ID,
+      name: EXTENSION_NAME,
+      extraProperties: {
+        // This property is not expected in the manifest and should trigger a warning!
+        wrongProperty: {},
+      },
+    },
+    doc
+  );
+  await SpecialPowers.popPrefEnv();
+
+  info("Wait until a debug target item appears");
+  await waitUntil(() => findDebugTargetByText(EXTENSION_NAME, doc));
+
+  const target = findDebugTargetByText(EXTENSION_NAME, doc);
+  const warningMessage = target.querySelector(".qa-message");
+  ok(
+    !!warningMessage,
+    "A warning message is displayed for the installed addon"
+  );
+
+  return warningMessage;
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_navigate.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_navigate.js
new file mode 100644
index 0000000000..281f01dbdc
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_navigate.js
@@ -0,0 +1,112 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+/**
+ * Check that navigating from This Firefox to Connect and back to This Firefox works and
+ * does not leak.
+ */
+
+const TAB_URL_1 = "data:text/html,<title>TAB1</title>";
+const TAB_URL_2 = "data:text/html,<title>TAB2</title>";
+
+add_task(async function () {
+  info("Force all debug target panes to be expanded");
+  prepareCollapsibilitiesTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  const AboutDebugging = window.AboutDebugging;
+  await selectThisFirefoxPage(document, AboutDebugging.store);
+
+  const connectSidebarItem = findSidebarItemByText("Setup", document);
+  const connectLink = connectSidebarItem.querySelector(".qa-sidebar-link");
+  ok(connectSidebarItem, "Found the Connect sidebar item");
+
+  const thisFirefoxString = getThisFirefoxString(window);
+  const thisFirefoxSidebarItem = findSidebarItemByText(
+    thisFirefoxString,
+    document
+  );
+  const thisFirefoxLink =
+    thisFirefoxSidebarItem.querySelector(".qa-sidebar-link");
+  ok(thisFirefoxSidebarItem, "Found the ThisFirefox sidebar item");
+  ok(
+    isSidebarItemSelected(thisFirefoxSidebarItem),
+    "ThisFirefox sidebar item is selected by default"
+  );
+
+  info("Open a new background tab TAB1");
+  const backgroundTab1 = await addTab(TAB_URL_1, { background: true });
+
+  info("Wait for the tab to appear in the debug targets with the correct name");
+  await waitUntil(() => findDebugTargetByText("TAB1", document));
+
+  await waitForAboutDebuggingRequests(AboutDebugging.store);
+  info("Click on the Connect item in the sidebar");
+  connectLink.click();
+
+  info("Wait until Connect page is displayed");
+  await waitUntil(() => document.querySelector(".qa-connect-page"));
+  // we need to wait here because the sidebar isn't updated after mounting the page
+  info("Wait until Connect sidebar item is selected");
+  await waitUntil(() => isSidebarItemSelected(connectSidebarItem));
+  ok(
+    !document.querySelector(".qa-runtime-page"),
+    "Runtime page no longer rendered"
+  );
+
+  info("Open a new tab which should be listed when we go back to This Firefox");
+  const backgroundTab2 = await addTab(TAB_URL_2, { background: true });
+
+  info("Click on the ThisFirefox item in the sidebar");
+  const requestsSuccess = waitForRequestsSuccess(AboutDebugging.store);
+  thisFirefoxLink.click();
+
+  info("Wait for all target requests to complete");
+  await requestsSuccess;
+
+  info("Wait until ThisFirefox page is displayed");
+  await waitUntil(() => document.querySelector(".qa-runtime-page"));
+  ok(
+    isSidebarItemSelected(thisFirefoxSidebarItem),
+    "ThisFirefox sidebar item is selected again"
+  );
+  ok(
+    !document.querySelector(".qa-connect-page"),
+    "Connect page no longer rendered"
+  );
+
+  info("TAB2 should already be displayed in the debug targets");
+  await waitUntil(() => findDebugTargetByText("TAB2", document));
+
+  info("Remove first background tab");
+  await removeTab(backgroundTab1);
+
+  info(
+    "Check TAB1 disappears, meaning ThisFirefox client is correctly connected"
+  );
+  await waitUntil(() => !findDebugTargetByText("TAB1", document));
+
+  info("Remove second background tab");
+  await removeTab(backgroundTab2);
+
+  info(
+    "Check TAB2 disappears, meaning ThisFirefox client is correctly connected"
+  );
+  await waitUntil(() => !findDebugTargetByText("TAB2", document));
+
+  await waitForAboutDebuggingRequests(AboutDebugging.store);
+
+  await removeTab(tab);
+});
+
+function isSidebarItemSelected(item) {
+  return item.classList.contains("qa-sidebar-item-selected");
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_persist_connection.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_persist_connection.js
new file mode 100644
index 0000000000..5ac1c2e188
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_persist_connection.js
@@ -0,0 +1,91 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const NETWORK_RUNTIME_HOST = "localhost:6080";
+const NETWORK_RUNTIME_APP_NAME = "TestNetworkApp";
+const USB_RUNTIME_ID = "test-runtime-id";
+const USB_DEVICE_NAME = "test device name";
+const USB_APP_NAME = "TestApp";
+
+// Test that remote runtime connections are persisted across about:debugging reloads.
+add_task(async function () {
+  const mocks = new Mocks();
+
+  info("Test with a USB runtime");
+  const usbClient = mocks.createUSBRuntime(USB_RUNTIME_ID, {
+    name: USB_APP_NAME,
+    deviceName: USB_DEVICE_NAME,
+  });
+
+  await testRemoteClientPersistConnection(mocks, {
+    client: usbClient,
+    id: USB_RUNTIME_ID,
+    runtimeName: USB_APP_NAME,
+    sidebarName: USB_DEVICE_NAME,
+    type: "usb",
+  });
+
+  info("Test with a network runtime");
+  const networkClient = mocks.createNetworkRuntime(NETWORK_RUNTIME_HOST, {
+    name: NETWORK_RUNTIME_APP_NAME,
+  });
+
+  await testRemoteClientPersistConnection(mocks, {
+    client: networkClient,
+    id: NETWORK_RUNTIME_HOST,
+    runtimeName: NETWORK_RUNTIME_APP_NAME,
+    sidebarName: NETWORK_RUNTIME_HOST,
+    type: "network",
+  });
+});
+
+async function testRemoteClientPersistConnection(
+  mocks,
+  { client, id, runtimeName, sidebarName, type }
+) {
+  info("Open about:debugging and connect to the test runtime");
+  let { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await connectToRuntime(sidebarName, document);
+  await selectRuntime(sidebarName, runtimeName, document);
+
+  info("Reload about:debugging");
+  document = await reloadAboutDebugging(tab);
+
+  info("Wait until the remote runtime appears as connected");
+  await waitUntil(() => {
+    const sidebarItem = findSidebarItemByText(sidebarName, document);
+    return sidebarItem && !sidebarItem.querySelector(".qa-connect-button");
+  });
+
+  info("Wait until the remote runtime page is selected");
+  await waitUntil(() => {
+    const runtimeInfo = document.querySelector(".qa-runtime-name");
+    return runtimeInfo && runtimeInfo.textContent.includes(runtimeName);
+  });
+
+  // Remove the runtime without emitting an update.
+  // This is what happens today when we simply close Firefox for Android.
+  info("Remove the runtime from the list of remote runtimes");
+  mocks.removeRuntime(id);
+
+  info(
+    "Emit 'closed' on the client and wait for the sidebar item to disappear"
+  );
+  client._eventEmitter.emit("closed");
+  if (type === "usb") {
+    await waitUntilUsbDeviceIsUnplugged(sidebarName, document);
+  } else {
+    await waitUntil(
+      () =>
+        !findSidebarItemByText(sidebarName, document) &&
+        !findSidebarItemByText(runtimeName, document)
+    );
+  }
+
+  info("Remove the tab");
+  await removeTab(tab);
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_process_category.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_process_category.js
new file mode 100644
index 0000000000..fd7fb9a852
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_process_category.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const CATEGORY_NAME = "Processes";
+const RUNTIME_ID = "test-runtime-id";
+const RUNTIME_DEVICE_NAME = "test device name";
+const RUNTIME_APP_NAME = "TestApp";
+
+// Test whether process category exists by the runtime type.
+add_task(async function () {
+  await pushPref("devtools.aboutdebugging.process-debugging", true);
+
+  const mocks = new Mocks();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const usbRuntime = mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceName: RUNTIME_DEVICE_NAME,
+    name: RUNTIME_APP_NAME,
+  });
+  usbRuntime.getMainProcess = () => {
+    return {
+      getTarget: () => {
+        return { actorID: 0 };
+      },
+    };
+  };
+  mocks.emitUSBUpdate();
+
+  info("Check the process category existence for this firefox");
+  ok(
+    !getDebugTargetPane(CATEGORY_NAME, document),
+    "Process category should not display for this firefox"
+  );
+
+  info("Check the process category existence for USB runtime");
+  await connectToRuntime(RUNTIME_DEVICE_NAME, document);
+  await selectRuntime(RUNTIME_DEVICE_NAME, RUNTIME_APP_NAME, document);
+  ok(
+    getDebugTargetPane(CATEGORY_NAME, document),
+    "Process category should display for USB runtime"
+  );
+
+  info("Remove USB runtime");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(RUNTIME_DEVICE_NAME, document);
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_process_main.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_process_main.js
new file mode 100644
index 0000000000..bd88545d58
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_process_main.js
@@ -0,0 +1,87 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+const MULTIPROCESS_TOOLBOX_NAME = "Multiprocess Toolbox";
+const MULTIPROCESS_TOOLBOX_DESCRIPTION =
+  "Main Process and Content Processes for the target browser";
+
+const RUNTIME_ID = "test-runtime-id";
+const RUNTIME_DEVICE_NAME = "test device name";
+const RUNTIME_APP_NAME = "TestApp";
+
+// Test for main process.
+add_task(async function () {
+  await pushPref("devtools.aboutdebugging.process-debugging", true);
+  const mocks = new Mocks();
+
+  const { document, tab, window } = await openAboutDebugging();
+
+  const usbRuntime = mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceName: RUNTIME_DEVICE_NAME,
+    name: RUNTIME_APP_NAME,
+  });
+
+  // Note: about:debugging assumes that the main process has the id 0 and will
+  // rely on it to create the about:devtools-toolbox URL.
+  // Only check that about:debugging doesn't create a target unnecessarily.
+  usbRuntime.getMainProcess = () => {
+    return {
+      getTarget: () => {
+        ok(false, "about:debugging should not create the main process target");
+      },
+    };
+  };
+  mocks.emitUSBUpdate();
+
+  info("Select USB runtime");
+  await connectToRuntime(RUNTIME_DEVICE_NAME, document);
+  await selectRuntime(RUNTIME_DEVICE_NAME, RUNTIME_APP_NAME, document);
+
+  info("Check debug target item of the main process");
+  await waitUntil(() =>
+    findDebugTargetByText(MULTIPROCESS_TOOLBOX_NAME, document)
+  );
+  const mainProcessItem = findDebugTargetByText(
+    MULTIPROCESS_TOOLBOX_NAME,
+    document
+  );
+  ok(mainProcessItem, "Debug target item of the main process should display");
+  ok(
+    mainProcessItem.textContent.includes(MULTIPROCESS_TOOLBOX_DESCRIPTION),
+    "Debug target item of the main process should contains the description"
+  );
+
+  info("Inspect main process");
+  const { devtoolsTab, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    MULTIPROCESS_TOOLBOX_NAME,
+    false
+  );
+
+  const url = new window.URL(devtoolsWindow.location.href);
+  const type = url.searchParams.get("type");
+  is(type, "process", "Correct type argument");
+  const remoteID = url.searchParams.get("remoteId");
+  is(remoteID, `${RUNTIME_ID}-usb`, "Correct remote runtime id");
+
+  info("Remove USB runtime");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(RUNTIME_DEVICE_NAME, document);
+
+  // Note that we can't use `closeAboutDevtoolsToolbox` because the toolbox init
+  // is expected to fail, and we are redirected to the error page.
+  await removeTab(devtoolsTab);
+  await waitUntil(() => !findDebugTargetByText("Toolbox - ", document));
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_process_main_local.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_process_main_local.js
new file mode 100644
index 0000000000..06bd29095c
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_process_main_local.js
@@ -0,0 +1,44 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+// Test for main process against This Firefox.
+//
+// The main added value for this test is to check that listing processes
+// and opening a toolbox targeting a process works, even though debugging
+// the main process of This Firefox is not really supported.
+add_task(async function () {
+  await pushPref("devtools.aboutdebugging.process-debugging", true);
+  await pushPref("devtools.aboutdebugging.test-local-process-debugging", true);
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Check debug target item of the main process");
+  const mainProcessItem = findDebugTargetByText("Multiprocess", document);
+  ok(mainProcessItem, "Debug target item of the main process should display");
+  ok(
+    mainProcessItem.textContent.includes(
+      "Main Process and Content Processes for the target browser"
+    ),
+    "Debug target item of the main process should contains the description"
+  );
+
+  info("Inspect main process and wait for DevTools to open");
+  const { devtoolsTab } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    "Main Process"
+  );
+
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_profiler_dialog.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_profiler_dialog.js
new file mode 100644
index 0000000000..fd546bd854
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_profiler_dialog.js
@@ -0,0 +1,238 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.scriptloader.loadSubScript(
+  "chrome://mochitests/content/browser/devtools/client/performance-new/test/browser/helpers.js",
+  this
+);
+
+const BackgroundJSM = ChromeUtils.importESModule(
+  "resource://devtools/client/performance-new/shared/background.sys.mjs"
+);
+
+registerCleanupFunction(() => {
+  BackgroundJSM.revertRecordingSettings();
+});
+
+const RUNTIME_ID = "1337id";
+const DEVICE_NAME = "Fancy Phone";
+const RUNTIME_NAME = "Lorem ipsum";
+
+/**
+ * Test opening and closing the profiler dialog.
+ */
+add_task(async function test_opening_profiler_dialog() {
+  const { mocks } = await connectToLocalFirefox();
+  const { document, tab, window } = await openAboutDebugging();
+
+  mocks.emitUSBUpdate();
+  await connectToRuntime(DEVICE_NAME, document);
+  await selectRuntime(DEVICE_NAME, RUNTIME_NAME, document);
+
+  info("Open the profiler dialog");
+  await openProfilerDialogWithRealClient(document);
+  assertDialogVisible(document);
+
+  info("Click on the close button and wait until the dialog disappears");
+  const closeDialogButton = document.querySelector(".qa-profiler-dialog-close");
+  closeDialogButton.click();
+  await waitUntil(() => !document.querySelector(".qa-profiler-dialog"));
+  assertDialogHidden(document);
+
+  info("Open the profiler dialog again");
+  await openProfilerDialogWithRealClient(document);
+  assertDialogVisible(document);
+
+  info("Click on the mask element and wait until the dialog disappears");
+  const mask = document.querySelector(".qa-profiler-dialog-mask");
+  EventUtils.synthesizeMouse(mask, 5, 5, {}, window);
+  await waitUntil(() => !document.querySelector(".qa-profiler-dialog"));
+  assertDialogHidden(document);
+
+  info("Open the profiler dialog again");
+  await openProfilerDialogWithRealClient(document);
+  assertDialogVisible(document);
+
+  info("Navigate to this-firefox and wait until the dialog disappears");
+  document.location.hash = "#/runtime/this-firefox";
+  await waitUntil(() => !document.querySelector(".qa-profiler-dialog"));
+  assertDialogHidden(document);
+
+  info("Select the remote runtime again, check the dialog is still hidden");
+  await selectRuntime(DEVICE_NAME, RUNTIME_NAME, document);
+  assertDialogHidden(document);
+
+  await disconnectFromLocalFirefox({ mocks, doc: document });
+  await removeTab(tab);
+});
+
+add_task(async function test_set_profiler_settings() {
+  const { mocks } = await connectToLocalFirefox();
+  const { document, tab } = await openAboutDebugging();
+
+  mocks.emitUSBUpdate();
+  await connectToRuntime(DEVICE_NAME, document);
+  await selectRuntime(DEVICE_NAME, RUNTIME_NAME, document);
+
+  info("Open the profiler dialog");
+  await openProfilerDialogWithRealClient(document);
+  assertDialogVisible(document);
+
+  const profilerSettingsDocument = await openProfilerSettings(document);
+  const radioButtonForCustomPreset = await getNearestInputFromText(
+    profilerSettingsDocument,
+    "Custom"
+  );
+  ok(
+    radioButtonForCustomPreset.checked,
+    "The radio button for the preset 'custom' is checked."
+  );
+
+  info("Change the preset to Graphics.");
+  const radioButtonForGraphicsPreset = await getNearestInputFromText(
+    profilerSettingsDocument,
+    "Graphics"
+  );
+  radioButtonForGraphicsPreset.click();
+
+  const profilerDocument = await saveSettingsAndGoBack(document);
+  const perfPresetsSelect = await getNearestInputFromText(
+    profilerDocument,
+    "Settings"
+  );
+  is(
+    perfPresetsSelect.value,
+    "graphics",
+    "The preset has been changed in the devtools panel UI as well."
+  );
+
+  await disconnectFromLocalFirefox({ mocks, doc: document });
+  await removeTab(tab);
+});
+
+async function connectToLocalFirefox() {
+  // This is a client to the current Firefox.
+  const clientWrapper = await createLocalClientWrapper();
+
+  // enable USB devices mocks
+  const mocks = new Mocks();
+  const usbClient = mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceName: DEVICE_NAME,
+    name: RUNTIME_NAME,
+    clientWrapper,
+  });
+
+  return { mocks, usbClient };
+}
+
+async function disconnectFromLocalFirefox({ doc, mocks }) {
+  info("Remove USB runtime");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(DEVICE_NAME, doc);
+}
+
+function assertDialogVisible(doc) {
+  ok(doc.querySelector(".qa-profiler-dialog"), "Dialog is displayed");
+  ok(doc.querySelector(".qa-profiler-dialog-mask"), "Dialog mask is displayed");
+}
+
+function assertDialogHidden(doc) {
+  ok(!doc.querySelector(".qa-profiler-dialog"), "Dialog is removed");
+  ok(!doc.querySelector(".qa-profiler-dialog-mask"), "Dialog mask is removed");
+}
+
+/**
+ * Retrieve the iframe containing the profiler UIs.
+ * Be careful as it's completely replaced when switching UIs.
+ */
+function getProfilerIframe(doc) {
+  return doc.querySelector(".profiler-dialog__frame");
+}
+
+/**
+ * This waits for the full render of the UI inside the profiler iframe, and
+ * returns the content document object.
+ */
+async function waitForProfilerUiRendering(doc, selector) {
+  // The iframe is replaced completely, so we need to retrieve a new reference
+  // each time.
+  const profilerIframe = getProfilerIframe(doc);
+  // Wait for the settings to render.
+  await TestUtils.waitForCondition(
+    () =>
+      profilerIframe.contentDocument &&
+      profilerIframe.contentDocument.querySelector(selector)
+  );
+
+  return profilerIframe.contentDocument;
+}
+
+/**
+ * Open the performance profiler dialog with a real client.
+ */
+async function openProfilerDialogWithRealClient(doc) {
+  info("Click on the Profile Runtime button");
+  const profileButton = doc.querySelector(".qa-profile-runtime-button");
+  profileButton.click();
+
+  info("Wait for the rendering of the profiler UI");
+  const contentDocument = await waitForProfilerUiRendering(
+    doc,
+    ".perf-presets"
+  );
+  await getActiveButtonFromText(contentDocument, "Start recording");
+  info("The profiler UI is rendered!");
+  return contentDocument;
+}
+
+/**
+ * Open the performance profiler settings. This assumes the profiler dialog is
+ * already open by the previous function openProfilerDialog.
+ */
+async function openProfilerSettings(doc) {
+  const profilerDocument = getProfilerIframe(doc).contentDocument;
+
+  // Select the custom preset.
+  const perfPresetsSelect = await getNearestInputFromText(
+    profilerDocument,
+    "Settings"
+  );
+  setReactFriendlyInputValue(perfPresetsSelect, "custom");
+
+  // Click on "Edit Settings".
+  const editSettingsLink = await getElementFromDocumentByText(
+    profilerDocument,
+    "Edit Settings"
+  );
+  editSettingsLink.click();
+
+  info("Wait for the rendering of the profiler settings UI");
+  const contentDocument = await waitForProfilerUiRendering(
+    doc,
+    ".perf-aboutprofiling-remote"
+  );
+  info("The profiler settings UI is rendered!");
+  return contentDocument;
+}
+
+async function saveSettingsAndGoBack(doc) {
+  const profilerDocument = getProfilerIframe(doc).contentDocument;
+
+  const saveSettingsAndGoBackButton = await getActiveButtonFromText(
+    profilerDocument,
+    "Save settings"
+  );
+  saveSettingsAndGoBackButton.click();
+
+  info("Wait for the rendering of the profiler UI");
+  const contentDocument = await waitForProfilerUiRendering(
+    doc,
+    ".perf-presets"
+  );
+  await getActiveButtonFromText(contentDocument, "Start recording");
+  info("The profiler UI is rendered!");
+  return contentDocument;
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_real_usb_runtime_page_runtime_info.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_real_usb_runtime_page_runtime_info.js
new file mode 100644
index 0000000000..16462fd2b3
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_real_usb_runtime_page_runtime_info.js
@@ -0,0 +1,62 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-real-usb.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-real-usb.js",
+  this
+);
+
+// Test that runtime info of USB runtime appears on main pane.
+// Documentation for real usb tests in /documentation/TESTS_REAL_DEVICES.md
+add_task(async function () {
+  if (!isAvailable()) {
+    ok(true, "Real usb runtime test is not available");
+    return;
+  }
+
+  const { document, tab } = await openAboutDebuggingWithADB();
+
+  const expectedRuntime = await getExpectedRuntime();
+  const { runtimeDetails, sidebarInfo } = expectedRuntime;
+
+  info("Connect a USB runtime");
+  await Promise.race([
+    connectToRuntime(sidebarInfo.deviceName, document),
+    /* eslint-disable mozilla/no-arbitrary-setTimeout */
+    new Promise(resolve =>
+      setTimeout(() => {
+        ok(
+          false,
+          "Failed to connect, did you disable the connection prompt for this runtime?"
+        );
+        resolve();
+      }, 5000)
+    ),
+    /* eslint-enable mozilla/no-arbitrary-setTimeout */
+  ]);
+
+  info("Select a USB runtime");
+  await selectRuntime(
+    sidebarInfo.deviceName,
+    runtimeDetails.info.name,
+    document
+  );
+
+  info("Check that runtime info is properly displayed");
+  const runtimeInfo = document.querySelector(".qa-runtime-name");
+  ok(runtimeInfo, "Runtime info is displayed");
+  const runtimeInfoText = runtimeInfo.textContent;
+  ok(
+    runtimeInfoText.includes(runtimeDetails.info.name),
+    "Runtime info shows the correct runtime name: " + runtimeInfoText
+  );
+  ok(
+    runtimeInfoText.includes(runtimeDetails.info.version),
+    "Runtime info shows the correct version number: " + runtimeInfoText
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_real_usb_sidebar.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_real_usb_sidebar.js
new file mode 100644
index 0000000000..0b091dff87
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_real_usb_sidebar.js
@@ -0,0 +1,34 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-real-usb.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-real-usb.js",
+  this
+);
+
+// Test that USB runtimes appear from the sidebar.
+// Documentation for real usb tests in /documentation/TESTS_REAL_DEVICES.md
+add_task(async function () {
+  if (!isAvailable()) {
+    ok(true, "Real usb runtime test is not available");
+    return;
+  }
+
+  const { document, tab } = await openAboutDebuggingWithADB();
+
+  for (const { sidebarInfo } of await getExpectedRuntimeAll()) {
+    const { deviceName, shortName } = sidebarInfo;
+    await waitUntil(() => findSidebarItemByText(deviceName, document));
+    const usbRuntimeSidebarItem = findSidebarItemByText(deviceName, document);
+    ok(
+      usbRuntimeSidebarItem.textContent.includes(shortName),
+      "The device name and short name of the usb runtime are visible in sidebar item " +
+        `[${usbRuntimeSidebarItem.textContent}]`
+    );
+  }
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_routes.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_routes.js
new file mode 100644
index 0000000000..6295d37503
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_routes.js
@@ -0,0 +1,114 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that the initial route is /setup
+ */
+add_task(async function () {
+  info("Check root route redirects to setup page");
+  const { document, tab } = await openAboutDebugging();
+  is(document.location.hash, "#/setup");
+
+  await removeTab(tab);
+});
+
+/**
+ * Test that the routes in about:debugging show the proper views and document.title
+ */
+add_task(async function () {
+  // enable USB devices mocks
+  const mocks = new Mocks();
+
+  const { document, tab } = await openAboutDebugging();
+
+  info("Check 'This Firefox' route");
+  document.location.hash = "#/runtime/this-firefox";
+  await waitUntil(() => document.querySelector(".qa-runtime-page"));
+  const infoLabel = document.querySelector(".qa-runtime-name").textContent;
+  // NOTE: when using USB Mocks, we see only "Firefox" as the device name
+  ok(infoLabel.includes("Firefox"), "Runtime is displayed as Firefox");
+  ok(!infoLabel.includes(" on "), "Runtime is not associated to any device");
+  is(
+    document.title,
+    "Debugging - Runtime / this-firefox",
+    "Checking title for 'runtime' page"
+  );
+
+  info("Check 'Setup' page");
+  document.location.hash = "#/setup";
+  await waitUntil(() => document.querySelector(".qa-connect-page"));
+  ok(true, "Setup page has been shown");
+  is(document.title, "Debugging - Setup", "Checking title for 'setup' page");
+
+  info("Check 'USB device runtime' page");
+  // connect to a mocked USB runtime
+  mocks.createUSBRuntime("1337id", {
+    deviceName: "Fancy Phone",
+    name: "Lorem ipsum",
+  });
+  mocks.emitUSBUpdate();
+  await connectToRuntime("Fancy Phone", document);
+  // navigate to it via URL
+  document.location.hash = "#/runtime/1337id";
+  await waitUntil(() => document.querySelector(".qa-runtime-page"));
+  const runtimeLabel = document.querySelector(".qa-runtime-name").textContent;
+  is(
+    document.title,
+    "Debugging - Runtime / 1337id",
+    "Checking title for 'runtime' page with USB device"
+  );
+  ok(
+    runtimeLabel.includes("Lorem ipsum"),
+    "Runtime is displayed with the mocked name"
+  );
+
+  await removeTab(tab);
+});
+
+/**
+ * Test that an invalid route redirects to / (currently This Firefox page)
+ */
+add_task(async function () {
+  info("Check an invalid route redirects to root");
+  const { document, tab } = await openAboutDebugging();
+
+  info("Waiting for a non setup page to load");
+  document.location.hash = "#/runtime/this-firefox";
+  await waitUntil(() => document.querySelector(".qa-runtime-page"));
+
+  info("Update hash & wait for a redirect to root (connect page)");
+  document.location.hash = "#/lorem-ipsum";
+  await waitUntil(() => document.querySelector(".qa-connect-page"));
+  is(document.title, "Debugging - Setup", "Checking title for 'setup' page");
+  is(document.location.hash, "#/setup", "Redirected to root");
+
+  await removeTab(tab);
+});
+
+/**
+ * Test that routes from old about:debugging redirect to this Firefox.
+ */
+add_task(async function testOldAboutDebuggingRoutes() {
+  info("Check that routes from old about:debugging redirect to this Firefox");
+  const { document, tab } = await openAboutDebugging();
+
+  const routes = ["addons", "tabs", "workers"];
+  for (const route of routes) {
+    info("Move to setup page before testing the route");
+    document.location.hash = "#/setup";
+    await waitUntil(() => document.querySelector(".qa-connect-page"));
+
+    info(`Check that navigating to ${route} redirects to This Firefox`);
+    document.location.hash = route;
+    await waitUntil(() => document.querySelector(".qa-runtime-page"));
+    is(
+      document.location.hash,
+      "#/runtime/this-firefox",
+      `${route} was redirected to This Firefox`
+    );
+  }
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_rtl.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_rtl.js
new file mode 100644
index 0000000000..4424df6ea8
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_rtl.js
@@ -0,0 +1,62 @@
+/* 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";
+
+// Test that the about:debugging document and the profiler dialog document
+// use the expected document direction.
+add_task(async function test_direction_is_ltr_by_default() {
+  await testAboutDebuggingDocsDirection("ltr");
+});
+
+add_task(async function test_direction_is_rtl_for_bidi_pseudolocale() {
+  await pushPref("intl.l10n.pseudo", "bidi");
+  await testAboutDebuggingDocsDirection("rtl");
+});
+
+async function testAboutDebuggingDocsDirection(expectedDir) {
+  const mocks = new Mocks();
+  const { document, usbClient } = await setupTestForMockUSBRuntime(mocks);
+
+  is(document.dir, expectedDir, "document dir is " + expectedDir);
+
+  info("Open the profiler dialog");
+  await openProfilerDialog(usbClient, document);
+
+  const profilerDialogFrame = document.querySelector(
+    ".qa-profiler-dialog iframe"
+  );
+  ok(profilerDialogFrame, "Found Profiler dialog iframe");
+
+  const profilerDoc = profilerDialogFrame.contentWindow.document;
+  is(profilerDoc.dir, expectedDir, "Profiler document dir is " + expectedDir);
+
+  await teardownTestForMockUSBRuntime(mocks, document);
+}
+
+async function setupTestForMockUSBRuntime(mocks) {
+  info("Setup mock USB runtime");
+
+  const usbClient = mocks.createUSBRuntime("runtimeId", {
+    deviceName: "deviceName",
+    name: "runtimeName",
+  });
+
+  info("Open about:debugging and select runtime page for mock USB runtime");
+  const { document } = await openAboutDebugging();
+
+  mocks.emitUSBUpdate();
+  await connectToRuntime("deviceName", document);
+  await selectRuntime("deviceName", "runtimeName", document);
+
+  return { document, usbClient };
+}
+
+async function teardownTestForMockUSBRuntime(mocks, doc) {
+  info("Remove mock USB runtime");
+
+  mocks.removeUSBRuntime("runtimeId");
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged("deviceName", doc);
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_compatibility_warning.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_compatibility_warning.js
new file mode 100644
index 0000000000..3f45fa10d2
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_compatibility_warning.js
@@ -0,0 +1,90 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const COMPATIBLE_RUNTIME = "Compatible Runtime";
+const COMPATIBLE_DEVICE = "Compatible Device";
+const OLD_RUNTIME = "Old Runtime";
+const OLD_DEVICE = "Old Device";
+const FENNEC_68_RUNTIME = "Bad Runtime Fennec 68";
+const FENNEC_68_DEVICE = "Bad Device Fennec 68";
+const RECENT_RUNTIME = "Recent Runtime";
+const RECENT_DEVICE = "Recent Device";
+
+add_task(async function () {
+  const {
+    COMPATIBILITY_STATUS,
+  } = require("resource://devtools/client/shared/remote-debugging/version-checker.js");
+  const { COMPATIBLE, TOO_OLD, TOO_OLD_FENNEC, TOO_RECENT } =
+    COMPATIBILITY_STATUS;
+
+  info("Create several mocked runtimes, with different compatibility reports");
+  const mocks = new Mocks();
+  createRuntimeWithReport(
+    mocks,
+    COMPATIBLE_RUNTIME,
+    COMPATIBLE_DEVICE,
+    COMPATIBLE
+  );
+  createRuntimeWithReport(mocks, OLD_RUNTIME, OLD_DEVICE, TOO_OLD);
+  createRuntimeWithReport(mocks, RECENT_RUNTIME, RECENT_DEVICE, TOO_RECENT);
+  createRuntimeWithReport(
+    mocks,
+    FENNEC_68_RUNTIME,
+    FENNEC_68_DEVICE,
+    TOO_OLD_FENNEC
+  );
+
+  const { document, tab } = await openAboutDebugging();
+  mocks.emitUSBUpdate();
+
+  info("Connect to all runtimes");
+  await connectToRuntime(COMPATIBLE_DEVICE, document);
+  await connectToRuntime(OLD_DEVICE, document);
+  await connectToRuntime(RECENT_DEVICE, document);
+  await connectToRuntime(FENNEC_68_DEVICE, document);
+
+  info("Select the compatible runtime and check that no warning is displayed");
+  await selectRuntime(COMPATIBLE_DEVICE, COMPATIBLE_RUNTIME, document);
+  ok(
+    !document.querySelector(".qa-compatibility-warning"),
+    "Compatibility warning is not displayed"
+  );
+
+  info(
+    "Select the old runtime and check that the too-old warning is displayed"
+  );
+  await selectRuntime(OLD_DEVICE, OLD_RUNTIME, document);
+  ok(
+    document.querySelector(".qa-compatibility-warning-too-old"),
+    "Expected compatibility warning is displayed (too-old)"
+  );
+
+  info(
+    "Select the recent runtime and check that the too-recent warning is displayed"
+  );
+  await selectRuntime(RECENT_DEVICE, RECENT_RUNTIME, document);
+  ok(
+    document.querySelector(".qa-compatibility-warning-too-recent"),
+    "Expected compatibility warning is displayed (too-recent)"
+  );
+
+  info(
+    "Select the Fennec 68 runtime and check that the correct warning is displayed"
+  );
+  await selectRuntime(FENNEC_68_DEVICE, FENNEC_68_RUNTIME, document);
+  ok(document.querySelector(".qa-compatibility-warning-too-old-fennec"));
+
+  await removeTab(tab);
+});
+
+function createRuntimeWithReport(mocks, name, deviceName, status) {
+  const runtimeId = [name, deviceName].join("-");
+  const compatibleUsbClient = mocks.createUSBRuntime(runtimeId, {
+    deviceName,
+    name,
+  });
+  const report = { status };
+  compatibleUsbClient.checkVersionCompatibility = () => report;
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_disconnect_remote_runtime.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_disconnect_remote_runtime.js
new file mode 100644
index 0000000000..e7cae28d29
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_disconnect_remote_runtime.js
@@ -0,0 +1,65 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const USB_RUNTIME_ID = "1337id";
+const USB_DEVICE_NAME = "Fancy Phone";
+const USB_APP_NAME = "Lorem ipsum";
+
+const DEFAULT_PAGE = "#/runtime/this-firefox";
+
+/**
+ * Check if the disconnect button disconnects the remote runtime
+ * and redirects to the default page.
+ */
+add_task(async function () {
+  // Create a real local client and use it as the remote USB client for this
+  // test.
+  const clientWrapper = await createLocalClientWrapper();
+
+  // enable USB devices mocks
+  const mocks = new Mocks();
+  mocks.createUSBRuntime(USB_RUNTIME_ID, {
+    clientWrapper,
+    deviceName: USB_DEVICE_NAME,
+    name: USB_APP_NAME,
+  });
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  mocks.emitUSBUpdate();
+
+  const onRequestSuccess = waitForRequestsSuccess(window.AboutDebugging.store);
+  await connectToRuntime(USB_DEVICE_NAME, document);
+  await selectRuntime(USB_DEVICE_NAME, USB_APP_NAME, document);
+  await onRequestSuccess;
+
+  const disconnectRemoteRuntimeButton = document.querySelector(
+    ".qa-runtime-info__action"
+  );
+
+  info("Check whether disconnect remote runtime button exists");
+  ok(!!disconnectRemoteRuntimeButton, "Runtime contains the disconnect button");
+
+  info("Click on the disconnect button");
+  disconnectRemoteRuntimeButton.click();
+
+  info("Wait until the runtime is disconnected");
+  await waitUntil(() => document.querySelector(".qa-connect-button"));
+
+  is(
+    document.location.hash,
+    DEFAULT_PAGE,
+    "Redirection to the default page (this-firefox)"
+  );
+
+  info("Wait until the Runtime name is displayed");
+  await waitUntil(() => {
+    const runtimeInfo = document.querySelector(".qa-runtime-name");
+    return runtimeInfo && runtimeInfo.textContent.includes("Firefox");
+  });
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_remote_runtime_buttons.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_remote_runtime_buttons.js
new file mode 100644
index 0000000000..563fe659ce
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_remote_runtime_buttons.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const USB_RUNTIME_ID = "1337id";
+const USB_DEVICE_NAME = "Fancy Phone";
+const USB_APP_NAME = "Lorem ipsum";
+
+/**
+ * Test that remote runtimes show action buttons that are hidden for 'This Firefox'.
+ */
+add_task(async function () {
+  // enable USB devices mocks
+  const mocks = new Mocks();
+  mocks.createUSBRuntime(USB_RUNTIME_ID, {
+    deviceName: USB_DEVICE_NAME,
+    name: USB_APP_NAME,
+  });
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Checking This Firefox");
+  ok(
+    !document.querySelector(".qa-connection-prompt-toggle-button"),
+    "This Firefox does not contain the connection prompt button"
+  );
+  ok(
+    !document.querySelector(".qa-profile-runtime-button"),
+    "This Firefox does not contain the profile runtime button"
+  );
+  ok(
+    !document.querySelector(".qa-runtime-info__action"),
+    "This Firefox does not contain the disconnect button"
+  );
+
+  info("Checking a USB runtime");
+  mocks.emitUSBUpdate();
+  await connectToRuntime(USB_DEVICE_NAME, document);
+  await selectRuntime(USB_DEVICE_NAME, USB_APP_NAME, document);
+  ok(
+    !!document.querySelector(".qa-connection-prompt-toggle-button"),
+    "Runtime contains the connection prompt button"
+  );
+  ok(
+    !!document.querySelector(".qa-profile-runtime-button"),
+    "Remote runtime contains the profile runtime button"
+  );
+  ok(
+    !!document.querySelector(".qa-runtime-info__action"),
+    "Runtime contains the disconnect button"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_usbclient_closed.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_usbclient_closed.js
new file mode 100644
index 0000000000..9e9715a46b
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_runtime_usbclient_closed.js
@@ -0,0 +1,109 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const NETWORK_RUNTIME_HOST = "localhost:6080";
+const NETWORK_RUNTIME_APP_NAME = "TestNetworkApp";
+const USB_RUNTIME_ID = "test-runtime-id";
+const USB_DEVICE_NAME = "test device name";
+const USB_APP_NAME = "TestApp";
+
+// Test that about:debugging navigates back to the default page when a USB device is
+// unplugged.
+add_task(async function testUsbDeviceUnplugged() {
+  const mocks = new Mocks();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  mocks.createUSBRuntime(USB_RUNTIME_ID, {
+    deviceName: USB_DEVICE_NAME,
+    name: USB_APP_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Connect to and select the USB device");
+  await connectToRuntime(USB_DEVICE_NAME, document);
+  await selectRuntime(USB_DEVICE_NAME, USB_APP_NAME, document);
+
+  info("Simulate a device unplugged");
+  mocks.removeUSBRuntime(USB_RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(USB_DEVICE_NAME, document);
+
+  is(
+    document.location.hash,
+    `#/runtime/this-firefox`,
+    "Redirection to the default page (this-firefox)"
+  );
+
+  await removeTab(tab);
+});
+
+// Test that about:debugging navigates back to the default page when the server for the
+// current USB runtime is closed.
+add_task(async function testUsbClientDisconnected() {
+  const mocks = new Mocks();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const usbClient = mocks.createUSBRuntime(USB_RUNTIME_ID, {
+    deviceName: USB_DEVICE_NAME,
+    name: USB_APP_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Connect to and select the USB device");
+  await connectToRuntime(USB_DEVICE_NAME, document);
+  await selectRuntime(USB_DEVICE_NAME, USB_APP_NAME, document);
+
+  info("Simulate a client disconnection");
+  usbClient.isClosed = () => true;
+  usbClient._eventEmitter.emit("closed");
+
+  info("Wait until the connect button for this runtime appears");
+  await waitUntil(() => {
+    const item = findSidebarItemByText(USB_DEVICE_NAME, document);
+    return item && item.querySelector(".qa-connect-button");
+  });
+
+  is(
+    document.location.hash,
+    `#/runtime/this-firefox`,
+    "Redirection to the default page (this-firefox)"
+  );
+  await removeTab(tab);
+});
+
+// Test that about:debugging navigates back to the default page when the server for the
+// current network runtime is closed.
+add_task(async function testNetworkClientDisconnected() {
+  const mocks = new Mocks();
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const networkClient = mocks.createNetworkRuntime(NETWORK_RUNTIME_HOST, {
+    name: NETWORK_RUNTIME_APP_NAME,
+  });
+
+  info("Connect to and select the network runtime");
+  await connectToRuntime(NETWORK_RUNTIME_HOST, document);
+  await selectRuntime(NETWORK_RUNTIME_HOST, NETWORK_RUNTIME_APP_NAME, document);
+
+  info("Simulate a client disconnection");
+  networkClient.isClosed = () => true;
+  networkClient._eventEmitter.emit("closed");
+
+  info("Wait until the connect button for this runtime appears");
+  await waitUntil(() => {
+    const item = findSidebarItemByText(NETWORK_RUNTIME_HOST, document);
+    return item && item.querySelector(".qa-connect-button");
+  });
+
+  is(
+    document.location.hash,
+    `#/runtime/this-firefox`,
+    "Redirection to the default page (this-firefox)"
+  );
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_select_network_runtime.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_select_network_runtime.js
new file mode 100644
index 0000000000..e3f770f948
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_select_network_runtime.js
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const NETWORK_RUNTIME_HOST = "localhost:6080";
+const NETWORK_RUNTIME_APP_NAME = "TestNetworkApp";
+const NETWORK_RUNTIME_CHANNEL = "SomeChannel";
+const NETWORK_RUNTIME_VERSION = "12.3";
+
+// Test that network runtimes can be selected.
+add_task(async function () {
+  const mocks = new Mocks();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Prepare Network client mock");
+  const networkClient = mocks.createNetworkRuntime(NETWORK_RUNTIME_HOST, {
+    name: NETWORK_RUNTIME_APP_NAME,
+  });
+  networkClient.getDeviceDescription = () => {
+    return {
+      name: NETWORK_RUNTIME_APP_NAME,
+      channel: NETWORK_RUNTIME_CHANNEL,
+      version: NETWORK_RUNTIME_VERSION,
+    };
+  };
+
+  info("Test addons in runtime page for Network client");
+  await connectToRuntime(NETWORK_RUNTIME_HOST, document);
+  await selectRuntime(NETWORK_RUNTIME_HOST, NETWORK_RUNTIME_APP_NAME, document);
+
+  info("Check that the network runtime mock is properly displayed");
+  const thisFirefoxRuntimeInfo = document.querySelector(".qa-runtime-name");
+  ok(
+    thisFirefoxRuntimeInfo,
+    "Runtime info for this-firefox runtime is displayed"
+  );
+  const runtimeInfoText = thisFirefoxRuntimeInfo.textContent;
+
+  ok(
+    runtimeInfoText.includes(NETWORK_RUNTIME_APP_NAME),
+    "network runtime info shows the correct runtime name: " + runtimeInfoText
+  );
+  ok(
+    runtimeInfoText.includes(NETWORK_RUNTIME_VERSION),
+    "network runtime info shows the correct version number: " + runtimeInfoText
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_select_page_with_serviceworker.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_select_page_with_serviceworker.js
new file mode 100644
index 0000000000..41e69a0d42
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_select_page_with_serviceworker.js
@@ -0,0 +1,78 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const NETWORK_RUNTIME_HOST = "localhost:6080";
+const NETWORK_RUNTIME_APP_NAME = "TestNetworkApp";
+const WORKER_NAME = "testserviceworker";
+
+// Test that navigating from:
+// - a remote runtime page that contains a service worker
+// to:
+// - this firefox
+// does not crash. See Bug 1519088.
+add_task(async function () {
+  const mocks = new Mocks();
+
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Prepare Network client mock");
+  const networkClient = mocks.createNetworkRuntime(NETWORK_RUNTIME_HOST, {
+    name: NETWORK_RUNTIME_APP_NAME,
+  });
+
+  info("Connect and select the network runtime");
+  await connectToRuntime(NETWORK_RUNTIME_HOST, document);
+  await selectRuntime(NETWORK_RUNTIME_HOST, NETWORK_RUNTIME_APP_NAME, document);
+
+  info(`Add a service worker to the network client`);
+  const workers = {
+    otherWorkers: [],
+    serviceWorkers: [
+      {
+        name: WORKER_NAME,
+        workerDescriptorFront: { actorID: WORKER_NAME },
+      },
+    ],
+    sharedWorkers: [],
+  };
+  networkClient.listWorkers = () => workers;
+  networkClient._eventEmitter.emit("workersUpdated");
+
+  info("Wait until the service worker is displayed");
+  await waitUntil(() => findDebugTargetByText(WORKER_NAME, document));
+
+  info("Go to This Firefox again");
+  const thisFirefoxString = getThisFirefoxString(window);
+  const thisFirefoxSidebarItem = findSidebarItemByText(
+    thisFirefoxString,
+    document
+  );
+  const thisFirefoxLink =
+    thisFirefoxSidebarItem.querySelector(".qa-sidebar-link");
+  info("Click on the ThisFirefox item in the sidebar");
+  const requestsSuccess = waitForRequestsSuccess(window.AboutDebugging.store);
+  thisFirefoxLink.click();
+
+  info("Wait for all target requests to complete");
+  await requestsSuccess;
+
+  info("Check that the runtime info is rendered for This Firefox");
+  const thisFirefoxRuntimeInfo = document.querySelector(".qa-runtime-name");
+  ok(
+    thisFirefoxRuntimeInfo,
+    "Runtime info for this-firefox runtime is displayed"
+  );
+
+  const text = thisFirefoxRuntimeInfo.textContent;
+  ok(
+    text.includes("Firefox") && text.includes("63.0"),
+    "this-firefox runtime info shows the correct values"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_console.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_console.js
new file mode 100644
index 0000000000..742791668d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_console.js
@@ -0,0 +1,131 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-serviceworker.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-serviceworker.js",
+  this
+);
+
+Services.scriptloader.loadSubScript(
+  "chrome://mochitests/content/browser/devtools/client/debugger/test/mochitest/shared-head.js",
+  this
+);
+
+const SW_TAB_URL =
+  URL_ROOT_SSL + "resources/service-workers/controlled-sw.html";
+const SW_URL = URL_ROOT_SSL + "resources/service-workers/controlled-sw.js";
+
+/**
+ * Test various simple debugging operation against service workers debugged through about:debugging.
+ */
+add_task(async function () {
+  await enableServiceWorkerDebugging();
+
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Open a tab that registers a basic service worker.
+  const swTab = await addTab(SW_TAB_URL);
+
+  // Wait for the registration to make sure service worker has been started, and that we
+  // are not just reading STOPPED as the initial state.
+  await waitForRegistration(swTab);
+
+  info("Open a toolbox to debug the worker");
+  const { devtoolsTab, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    SW_URL
+  );
+
+  const toolbox = getToolbox(devtoolsWindow);
+
+  info("Assert the default tools displayed in worker toolboxes");
+  const toolTabs = toolbox.doc.querySelectorAll(".devtools-tab");
+  const activeTools = [...toolTabs].map(toolTab =>
+    toolTab.getAttribute("data-id")
+  );
+
+  is(
+    activeTools.join(","),
+    "webconsole,jsdebugger",
+    "Correct set of tools supported by worker"
+  );
+
+  const webconsole = await toolbox.selectTool("webconsole");
+  const { hud } = webconsole;
+
+  info("Evaluate location in the console");
+  await executeAndWaitForMessage(hud, "this.location.toString()", SW_URL);
+  ok(true, "Got the location logged in the console");
+
+  info(
+    "Evaluate Date and RegExp to ensure their formater also work from worker threads"
+  );
+  await executeAndWaitForMessage(
+    hud,
+    "new Date(2013, 3, 1)",
+    "Mon Apr 01 2013 00:00:00"
+  );
+  ok(true, "Date object has expected text content");
+  await executeAndWaitForMessage(hud, "new RegExp('.*')", "/.*/");
+  ok(true, "RegExp has expected text content");
+
+  await toolbox.selectTool("jsdebugger");
+  const dbg = createDebuggerContext(toolbox);
+  const {
+    selectors: { getIsWaitingOnBreak, getCurrentThread },
+  } = dbg;
+
+  info("Wait for next interupt in the worker thread");
+  await clickElement(dbg, "pause");
+  await waitForState(dbg, state => getIsWaitingOnBreak(getCurrentThread()));
+
+  info("Trigger some code in the worker and wait for pause");
+  await SpecialPowers.spawn(swTab.linkedBrowser, [], async function () {
+    content.wrappedJSObject.installServiceWorker();
+  });
+  await waitForPaused(dbg);
+  ok(true, "successfully paused");
+
+  info(
+    "Evaluate some variable only visible if we execute in the breakpoint frame"
+  );
+  await executeAndWaitForMessage(hud, "event.data", "install-service-worker");
+
+  info("Resume execution");
+  await resume(dbg);
+
+  info("Test pausing from console evaluation");
+  hud.ui.wrapper.dispatchEvaluateExpression("debugger; 42");
+  await waitForPaused(dbg);
+  ok(true, "successfully paused");
+  info("Immediately resume");
+  await resume(dbg);
+  await waitFor(() => findMessagesByType(hud, "42", ".result"));
+  ok("The paused console evaluation resumed and logged its magic number");
+
+  info("Destroy the toolbox");
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+
+  info("Unregister service worker");
+  await unregisterServiceWorker(swTab);
+
+  info("Wait until the service worker disappears from about:debugging");
+  await waitUntil(() => !findDebugTargetByText(SW_URL, document));
+
+  info("Remove tabs");
+  await removeTab(swTab);
+  await removeTab(tab);
+});
+
+async function executeAndWaitForMessage(hud, evaluationString, expectedResult) {
+  hud.ui.wrapper.dispatchEvaluateExpression();
+  await waitFor(() => findMessagesByType(hud, expectedResult, ".result"));
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_fetch_flag.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_fetch_flag.js
new file mode 100644
index 0000000000..960635a56d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_fetch_flag.js
@@ -0,0 +1,68 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-serviceworker.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-serviceworker.js",
+  this
+);
+
+const FETCH_SW_JS = URL_ROOT_SSL + "resources/service-workers/fetch-sw.js";
+const FETCH_SW_HTML = URL_ROOT_SSL + "resources/service-workers/fetch-sw.html";
+
+const EMPTY_SW_JS = URL_ROOT_SSL + "resources/service-workers/empty-sw.js";
+const EMPTY_SW_HTML = URL_ROOT_SSL + "resources/service-workers/empty-sw.html";
+
+/**
+ * Test that the appropriate fetch flag is displayed for service workers.
+ */
+add_task(async function () {
+  await enableServiceWorkerDebugging();
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Test fetch status for a service worker listening to fetch events");
+  await testServiceWorkerFetchStatus(
+    document,
+    FETCH_SW_HTML,
+    FETCH_SW_JS,
+    true
+  );
+
+  info("Test fetch status for a service worker not listening to fetch events");
+  await testServiceWorkerFetchStatus(
+    document,
+    EMPTY_SW_HTML,
+    EMPTY_SW_JS,
+    false
+  );
+
+  await removeTab(tab);
+});
+
+async function testServiceWorkerFetchStatus(doc, url, workerUrl, isListening) {
+  // Open a tab that registers a fetch service worker.
+  const swTab = await addTab(url);
+
+  info("Wait until the service worker appears and is running");
+  const targetElement = await waitForServiceWorkerRunning(workerUrl, doc);
+
+  const expectedClassName = isListening
+    ? ".qa-worker-fetch-listening"
+    : ".qa-worker-fetch-not-listening";
+  const fetchStatus = targetElement.querySelector(expectedClassName);
+  ok(!!fetchStatus, "Found the expected fetch status: " + expectedClassName);
+
+  info("Unregister the service worker");
+  await unregisterServiceWorker(swTab);
+
+  info("Wait until the service worker disappears from about:debugging");
+  await waitUntil(() => !findDebugTargetByText(workerUrl, doc));
+
+  info("Remove the service worker tab");
+  await removeTab(swTab);
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_not_compatible.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_not_compatible.js
new file mode 100644
index 0000000000..641207a031
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_not_compatible.js
@@ -0,0 +1,125 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// This test started running during a GC and timing out on coverage platforms.
+// See Bug 1526153.
+requestLongerTimeout(2);
+
+const TEST_DATA = [
+  {
+    serviceWorkersEnabled: true,
+    privateBrowsingEnabled: false,
+    expectedMessage: false,
+  },
+  {
+    serviceWorkersEnabled: false,
+    privateBrowsingEnabled: false,
+    expectedMessage: true,
+  },
+  {
+    serviceWorkersEnabled: true,
+    privateBrowsingEnabled: true,
+    expectedMessage: true,
+  },
+  {
+    serviceWorkersEnabled: false,
+    privateBrowsingEnabled: true,
+    expectedMessage: true,
+  },
+];
+
+/**
+ * Check that the warning message for service workers is displayed if permanent private
+ * browsing is enabled or/and if service workers are disabled.
+ */
+add_task(async function testLocalRuntime() {
+  for (const testData of TEST_DATA) {
+    const { serviceWorkersEnabled, privateBrowsingEnabled, expectedMessage } =
+      testData;
+
+    info(
+      `Test warning message on this-firefox ` +
+        `with serviceWorkersEnabled: ${serviceWorkersEnabled} ` +
+        `and with privateBrowsingEnabled: ${privateBrowsingEnabled}`
+    );
+
+    await pushPref("dom.serviceWorkers.enabled", serviceWorkersEnabled);
+    await pushPref("browser.privatebrowsing.autostart", privateBrowsingEnabled);
+
+    const { document, tab, window } = await openAboutDebugging({
+      // Even though this is a service worker test, we are not adding/removing
+      // workers here. Since the test is really fast it can create intermittent
+      // failures due to pending requests to update the worker list
+      // We are updating the worker list whenever the list of processes changes
+      // and this can happen very frequently, and it's hard to control from
+      // DevTools.
+      // Set enableWorkerUpdates to false to avoid intermittent failures.
+      enableWorkerUpdates: false,
+    });
+    await selectThisFirefoxPage(document, window.AboutDebugging.store);
+    assertWarningMessage(document, expectedMessage);
+    await removeTab(tab);
+  }
+});
+
+add_task(async function testRemoteRuntime() {
+  const {
+    remoteClientManager,
+  } = require("resource://devtools/client/shared/remote-debugging/remote-client-manager.js");
+
+  // enable USB devices mocks
+  const mocks = new Mocks();
+  const client = mocks.createUSBRuntime("1337id", {
+    deviceName: "Fancy Phone",
+    name: "Lorem ipsum",
+  });
+
+  for (const testData of TEST_DATA) {
+    const { serviceWorkersEnabled, privateBrowsingEnabled, expectedMessage } =
+      testData;
+
+    info(
+      `Test warning message on mocked USB runtime ` +
+        `with serviceWorkersEnabled: ${serviceWorkersEnabled} ` +
+        `and with privateBrowsingEnabled: ${privateBrowsingEnabled}`
+    );
+
+    client.setPreference("dom.serviceWorkers.enabled", serviceWorkersEnabled);
+    client.setPreference(
+      "browser.privatebrowsing.autostart",
+      privateBrowsingEnabled
+    );
+
+    const { document, tab, window } = await openAboutDebugging({
+      enableWorkerUpdates: false,
+    });
+    await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+    info("Checking a USB runtime");
+    mocks.emitUSBUpdate();
+    await connectToRuntime("Fancy Phone", document);
+    await selectRuntime("Fancy Phone", "Lorem ipsum", document);
+
+    assertWarningMessage(document, expectedMessage);
+
+    // We remove all clients in order to be able to simply connect to the runtime at
+    // every iteration of the loop without checking of the runtime is already connected.
+    info("Remove all remote clients");
+    await remoteClientManager.removeAllClients();
+
+    await removeTab(tab);
+  }
+});
+
+function assertWarningMessage(doc, expectedMessage) {
+  const hasMessage = !!doc.querySelector(".qa-service-workers-warning");
+  Assert.strictEqual(
+    hasMessage,
+    expectedMessage,
+    expectedMessage
+      ? "Warning message is displayed"
+      : "Warning message is not displayed"
+  );
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_push.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_push.js
new file mode 100644
index 0000000000..740f066903
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_push.js
@@ -0,0 +1,61 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-serviceworker.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-serviceworker.js",
+  this
+);
+
+const SERVICE_WORKER = URL_ROOT_SSL + "resources/service-workers/push-sw.js";
+const TAB_URL = URL_ROOT_SSL + "resources/service-workers/push-sw.html";
+
+// Test that clicking on the Push button next to a Service Worker works as intended.
+// It should trigger a "push" notification in the worker.
+add_task(async function () {
+  await enableServiceWorkerDebugging();
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Open a tab that registers a push service worker.
+  const swTab = await addTab(TAB_URL);
+
+  info(
+    "Wait for the service worker to claim the test window before proceeding."
+  );
+  await SpecialPowers.spawn(
+    swTab.linkedBrowser,
+    [],
+    () => content.wrappedJSObject.onSwClaimed
+  );
+
+  info("Wait until the service worker appears and is running");
+  const targetElement = await waitForServiceWorkerRunning(
+    SERVICE_WORKER,
+    document
+  );
+
+  // Retrieve the Push button for the worker.
+  const pushButton = targetElement.querySelector(".qa-push-button");
+  ok(pushButton, "Found its push button");
+
+  info("Click on the Push button and wait for the push notification");
+  const onPushNotification = onServiceWorkerMessage(swTab, "sw-pushed");
+  pushButton.click();
+  await onPushNotification;
+
+  info("Unregister the service worker");
+  await unregisterServiceWorker(swTab);
+
+  info("Wait until the service worker disappears from about:debugging");
+  await waitUntil(() => !findDebugTargetByText(SERVICE_WORKER, document));
+
+  info("Remove the service worker tab");
+  await removeTab(swTab);
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_pushservice_url.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_pushservice_url.js
new file mode 100644
index 0000000000..9581a493d9
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_pushservice_url.js
@@ -0,0 +1,118 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-serviceworker.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-serviceworker.js",
+  this
+);
+
+const SERVICE_WORKER = URL_ROOT_SSL + "resources/service-workers/push-sw.js";
+const TAB_URL = URL_ROOT_SSL + "resources/service-workers/push-sw.html";
+
+const FAKE_ENDPOINT = "https://fake/endpoint";
+
+// Test that the push service url is displayed for service workers subscribed to a push
+// service.
+add_task(async function () {
+  await enableServiceWorkerDebugging();
+
+  info("Mock the push service");
+  mockPushService(FAKE_ENDPOINT);
+
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Open a tab that registers a push service worker.
+  const swTab = await addTab(TAB_URL);
+
+  info(
+    "Wait for the service worker to claim the test window before proceeding."
+  );
+  await SpecialPowers.spawn(
+    swTab.linkedBrowser,
+    [],
+    () => content.wrappedJSObject.onSwClaimed
+  );
+
+  info("Wait until the service worker appears and is running");
+  const targetElement = await waitForServiceWorkerRunning(
+    SERVICE_WORKER,
+    document
+  );
+
+  info("Subscribe from the push service");
+  SpecialPowers.spawn(swTab.linkedBrowser, [], () => {
+    content.wrappedJSObject.subscribeToPush();
+  });
+
+  info("Wait until the push service appears");
+  await waitUntil(() =>
+    targetElement.querySelector(".qa-worker-push-service-value")
+  );
+  const pushUrl = targetElement.querySelector(".qa-worker-push-service-value");
+
+  ok(!!pushUrl, "Push URL is displayed for the serviceworker");
+  is(pushUrl.textContent, FAKE_ENDPOINT, "Push URL shows the expected content");
+
+  info("Unsubscribe from the push service");
+  SpecialPowers.spawn(swTab.linkedBrowser, [], () => {
+    content.wrappedJSObject.unsubscribeToPush();
+  });
+
+  info("Wait until the push service disappears");
+  await waitUntil(
+    () => !targetElement.querySelector(".qa-worker-push-service-value")
+  );
+
+  info("Unregister the service worker");
+  await unregisterServiceWorker(swTab);
+
+  info("Wait until the service worker disappears from about:debugging");
+  await waitUntil(() => !findDebugTargetByText(SERVICE_WORKER, document));
+
+  info("Remove the service worker tab");
+  await removeTab(swTab);
+
+  await removeTab(tab);
+});
+
+function mockPushService(endpoint) {
+  const PushService = Cc["@mozilla.org/push/Service;1"].getService(
+    Ci.nsIPushService
+  ).wrappedJSObject;
+
+  PushService.service = {
+    _registrations: new Map(),
+    _notify(scope) {
+      Services.obs.notifyObservers(
+        null,
+        PushService.subscriptionModifiedTopic,
+        scope
+      );
+    },
+    init() {},
+    register(pageRecord) {
+      const registration = {
+        endpoint,
+      };
+      this._registrations.set(pageRecord.scope, registration);
+      this._notify(pageRecord.scope);
+      return Promise.resolve(registration);
+    },
+    registration(pageRecord) {
+      return Promise.resolve(this._registrations.get(pageRecord.scope));
+    },
+    unregister(pageRecord) {
+      const deleted = this._registrations.delete(pageRecord.scope);
+      if (deleted) {
+        this._notify(pageRecord.scope);
+      }
+      return Promise.resolve(deleted);
+    },
+  };
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_runtime-page.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_runtime-page.js
new file mode 100644
index 0000000000..dce42ec305
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_runtime-page.js
@@ -0,0 +1,71 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-serviceworker.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-serviceworker.js",
+  this
+);
+/* import-globals-from helper-collapsibilities.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-collapsibilities.js",
+  this
+);
+
+const SW_TAB_URL = URL_ROOT_SSL + "resources/service-workers/push-sw.html";
+const SW_URL = URL_ROOT_SSL + "resources/service-workers/push-sw.js";
+
+/**
+ * Test that service workers appear and dissapear from the runtime page when they
+ * are registered / unregistered.
+ */
+add_task(async function () {
+  prepareCollapsibilitiesTest();
+  await enableServiceWorkerDebugging();
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  const store = window.AboutDebugging.store;
+
+  await selectThisFirefoxPage(document, store);
+
+  // check that SW list is empty
+  info("Check that the SW pane is empty");
+  let swPane = getDebugTargetPane("Service Workers", document);
+  ok(!swPane.querySelector(".qa-debug-target-item"), "SW list is empty");
+
+  // open a tab and register service worker
+  info("Register a service worker");
+  const swTab = await addTab(SW_TAB_URL);
+
+  // check that service worker is rendered
+  info("Wait until the service worker appears and is running");
+  await waitForServiceWorkerRunning(SW_URL, document);
+
+  swPane = getDebugTargetPane("Service Workers", document);
+  Assert.strictEqual(
+    swPane.querySelectorAll(".qa-debug-target-item").length,
+    1,
+    "Service worker list has one element"
+  );
+  ok(
+    swPane.querySelector(".qa-debug-target-item").textContent.includes(SW_URL),
+    "Service worker list is the one we registered"
+  );
+
+  // unregister the service worker
+  info("Unregister service worker");
+  await unregisterServiceWorker(swTab);
+  // check that service worker is not rendered anymore
+  info("Wait for service worker to disappear");
+  await waitUntil(() => {
+    swPane = getDebugTargetPane("Service Workers", document);
+    return swPane.querySelectorAll(".qa-debug-target-item").length === 0;
+  });
+
+  info("Remove tabs");
+  await removeTab(swTab);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_start.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_start.js
new file mode 100644
index 0000000000..483a1cad43
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_start.js
@@ -0,0 +1,71 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-serviceworker.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-serviceworker.js",
+  this
+);
+
+const SW_TAB_URL = URL_ROOT_SSL + "resources/service-workers/empty-sw.html";
+const SW_URL = URL_ROOT_SSL + "resources/service-workers/empty-sw.js";
+
+/**
+ * Test that service workers can be started using about:debugging.
+ */
+add_task(async function () {
+  await enableServiceWorkerDebugging();
+
+  // Setting a low idle_timeout and idle_extended_timeout will allow the service worker
+  // to reach the STOPPED state quickly, which will allow us to test the start button.
+  // The default value is 30000 milliseconds.
+  info("Set a low service worker idle timeout");
+  await pushPref("dom.serviceWorkers.idle_timeout", 1000);
+  await pushPref("dom.serviceWorkers.idle_extended_timeout", 1000);
+
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Open a tab that registers a basic service worker.
+  const swTab = await addTab(SW_TAB_URL);
+
+  // Wait for the registration to make sure service worker has been started, and that we
+  // are not just reading STOPPED as the initial state.
+  await waitForRegistration(swTab);
+
+  info("Wait until the service worker stops");
+  const targetElement = await waitForServiceWorkerStopped(SW_URL, document);
+
+  // Retrieve the Start button for the worker.
+  const startButton = targetElement.querySelector(".qa-start-button");
+  ok(startButton, "Found its start button");
+
+  info(
+    "Click on the start button and wait for the service worker to be running"
+  );
+  const onServiceWorkerRunning = waitForServiceWorkerRunning(SW_URL, document);
+  startButton.click();
+  const updatedTarget = await onServiceWorkerRunning;
+
+  // Check that the buttons are displayed as expected.
+  const hasInspectButton = updatedTarget.querySelector(
+    ".qa-debug-target-inspect-button"
+  );
+  const hasStartButton = updatedTarget.querySelector(".qa-start-button");
+  ok(hasInspectButton, "Service worker has an inspect button");
+  ok(!hasStartButton, "Service worker does not have a start button");
+
+  info("Unregister service worker");
+  await unregisterServiceWorker(swTab);
+
+  info("Wait until the service worker disappears from about:debugging");
+  await waitUntil(() => !findDebugTargetByText(SW_URL, document));
+
+  info("Remove tabs");
+  await removeTab(swTab);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_status.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_status.js
new file mode 100644
index 0000000000..50426dcb47
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_status.js
@@ -0,0 +1,104 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-serviceworker.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-serviceworker.js",
+  this
+);
+
+const SW_TAB_URL =
+  URL_ROOT_SSL + "resources/service-workers/controlled-sw.html";
+const SW_URL = URL_ROOT_SSL + "resources/service-workers/controlled-sw.js";
+
+/**
+ * Test that the service worker has the status "registering" when the service worker is
+ * not installed yet. Other states (stopped, running) are covered by the existing tests.
+ */
+add_task(async function () {
+  await enableServiceWorkerDebugging();
+
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Open tab with a service worker that never leaves `registering` status");
+  const swTab = await addTab(SW_TAB_URL);
+
+  // Wait for the registration to make sure service worker has been started, and that we
+  // are not just reading STOPPED as the initial state.
+  await waitForRegistration(swTab);
+
+  info("Wait until the service worker is in registering status");
+  await waitForServiceWorkerRegistering(SW_URL, document);
+
+  // Check that the buttons are displayed as expected.
+  checkButtons(
+    { inspect: true, push: false, start: false, unregister: false },
+    SW_URL,
+    document
+  );
+
+  info("Install the service worker");
+  SpecialPowers.spawn(swTab.linkedBrowser, [], () =>
+    content.wrappedJSObject.installServiceWorker()
+  );
+
+  info("Wait until the service worker is running");
+  await waitForServiceWorkerRunning(SW_URL, document);
+
+  checkButtons(
+    { inspect: true, push: true, start: false, unregister: true },
+    SW_URL,
+    document
+  );
+
+  info("Unregister service worker");
+  await unregisterServiceWorker(swTab);
+
+  info("Wait until the service worker disappears from about:debugging");
+  await waitUntil(() => !findDebugTargetByText(SW_URL, document));
+
+  info("Remove tabs");
+  await removeTab(swTab);
+  await removeTab(tab);
+});
+
+function checkButtons(
+  { inspect, push, start, unregister },
+  workerText,
+  document
+) {
+  const targetElement = findDebugTargetByText(SW_URL, document);
+
+  const inspectButton = targetElement.querySelector(
+    ".qa-debug-target-inspect-button"
+  );
+  const pushButton = targetElement.querySelector(".qa-push-button");
+  const startButton = targetElement.querySelector(".qa-start-button");
+  const unregisterButton = targetElement.querySelector(".qa-unregister-button");
+
+  is(
+    !!inspectButton,
+    inspect,
+    "Inspect button should be " + (inspect ? "visible" : "hidden")
+  );
+  is(
+    !!pushButton,
+    push,
+    "Push button should be " + (push ? "visible" : "hidden")
+  );
+  is(
+    !!startButton,
+    start,
+    "Start button should be " + (start ? "visible" : "hidden")
+  );
+  is(
+    !!unregisterButton,
+    unregister,
+    "Unregister button should be " + (unregister ? "visible" : "hidden")
+  );
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_timeout.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_timeout.js
new file mode 100644
index 0000000000..f4fc04d229
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_timeout.js
@@ -0,0 +1,104 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// This test will be idle for a long period to give a chance to the service worker to
+// timeout.
+requestLongerTimeout(3);
+
+/* import-globals-from helper-serviceworker.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-serviceworker.js",
+  this
+);
+
+const SW_TAB_URL = URL_ROOT_SSL + "resources/service-workers/empty-sw.html";
+const SW_URL = URL_ROOT_SSL + "resources/service-workers/empty-sw.js";
+const SW_TIMEOUT = 4000;
+
+/**
+ * Test that service workers will _not_ timeout and be stopped when a toolbox is attached
+ * to them. Feature implemented in Bug 1228382.
+ */
+add_task(async function () {
+  await enableServiceWorkerDebugging();
+
+  // Setting a low idle_timeout and idle_extended_timeout will allow the service worker
+  // to reach the STOPPED state quickly, which will allow us to test the start button.
+  // The default value is 30000 milliseconds.
+  info("Set a low service worker idle timeout");
+  await pushPref("dom.serviceWorkers.idle_timeout", SW_TIMEOUT);
+  await pushPref("dom.serviceWorkers.idle_extended_timeout", SW_TIMEOUT);
+
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Open a tab that registers a basic service worker.
+  const swTab = await addTab(SW_TAB_URL);
+
+  // Wait for the registration to make sure service worker has been started, and that we
+  // are not just reading STOPPED as the initial state.
+  await waitForRegistration(swTab);
+
+  info("Wait until the service worker stops");
+  await waitForServiceWorkerStopped(SW_URL, document);
+
+  info(
+    "Click on the start button and wait for the service worker to be running"
+  );
+  const onServiceWorkerRunning = waitForServiceWorkerRunning(SW_URL, document);
+  const startButton = getStartButton(SW_URL, document);
+  startButton.click();
+  await onServiceWorkerRunning;
+
+  const inspectButton = getInspectButton(SW_URL, document);
+  ok(!!inspectButton, "Service worker target has an inspect button");
+
+  info("Click on inspect and wait for the toolbox to open");
+  const onToolboxReady = gDevTools.once("toolbox-ready");
+  inspectButton.click();
+  await onToolboxReady;
+
+  // Wait for more 5 times the service worker timeout to check that the toolbox prevents
+  // the worker from being destroyed.
+  await wait(SW_TIMEOUT * 5);
+
+  // Check that the service worker is still running, even after waiting 5 times the
+  // service worker timeout.
+  const hasInspectButton = !!getInspectButton(SW_URL, document);
+  ok(hasInspectButton, "Service worker target still has an inspect button");
+
+  info("Destroy the toolbox");
+  const devtoolsTab = gBrowser.selectedTab;
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+
+  // After stopping the toolbox, the service worker instance should be released and the
+  // service worker registration should be displayed as stopped again.
+  info("Wait until the service worker stops after closing the toolbox");
+  await waitForServiceWorkerStopped(SW_URL, document);
+
+  info("Unregister service worker");
+  await unregisterServiceWorker(swTab);
+
+  info("Wait until the service worker disappears from about:debugging");
+  await waitUntil(() => !findDebugTargetByText(SW_URL, document));
+
+  info("Remove tabs");
+  await removeTab(swTab);
+  await removeTab(tab);
+});
+
+function getStartButton(workerText, doc) {
+  const target = findDebugTargetByText(workerText, doc);
+  return target ? target.querySelector(".qa-start-button") : null;
+}
+
+function getInspectButton(workerText, doc) {
+  const target = findDebugTargetByText(workerText, doc);
+  return target
+    ? target.querySelector(".qa-debug-target-inspect-button")
+    : null;
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_unregister.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_unregister.js
new file mode 100644
index 0000000000..f9237e1795
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_serviceworker_unregister.js
@@ -0,0 +1,48 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-serviceworker.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-serviceworker.js",
+  this
+);
+
+const SW_TAB_URL = URL_ROOT_SSL + "resources/service-workers/empty-sw.html";
+const SW_URL = URL_ROOT_SSL + "resources/service-workers/empty-sw.js";
+
+/**
+ * Test that service workers can be started using about:debugging.
+ */
+add_task(async function () {
+  await enableServiceWorkerDebugging();
+
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Open a tab that registers a basic service worker.
+  const swTab = await addTab(SW_TAB_URL);
+
+  info("Wait until the service worker appears and is running");
+  const targetElement = await waitForServiceWorkerRunning(SW_URL, document);
+
+  // Retrieve the Start button for the worker.
+  const unregisterButton = targetElement.querySelector(".qa-unregister-button");
+  ok(unregisterButton, "Found its unregister button");
+
+  info(
+    "Click on the unregister button and wait for the service worker to disappear"
+  );
+  unregisterButton.click();
+  await waitUntil(() => !findDebugTargetByText(SW_URL, document));
+
+  const hasServiceWorkerTarget = !!findDebugTargetByText(SW_URL, document);
+  ok(!hasServiceWorkerTarget, "Service worker was successfully unregistered");
+
+  info("Remove tabs");
+  await removeTab(swTab);
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_connection_state.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_connection_state.js
new file mode 100644
index 0000000000..d4d31a7522
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_connection_state.js
@@ -0,0 +1,192 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const RUNTIME_ID = "test-runtime-id";
+const RUNTIME_NAME = "test runtime name";
+const RUNTIME_DEVICE_NAME = "test device name";
+const RUNTIME_SHORT_NAME = "test short name";
+
+const CONNECTION_TIMING_OUT_DELAY = 1000;
+const CONNECTION_CANCEL_DELAY = 2000;
+
+// Test following connection state tests.
+// * Connect button label and state will change during connecting.
+// * Show error message if connection failed.
+// * Show warninng if connection has been taken time.
+add_task(async function () {
+  await setupPreferences();
+
+  const mocks = new Mocks();
+
+  const { document, tab } = await openAboutDebugging();
+
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    name: RUNTIME_NAME,
+    deviceName: RUNTIME_DEVICE_NAME,
+    shortName: RUNTIME_SHORT_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait until the USB sidebar item appears");
+  await waitUntil(() => findSidebarItemByText(RUNTIME_DEVICE_NAME, document));
+  const usbRuntimeSidebarItem = findSidebarItemByText(
+    RUNTIME_DEVICE_NAME,
+    document
+  );
+  const connectButton =
+    usbRuntimeSidebarItem.querySelector(".qa-connect-button");
+
+  info("Simulate to happen connection error");
+  mocks.runtimeClientFactoryMock.createClientForRuntime = async runtime => {
+    throw new Error("Dummy connection error");
+  };
+
+  info(
+    "Check whether the error message displayed after clicking connect button"
+  );
+  connectButton.click();
+  await waitUntil(() => document.querySelector(".qa-connection-error"));
+  ok(true, "Error message displays when connection failed");
+
+  info("Simulate to wait for the connection prompt on remote runtime");
+  let resumeConnection;
+  const resumeConnectionPromise = new Promise(r => {
+    resumeConnection = r;
+  });
+  mocks.runtimeClientFactoryMock.createClientForRuntime = async runtime => {
+    await resumeConnectionPromise;
+    return mocks._clients[runtime.type][runtime.id];
+  };
+
+  info("Click on the connect button and wait until it disappears");
+  connectButton.click();
+  info("Check whether a warning of connection not responding displays");
+  await waitUntil(() =>
+    document.querySelector(".qa-connection-not-responding")
+  );
+  ok(
+    document.querySelector(".qa-connection-not-responding"),
+    "A warning of connection not responding displays"
+  );
+  ok(connectButton.disabled, "Connect button is disabled");
+  ok(
+    connectButton.textContent.startsWith("Connecting"),
+    "Label of the connect button changes"
+  );
+  ok(
+    !document.querySelector(".qa-connection-error"),
+    "Error message disappears"
+  );
+
+  info(
+    "Unblock the connection and check the message and connect button disappear"
+  );
+  resumeConnection();
+  await waitUntil(
+    () => !usbRuntimeSidebarItem.querySelector(".qa-connect-button")
+  );
+  ok(!document.querySelector(".qa-connection-error"), "Error disappears");
+  ok(
+    !document.querySelector(".qa-connection-not-responding"),
+    "Warning disappears"
+  );
+
+  info("Remove a USB runtime");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(RUNTIME_DEVICE_NAME, document);
+
+  await removeTab(tab);
+});
+
+// Test whether the status of all will be reverted after a certain period of time during
+// waiting connection.
+add_task(async function () {
+  await setupPreferences();
+
+  const mocks = new Mocks();
+
+  const { document, tab } = await openAboutDebugging();
+
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    name: RUNTIME_NAME,
+    deviceName: RUNTIME_DEVICE_NAME,
+    shortName: RUNTIME_SHORT_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait until the USB sidebar item appears");
+  await waitUntil(() => findSidebarItemByText(RUNTIME_DEVICE_NAME, document));
+  const usbRuntimeSidebarItem = findSidebarItemByText(
+    RUNTIME_DEVICE_NAME,
+    document
+  );
+  const connectButton =
+    usbRuntimeSidebarItem.querySelector(".qa-connect-button");
+
+  let resumeConnection;
+  const resumeConnectionPromise = new Promise(r => {
+    resumeConnection = r;
+  });
+  mocks.runtimeClientFactoryMock.createClientForRuntime = async runtime => {
+    await resumeConnectionPromise;
+    return mocks._clients[runtime.type][runtime.id];
+  };
+
+  info("Click on the connect button and wait until it disappears");
+  connectButton.click();
+  await waitUntil(() =>
+    document.querySelector(".qa-connection-not-responding")
+  );
+  info("Check whether the all status will be reverted");
+  await waitUntil(
+    () => !document.querySelector(".qa-connection-not-responding")
+  );
+  ok(
+    document.querySelector(".qa-connection-timeout"),
+    "Connection timeout message displays"
+  );
+  ok(!connectButton.disabled, "Connect button is enabled");
+  is(
+    connectButton.textContent,
+    "Connect",
+    "Label of the connect button reverted"
+  );
+  ok(
+    !document.querySelector(".qa-connection-error"),
+    "Error message disappears"
+  );
+
+  info("Check whether the timeout message disappears");
+  resumeConnection();
+  await waitUntil(() => !document.querySelector(".qa-connection-timeout"));
+
+  info("Remove a USB runtime");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+
+  info("Wait until the USB sidebar item disappears");
+  await waitUntilUsbDeviceIsUnplugged(RUNTIME_DEVICE_NAME, document);
+
+  await removeTab(tab);
+});
+
+async function setupPreferences() {
+  if (SpecialPowers.isDebugBuild) {
+    // On debug builds, reducing the timings might lead to skip the "warning"
+    // state and will block the test execution.
+    // Do not change the timings in debug builds.
+    return;
+  }
+
+  await pushPref(
+    "devtools.aboutdebugging.test-connection-timing-out-delay",
+    CONNECTION_TIMING_OUT_DELAY
+  );
+  await pushPref(
+    "devtools.aboutdebugging.test-connection-cancel-delay",
+    CONNECTION_CANCEL_DELAY
+  );
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_network_runtimes.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_network_runtimes.js
new file mode 100644
index 0000000000..0482aa70c2
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_network_runtimes.js
@@ -0,0 +1,43 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const networkLocationsModule = require("resource://devtools/client/aboutdebugging/src/modules/network-locations.js");
+
+/**
+ * Test the sidebar is updated correctly when network runtimes are added/removed.
+ */
+
+add_task(async function () {
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("devtools.aboutdebugging.network-locations");
+  });
+
+  const { document, tab } = await openAboutDebugging();
+
+  const noDevicesElement = document.querySelector(".qa-sidebar-no-devices");
+  ok(noDevicesElement, "Sidebar shows the 'no devices' element");
+
+  info("Add a network location");
+  networkLocationsModule.addNetworkLocation("localhost:6080");
+
+  info("Wait for 'no devices' element to disappear");
+  waitUntil(() => !document.querySelector(".qa-sidebar-no-devices"));
+  ok(
+    findSidebarItemByText("localhost:6080", document),
+    "Found a sidebar item for localhost:6080"
+  );
+
+  info("Remove the network location");
+  networkLocationsModule.removeNetworkLocation("localhost:6080");
+
+  info("Wait for 'no devices' element to reappear");
+  waitUntil(() => document.querySelector(".qa-sidebar-no-devices"));
+  ok(
+    !findSidebarItemByText("localhost:6080", document),
+    "Sidebar item for localhost:6080 removed"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime.js
new file mode 100644
index 0000000000..b63b7ae08e
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime.js
@@ -0,0 +1,38 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const RUNTIME_ID = "RUNTIME_ID";
+const RUNTIME_DEVICE_NAME = "RUNTIME_DEVICE_NAME";
+const RUNTIME_SHORT_NAME = "testshort";
+
+// Test that USB runtimes appear and disappear from the sidebar.
+add_task(async function () {
+  const mocks = new Mocks();
+
+  const { document, tab } = await openAboutDebugging();
+
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceName: RUNTIME_DEVICE_NAME,
+    shortName: RUNTIME_SHORT_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait until the USB sidebar item appears");
+  await waitUntil(() => findSidebarItemByText(RUNTIME_DEVICE_NAME, document));
+  const usbRuntimeSidebarItem = findSidebarItemByText(
+    RUNTIME_DEVICE_NAME,
+    document
+  );
+  ok(
+    usbRuntimeSidebarItem.textContent.includes(RUNTIME_SHORT_NAME),
+    "The short name of the usb runtime is visible"
+  );
+
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(RUNTIME_DEVICE_NAME, document);
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime_connect.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime_connect.js
new file mode 100644
index 0000000000..f4978b0495
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime_connect.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const RUNTIME_ID = "test-runtime-id";
+const RUNTIME_NAME = "test runtime name";
+const RUNTIME_DEVICE_NAME = "test device name";
+const RUNTIME_SHORT_NAME = "test short name";
+
+// Test that USB runtimes appear and disappear from the sidebar,
+// as well as their connect button.
+// Also checks whether the label of item is updated after connecting.
+add_task(async function () {
+  const mocks = new Mocks();
+
+  const { document, tab } = await openAboutDebugging();
+
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    name: RUNTIME_NAME,
+    deviceName: RUNTIME_DEVICE_NAME,
+    shortName: RUNTIME_SHORT_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait until the USB sidebar item appears");
+  await waitUntil(() => findSidebarItemByText(RUNTIME_DEVICE_NAME, document));
+  const usbRuntimeSidebarItem = findSidebarItemByText(
+    RUNTIME_DEVICE_NAME,
+    document
+  );
+  const connectButton =
+    usbRuntimeSidebarItem.querySelector(".qa-connect-button");
+  ok(connectButton, "Connect button is displayed for the USB runtime");
+
+  info("Click on the connect button and wait until it disappears");
+  connectButton.click();
+  await waitUntil(
+    () => !usbRuntimeSidebarItem.querySelector(".qa-connect-button")
+  );
+
+  info("Check whether the label of item is updated after connecting");
+  ok(
+    usbRuntimeSidebarItem.textContent.includes(RUNTIME_NAME),
+    "Label of item updated"
+  );
+
+  info("Remove all USB runtimes");
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(RUNTIME_DEVICE_NAME, document);
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime_refresh.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime_refresh.js
new file mode 100644
index 0000000000..47ecc03239
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime_refresh.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const RUNTIME_ID = "test-runtime-id";
+const RUNTIME_DEVICE_NAME = "test device name";
+const RUNTIME_APP_NAME = "TestApp";
+
+const OTHER_RUNTIME_ID = "other-runtime-id";
+const OTHER_RUNTIME_APP_NAME = "OtherApp";
+
+// Test that USB runtimes are not disconnected on refresh.
+add_task(async function () {
+  const mocks = new Mocks();
+
+  const { document, tab } = await openAboutDebugging();
+
+  info("Create a first runtime and connect to it");
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceName: RUNTIME_DEVICE_NAME,
+    name: RUNTIME_APP_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  await connectToRuntime(RUNTIME_DEVICE_NAME, document);
+  await selectRuntime(RUNTIME_DEVICE_NAME, RUNTIME_APP_NAME, document);
+
+  info("Create a second runtime and click on Refresh Devices");
+  mocks.createUSBRuntime(OTHER_RUNTIME_ID, {
+    deviceName: OTHER_RUNTIME_APP_NAME,
+  });
+
+  // adb.updateRuntimes should ultimately fire the "runtime-list-updated" event.
+  mocks.adbMock.adb.updateRuntimes = () => mocks.emitUSBUpdate();
+  document.querySelector(".qa-refresh-devices-button").click();
+
+  info(`Wait until the sidebar item for ${OTHER_RUNTIME_APP_NAME} appears`);
+  await waitUntil(() =>
+    findSidebarItemByText(OTHER_RUNTIME_APP_NAME, document)
+  );
+
+  const sidebarItem = findSidebarItemByText(RUNTIME_DEVICE_NAME, document);
+  ok(
+    !sidebarItem.querySelector(".qa-connect-button"),
+    "Original USB runtime is still connected"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime_select.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime_select.js
new file mode 100644
index 0000000000..66ca219bf3
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_runtime_select.js
@@ -0,0 +1,44 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const RUNTIME_DEVICE_ID = "1234";
+const RUNTIME_DEVICE_NAME = "A device";
+
+// Test that we can select a runtime in the sidebar
+add_task(async function () {
+  const mocks = new Mocks();
+
+  const { document, tab } = await openAboutDebugging();
+
+  mocks.createUSBRuntime(RUNTIME_DEVICE_ID, {
+    deviceName: RUNTIME_DEVICE_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait until the USB sidebar item appears");
+  await waitUntil(() => findSidebarItemByText(RUNTIME_DEVICE_NAME, document));
+  const sidebarItem = findSidebarItemByText(RUNTIME_DEVICE_NAME, document);
+  const connectButton = sidebarItem.querySelector(".qa-connect-button");
+  ok(connectButton, "Connect button is displayed for the USB runtime");
+
+  info(
+    "Click on the connect button and wait until the sidebar displays a link"
+  );
+  connectButton.click();
+  await waitUntil(() =>
+    findSidebarItemLinkByText(RUNTIME_DEVICE_NAME, document)
+  );
+
+  info("Click on the runtime link");
+  const link = findSidebarItemLinkByText(RUNTIME_DEVICE_NAME, document);
+  link.click();
+  is(
+    document.location.hash,
+    `#/runtime/${RUNTIME_DEVICE_ID}`,
+    "Redirection to runtime page"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_status.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_status.js
new file mode 100644
index 0000000000..e67cde31bb
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_status.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  adbAddon,
+} = require("resource://devtools/client/shared/remote-debugging/adb/adb-addon.js");
+
+/**
+ * This test asserts that the sidebar shows a message describing the status of the USB
+ * devices scanning.
+ */
+add_task(async function () {
+  const mocks = new Mocks();
+
+  await pushPref(
+    "devtools.remote.adb.extensionURL",
+    CHROME_URL_ROOT + "resources/test-adb-extension/adb-extension-#OS#.xpi"
+  );
+  const { document, tab } = await openAboutDebugging();
+
+  const usbStatusElement = document.querySelector(".qa-sidebar-usb-status");
+  ok(usbStatusElement, "Sidebar shows the USB status element");
+  ok(
+    usbStatusElement.textContent.includes("USB disabled"),
+    "USB status element has 'disabled' content"
+  );
+
+  info("Install the adb extension and wait for the message to udpate");
+  // Use "internal" as the install source to avoid triggering telemetry.
+  adbAddon.install("internal");
+  // When using mocks, we manually control the .start() call
+  await mocks.adbProcessMock.adbProcess.start();
+
+  info("Wait till the USB status element has 'enabled' content");
+  await waitUntil(() => {
+    const el = document.querySelector(".qa-sidebar-usb-status");
+    return el.textContent.includes("USB enabled");
+  });
+
+  info("Uninstall the adb extension and wait for USB status element to update");
+  adbAddon.uninstall();
+  await waitUntil(() => {
+    const el = document.querySelector(".qa-sidebar-usb-status");
+    return el.textContent.includes("USB disabled");
+  });
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_unavailable_runtime.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_unavailable_runtime.js
new file mode 100644
index 0000000000..e073939b6d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_unavailable_runtime.js
@@ -0,0 +1,65 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const RUNTIME_NAME = "Firefox 123";
+const DEVICE_NAME = "DEVICE_NAME";
+const DEVICE_ID = "DEVICE_ID";
+const RUNTIME_ID = "RUNTIME_ID";
+
+// Test that unavailable runtimes:
+// - are displayed without a connect button.
+// - cannot be selected
+// - display a specific text ("Waiting for runtime") instead of the runtime name
+add_task(async function () {
+  const mocks = new Mocks();
+  const { document, tab } = await openAboutDebugging();
+
+  info("Create a device without a corresponding runtime");
+  mocks.addDevice(DEVICE_ID, DEVICE_NAME);
+  mocks.emitUSBUpdate();
+
+  info("Wait until the USB sidebar item appears");
+  await waitUntil(() => findSidebarItemByText(DEVICE_NAME, document));
+
+  const usbRuntimeSidebarItem = findSidebarItemByText(DEVICE_NAME, document);
+
+  ok(
+    usbRuntimeSidebarItem.querySelector(".qa-runtime-item-waiting-for-browser"),
+    "Sidebar item shows as `Waiting for browser`"
+  );
+
+  const hasConnectButton =
+    usbRuntimeSidebarItem.querySelector(".qa-connect-button");
+  ok(!hasConnectButton, "Connect button is not displayed");
+
+  const hasLink = usbRuntimeSidebarItem.querySelector(".qa-sidebar-link");
+  ok(!hasLink, "Unavailable runtime is not selectable");
+
+  info("Add a valid runtime for the same device id and emit update event");
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceId: DEVICE_ID,
+    deviceName: DEVICE_NAME,
+    shortName: RUNTIME_NAME,
+  });
+  mocks.removeDevice(DEVICE_ID);
+  mocks.emitUSBUpdate();
+
+  info("Wait until connect button appears for the USB runtime");
+  let updatedSidebarItem = null;
+  await waitUntil(() => {
+    updatedSidebarItem = findSidebarItemByText(DEVICE_NAME, document);
+    return (
+      updatedSidebarItem &&
+      updatedSidebarItem.querySelector(".qa-connect-button")
+    );
+  });
+
+  ok(
+    updatedSidebarItem.querySelector(".qa-runtime-item-standard"),
+    "Sidebar item for the USB runtime is now a standard sidebar item"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_unplugged_device.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_unplugged_device.js
new file mode 100644
index 0000000000..5074538a94
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_sidebar_usb_unplugged_device.js
@@ -0,0 +1,69 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const RUNTIME_NAME = "RUNTIME_NAME_1";
+const DEVICE_NAME = "DEVICE_NAME_1";
+const DEVICE_ID = "DEVICE_ID_1";
+const RUNTIME_ID = "RUNTIME_ID_1";
+
+const RUNTIME_NAME_2 = "RUNTIME_NAME_2";
+const DEVICE_NAME_2 = "DEVICE_NAME_2";
+const DEVICE_ID_2 = "DEVICE_ID_2";
+const RUNTIME_ID_2 = "RUNTIME_ID_2";
+
+// Test that removed USB devices are still visible as "Unplugged devices", until
+// about:debugging is reloaded.
+add_task(async function () {
+  const mocks = new Mocks();
+  let { document, tab } = await openAboutDebugging();
+
+  info("Create a mocked USB runtime");
+  mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceId: DEVICE_ID,
+    deviceName: DEVICE_NAME,
+    shortName: RUNTIME_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait until the USB sidebar item appears");
+  await waitUntil(() => findSidebarItemByText(DEVICE_NAME, document));
+  const sidebarItem = findSidebarItemByText(DEVICE_NAME, document);
+  ok(
+    sidebarItem.textContent.includes(RUNTIME_NAME),
+    "Sidebar item shows the runtime name"
+  );
+
+  mocks.removeUSBRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntilUsbDeviceIsUnplugged(DEVICE_NAME, document);
+
+  const unpluggedItem = findSidebarItemByText(DEVICE_NAME, document);
+  ok(
+    unpluggedItem.querySelector(".qa-runtime-item-unplugged"),
+    "Sidebar item is shown as `Unplugged…`"
+  );
+
+  info("Reload about:debugging");
+  document = await reloadAboutDebugging(tab);
+
+  info(
+    "Add another mocked USB runtime, to make sure the sidebar items are rendered."
+  );
+  mocks.createUSBRuntime(RUNTIME_ID_2, {
+    deviceId: DEVICE_ID_2,
+    deviceName: DEVICE_NAME_2,
+    shortName: RUNTIME_NAME_2,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait until the other USB sidebar item appears");
+  await waitUntil(() => findSidebarItemByText(DEVICE_NAME_2, document));
+  ok(
+    !findSidebarItemByText(DEVICE_NAME, document),
+    "Unplugged device is no longer displayed after reloading aboutdebugging"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_tab_favicons.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_tab_favicons.js
new file mode 100644
index 0000000000..e4acd1727d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_tab_favicons.js
@@ -0,0 +1,57 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that about:debugging uses the favicon of tab targets as the icon of their debug
+ * target item, and doesn't always use the default globe icon.
+ */
+
+// PlaceUtils will not store any favicon for data: uris so we need to use a dedicated page
+// here.
+const TAB_URL =
+  "https://example.com/browser/devtools/client/aboutdebugging/" +
+  "test/browser/test-tab-favicons.html";
+
+// This is the same png data-url as the one used in test-tab-favicons.html.
+const EXPECTED_FAVICON =
+  "data:image/png;base64," +
+  "iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAAATklEQVRYhe3SIQ4AI" +
+  "BADwf7/04elBAtrVlSduGnSTDJ7cuT1PQJwwO+Hl7sAGAA07gjAAfgIBeAAoH" +
+  "FHAA7ARygABwCNOwJwAD5CATRgAYXh+kypw86nAAAAAElFTkSuQmCC";
+
+add_task(async function () {
+  const faviconTab = await addTab(TAB_URL, { background: true });
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  await waitUntil(() => {
+    const target = findDebugTargetByText("Favicon tab", document);
+    if (!target) {
+      return false;
+    }
+    // We may get a default globe.svg icon for a short period of time while
+    // the target tab is still loading.
+    return target
+      .querySelector(".qa-debug-target-item-icon")
+      .src.includes("data:");
+  });
+  const faviconTabTarget = findDebugTargetByText("Favicon tab", document);
+  const faviconTabIcon = faviconTabTarget.querySelector(
+    ".qa-debug-target-item-icon"
+  );
+
+  // Note this relies on PlaceUtils.promiseFaviconData returning the same data-url as the
+  // one provided in the test page. If the implementation changes and PlaceUtils returns a
+  // different base64 from the one we defined, we can instead load the image and check a
+  // few pixels to verify it matches the expected icon.
+  is(
+    faviconTabIcon.src,
+    EXPECTED_FAVICON,
+    "The debug target item for the tab shows the favicon of the tab"
+  );
+
+  await removeTab(tab);
+  await removeTab(faviconTab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_tab_navigate.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_tab_navigate.js
new file mode 100644
index 0000000000..45355203e3
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_tab_navigate.js
@@ -0,0 +1,31 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TAB_1_URL =
+  "http://example.org/document-builder.sjs?html=<title>TITLE1</title>";
+const TAB_2_URL =
+  "http://example.org/document-builder.sjs?html=<title>TITLE2</title>";
+
+// Check that the list of tabs in about:debugging is updated when a page
+// navigates. This indirectly checks that the tabListChanged event is correctly
+// fired from the root actor.
+add_task(async function () {
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const testTab = await addTab(TAB_1_URL, { background: true });
+  await waitFor(() => findDebugTargetByText("TITLE1", document));
+
+  navigateTo(TAB_2_URL, { browser: testTab.linkedBrowser });
+  await waitFor(() => findDebugTargetByText("TITLE2", document));
+
+  ok(
+    !findDebugTargetByText("TITLE1", document),
+    "TITLE2 target replaced TITLE1"
+  );
+
+  await removeTab(tab);
+  await removeTab(testTab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_tab_zombietab.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_tab_zombietab.js
new file mode 100644
index 0000000000..1243d3374d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_tab_zombietab.js
@@ -0,0 +1,108 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+let gUniqueCounter = 0;
+
+const triggeringPrincipal_base64 = E10SUtils.SERIALIZED_SYSTEMPRINCIPAL;
+
+const BROWSER_STATE_TABS = [
+  "about:debugging",
+  "data:text/html,<title>TEST_TAB_1</title>",
+  "data:text/html,<title>TEST_TAB_2</title>",
+  "data:text/html,<title>TEST_TAB_3</title>",
+];
+const BROWSER_STATE = {
+  windows: [
+    {
+      tabs: BROWSER_STATE_TABS.map(url => {
+        return {
+          entries: [{ url, triggeringPrincipal_base64 }],
+          extData: { uniq: Date.now() + "-" + ++gUniqueCounter },
+        };
+      }),
+      selected: 1,
+    },
+  ],
+};
+
+// Check that the inspect action is disabled for lazy/zombie tabs, such as the
+// ones created after a session restore.
+add_task(async function () {
+  // This setup is normally handed by the openAboutDebugging helper, but here we
+  // open about:debugging via session restore.
+  silenceWorkerUpdates();
+  await pushPref("devtools.aboutdebugging.local-tab-debugging", true);
+
+  info("Restore 4 tabs including a selected about:debugging tab");
+  const onBrowserSessionRestored = Promise.all([
+    TestUtils.topicObserved("sessionstore-browser-state-restored"),
+    BrowserTestUtils.waitForEvent(gBrowser.tabContainer, "SSTabRestored"),
+  ]);
+  SessionStore.setBrowserState(JSON.stringify(BROWSER_STATE));
+  await onBrowserSessionRestored;
+
+  const tab = gBrowser.selectedTab;
+  const browser = tab.linkedBrowser;
+  const doc = browser.contentDocument;
+  const win = browser.contentWindow;
+  const store = win.AboutDebugging.store;
+
+  info("Wait until Connect page is displayed");
+  await waitUntil(() => doc.querySelector(".qa-connect-page"));
+
+  await selectThisFirefoxPage(doc, store);
+
+  // Check that all inspect butttons are disabled.
+  checkInspectButton("TEST_TAB_1", doc, { expectDisabled: true });
+  checkInspectButton("TEST_TAB_2", doc, { expectDisabled: true });
+  checkInspectButton("TEST_TAB_3", doc, { expectDisabled: true });
+
+  info("Select the TEST_TAB_2 tab top restore it completely");
+  const onTabRestored = BrowserTestUtils.waitForEvent(
+    gBrowser.tabContainer,
+    "SSTabRestored"
+  );
+  gBrowser.selectedTab = gBrowser.tabs[2];
+  await onTabRestored;
+
+  const onTabsSuccess = waitForDispatch(store, "REQUEST_TABS_SUCCESS");
+
+  info("Select the about:debugging tab again");
+  gBrowser.selectedTab = tab;
+
+  info("Wait until the tabs update is finished");
+  await onTabsSuccess;
+
+  info("Wait until the inspect button for TEST_TAB_2 is enabled");
+  await waitUntil(() => {
+    const target = findDebugTargetByText("TEST_TAB_2", doc);
+    if (!target) {
+      // TEST_TAB_2 target might be missing while the tab target list updates.
+      return false;
+    }
+
+    const button = target.querySelector(".qa-debug-target-inspect-button");
+    return !button.disabled;
+  });
+
+  // Check that all inspect butttons are disabled, except for #2.
+  checkInspectButton("TEST_TAB_1", doc, { expectDisabled: true });
+  checkInspectButton("TEST_TAB_2", doc, { expectDisabled: false });
+  checkInspectButton("TEST_TAB_3", doc, { expectDisabled: true });
+});
+
+function checkInspectButton(targetText, doc, { expectDisabled }) {
+  const inspectButton = getInspectButton(targetText, doc);
+  if (expectDisabled) {
+    ok(inspectButton.disabled, `Inspect button is disabled for ${targetText}`);
+  } else {
+    ok(!inspectButton.disabled, `Inspect button is enabled for ${targetText}`);
+  }
+}
+
+function getInspectButton(targetText, doc) {
+  const targetElement = findDebugTargetByText(targetText, doc);
+  return targetElement.querySelector(".qa-debug-target-inspect-button");
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_targets_sorted.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_targets_sorted.js
new file mode 100644
index 0000000000..4fc9bb87c0
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_targets_sorted.js
@@ -0,0 +1,111 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Check that all debug targets except tabs are sorted alphabetically.
+add_task(async function () {
+  const thisFirefoxClient = setupThisFirefoxMock();
+
+  thisFirefoxClient.listAddons = () => [
+    createAddonData({ id: "addon-b", name: "Addon B" }),
+    createAddonData({ id: "addon-c", name: "Addon C" }),
+    createAddonData({ id: "addon-a", name: "Addon A" }),
+    createAddonData({ id: "tmp-b", name: "Temporary B", temporary: true }),
+    createAddonData({ id: "tmp-c", name: "Temporary C", temporary: true }),
+    createAddonData({ id: "tmp-a", name: "Temporary A", temporary: true }),
+  ];
+
+  thisFirefoxClient.listWorkers = () => {
+    return {
+      otherWorkers: [
+        { id: "worker-b", name: "Worker B" },
+        { id: "worker-c", name: "Worker C" },
+        { id: "worker-a", name: "Worker A" },
+      ],
+      sharedWorkers: [
+        { id: "shared-worker-b", name: "Shared Worker B" },
+        { id: "shared-worker-c", name: "Shared Worker C" },
+        { id: "shared-worker-a", name: "Shared Worker A" },
+      ],
+      serviceWorkers: [
+        { id: "service-worker-b", name: "Service Worker B" },
+        { id: "service-worker-c", name: "Service Worker C" },
+        { id: "service-worker-a", name: "Service Worker A" },
+      ],
+    };
+  };
+
+  thisFirefoxClient.listTabs = () => [
+    {
+      browserId: 2,
+      title: "Tab B",
+      url: "https://www.b.com",
+      retrieveFavicon: () => {},
+    },
+    {
+      browserId: 3,
+      title: "Tab C",
+      url: "https://www.c.com",
+      retrieveFavicon: () => {},
+    },
+    {
+      browserId: 1,
+      title: "Tab A",
+      url: "https://www.a.com",
+      retrieveFavicon: () => {},
+    },
+  ];
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  function findTargetIndex(name) {
+    const targets = [...document.querySelectorAll(".qa-debug-target-item")];
+    return targets.findIndex(target => target.textContent.includes(name));
+  }
+
+  function assertTargetOrder(targetNames, message) {
+    let isSorted = true;
+    for (let i = 1; i < targetNames.length; i++) {
+      const index1 = findTargetIndex(targetNames[i - 1]);
+      const index2 = findTargetIndex(targetNames[i]);
+      if (index1 > index2) {
+        isSorted = false;
+        info(
+          `Targets ${targetNames[i - 1]} and ${targetNames[i]} ` +
+            `are not sorted as expected`
+        );
+      }
+    }
+
+    ok(isSorted, message);
+  }
+
+  assertTargetOrder(
+    ["Tab B", "Tab C", "Tab A"],
+    "Tabs are sorted as returned by the back-end"
+  );
+  assertTargetOrder(
+    ["Addon A", "Addon B", "Addon C"],
+    "Addons are sorted alphabetically"
+  );
+  assertTargetOrder(
+    ["Temporary A", "Temporary B", "Temporary C"],
+    "Temporary addons are sorted alphabetically"
+  );
+  assertTargetOrder(
+    ["Worker A", "Worker B", "Worker C"],
+    "Workers are sorted alphabetically"
+  );
+  assertTargetOrder(
+    ["Shared Worker A", "Shared Worker B", "Shared Worker C"],
+    "Shared workers are sorted alphabetically"
+  );
+  assertTargetOrder(
+    ["Service Worker A", "Service Worker B", "Service Worker C"],
+    "Service workers are sorted alphabetically"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_basic.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_basic.js
new file mode 100644
index 0000000000..5970d6a70d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_basic.js
@@ -0,0 +1,46 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-telemetry.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-telemetry.js",
+  this
+);
+
+/**
+ * Check that telemetry events are recorded when opening and closing about debugging.
+ */
+add_task(async function () {
+  setupTelemetryTest();
+
+  const { tab } = await openAboutDebugging();
+
+  const openEvents = readAboutDebuggingEvents().filter(
+    e => e.method === "open_adbg"
+  );
+  is(
+    openEvents.length,
+    1,
+    "Exactly one open event was logged for about:debugging"
+  );
+  const sessionId = openEvents[0].extras.session_id;
+  ok(!isNaN(sessionId), "Open event has a valid session id");
+
+  await removeTab(tab);
+
+  const closeEvents = readAboutDebuggingEvents().filter(
+    e => e.method === "close_adbg"
+  );
+  is(
+    closeEvents.length,
+    1,
+    "Exactly one close event was logged for about:debugging"
+  );
+  is(
+    closeEvents[0].extras.session_id,
+    sessionId,
+    "Close event has the same session id as the open event"
+  );
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_connection_attempt.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_connection_attempt.js
new file mode 100644
index 0000000000..a5836ad50a
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_connection_attempt.js
@@ -0,0 +1,274 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-telemetry.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-telemetry.js",
+  this
+);
+
+const USB_RUNTIME = {
+  id: "runtime-id-1",
+  deviceName: "Device A",
+  name: "Runtime 1",
+  shortName: "R1",
+};
+
+/**
+ * Check that telemetry events for connection attempts are correctly recorded in various
+ * scenarios:
+ * - successful connection
+ * - successful connection after showing the timeout warning
+ * - failed connection
+ * - connection timeout
+ */
+add_task(async function testSuccessfulConnectionAttempt() {
+  const { doc, mocks, runtimeId, sessionId, tab } =
+    await setupConnectionAttemptTest();
+
+  await connectToRuntime(USB_RUNTIME.deviceName, doc);
+
+  const connectionEvents = checkTelemetryEvents(
+    [
+      { method: "runtime_connected", extras: { runtime_id: runtimeId } },
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("start", runtimeId),
+      },
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("success", runtimeId),
+      },
+    ],
+    sessionId
+  ).filter(({ method }) => method === "connection_attempt");
+
+  checkConnectionId(connectionEvents);
+
+  await removeUsbRuntime(USB_RUNTIME, mocks, doc);
+  await removeTab(tab);
+});
+
+add_task(async function testFailedConnectionAttempt() {
+  const { doc, mocks, runtimeId, sessionId, tab } =
+    await setupConnectionAttemptTest();
+  mocks.runtimeClientFactoryMock.createClientForRuntime = async runtime => {
+    throw new Error("failed");
+  };
+
+  info(
+    "Try to connect to the runtime and wait for the connection error message"
+  );
+  const usbRuntimeSidebarItem = findSidebarItemByText(
+    USB_RUNTIME.deviceName,
+    doc
+  );
+  const connectButton =
+    usbRuntimeSidebarItem.querySelector(".qa-connect-button");
+  connectButton.click();
+  await waitUntil(() =>
+    usbRuntimeSidebarItem.querySelector(".qa-connection-error")
+  );
+
+  const connectionEvents = checkTelemetryEvents(
+    [
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("start", runtimeId),
+      },
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("failed", runtimeId),
+      },
+    ],
+    sessionId
+  ).filter(({ method }) => method === "connection_attempt");
+
+  checkConnectionId(connectionEvents);
+
+  await removeUsbRuntime(USB_RUNTIME, mocks, doc);
+  await removeTab(tab);
+});
+
+add_task(async function testPendingConnectionAttempt() {
+  info("Set timeout preferences to avoid cancelling the connection");
+  await pushPref(
+    "devtools.aboutdebugging.test-connection-timing-out-delay",
+    100
+  );
+  await pushPref(
+    "devtools.aboutdebugging.test-connection-cancel-delay",
+    100000
+  );
+
+  const { doc, mocks, runtimeId, sessionId, tab } =
+    await setupConnectionAttemptTest();
+
+  info("Simulate a pending connection");
+  let resumeConnection;
+  const resumeConnectionPromise = new Promise(r => {
+    resumeConnection = r;
+  });
+  mocks.runtimeClientFactoryMock.createClientForRuntime = async runtime => {
+    await resumeConnectionPromise;
+    return mocks._clients[runtime.type][runtime.id];
+  };
+
+  info("Click on the connect button and wait for the warning message");
+  const usbRuntimeSidebarItem = findSidebarItemByText(
+    USB_RUNTIME.deviceName,
+    doc
+  );
+  const connectButton =
+    usbRuntimeSidebarItem.querySelector(".qa-connect-button");
+  connectButton.click();
+  await waitUntil(() => doc.querySelector(".qa-connection-not-responding"));
+
+  info("Resume the connection and wait for the connection to succeed");
+  resumeConnection();
+  await waitUntil(
+    () => !usbRuntimeSidebarItem.querySelector(".qa-connect-button")
+  );
+
+  const connectionEvents = checkTelemetryEvents(
+    [
+      { method: "runtime_connected", extras: { runtime_id: runtimeId } },
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("start", runtimeId),
+      },
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("not responding", runtimeId),
+      },
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("success", runtimeId),
+      },
+    ],
+    sessionId
+  ).filter(({ method }) => method === "connection_attempt");
+  checkConnectionId(connectionEvents);
+
+  await removeUsbRuntime(USB_RUNTIME, mocks, doc);
+  await removeTab(tab);
+});
+
+add_task(async function testCancelledConnectionAttempt() {
+  info("Set timeout preferences to quickly cancel the connection");
+  await pushPref(
+    "devtools.aboutdebugging.test-connection-timing-out-delay",
+    100
+  );
+  await pushPref("devtools.aboutdebugging.test-connection-cancel-delay", 1000);
+
+  const { doc, mocks, runtimeId, sessionId, tab } =
+    await setupConnectionAttemptTest();
+
+  info("Simulate a connection timeout");
+  mocks.runtimeClientFactoryMock.createClientForRuntime = async runtime => {
+    await new Promise(r => {});
+  };
+
+  info("Click on the connect button and wait for the error message");
+  const usbRuntimeSidebarItem = findSidebarItemByText(
+    USB_RUNTIME.deviceName,
+    doc
+  );
+  const connectButton =
+    usbRuntimeSidebarItem.querySelector(".qa-connect-button");
+  connectButton.click();
+  await waitUntil(() =>
+    usbRuntimeSidebarItem.querySelector(".qa-connection-timeout")
+  );
+
+  const connectionEvents = checkTelemetryEvents(
+    [
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("start", runtimeId),
+      },
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("not responding", runtimeId),
+      },
+      {
+        method: "connection_attempt",
+        extras: getEventExtras("cancelled", runtimeId),
+      },
+    ],
+    sessionId
+  ).filter(({ method }) => method === "connection_attempt");
+  checkConnectionId(connectionEvents);
+
+  await removeUsbRuntime(USB_RUNTIME, mocks, doc);
+  await removeTab(tab);
+});
+
+function checkConnectionId(connectionEvents) {
+  const connectionId = connectionEvents[0].extras.connection_id;
+  ok(
+    !!connectionId,
+    "Found a valid connection id in the first connection_attempt event"
+  );
+  for (const evt of connectionEvents) {
+    is(
+      evt.extras.connection_id,
+      connectionId,
+      "All connection_attempt events share the same connection id"
+    );
+  }
+}
+
+// Small helper to create the expected event extras object for connection_attempt events
+function getEventExtras(status, runtimeId) {
+  return {
+    connection_type: "usb",
+    runtime_id: runtimeId,
+    status,
+  };
+}
+
+// Open about:debugging, setup telemetry, mocks and create a mocked USB runtime.
+async function setupConnectionAttemptTest() {
+  const mocks = new Mocks();
+  setupTelemetryTest();
+
+  const { tab, document } = await openAboutDebugging();
+
+  const sessionId = getOpenEventSessionId();
+  ok(!isNaN(sessionId), "Open event has a valid session id");
+
+  mocks.createUSBRuntime(USB_RUNTIME.id, {
+    deviceName: USB_RUNTIME.deviceName,
+    name: USB_RUNTIME.name,
+    shortName: USB_RUNTIME.shortName,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait for the runtime to appear in the sidebar");
+  await waitUntil(() => findSidebarItemByText(USB_RUNTIME.shortName, document));
+  const evts = checkTelemetryEvents(
+    [
+      { method: "device_added", extras: {} },
+      { method: "runtime_added", extras: {} },
+    ],
+    sessionId
+  );
+
+  const runtimeId = evts.filter(e => e.method === "runtime_added")[0].extras
+    .runtime_id;
+  return { doc: document, mocks, runtimeId, sessionId, tab };
+}
+
+async function removeUsbRuntime(runtime, mocks, doc) {
+  mocks.removeRuntime(runtime.id);
+  mocks.emitUSBUpdate();
+  await waitUntil(
+    () =>
+      !findSidebarItemByText(runtime.name, doc) &&
+      !findSidebarItemByText(runtime.shortName, doc)
+  );
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_inspect.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_inspect.js
new file mode 100644
index 0000000000..60176258b1
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_inspect.js
@@ -0,0 +1,67 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-telemetry.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-telemetry.js",
+  this
+);
+
+const TAB_URL = "data:text/html,<title>TEST_TAB</title>";
+
+/**
+ * Check that telemetry events are recorded when inspecting a target.
+ */
+add_task(async function () {
+  setupTelemetryTest();
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const sessionId = getOpenEventSessionId();
+  ok(!isNaN(sessionId), "Open event has a valid session id");
+
+  info("Open a new background tab TEST_TAB");
+  const backgroundTab1 = await addTab(TAB_URL, { background: true });
+
+  info("Wait for the tab to appear in the debug targets with the correct name");
+  await waitUntil(() => findDebugTargetByText("TEST_TAB", document));
+
+  const { devtoolsTab } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    "TEST_TAB"
+  );
+
+  const evts = readAboutDebuggingEvents().filter(e => e.method === "inspect");
+  is(evts.length, 1, "Exactly one Inspect event found");
+  is(
+    evts[0].extras.target_type,
+    "TAB",
+    "Inspect event has the expected target type"
+  );
+  is(
+    evts[0].extras.runtime_type,
+    "this-firefox",
+    "Inspect event has the expected runtime type"
+  );
+  is(
+    evts[0].extras.session_id,
+    sessionId,
+    "Inspect event has the expected session"
+  );
+
+  info("Close the about:devtools-toolbox tab");
+  await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
+  await waitForAboutDebuggingRequests(window.AboutDebugging.store);
+
+  info("Remove first background tab");
+  await removeTab(backgroundTab1);
+  await waitUntil(() => !findDebugTargetByText("TEST_TAB", document));
+  await waitForAboutDebuggingRequests(window.AboutDebugging.store);
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_navigate.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_navigate.js
new file mode 100644
index 0000000000..946f5e9e43
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_navigate.js
@@ -0,0 +1,67 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+/* import-globals-from helper-telemetry.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-telemetry.js",
+  this
+);
+
+/**
+ * Check that telemetry events are recorded when navigating between different
+ * about:debugging pages.
+ */
+add_task(async function () {
+  // enable USB devices mocks
+  const mocks = new Mocks();
+
+  setupTelemetryTest();
+
+  const { tab, document, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  const sessionId = getOpenEventSessionId();
+  ok(!isNaN(sessionId), "Open event has a valid session id");
+
+  info("Navigate to 'Connect' page");
+  document.location.hash = "#/connect";
+  await waitUntil(() => document.querySelector(".qa-connect-page"));
+  checkSelectPageEvent("connect", sessionId);
+
+  info("Navigate to 'USB device runtime' page");
+  await navigateToUSBRuntime(mocks, document);
+  checkSelectPageEvent("runtime", sessionId);
+  await waitForAboutDebuggingRequests(window.AboutDebugging.store);
+
+  await removeTab(tab);
+});
+
+function checkSelectPageEvent(expectedType, expectedSessionId) {
+  const evts = readAboutDebuggingEvents().filter(
+    e => e.method === "select_page"
+  );
+  is(evts.length, 1, "Exactly one select_page event recorded");
+  is(
+    evts[0].extras.page_type,
+    expectedType,
+    "Select page event has the expected type"
+  );
+  is(
+    evts[0].extras.session_id,
+    expectedSessionId,
+    "Select page event has the expected session"
+  );
+}
+
+async function navigateToUSBRuntime(mocks, doc) {
+  mocks.createUSBRuntime("1337id", {
+    deviceName: "Fancy Phone",
+    name: "Lorem ipsum",
+  });
+  mocks.emitUSBUpdate();
+  await connectToRuntime("Fancy Phone", doc);
+  // navigate to it via URL
+  doc.location.hash = "#/runtime/1337id";
+  await waitUntil(() => doc.querySelector(".qa-runtime-page"));
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_actions.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_actions.js
new file mode 100644
index 0000000000..92d07a3d9c
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_actions.js
@@ -0,0 +1,97 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-telemetry.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-telemetry.js",
+  this
+);
+
+const RUNTIME_ID = "test-runtime-id";
+const RUNTIME_NAME = "Test Runtime";
+const RUNTIME_DEVICE_NAME = "Test Device";
+
+/**
+ * Test that runtime specific actions are logged as telemetry events with the expected
+ * runtime id and action type.
+ */
+add_task(async function testUsbRuntimeUpdates() {
+  // enable USB devices mocks
+  const mocks = new Mocks();
+  setupTelemetryTest();
+
+  const { tab, document } = await openAboutDebugging();
+
+  const sessionId = getOpenEventSessionId();
+  ok(!isNaN(sessionId), "Open event has a valid session id");
+
+  const usbClient = mocks.createUSBRuntime(RUNTIME_ID, {
+    deviceName: RUNTIME_DEVICE_NAME,
+    name: RUNTIME_NAME,
+    shortName: RUNTIME_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait for the runtime to appear in the sidebar");
+  await waitUntil(() => findSidebarItemByText(RUNTIME_NAME, document));
+  await connectToRuntime(RUNTIME_DEVICE_NAME, document);
+  await selectRuntime(RUNTIME_DEVICE_NAME, RUNTIME_NAME, document);
+
+  info("Read telemetry events to flush unrelated events");
+  const evts = readAboutDebuggingEvents();
+  const runtimeAddedEvent = evts.filter(e => e.method === "runtime_added")[0];
+  const telemetryRuntimeId = runtimeAddedEvent.extras.runtime_id;
+
+  info("Click on the toggle button and wait until the text is updated");
+  const promptButton = document.querySelector(
+    ".qa-connection-prompt-toggle-button"
+  );
+  promptButton.click();
+  await waitUntil(() => promptButton.textContent.includes("Enable"));
+
+  checkTelemetryEvents(
+    [
+      {
+        method: "update_conn_prompt",
+        extras: { prompt_enabled: "false", runtime_id: telemetryRuntimeId },
+      },
+    ],
+    sessionId
+  );
+
+  info("Click on the toggle button again and check we log the correct value");
+  promptButton.click();
+  await waitUntil(() => promptButton.textContent.includes("Disable"));
+
+  checkTelemetryEvents(
+    [
+      {
+        method: "update_conn_prompt",
+        extras: { prompt_enabled: "true", runtime_id: telemetryRuntimeId },
+      },
+    ],
+    sessionId
+  );
+
+  info("Open the profiler dialog");
+  await openProfilerDialog(usbClient, document);
+
+  checkTelemetryEvents(
+    [
+      {
+        method: "show_profiler",
+        extras: { runtime_id: telemetryRuntimeId },
+      },
+    ],
+    sessionId
+  );
+
+  info("Remove runtime");
+  mocks.removeRuntime(RUNTIME_ID);
+  mocks.emitUSBUpdate();
+  await waitUntil(() => !findSidebarItemByText(RUNTIME_NAME, document));
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_connected_details.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_connected_details.js
new file mode 100644
index 0000000000..808cfdcae8
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_connected_details.js
@@ -0,0 +1,69 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-telemetry.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-telemetry.js",
+  this
+);
+
+const REMOTE_RUNTIME_ID = "remote-runtime";
+const REMOTE_RUNTIME = "Remote Runtime";
+const REMOTE_DEVICE = "Remote Device";
+
+const REMOTE_VERSION = "12.0a1";
+const REMOTE_OS = "SOME_OS";
+
+/**
+ * Runtime connected events will log additional extras about the runtime connection that
+ * was established.
+ */
+add_task(async function () {
+  const mocks = new Mocks();
+
+  const usbClient = mocks.createUSBRuntime(REMOTE_RUNTIME_ID, {
+    deviceName: REMOTE_DEVICE,
+    name: REMOTE_RUNTIME,
+    shortName: REMOTE_RUNTIME,
+  });
+  usbClient.getDeviceDescription = () => {
+    return {
+      os: REMOTE_OS,
+      version: REMOTE_VERSION,
+    };
+  };
+
+  const { document, tab } = await openAboutDebugging();
+
+  mocks.emitUSBUpdate();
+  await connectToRuntime(REMOTE_DEVICE, document);
+  const evts = readAboutDebuggingEvents().filter(
+    e => e.method === "runtime_connected"
+  );
+
+  is(
+    evts.length,
+    1,
+    "runtime_connected event logged when connecting to remote runtime"
+  );
+  const {
+    connection_type,
+    device_name,
+    runtime_name,
+    runtime_os,
+    runtime_version,
+  } = evts[0].extras;
+  is(connection_type, "usb", "Expected value for `connection_type` extra");
+  is(device_name, REMOTE_DEVICE, "Expected value for `device_name` extra");
+  is(runtime_name, REMOTE_RUNTIME, "Expected value for `runtime_name` extra");
+  is(runtime_os, REMOTE_OS, "Expected value for `runtime_os` extra");
+  is(
+    runtime_version,
+    REMOTE_VERSION,
+    "Expected value for `runtime_version` extra"
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_updates.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_updates.js
new file mode 100644
index 0000000000..51934550a8
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_updates.js
@@ -0,0 +1,154 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-telemetry.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-telemetry.js",
+  this
+);
+
+const DEVICE_A = "Device A";
+const USB_RUNTIME_1 = {
+  id: "runtime-id-1",
+  deviceName: DEVICE_A,
+  name: "Runtime 1",
+  shortName: "R1",
+};
+
+const USB_RUNTIME_2 = {
+  id: "runtime-id-2",
+  deviceName: DEVICE_A,
+  name: "Runtime 2",
+  shortName: "R2",
+};
+
+const DEVICE_A_EXTRAS = {
+  connection_type: "usb",
+  device_name: DEVICE_A,
+};
+
+const RUNTIME_1_EXTRAS = {
+  connection_type: "usb",
+  device_name: USB_RUNTIME_1.deviceName,
+  runtime_name: USB_RUNTIME_1.shortName,
+};
+
+const RUNTIME_2_EXTRAS = {
+  connection_type: "usb",
+  device_name: USB_RUNTIME_2.deviceName,
+  runtime_name: USB_RUNTIME_2.shortName,
+};
+
+/**
+ * Check that telemetry events are recorded for USB runtimes when:
+ * - adding a device/runtime
+ * - removing a device/runtime
+ * - connecting to a runtime
+ */
+add_task(async function testUsbRuntimeUpdates() {
+  // enable USB devices mocks
+  const mocks = new Mocks();
+  setupTelemetryTest();
+
+  const { tab, document } = await openAboutDebugging();
+
+  const sessionId = getOpenEventSessionId();
+  ok(!isNaN(sessionId), "Open event has a valid session id");
+
+  await addUsbRuntime(USB_RUNTIME_1, mocks, document);
+
+  let evts = checkTelemetryEvents(
+    [
+      { method: "device_added", extras: DEVICE_A_EXTRAS },
+      { method: "runtime_added", extras: RUNTIME_1_EXTRAS },
+    ],
+    sessionId
+  );
+
+  // Now that a first telemetry event has been logged for RUNTIME_1, retrieve the id
+  // generated for telemetry, and check that we keep logging the same id for all events
+  // related to runtime 1.
+  const runtime1Id = evts.filter(e => e.method === "runtime_added")[0].extras
+    .runtime_id;
+  const runtime1Extras = Object.assign({}, RUNTIME_1_EXTRAS, {
+    runtime_id: runtime1Id,
+  });
+  // Same as runtime1Extras, but the runtime name should be the complete one.
+  const runtime1ConnectedExtras = Object.assign({}, runtime1Extras, {
+    runtime_name: USB_RUNTIME_1.name,
+  });
+
+  await connectToRuntime(USB_RUNTIME_1.deviceName, document);
+
+  checkTelemetryEvents(
+    [
+      { method: "runtime_connected", extras: runtime1ConnectedExtras },
+      { method: "connection_attempt", extras: { status: "start" } },
+      { method: "connection_attempt", extras: { status: "success" } },
+    ],
+    sessionId
+  );
+
+  info("Add a second runtime");
+  await addUsbRuntime(USB_RUNTIME_2, mocks, document);
+  evts = checkTelemetryEvents(
+    [{ method: "runtime_added", extras: RUNTIME_2_EXTRAS }],
+    sessionId
+  );
+
+  // Similar to what we did for RUNTIME_1,w e want to check we reuse the same telemetry id
+  // for all the events related to RUNTIME_2.
+  const runtime2Id = evts.filter(e => e.method === "runtime_added")[0].extras
+    .runtime_id;
+  const runtime2Extras = Object.assign({}, RUNTIME_2_EXTRAS, {
+    runtime_id: runtime2Id,
+  });
+
+  info("Remove runtime 1");
+  await removeUsbRuntime(USB_RUNTIME_1, mocks, document);
+
+  checkTelemetryEvents(
+    [
+      { method: "runtime_disconnected", extras: runtime1ConnectedExtras },
+      { method: "runtime_removed", extras: runtime1Extras },
+    ],
+    sessionId
+  );
+
+  info("Remove runtime 2");
+  await removeUsbRuntime(USB_RUNTIME_2, mocks, document);
+
+  checkTelemetryEvents(
+    [
+      { method: "runtime_removed", extras: runtime2Extras },
+      { method: "device_removed", extras: DEVICE_A_EXTRAS },
+    ],
+    sessionId
+  );
+
+  await removeTab(tab);
+});
+
+async function addUsbRuntime(runtime, mocks, doc) {
+  mocks.createUSBRuntime(runtime.id, {
+    deviceName: runtime.deviceName,
+    name: runtime.name,
+    shortName: runtime.shortName,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Wait for the runtime to appear in the sidebar");
+  await waitUntil(() => findSidebarItemByText(runtime.shortName, doc));
+}
+
+async function removeUsbRuntime(runtime, mocks, doc) {
+  mocks.removeRuntime(runtime.id);
+  mocks.emitUSBUpdate();
+  await waitUntil(
+    () =>
+      !findSidebarItemByText(runtime.name, doc) &&
+      !findSidebarItemByText(runtime.shortName, doc)
+  );
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_updates_multi.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_updates_multi.js
new file mode 100644
index 0000000000..707ddf4621
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_updates_multi.js
@@ -0,0 +1,111 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-telemetry.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-telemetry.js",
+  this
+);
+
+const DEVICE_A = "Device A";
+const USB_RUNTIME_1 = {
+  id: "runtime-id-1",
+  deviceName: DEVICE_A,
+  name: "Runtime 1",
+  shortName: "R1",
+};
+
+const USB_RUNTIME_2 = {
+  id: "runtime-id-2",
+  deviceName: DEVICE_A,
+  name: "Runtime 2",
+  shortName: "R2",
+};
+
+const DEVICE_A_EXTRAS = {
+  connection_type: "usb",
+  device_name: DEVICE_A,
+};
+
+const RUNTIME_1_EXTRAS = {
+  connection_type: "usb",
+  device_name: USB_RUNTIME_1.deviceName,
+  runtime_name: USB_RUNTIME_1.shortName,
+};
+
+const RUNTIME_2_EXTRAS = {
+  connection_type: "usb",
+  device_name: USB_RUNTIME_2.deviceName,
+  runtime_name: USB_RUNTIME_2.shortName,
+};
+
+/**
+ * Test runtime update events when a device is connected/disconnected with multiple
+ * runtimes available on the same device.
+ */
+add_task(async function () {
+  // enable USB devices mocks
+  const mocks = new Mocks();
+  setupTelemetryTest();
+
+  const { tab, document } = await openAboutDebugging();
+
+  const sessionId = getOpenEventSessionId();
+  ok(!isNaN(sessionId), "Open event has a valid session id");
+
+  info("Add two runtimes on the same device at the same time");
+  mocks.createUSBRuntime(USB_RUNTIME_1.id, {
+    deviceName: USB_RUNTIME_1.deviceName,
+    name: USB_RUNTIME_1.name,
+    shortName: USB_RUNTIME_1.shortName,
+  });
+  mocks.createUSBRuntime(USB_RUNTIME_2.id, {
+    deviceName: USB_RUNTIME_2.deviceName,
+    name: USB_RUNTIME_2.name,
+    shortName: USB_RUNTIME_2.shortName,
+  });
+  mocks.emitUSBUpdate();
+  await waitUntil(() =>
+    findSidebarItemByText(USB_RUNTIME_1.shortName, document)
+  );
+  await waitUntil(() =>
+    findSidebarItemByText(USB_RUNTIME_2.shortName, document)
+  );
+
+  checkTelemetryEvents(
+    [
+      { method: "device_added", extras: DEVICE_A_EXTRAS },
+      { method: "runtime_added", extras: RUNTIME_1_EXTRAS },
+      { method: "runtime_added", extras: RUNTIME_2_EXTRAS },
+    ],
+    sessionId
+  );
+
+  info("Remove both runtimes at once to simulate a device disconnection");
+  mocks.removeRuntime(USB_RUNTIME_1.id);
+  mocks.removeRuntime(USB_RUNTIME_2.id);
+  mocks.emitUSBUpdate();
+  await waitUntil(
+    () =>
+      !findSidebarItemByText(USB_RUNTIME_1.name, document) &&
+      !findSidebarItemByText(USB_RUNTIME_1.shortName, document)
+  );
+  await waitUntil(
+    () =>
+      !findSidebarItemByText(USB_RUNTIME_2.name, document) &&
+      !findSidebarItemByText(USB_RUNTIME_2.shortName, document)
+  );
+
+  checkTelemetryEvents(
+    [
+      { method: "runtime_removed", extras: RUNTIME_1_EXTRAS },
+      { method: "runtime_removed", extras: RUNTIME_2_EXTRAS },
+      { method: "device_removed", extras: DEVICE_A_EXTRAS },
+    ],
+    sessionId
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_updates_network.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_updates_network.js
new file mode 100644
index 0000000000..d33810dc59
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_telemetry_runtime_updates_network.js
@@ -0,0 +1,90 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-telemetry.js */
+Services.scriptloader.loadSubScript(
+  CHROME_URL_ROOT + "helper-telemetry.js",
+  this
+);
+
+const NETWORK_RUNTIME = {
+  host: "localhost:1234",
+  // No device name for network runtimes.
+  name: "Local Network Runtime",
+};
+
+/**
+ * Test runtime update events for network runtimes.
+ */
+add_task(async function testNetworkRuntimeUpdates() {
+  // enable USB devices mocks
+  const mocks = new Mocks();
+  setupTelemetryTest();
+
+  const { tab, document } = await openAboutDebugging();
+
+  const sessionId = getOpenEventSessionId();
+  ok(!isNaN(sessionId), "Open event has a valid session id");
+
+  info("Add a network runtime");
+  await addNetworkRuntime(NETWORK_RUNTIME, mocks, document);
+
+  // Before the connection, we don't have any information about the runtime.
+  // Device information is also not available to network runtimes.
+  const networkRuntimeExtras = {
+    connection_type: "network",
+    device_name: "",
+    runtime_name: "",
+  };
+
+  // Once connected we should be able to log a valid runtime name.
+  const connectedNetworkRuntimeExtras = Object.assign(
+    {},
+    networkRuntimeExtras,
+    {
+      runtime_name: NETWORK_RUNTIME.name,
+    }
+  );
+
+  // For network runtimes, we don't have any device information, so we shouldn't have any
+  // device_added event.
+  checkTelemetryEvents(
+    [{ method: "runtime_added", extras: networkRuntimeExtras }],
+    sessionId
+  );
+
+  await connectToRuntime(NETWORK_RUNTIME.host, document);
+  checkTelemetryEvents(
+    [
+      { method: "runtime_connected", extras: connectedNetworkRuntimeExtras },
+      { method: "connection_attempt", extras: { status: "start" } },
+      { method: "connection_attempt", extras: { status: "success" } },
+    ],
+    sessionId
+  );
+
+  info("Remove network runtime");
+  mocks.removeRuntime(NETWORK_RUNTIME.host);
+  await waitUntil(() => !findSidebarItemByText(NETWORK_RUNTIME.host, document));
+  // Similarly we should not have any device removed event.
+  checkTelemetryEvents(
+    [
+      { method: "runtime_disconnected", extras: connectedNetworkRuntimeExtras },
+      { method: "runtime_removed", extras: networkRuntimeExtras },
+    ],
+    sessionId
+  );
+
+  await removeTab(tab);
+});
+
+async function addNetworkRuntime(runtime, mocks, doc) {
+  mocks.createNetworkRuntime(runtime.host, {
+    name: runtime.name,
+  });
+
+  info("Wait for the Network Runtime to appear in the sidebar");
+  await waitUntil(() => findSidebarItemByText(runtime.host, doc));
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_thisfirefox.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_thisfirefox.js
new file mode 100644
index 0000000000..3f673df758
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_thisfirefox.js
@@ -0,0 +1,121 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const EXPECTED_TARGET_PANES = [
+  "Tabs",
+  "Temporary Extensions",
+  "Extensions",
+  "Service Workers",
+  "Shared Workers",
+  "Other Workers",
+];
+
+/**
+ * Check that the This Firefox runtime page contains the expected categories if
+ * the preference to enable local tab debugging is true.
+ */
+add_task(async function testThisFirefoxWithLocalTab() {
+  const { document, tab, window } = await openAboutDebugging({
+    enableLocalTabs: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Expect all target panes to be displayed including tabs.
+  await checkThisFirefoxTargetPanes(document, EXPECTED_TARGET_PANES);
+
+  await removeTab(tab);
+});
+
+/**
+ * Check that the This Firefox runtime page contains the expected categories if
+ * the preference to enable local tab debugging is false.
+ */
+add_task(async function testThisFirefoxWithoutLocalTab() {
+  const { document, tab, window } = await openAboutDebugging({
+    enableLocalTabs: false,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Expect all target panes but tabs to be displayed.
+  const expectedTargetPanesWithoutTabs = EXPECTED_TARGET_PANES.filter(
+    p => p !== "Tabs"
+  );
+  await checkThisFirefoxTargetPanes(document, expectedTargetPanesWithoutTabs);
+
+  await removeTab(tab);
+});
+
+/**
+ * Check that the tab which is discarded keeps the state after open the aboutdebugging.
+ */
+add_task(async function testThisFirefoxKeepDiscardedTab() {
+  const targetTab = await addTab("https://example.com/");
+  const blankTab = await addTab("about:blank");
+  targetTab.ownerGlobal.gBrowser.discardBrowser(targetTab);
+
+  const { document, tab, window } = await openAboutDebugging({
+    enableLocalTabs: false,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  ok(!targetTab.linkedPanel, "The target tab is still discarded");
+
+  await removeTab(blankTab);
+  await removeTab(targetTab);
+  await removeTab(tab);
+});
+
+/**
+ * Check that the Temporary Extensions is hidden if "xpinstall.enabled" is set to false.
+ */
+add_task(async function testThisFirefoxWithXpinstallDisabled() {
+  await pushPref("xpinstall.enabled", false);
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  // Expect all target panes but temporary extensions to be displayed.
+  const expectedTargetPanesWithXpinstallDisabled = EXPECTED_TARGET_PANES.filter(
+    p => p !== "Temporary Extensions"
+  );
+  await checkThisFirefoxTargetPanes(
+    document,
+    expectedTargetPanesWithXpinstallDisabled
+  );
+
+  await removeTab(tab);
+});
+
+async function checkThisFirefoxTargetPanes(doc, expectedTargetPanes) {
+  const win = doc.ownerGlobal;
+  // Check that the selected sidebar item is "This Firefox"/"This Nightly"/...
+  const selectedSidebarItem = doc.querySelector(".qa-sidebar-item-selected");
+  ok(selectedSidebarItem, "An item is selected in the sidebar");
+
+  const thisFirefoxString = getThisFirefoxString(win);
+  is(
+    selectedSidebarItem.textContent,
+    thisFirefoxString,
+    "The selected sidebar item is " + thisFirefoxString
+  );
+
+  const paneTitlesEls = doc.querySelectorAll(".qa-debug-target-pane-title");
+  is(
+    paneTitlesEls.length,
+    expectedTargetPanes.length,
+    "This Firefox has the expected number of debug target categories"
+  );
+
+  const paneTitles = [...paneTitlesEls].map(el => el.textContent);
+
+  for (let i = 0; i < expectedTargetPanes.length; i++) {
+    const expectedPaneTitle = expectedTargetPanes[i];
+    const actualPaneTitle = paneTitles[i];
+    ok(
+      actualPaneTitle.startsWith(expectedPaneTitle),
+      `Expected debug target category found: ${expectedPaneTitle}`
+    );
+  }
+}
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_thisfirefox_runtime_info.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_thisfirefox_runtime_info.js
new file mode 100644
index 0000000000..2475994fed
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_thisfirefox_runtime_info.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check that the runtime info is correctly displayed for ThisFirefox.
+ * Also acts as basic sanity check for the default mock of the this-firefox client.
+ */
+
+add_task(async function () {
+  // Setup a mock for our runtime client factory to return the default THIS_FIREFOX client
+  // when the client for the this-firefox runtime is requested.
+  const runtimeClientFactoryMock = createRuntimeClientFactoryMock();
+  const thisFirefoxClient = createThisFirefoxClientMock();
+  runtimeClientFactoryMock.createClientForRuntime = runtime => {
+    const {
+      RUNTIMES,
+    } = require("resource://devtools/client/aboutdebugging/src/constants.js");
+    if (runtime.id === RUNTIMES.THIS_FIREFOX) {
+      return thisFirefoxClient;
+    }
+    throw new Error("Unexpected runtime id " + runtime.id);
+  };
+
+  info("Enable mocks");
+  enableRuntimeClientFactoryMock(runtimeClientFactoryMock);
+  registerCleanupFunction(() => {
+    disableRuntimeClientFactoryMock();
+  });
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Check that the 'This Firefox' mock is properly displayed");
+  const thisFirefoxRuntimeInfo = document.querySelector(".qa-runtime-name");
+  ok(
+    thisFirefoxRuntimeInfo,
+    "Runtime info for this-firefox runtime is displayed"
+  );
+  const runtimeInfoText = thisFirefoxRuntimeInfo.textContent;
+  ok(
+    runtimeInfoText.includes("Firefox"),
+    "this-firefox runtime info shows the correct runtime name: " +
+      runtimeInfoText
+  );
+  ok(
+    runtimeInfoText.includes("63.0"),
+    "this-firefox runtime info shows the correct version number: " +
+      runtimeInfoText
+  );
+
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_thisfirefox_worker_inspection.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_thisfirefox_worker_inspection.js
new file mode 100644
index 0000000000..4d02c73b1b
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_thisfirefox_worker_inspection.js
@@ -0,0 +1,68 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function () {
+  const thisFirefoxClient = createThisFirefoxClientMock();
+  // Prepare a worker mock.
+  const testWorker = {
+    id: "test-worker-id",
+    name: "Test Worker",
+  };
+  // Add a worker mock as other worker.
+  thisFirefoxClient.listWorkers = () => ({
+    otherWorkers: [testWorker],
+    serviceWorkers: [],
+    sharedWorkers: [],
+  });
+  thisFirefoxClient.client.mainRoot = {
+    getWorker: id => {
+      return id === testWorker.id ? testWorker : null;
+    },
+  };
+
+  const runtimeClientFactoryMock = createRuntimeClientFactoryMock();
+  runtimeClientFactoryMock.createClientForRuntime = runtime => {
+    const {
+      RUNTIMES,
+    } = require("resource://devtools/client/aboutdebugging/src/constants.js");
+    if (runtime.id === RUNTIMES.THIS_FIREFOX) {
+      return thisFirefoxClient;
+    }
+    throw new Error("Unexpected runtime id " + runtime.id);
+  };
+
+  info("Enable mocks");
+  enableRuntimeClientFactoryMock(runtimeClientFactoryMock);
+  registerCleanupFunction(() => {
+    disableRuntimeClientFactoryMock();
+  });
+
+  const { document, tab, window } = await openAboutDebugging();
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Open a toolbox to debug the worker");
+  const { devtoolsTab, devtoolsWindow } = await openAboutDevtoolsToolbox(
+    document,
+    tab,
+    window,
+    testWorker.name,
+    false
+  );
+
+  info(
+    "Check whether the correct actor front will be opened in worker toolbox"
+  );
+  const url = new window.URL(devtoolsWindow.location.href);
+  const workerID = url.searchParams.get("id");
+  is(
+    workerID,
+    testWorker.id,
+    "Correct actor front will be opened in worker toolbox"
+  );
+
+  await removeTab(devtoolsTab);
+  await waitUntil(() => !findDebugTargetByText("Toolbox - ", document));
+  await removeTab(tab);
+});
diff --git a/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_workers_remote_runtime.js b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_workers_remote_runtime.js
new file mode 100644
index 0000000000..3e0ccf1532
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_workers_remote_runtime.js
@@ -0,0 +1,160 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const NETWORK_RUNTIME_HOST = "localhost:6080";
+const NETWORK_RUNTIME_APP_NAME = "TestNetworkApp";
+const USB_RUNTIME_ID = "test-runtime-id";
+const USB_RUNTIME_DEVICE_NAME = "test device name";
+const USB_RUNTIME_APP_NAME = "TestUsbApp";
+
+const TESTS = [
+  {
+    category: "Other Workers",
+    propertyName: "otherWorkers",
+    workerName: "other/worker/script.js",
+  },
+  {
+    category: "Service Workers",
+    propertyName: "serviceWorkers",
+    workerName: "service/worker/script.js",
+  },
+  {
+    category: "Shared Workers",
+    propertyName: "sharedWorkers",
+    workerName: "shared/worker/script.js",
+  },
+];
+
+const EMPTY_WORKERS_RESPONSE = {
+  otherWorkers: [],
+  serviceWorkers: [],
+  sharedWorkers: [],
+};
+
+// Test that workers are displayed and updated for remote runtimes when expected.
+add_task(async function () {
+  const mocks = new Mocks();
+
+  const { document, tab, window } = await openAboutDebugging({
+    enableWorkerUpdates: true,
+  });
+  await selectThisFirefoxPage(document, window.AboutDebugging.store);
+
+  info("Prepare USB client mock");
+  const usbClient = mocks.createUSBRuntime(USB_RUNTIME_ID, {
+    deviceName: USB_RUNTIME_DEVICE_NAME,
+    name: USB_RUNTIME_APP_NAME,
+  });
+  mocks.emitUSBUpdate();
+
+  info("Test addons in runtime page for USB client");
+  await connectToRuntime(USB_RUNTIME_DEVICE_NAME, document);
+  await selectRuntime(USB_RUNTIME_DEVICE_NAME, USB_RUNTIME_APP_NAME, document);
+  for (const testData of TESTS) {
+    await testWorkerOnMockedRemoteClient(
+      testData,
+      usbClient,
+      mocks.thisFirefoxClient,
+      document
+    );
+  }
+
+  info("Prepare Network client mock");
+  const networkClient = mocks.createNetworkRuntime(NETWORK_RUNTIME_HOST, {
+    name: NETWORK_RUNTIME_APP_NAME,
+  });
+
+  info("Test workers in runtime page for Network client");
+  await connectToRuntime(NETWORK_RUNTIME_HOST, document);
+  await selectRuntime(NETWORK_RUNTIME_HOST, NETWORK_RUNTIME_APP_NAME, document);
+
+  for (const testData of TESTS) {
+    await testWorkerOnMockedRemoteClient(
+      testData,
+      networkClient,
+      mocks.thisFirefoxClient,
+      document
+    );
+  }
+
+  await removeTab(tab);
+});
+
+/**
+ * Check that workers are visible in the runtime page for a remote client.
+ */
+async function testWorkerOnMockedRemoteClient(
+  testData,
+  remoteClient,
+  firefoxClient,
+  document
+) {
+  const { category, propertyName, workerName } = testData;
+  info(`Test workers for category [${category}] in remote runtime`);
+
+  const workersPane = getDebugTargetPane(category, document);
+  info("Check an empty target pane message is displayed");
+  ok(
+    workersPane.querySelector(".qa-debug-target-list-empty"),
+    "Workers list is empty"
+  );
+
+  info(`Add a worker of type [${propertyName}] to the remote client`);
+  const workers = Object.assign({}, EMPTY_WORKERS_RESPONSE, {
+    [propertyName]: [
+      {
+        name: workerName,
+        workerDescriptorFront: {
+          actorID: workerName,
+        },
+      },
+    ],
+  });
+  remoteClient.listWorkers = () => workers;
+  remoteClient._eventEmitter.emit("workersUpdated");
+
+  info("Wait until the worker appears");
+  await waitUntil(
+    () => !workersPane.querySelector(".qa-debug-target-list-empty")
+  );
+
+  const workerTarget = findDebugTargetByText(workerName, document);
+  ok(workerTarget, "Worker target appeared for the remote runtime");
+
+  // Check that the list of REMOTE workers are NOT updated when the local this-firefox
+  // emits a workersUpdated event.
+  info("Remove the worker from the remote client WITHOUT sending an event");
+  remoteClient.listWorkers = () => EMPTY_WORKERS_RESPONSE;
+
+  info("Simulate a worker update on the ThisFirefox client");
+  firefoxClient._eventEmitter.emit("workersUpdated");
+
+  // To avoid wait for a set period of time we trigger another async update, adding a new
+  // tab. We assume that if the worker update mechanism had started, it would also be done
+  // when the new tab was processed.
+  info("Wait until the tab target for 'http://some.random/url.com' appears");
+  const testTab = {
+    retrieveFavicon: () => {},
+    outerWindowID: 0,
+    traits: {},
+    url: "http://some.random/url.com",
+  };
+  remoteClient.listTabs = () => [testTab];
+  remoteClient._eventEmitter.emit("tabListChanged");
+  await waitUntil(() =>
+    findDebugTargetByText("http://some.random/url.com", document)
+  );
+
+  ok(
+    findDebugTargetByText(workerName, document),
+    "The test worker is still visible"
+  );
+
+  info(
+    "Emit `workersUpdated` on remoteClient and wait for the target list to update"
+  );
+  remoteClient._eventEmitter.emit("workersUpdated");
+  await waitUntil(() => !findDebugTargetByText(workerName, document));
+}
diff --git a/devtools/client/aboutdebugging/test/browser/empty.html b/devtools/client/aboutdebugging/test/browser/empty.html
new file mode 100644
index 0000000000..d0fd95ab08
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/empty.html
@@ -0,0 +1 @@
+<body>fake_profiler_page</body>
diff --git a/devtools/client/aboutdebugging/test/browser/head.js b/devtools/client/aboutdebugging/test/browser/head.js
new file mode 100644
index 0000000000..c1b509b97c
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/head.js
@@ -0,0 +1,526 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* eslint-env browser */
+/* eslint no-unused-vars: [2, {"vars": "local"}] */
+
+// Load the shared-head file first.
+Services.scriptloader.loadSubScript(
+  "chrome://mochitests/content/browser/devtools/client/shared/test/shared-head.js",
+  this
+);
+
+/* import-globals-from helper-mocks.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-mocks.js", this);
+
+Services.scriptloader.loadSubScript(
+  "chrome://mochitests/content/browser/devtools/client/webconsole/test/browser/shared-head.js",
+  this
+);
+
+// Make sure the ADB addon is removed and ADB is stopped when the test ends.
+registerCleanupFunction(async function () {
+  // Reset the selected tool in case we opened about:devtools-toolbox to
+  // avoid side effects between tests.
+  Services.prefs.clearUserPref("devtools.toolbox.selectedTool");
+
+  try {
+    const {
+      adbAddon,
+    } = require("resource://devtools/client/shared/remote-debugging/adb/adb-addon.js");
+    await adbAddon.uninstall();
+  } catch (e) {
+    // Will throw if the addon is already uninstalled, ignore exceptions here.
+  }
+  const {
+    adbProcess,
+  } = require("resource://devtools/client/shared/remote-debugging/adb/adb-process.js");
+  await adbProcess.kill();
+
+  const {
+    remoteClientManager,
+  } = require("resource://devtools/client/shared/remote-debugging/remote-client-manager.js");
+  await remoteClientManager.removeAllClients();
+});
+
+async function openAboutDebugging({
+  enableWorkerUpdates,
+  enableLocalTabs = true,
+} = {}) {
+  if (!enableWorkerUpdates) {
+    silenceWorkerUpdates();
+  }
+
+  // This preference changes value depending on the build type, tests need to use a
+  // consistent value regarless of the build used.
+  await pushPref(
+    "devtools.aboutdebugging.local-tab-debugging",
+    enableLocalTabs
+  );
+
+  info("opening about:debugging");
+
+  const tab = await addTab("about:debugging");
+  const browser = tab.linkedBrowser;
+  const document = browser.contentDocument;
+  const window = browser.contentWindow;
+
+  info("Wait until Connect page is displayed");
+  await waitUntil(() => document.querySelector(".qa-connect-page"));
+
+  return { tab, document, window };
+}
+
+async function openAboutDevtoolsToolbox(
+  doc,
+  tab,
+  win,
+  targetText = "about:debugging",
+  shouldWaitToolboxReady = true
+) {
+  info("Open about:devtools-toolbox page");
+
+  info("Wait for the target to appear: " + targetText);
+  await waitUntil(() => findDebugTargetByText(targetText, doc));
+
+  const target = findDebugTargetByText(targetText, doc);
+  ok(target, `${targetText} target appeared`);
+
+  const {
+    DEBUG_TARGETS,
+  } = require("resource://devtools/client/aboutdebugging/src/constants.js");
+  const isWebExtension = target.dataset.qaTargetType == DEBUG_TARGETS.EXTENSION;
+
+  const inspectButton = target.querySelector(".qa-debug-target-inspect-button");
+  ok(inspectButton, `Inspect button for ${targetText} appeared`);
+  inspectButton.click();
+  const onToolboxReady = gDevTools.once("toolbox-ready");
+  await Promise.all([
+    waitForAboutDebuggingRequests(win.AboutDebugging.store),
+    shouldWaitToolboxReady ? onToolboxReady : Promise.resolve(),
+  ]);
+
+  // WebExtension open a toolbox in a dedicated window
+  if (isWebExtension) {
+    const toolbox = await onToolboxReady;
+    // For some reason the test helpers prevents the toolbox from being automatically focused on opening,
+    // whereas it is IRL.
+    const focusedWin = Services.focus.focusedWindow;
+    if (focusedWin?.top != toolbox.win) {
+      info("Wait for the toolbox window to be focused");
+      await new Promise(r => {
+        // focus event only fired on the chrome event handler and in capture phase
+        toolbox.win.docShell.chromeEventHandler.addEventListener("focus", r, {
+          once: true,
+          capture: true,
+        });
+        toolbox.win.focus();
+      });
+      info("The toolbox is focused");
+    }
+    return {
+      devtoolsBrowser: null,
+      devtoolsDocument: toolbox.doc,
+      devtoolsTab: null,
+      devtoolsWindow: toolbox.win,
+    };
+  }
+
+  await waitUntil(() => tab.nextElementSibling);
+
+  info("Wait for about:devtools-toolbox tab will be selected");
+  const devtoolsTab = tab.nextElementSibling;
+  await waitUntil(() => gBrowser.selectedTab === devtoolsTab);
+  const devtoolsBrowser = gBrowser.selectedBrowser;
+  await waitUntil(() =>
+    devtoolsBrowser.contentWindow.location.href.startsWith(
+      "about:devtools-toolbox?"
+    )
+  );
+
+  if (!shouldWaitToolboxReady) {
+    // Wait for show error page.
+    await waitUntil(() =>
+      devtoolsBrowser.contentDocument.querySelector(".qa-error-page")
+    );
+  }
+
+  return {
+    devtoolsBrowser,
+    devtoolsDocument: devtoolsBrowser.contentDocument,
+    devtoolsTab,
+    devtoolsWindow: devtoolsBrowser.contentWindow,
+  };
+}
+
+async function closeAboutDevtoolsToolbox(
+  aboutDebuggingDocument,
+  devtoolsTab,
+  win
+) {
+  // Wait for all requests to settle on the opened about:devtools toolbox.
+  const devtoolsBrowser = devtoolsTab.linkedBrowser;
+  const devtoolsWindow = devtoolsBrowser.contentWindow;
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.commands.client.waitForRequestsToSettle();
+
+  info("Close about:devtools-toolbox page");
+  const onToolboxDestroyed = gDevTools.once("toolbox-destroyed");
+
+  info("Wait for removeTab");
+  await removeTab(devtoolsTab);
+
+  info("Wait for toolbox destroyed");
+  await onToolboxDestroyed;
+
+  // Changing the tab will also trigger a request to list tabs, so wait until the selected
+  // tab has changed to wait for requests to settle.
+  info("Wait until aboutdebugging is selected");
+  await waitUntil(() => gBrowser.selectedTab !== devtoolsTab);
+
+  // Wait for removing about:devtools-toolbox tab info from about:debugging.
+  info("Wait until about:devtools-toolbox is removed from debug targets");
+  await waitUntil(
+    () => !findDebugTargetByText("Toolbox - ", aboutDebuggingDocument)
+  );
+
+  await waitForAboutDebuggingRequests(win.AboutDebugging.store);
+}
+
+async function closeWebExtAboutDevtoolsToolbox(devtoolsWindow, win) {
+  // Wait for all requests to settle on the opened about:devtools toolbox.
+  const toolbox = getToolbox(devtoolsWindow);
+  await toolbox.commands.client.waitForRequestsToSettle();
+
+  info("Close the toolbox and wait for its destruction");
+  await toolbox.destroy();
+
+  await waitForAboutDebuggingRequests(win.AboutDebugging.store);
+}
+
+async function reloadAboutDebugging(tab) {
+  info("reload about:debugging");
+
+  await reloadBrowser(tab.linkedBrowser);
+  const browser = tab.linkedBrowser;
+  const document = browser.contentDocument;
+  const window = browser.contentWindow;
+  info("wait for the initial about:debugging requests to settle");
+  await waitForAboutDebuggingRequests(window.AboutDebugging.store);
+
+  return document;
+}
+
+// Wait for all about:debugging target request actions to succeed.
+// They will typically be triggered after watching a new runtime or loading
+// about:debugging.
+function waitForRequestsSuccess(store) {
+  return Promise.all([
+    waitForDispatch(store, "REQUEST_EXTENSIONS_SUCCESS"),
+    waitForDispatch(store, "REQUEST_TABS_SUCCESS"),
+    waitForDispatch(store, "REQUEST_WORKERS_SUCCESS"),
+  ]);
+}
+
+/**
+ * Wait for all aboutdebugging REQUEST_*_SUCCESS actions to settle, meaning here
+ * that no new request has been dispatched after the provided delay.
+ */
+async function waitForAboutDebuggingRequests(store, delay = 500) {
+  let hasSettled = false;
+
+  // After each iteration of this while loop, we check is the timerPromise had the time
+  // to resolve or if we captured a REQUEST_*_SUCCESS action before.
+  while (!hasSettled) {
+    let timer;
+
+    // This timer will be executed only if no REQUEST_*_SUCCESS action is dispatched
+    // during the delay. We consider that when no request are received for some time, it
+    // means there are no ongoing requests anymore.
+    const timerPromise = new Promise(resolve => {
+      timer = setTimeout(() => {
+        hasSettled = true;
+        resolve();
+      }, delay);
+    });
+
+    // Wait either for a REQUEST_*_SUCCESS to be dispatched, or for the timer to resolve.
+    await Promise.race([
+      waitForDispatch(store, "REQUEST_EXTENSIONS_SUCCESS"),
+      waitForDispatch(store, "REQUEST_TABS_SUCCESS"),
+      waitForDispatch(store, "REQUEST_WORKERS_SUCCESS"),
+      timerPromise,
+    ]);
+
+    // Clear the timer to avoid setting hasSettled to true accidently unless timerPromise
+    // was the first to resolve.
+    clearTimeout(timer);
+  }
+}
+
+/**
+ * Navigate to "This Firefox"
+ */
+async function selectThisFirefoxPage(doc, store) {
+  info("Select This Firefox page");
+
+  const onRequestSuccess = waitForRequestsSuccess(store);
+  doc.location.hash = "#/runtime/this-firefox";
+  info("Wait for requests to be complete");
+  await onRequestSuccess;
+
+  info("Wait for runtime page to be rendered");
+  await waitUntil(() => doc.querySelector(".qa-runtime-page"));
+
+  // Navigating to this-firefox will trigger a title change for the
+  // about:debugging tab. This title change _might_ trigger a tablist update.
+  // If it does, we should make sure to wait for pending tab requests.
+  await waitForAboutDebuggingRequests(store);
+}
+
+/**
+ * Navigate to the Connect page. Resolves when the Connect page is rendered.
+ */
+async function selectConnectPage(doc) {
+  const sidebarItems = doc.querySelectorAll(".qa-sidebar-item");
+  const connectSidebarItem = [...sidebarItems].find(element => {
+    return element.textContent === "Setup";
+  });
+  ok(connectSidebarItem, "Sidebar contains a Connect item");
+  const connectLink = connectSidebarItem.querySelector(".qa-sidebar-link");
+  ok(connectLink, "Sidebar contains a Connect link");
+
+  info("Click on the Connect link in the sidebar");
+  connectLink.click();
+
+  info("Wait until Connect page is displayed");
+  await waitUntil(() => doc.querySelector(".qa-connect-page"));
+}
+
+function getDebugTargetPane(title, document) {
+  // removes the suffix "(<NUMBER>)" in debug target pane's title, if needed
+  const sanitizeTitle = x => {
+    return x.replace(/\s+\(\d+\)$/, "");
+  };
+
+  const targetTitle = sanitizeTitle(title);
+  for (const titleEl of document.querySelectorAll(
+    ".qa-debug-target-pane-title"
+  )) {
+    if (sanitizeTitle(titleEl.textContent) !== targetTitle) {
+      continue;
+    }
+
+    return titleEl.closest(".qa-debug-target-pane");
+  }
+
+  return null;
+}
+
+function findDebugTargetByText(text, document) {
+  const targets = [...document.querySelectorAll(".qa-debug-target-item")];
+  return targets.find(target => target.textContent.includes(text));
+}
+
+function findSidebarItemByText(text, document) {
+  const sidebarItems = document.querySelectorAll(".qa-sidebar-item");
+  return [...sidebarItems].find(element => {
+    return element.textContent.includes(text);
+  });
+}
+
+function findSidebarItemLinkByText(text, document) {
+  const links = document.querySelectorAll(".qa-sidebar-link");
+  return [...links].find(element => {
+    return element.textContent.includes(text);
+  });
+}
+
+async function connectToRuntime(deviceName, document) {
+  info(`Wait until the sidebar item for ${deviceName} appears`);
+  await waitUntil(() => findSidebarItemByText(deviceName, document));
+  const sidebarItem = findSidebarItemByText(deviceName, document);
+  const connectButton = sidebarItem.querySelector(".qa-connect-button");
+  ok(
+    connectButton,
+    `Connect button is displayed for the runtime ${deviceName}`
+  );
+
+  info("Click on the connect button and wait until it disappears");
+  connectButton.click();
+  await waitUntil(() => !sidebarItem.querySelector(".qa-connect-button"));
+}
+
+async function selectRuntime(deviceName, name, document) {
+  const sidebarItem = findSidebarItemByText(deviceName, document);
+  const store = document.defaultView.AboutDebugging.store;
+  const onSelectPageSuccess = waitForDispatch(store, "SELECT_PAGE_SUCCESS");
+
+  sidebarItem.querySelector(".qa-sidebar-link").click();
+
+  await waitUntil(() => {
+    const runtimeInfo = document.querySelector(".qa-runtime-name");
+    return runtimeInfo && runtimeInfo.textContent.includes(name);
+  });
+
+  info("Wait for SELECT_PAGE_SUCCESS to be dispatched");
+  await onSelectPageSuccess;
+}
+
+function getToolbox(win) {
+  return gDevTools.getToolboxes().find(toolbox => toolbox.win === win);
+}
+
+/**
+ * Open the performance profiler dialog. Assumes the client is a mocked remote runtime
+ * client.
+ */
+async function openProfilerDialog(client, doc) {
+  const onProfilerLoaded = new Promise(r => {
+    client.loadPerformanceProfiler = r;
+  });
+
+  info("Click on the Profile Runtime button");
+  const profileButton = doc.querySelector(".qa-profile-runtime-button");
+  profileButton.click();
+
+  info(
+    "Wait for the loadPerformanceProfiler callback to be executed on client-wrapper"
+  );
+  return onProfilerLoaded;
+}
+
+/**
+ * The "This Firefox" string depends on the brandShortName, which will be different
+ * depending on the channel where tests are running.
+ */
+function getThisFirefoxString(aboutDebuggingWindow) {
+  const loader = aboutDebuggingWindow.getBrowserLoaderForWindow();
+  const { l10n } = loader.require(
+    "resource://devtools/client/aboutdebugging/src/modules/l10n.js"
+  );
+  return l10n.getString("about-debugging-this-firefox-runtime-name");
+}
+
+function waitUntilUsbDeviceIsUnplugged(deviceName, aboutDebuggingDocument) {
+  info("Wait until the USB sidebar item appears as unplugged");
+  return waitUntil(() => {
+    const sidebarItem = findSidebarItemByText(
+      deviceName,
+      aboutDebuggingDocument
+    );
+    return !!sidebarItem.querySelector(".qa-runtime-item-unplugged");
+  });
+}
+
+/**
+ * Changing the selected tab in the current browser will trigger a tablist
+ * update.
+ * If the currently selected page is "this-firefox", we should wait for the
+ * the corresponding REQUEST_TABS_SUCCESS that will be triggered by the change.
+ *
+ * @param {Browser} browser
+ *        The browser instance to update.
+ * @param {XULTab} tab
+ *        The tab to select.
+ * @param {Object} store
+ *        The about:debugging redux store.
+ */
+async function updateSelectedTab(browser, tab, store) {
+  info("Update the selected tab");
+
+  const { runtimes, ui } = store.getState();
+  const isOnThisFirefox =
+    runtimes.selectedRuntimeId === "this-firefox" &&
+    ui.selectedPage === "runtime";
+
+  // A tabs request will only be issued if we are on this-firefox.
+  const onTabsSuccess = isOnThisFirefox
+    ? waitForDispatch(store, "REQUEST_TABS_SUCCESS")
+    : null;
+
+  // Update the selected tab.
+  browser.selectedTab = tab;
+
+  if (onTabsSuccess) {
+    info("Wait for the tablist update after updating the selected tab");
+    await onTabsSuccess;
+  }
+}
+
+/**
+ * Synthesizes key input inside the DebugTargetInfo's URL component.
+ *
+ * @param {DevToolsToolbox} toolbox
+ *        The DevToolsToolbox debugging the target.
+ * @param {HTMLElement} inputEl
+ *        The <input> element to submit the URL with.
+ * @param {String}  url
+ *        The URL to navigate to.
+ */
+async function synthesizeUrlKeyInput(toolbox, inputEl, url) {
+  const { devtoolsDocument, devtoolsWindow } = toolbox;
+  info("Wait for URL input to be focused.");
+  const onInputFocused = waitUntil(
+    () => devtoolsDocument.activeElement === inputEl
+  );
+  inputEl.focus();
+  await onInputFocused;
+
+  info("Synthesize entering URL into text field");
+  const onInputChange = waitUntil(() => inputEl.value === url);
+  for (const key of url.split("")) {
+    EventUtils.synthesizeKey(key, {}, devtoolsWindow);
+  }
+  await onInputChange;
+
+  info("Submit URL to navigate to");
+  EventUtils.synthesizeKey("KEY_Enter");
+}
+
+/**
+ * Click on a given add-on widget button so that its browser actor is fired.
+ * Typically a popup would open, or a listener would be called in the background page.
+ *
+ * @param {String} addonId
+ *        The ID of the add-on to click on.
+ */
+function clickOnAddonWidget(addonId) {
+  // Devtools are in another window and may have the focus.
+  // Ensure focusing the browser window when clicking on the widget.
+  const focusedWin = Services.focus.focusedWindow;
+  if (focusedWin != window) {
+    window.focus();
+  }
+  // Find the browserAction button that will show the webextension popup.
+  const widgetId = addonId.toLowerCase().replace(/[^a-z0-9_-]/g, "_");
+  const browserActionId = widgetId + "-browser-action";
+  const browserActionEl = window.document.getElementById(browserActionId);
+  ok(browserActionEl, "Got the browserAction button from the browser UI");
+
+  info("Show the web extension popup");
+  browserActionEl.firstElementChild.click();
+}
+
+// Create basic addon data as the DevToolsClient would return it.
+function createAddonData({
+  id,
+  name,
+  isSystem = false,
+  hidden = false,
+  temporary = false,
+}) {
+  return {
+    actor: `actorid-${id}`,
+    hidden,
+    iconURL: `moz-extension://${id}/icon-url.png`,
+    id,
+    manifestURL: `moz-extension://${id}/manifest-url.json`,
+    name,
+    isSystem,
+    temporarilyInstalled: temporary,
+    debuggable: true,
+  };
+}
diff --git a/devtools/client/aboutdebugging/test/browser/helper-adb.js b/devtools/client/aboutdebugging/test/browser/helper-adb.js
new file mode 100644
index 0000000000..f5e6adfc6b
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/helper-adb.js
@@ -0,0 +1,59 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from head.js */
+
+async function checkAdbNotRunning() {
+  info("Check if ADB is already running before the test starts");
+  const {
+    check,
+  } = require("resource://devtools/client/shared/remote-debugging/adb/adb-running-checker.js");
+  const isAdbAlreadyRunning = await check();
+  if (isAdbAlreadyRunning) {
+    throw new Error(
+      "The ADB process is already running on this machine, it should be " +
+        "stopped before running this test"
+    );
+  }
+}
+/* exported checkAdbNotRunning */
+
+// Returns a promise that resolves when the adb process exists and is running.
+async function waitForAdbStart() {
+  info("Wait for ADB to start");
+  const {
+    adbProcess,
+  } = require("resource://devtools/client/shared/remote-debugging/adb/adb-process.js");
+  const {
+    check,
+  } = require("resource://devtools/client/shared/remote-debugging/adb/adb-running-checker.js");
+  return asyncWaitUntil(async () => {
+    const isProcessReady = adbProcess.ready;
+    const isRunning = await check();
+    return isProcessReady && isRunning;
+  });
+}
+/* exported waitForAdbStart */
+
+// Attempt to stop ADB. Will only work if ADB was started by the current Firefox instance.
+// Returns a promise that resolves when the adb process is no longer running.
+async function stopAdbProcess() {
+  info("Attempt to stop ADB");
+  const {
+    adbProcess,
+  } = require("resource://devtools/client/shared/remote-debugging/adb/adb-process.js");
+  await adbProcess.stop();
+
+  info("Wait for ADB to stop");
+  const {
+    check,
+  } = require("resource://devtools/client/shared/remote-debugging/adb/adb-running-checker.js");
+  return asyncWaitUntil(async () => {
+    const isProcessReady = adbProcess.ready;
+    const isRunning = await check();
+    return !isProcessReady && !isRunning;
+  });
+}
+/* exported stopAdbProcess */
diff --git a/devtools/client/aboutdebugging/test/browser/helper-addons.js b/devtools/client/aboutdebugging/test/browser/helper-addons.js
new file mode 100644
index 0000000000..e3a8be3761
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/helper-addons.js
@@ -0,0 +1,262 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from head.js */
+
+function _getSupportsFile(path) {
+  const cr = Cc["@mozilla.org/chrome/chrome-registry;1"].getService(
+    Ci.nsIChromeRegistry
+  );
+  const uri = Services.io.newURI(CHROME_URL_ROOT + path);
+  const fileurl = cr.convertChromeURL(uri);
+  return fileurl.QueryInterface(Ci.nsIFileURL);
+}
+
+async function enableExtensionDebugging() {
+  // Disable security prompt
+  await pushPref("devtools.debugger.prompt-connection", false);
+}
+/* exported enableExtensionDebugging */
+
+/**
+ * Install an extension using the AddonManager so it does not show up as temporary.
+ */
+async function installRegularExtension(pathOrFile) {
+  const isFile = typeof pathOrFile.isFile === "function" && pathOrFile.isFile();
+  const file = isFile ? pathOrFile : _getSupportsFile(pathOrFile).file;
+  const install = await AddonManager.getInstallForFile(file);
+  return new Promise((resolve, reject) => {
+    if (!install) {
+      throw new Error(`An install was not created for ${file.path}`);
+    }
+    install.addListener({
+      onDownloadFailed: reject,
+      onDownloadCancelled: reject,
+      onInstallFailed: reject,
+      onInstallCancelled: reject,
+      onInstallEnded: resolve,
+    });
+    install.install();
+  });
+}
+/* exported installRegularExtension */
+
+/**
+ * Install a temporary extension at the provided path, with the provided name.
+ * Will use a mock file picker to select the file.
+ */
+async function installTemporaryExtension(pathOrFile, name, document) {
+  const { Management } = ChromeUtils.importESModule(
+    "resource://gre/modules/Extension.sys.mjs"
+  );
+
+  info("Install temporary extension named " + name);
+  // Mock the file picker to select a test addon
+  prepareMockFilePicker(pathOrFile);
+
+  const onAddonInstalled = new Promise(done => {
+    Management.on("startup", function listener(event, extension) {
+      if (extension.name != name) {
+        return;
+      }
+
+      Management.off("startup", listener);
+      done(extension);
+    });
+  });
+
+  // Trigger the file picker by clicking on the button
+  document.querySelector(".qa-temporary-extension-install-button").click();
+
+  info("Wait for addon to be installed");
+  return onAddonInstalled;
+}
+/* exported installTemporaryExtension */
+
+function createTemporaryXPI(xpiData) {
+  const { ExtensionTestCommon } = ChromeUtils.importESModule(
+    "resource://testing-common/ExtensionTestCommon.sys.mjs"
+  );
+
+  const { background, files, id, name, extraProperties } = xpiData;
+  info("Generate XPI file for " + id);
+
+  const manifest = Object.assign(
+    {},
+    {
+      browser_specific_settings: { gecko: { id } },
+      manifest_version: 2,
+      name,
+      version: "1.0",
+    },
+    extraProperties
+  );
+
+  const xpiFile = ExtensionTestCommon.generateXPI({
+    background,
+    files,
+    manifest,
+  });
+  registerCleanupFunction(() => xpiFile.exists() && xpiFile.remove(false));
+  return xpiFile;
+}
+/* exported createTemporaryXPI */
+
+/**
+ * Remove the existing temporary XPI file generated by ExtensionTestCommon and create a
+ * new one at the same location.
+ * @return {File} the temporary extension XPI file created
+ */
+function updateTemporaryXPI(xpiData, existingXPI) {
+  info("Delete and regenerate XPI for " + xpiData.id);
+
+  // Store the current name to check the xpi is correctly replaced.
+  const existingName = existingXPI.leafName;
+  info("Delete existing XPI named: " + existingName);
+  existingXPI.exists() && existingXPI.remove(false);
+
+  const xpiFile = createTemporaryXPI(xpiData);
+  // Check that the name of the new file is correct
+  if (xpiFile.leafName !== existingName) {
+    throw new Error(
+      "New XPI created with unexpected name: " + xpiFile.leafName
+    );
+  }
+  return xpiFile;
+}
+/* exported updateTemporaryXPI */
+
+/**
+ * Install a fake temporary extension by creating a temporary in-memory XPI file.
+ * @return {File} the temporary extension XPI file created
+ */
+async function installTemporaryExtensionFromXPI(xpiData, document) {
+  const xpiFile = createTemporaryXPI(xpiData);
+  const extension = await installTemporaryExtension(
+    xpiFile,
+    xpiData.name,
+    document
+  );
+
+  info("Wait until the addon debug target appears");
+  await waitUntil(() => findDebugTargetByText(xpiData.name, document));
+  return { extension, xpiFile };
+}
+/* exported installTemporaryExtensionFromXPI */
+
+async function removeTemporaryExtension(name, document) {
+  info(`Wait for removable extension with name: '${name}'`);
+  const buttonName = ".qa-temporary-extension-remove-button";
+  await waitUntil(() => {
+    const extension = findDebugTargetByText(name, document);
+    return extension && extension.querySelector(buttonName);
+  });
+  info(`Remove the temporary extension with name: '${name}'`);
+  const temporaryExtensionItem = findDebugTargetByText(name, document);
+  temporaryExtensionItem.querySelector(buttonName).click();
+
+  info("Wait until the debug target item disappears");
+  await waitUntil(() => !findDebugTargetByText(name, document));
+}
+/* exported removeTemporaryExtension */
+
+async function removeExtension(id, name, document) {
+  info(
+    "Retrieve the extension instance from the addon manager, and uninstall it"
+  );
+  const extension = await AddonManager.getAddonByID(id);
+  extension.uninstall();
+
+  info("Wait until the addon disappears from about:debugging");
+  await waitUntil(() => !findDebugTargetByText(name, document));
+}
+/* exported removeExtension */
+
+function prepareMockFilePicker(pathOrFile) {
+  const isFile = typeof pathOrFile.isFile === "function" && pathOrFile.isFile();
+  const file = isFile ? pathOrFile : _getSupportsFile(pathOrFile).file;
+
+  // Mock the file picker to select a test addon
+  const MockFilePicker = SpecialPowers.MockFilePicker;
+  MockFilePicker.init(window);
+  MockFilePicker.setFiles([file]);
+}
+/* exported prepareMockFilePicker */
+
+function promiseBackgroundContextEvent(extensionId, eventName) {
+  const { Management } = ChromeUtils.importESModule(
+    "resource://gre/modules/Extension.sys.mjs"
+  );
+
+  return new Promise(resolve => {
+    Management.on(eventName, function listener(_evtName, context) {
+      if (context.extension.id === extensionId) {
+        Management.off(eventName, listener);
+        resolve();
+      }
+    });
+  });
+}
+
+function promiseBackgroundContextLoaded(extensionId) {
+  return promiseBackgroundContextEvent(extensionId, "proxy-context-load");
+}
+/* exported promiseBackgroundContextLoaded */
+
+function promiseBackgroundContextUnloaded(extensionId) {
+  return promiseBackgroundContextEvent(extensionId, "proxy-context-unload");
+}
+/* exported promiseBackgroundContextUnloaded */
+
+async function assertBackgroundStatus(
+  extName,
+  { document, expectedStatus, targetElement }
+) {
+  const target = targetElement || findDebugTargetByText(extName, document);
+  const getBackgroundStatusElement = () =>
+    target.querySelector(".extension-backgroundscript__status");
+  await waitFor(
+    () =>
+      getBackgroundStatusElement()?.classList.contains(
+        `extension-backgroundscript__status--${expectedStatus}`
+      ),
+    `Wait ${extName} Background script status "${expectedStatus}" to be rendered`
+  );
+}
+/* exported assertBackgroundStatus */
+
+function getExtensionInstance(extensionId) {
+  const policy = WebExtensionPolicy.getByID(extensionId);
+  ok(policy, `Got a WebExtensionPolicy instance for ${extensionId}`);
+  ok(policy.extension, `Got an Extension class instance for ${extensionId}`);
+  return policy.extension;
+}
+/* exported getExtensionInstance */
+
+async function triggerExtensionEventPageIdleTimeout(extensionId) {
+  await getExtensionInstance(extensionId).terminateBackground();
+}
+/* exported triggerExtensionEventPageIdleTimeout */
+
+async function wakeupExtensionEventPage(extensionId) {
+  await getExtensionInstance(extensionId).wakeupBackground();
+}
+/* exported wakeupExtensionEventPage */
+
+function promiseTerminateBackgroundScriptIgnored(extensionId) {
+  const extension = getExtensionInstance(extensionId);
+  return new Promise(resolve => {
+    extension.once("background-script-suspend-ignored", resolve);
+  });
+}
+/* exported promiseTerminateBackgroundScriptIgnored */
+
+async function promiseBackgroundStatusUpdate(window) {
+  waitForDispatch(
+    window.AboutDebugging.store,
+    "EXTENSION_BGSCRIPT_STATUS_UPDATED"
+  );
+}
+/* exported promiseBackgroundStatusUpdate */
diff --git a/devtools/client/aboutdebugging/test/browser/helper-collapsibilities.js b/devtools/client/aboutdebugging/test/browser/helper-collapsibilities.js
new file mode 100644
index 0000000000..0f0d28da1d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/helper-collapsibilities.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TARGET_PANES = [
+  {
+    title: "Temporary Extensions",
+    pref: "devtools.aboutdebugging.collapsibilities.temporaryExtension",
+  },
+  {
+    title: "Extensions",
+    pref: "devtools.aboutdebugging.collapsibilities.installedExtension",
+  },
+  {
+    title: "Tabs",
+    pref: "devtools.aboutdebugging.collapsibilities.tab",
+  },
+  {
+    title: "Service Workers",
+    pref: "devtools.aboutdebugging.collapsibilities.serviceWorker",
+  },
+  {
+    title: "Shared Workers",
+    pref: "devtools.aboutdebugging.collapsibilities.sharedWorker",
+  },
+  {
+    title: "Other Workers",
+    pref: "devtools.aboutdebugging.collapsibilities.otherWorker",
+  },
+];
+/* exported TARGET_PANES */
+
+function prepareCollapsibilitiesTest() {
+  // Make all collapsibilities to be expanded.
+  for (const { pref } of TARGET_PANES) {
+    Services.prefs.setBoolPref(pref, false);
+  }
+}
+/* exported prepareCollapsibilitiesTest */
+
+async function toggleCollapsibility(debugTargetPane) {
+  debugTargetPane.querySelector(".qa-debug-target-pane-title").click();
+  // Wait for animation of collapse/expand.
+  const animations = debugTargetPane.ownerDocument.getAnimations();
+  await Promise.all(animations.map(animation => animation.finished));
+}
+/* exported toggleCollapsibility */
+
+registerCleanupFunction(() => {
+  for (const { pref } of TARGET_PANES) {
+    Services.prefs.clearUserPref(pref);
+  }
+});
diff --git a/devtools/client/aboutdebugging/test/browser/helper-mocks.js b/devtools/client/aboutdebugging/test/browser/helper-mocks.js
new file mode 100644
index 0000000000..b1c9c910ff
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/helper-mocks.js
@@ -0,0 +1,284 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from ../../../shared/test/shared-head.js */
+
+const MOCKS_ROOT = CHROME_URL_ROOT + "mocks/";
+/* import-globals-from mocks/helper-adb-mock.js */
+Services.scriptloader.loadSubScript(MOCKS_ROOT + "helper-adb-mock.js", this);
+/* import-globals-from mocks/helper-client-wrapper-mock.js */
+Services.scriptloader.loadSubScript(
+  MOCKS_ROOT + "helper-client-wrapper-mock.js",
+  this
+);
+/* import-globals-from mocks/helper-runtime-client-factory-mock.js */
+Services.scriptloader.loadSubScript(
+  MOCKS_ROOT + "helper-runtime-client-factory-mock.js",
+  this
+);
+
+const {
+  RUNTIMES,
+} = require("resource://devtools/client/aboutdebugging/src/constants.js");
+
+/**
+ * This wrapper around the mocks used in about:debugging tests provides helpers to
+ * quickly setup mocks for runtime tests involving USB, network or wifi runtimes that can
+ * are difficult to setup in a test environment.
+ */
+class Mocks {
+  constructor() {
+    // Setup the adb mock to rely on internal arrays.
+    this.adbMock = createAdbMock();
+    this.adbProcessMock = createAdbProcessMock();
+    this._usbRuntimes = [];
+    this._usbDevices = [];
+    this.adbMock.adb.getRuntimes = () => {
+      return this._usbRuntimes;
+    };
+    this.adbMock.adb.getDevices = () => {
+      const runtimeDevices = this._usbRuntimes.map(r => {
+        return { id: r.deviceId, name: r.deviceName };
+      });
+      return runtimeDevices.concat(this._usbDevices);
+    };
+
+    // adb.updateRuntimes should ultimately fire the "runtime-list-updated" event.
+    this.adbMock.adb.updateRuntimes = () => {
+      this.emitUSBUpdate();
+    };
+
+    this.adbMock.adb.isProcessStarted = () => true;
+
+    // Prepare a fake observer to be able to emit events from this mock.
+    this._observerMock = addObserverMock(this.adbMock.adb);
+
+    // Setup the runtime-client-factory mock to rely on the internal _clients map.
+    this.runtimeClientFactoryMock = createRuntimeClientFactoryMock();
+    this._clients = {
+      [RUNTIMES.NETWORK]: {},
+      [RUNTIMES.THIS_FIREFOX]: {},
+      [RUNTIMES.USB]: {},
+    };
+    this.runtimeClientFactoryMock.createClientForRuntime = runtime => {
+      return this._clients[runtime.type][runtime.id];
+    };
+
+    // Add a client for THIS_FIREFOX, since about:debugging will start on the This Firefox
+    // page.
+    this._thisFirefoxClient = createThisFirefoxClientMock();
+    this._clients[RUNTIMES.THIS_FIREFOX][RUNTIMES.THIS_FIREFOX] =
+      this._thisFirefoxClient;
+
+    // Enable mocks and remove them after the test.
+    this.enableMocks();
+    registerCleanupFunction(() => this.disableMocks());
+  }
+
+  get thisFirefoxClient() {
+    return this._thisFirefoxClient;
+  }
+
+  enableMocks() {
+    enableAdbMock(this.adbMock);
+    enableAdbProcessMock(this.adbProcessMock);
+    enableRuntimeClientFactoryMock(this.runtimeClientFactoryMock);
+  }
+
+  disableMocks() {
+    disableAdbMock();
+    disableAdbProcessMock();
+    disableRuntimeClientFactoryMock();
+
+    for (const host of Object.keys(this._clients[RUNTIMES.NETWORK])) {
+      this.removeNetworkRuntime(host);
+    }
+  }
+
+  createNetworkRuntime(host, runtimeInfo) {
+    const {
+      addNetworkLocation,
+    } = require("resource://devtools/client/aboutdebugging/src/modules/network-locations.js");
+    addNetworkLocation(host);
+
+    // Add a valid client that can be returned for this particular runtime id.
+    const mockNetworkClient = createClientMock();
+    mockNetworkClient.getDeviceDescription = () => {
+      return {
+        name: runtimeInfo.name || "TestBrand",
+        channel: runtimeInfo.channel || "release",
+        version: runtimeInfo.version || "1.0",
+      };
+    };
+    this._clients[RUNTIMES.NETWORK][host] = mockNetworkClient;
+
+    return mockNetworkClient;
+  }
+
+  removeNetworkRuntime(host) {
+    const {
+      removeNetworkLocation,
+    } = require("resource://devtools/client/aboutdebugging/src/modules/network-locations.js");
+    removeNetworkLocation(host);
+
+    delete this._clients[RUNTIMES.NETWORK][host];
+  }
+
+  emitUSBUpdate() {
+    this._observerMock.emit("runtime-list-updated");
+  }
+
+  /**
+   * Creates a USB runtime for which a client conenction can be established.
+   * @param {String} id
+   *        The id of the runtime.
+   * @param {Object} optional object used to create the fake runtime & device
+   *        - channel: {String} Release channel, for instance "release", "nightly"
+   *        - clientWrapper: {ClientWrapper} optional ClientWrapper for this runtime
+   *        - deviceId: {String} Device id
+   *        - deviceName: {String} Device name
+   *        - isFenix: {Boolean} set by ADB if the package name matches a Fenix package
+   *        - name: {String} Application name, for instance "Firefox"
+   *        - shortName: {String} Short name for the device
+   *        - socketPath: {String} (should only be used for connecting, so not here)
+   *        - version: {String} Version, for instance "63.0a"
+   *        - versionName: {String} Version return by ADB "63.0a"
+   * @return {Object} Returns the mock client created for this runtime so that methods
+   * can be overridden on it.
+   */
+  createUSBRuntime(id, runtimeInfo = {}) {
+    // Add a new runtime to the list of scanned runtimes.
+    this._usbRuntimes.push({
+      deviceId: runtimeInfo.deviceId || "test device id",
+      deviceName: runtimeInfo.deviceName || "test device name",
+      id,
+      isFenix: runtimeInfo.isFenix,
+      shortName: runtimeInfo.shortName || "testshort",
+      socketPath: runtimeInfo.socketPath || "test/path",
+      versionName: runtimeInfo.versionName || "1.0",
+    });
+
+    // Add a valid client that can be returned for this particular runtime id.
+    let mockUsbClient = runtimeInfo.clientWrapper;
+    if (mockUsbClient) {
+      const originalGetDeviceDescription =
+        mockUsbClient.getDeviceDescription.bind(mockUsbClient);
+      mockUsbClient.getDeviceDescription = async () => {
+        const deviceDescription = await originalGetDeviceDescription();
+        return {
+          channel: runtimeInfo.channel || deviceDescription.channel,
+          name: runtimeInfo.name || deviceDescription.name,
+          version: runtimeInfo.version || deviceDescription.version,
+        };
+      };
+    } else {
+      // If no clientWrapper was provided, create a mock client here.
+      mockUsbClient = createClientMock();
+      mockUsbClient.getDeviceDescription = () => {
+        return {
+          channel: runtimeInfo.channel || "release",
+          name: runtimeInfo.name || "TestBrand",
+          version: runtimeInfo.version || "1.0",
+        };
+      };
+    }
+
+    this._clients[RUNTIMES.USB][id] = mockUsbClient;
+
+    return mockUsbClient;
+  }
+
+  removeUSBRuntime(id) {
+    this._usbRuntimes = this._usbRuntimes.filter(runtime => runtime.id !== id);
+    delete this._clients[RUNTIMES.USB][id];
+  }
+
+  addDevice(deviceId, deviceName) {
+    this._usbDevices.push({
+      id: deviceId,
+      name: deviceName,
+    });
+  }
+
+  removeDevice(deviceId) {
+    this._usbDevices = this._usbDevices.filter(d => {
+      return d.id !== deviceId;
+    });
+  }
+
+  removeRuntime(id) {
+    if (this._clients[RUNTIMES.USB][id]) {
+      this.removeUSBRuntime(id);
+    } else if (this._clients[RUNTIMES.NETWORK][id]) {
+      this.removeNetworkRuntime(id);
+    }
+  }
+}
+/* exported Mocks */
+
+const silenceWorkerUpdates = function () {
+  const {
+    removeMockedModule,
+    setMockedModule,
+  } = require("resource://devtools/shared/loader/browser-loader-mocks.js");
+
+  const mock = {
+    WorkersListener: () => {
+      return {
+        addListener: () => {},
+        removeListener: () => {},
+      };
+    },
+  };
+  setMockedModule(mock, "devtools/client/shared/workers-listener");
+
+  registerCleanupFunction(() => {
+    removeMockedModule("devtools/client/shared/workers-listener");
+  });
+};
+/* exported silenceWorkerUpdates */
+
+async function createLocalClientWrapper() {
+  info("Create a local DevToolsClient");
+  const {
+    DevToolsServer,
+  } = require("resource://devtools/server/devtools-server.js");
+  const {
+    DevToolsClient,
+  } = require("resource://devtools/client/devtools-client.js");
+  const {
+    ClientWrapper,
+  } = require("resource://devtools/client/aboutdebugging/src/modules/client-wrapper.js");
+
+  DevToolsServer.init();
+  DevToolsServer.registerAllActors();
+  const client = new DevToolsClient(DevToolsServer.connectPipe());
+
+  await client.connect();
+  return new ClientWrapper(client);
+}
+/* exported createLocalClientWrapper */
+
+// Create a basic mock for this-firefox client, and setup a runtime-client-factory mock
+// to return our mock client when needed.
+function setupThisFirefoxMock() {
+  const runtimeClientFactoryMock = createRuntimeClientFactoryMock();
+  const thisFirefoxClient = createThisFirefoxClientMock();
+  runtimeClientFactoryMock.createClientForRuntime = runtime => {
+    if (runtime.id === RUNTIMES.THIS_FIREFOX) {
+      return thisFirefoxClient;
+    }
+    throw new Error("Unexpected runtime id " + runtime.id);
+  };
+
+  info("Enable mocks");
+  enableRuntimeClientFactoryMock(runtimeClientFactoryMock);
+  registerCleanupFunction(() => {
+    disableRuntimeClientFactoryMock();
+  });
+
+  return thisFirefoxClient;
+}
+/* exported setupThisFirefoxMock */
diff --git a/devtools/client/aboutdebugging/test/browser/helper-real-usb.js b/devtools/client/aboutdebugging/test/browser/helper-real-usb.js
new file mode 100644
index 0000000000..dd6c8c263d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/helper-real-usb.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from helper-adb.js */
+Services.scriptloader.loadSubScript(CHROME_URL_ROOT + "helper-adb.js", this);
+
+async function getExpectedRuntime() {
+  const runtimes = await getExpectedRuntimeAll();
+  return runtimes[0];
+}
+/* exported getExpectedRuntime */
+
+async function getExpectedRuntimeAll() {
+  const runtimesPath = _getExpectedRuntimesPath();
+  const currentPath = Services.env.get("PWD");
+  const path = `${currentPath}/${runtimesPath}`;
+  info(`Load ${path}`);
+  const buffer = await IOUtils.read(path);
+  const data = new TextDecoder().decode(buffer);
+  return JSON.parse(data);
+}
+/* exported getExpectedRuntimeAll */
+
+function isAvailable() {
+  return !!_getExpectedRuntimesPath();
+}
+/* exported isAvailable */
+
+async function openAboutDebuggingWithADB() {
+  const { document, tab, window } = await openAboutDebugging();
+
+  await pushPref(
+    "devtools.remote.adb.extensionURL",
+    CHROME_URL_ROOT + "resources/test-adb-extension/adb-extension-#OS#.xpi"
+  );
+  await checkAdbNotRunning();
+
+  const {
+    adbAddon,
+  } = require("resource://devtools/client/shared/remote-debugging/adb/adb-addon.js");
+  adbAddon.install("internal");
+  const usbStatusElement = document.querySelector(".qa-sidebar-usb-status");
+  await waitUntil(() => usbStatusElement.textContent.includes("USB enabled"));
+  await waitForAdbStart();
+
+  return { document, tab, window };
+}
+/* exported openAboutDebuggingWithADB */
+
+function _getExpectedRuntimesPath() {
+  return Services.env.get("USB_RUNTIMES");
+}
diff --git a/devtools/client/aboutdebugging/test/browser/helper-serviceworker.js b/devtools/client/aboutdebugging/test/browser/helper-serviceworker.js
new file mode 100644
index 0000000000..e57b62b7eb
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/helper-serviceworker.js
@@ -0,0 +1,111 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from head.js */
+
+/**
+ * Temporarily flip all the preferences necessary for service worker testing.
+ */
+async function enableServiceWorkerDebugging() {
+  // Enable service workers.
+  await pushPref("dom.serviceWorkers.enabled", true);
+
+  // Accept workers from mochitest's http (normally only available in https).
+  await pushPref("dom.serviceWorkers.testing.enabled", true);
+
+  // Force single content process. Necessary until sw e10s refactor is done (Bug 1231208).
+  await pushPref("dom.ipc.processCount", 1);
+  Services.ppmm.releaseCachedProcesses();
+}
+/* exported enableServiceWorkerDebugging */
+
+/**
+ * Helper to listen once on a message sent using postMessage from the provided tab.
+ *
+ * @param {Tab} tab
+ *        The tab on which the message will be received.
+ * @param {String} message
+ *        The name of the expected message.
+ */
+function onServiceWorkerMessage(tab, message) {
+  info("Make the test page notify us when the service worker sends a message.");
+  return SpecialPowers.spawn(
+    tab.linkedBrowser,
+    [message],
+    function (messageChild) {
+      return new Promise(resolve => {
+        const win = content.wrappedJSObject;
+        win.navigator.serviceWorker.addEventListener(
+          "message",
+          function (event) {
+            if (event.data == messageChild) {
+              resolve();
+            }
+          }
+        );
+      });
+    }
+  );
+}
+/* exported onServiceWorkerMessage */
+
+async function _waitForServiceWorkerStatus(workerText, status, document) {
+  await waitUntil(() => {
+    const target = findDebugTargetByText(workerText, document);
+    const statusElement = target && target.querySelector(".qa-worker-status");
+    return statusElement && statusElement.textContent === status;
+  });
+
+  return findDebugTargetByText(workerText, document);
+}
+/* exported waitForServiceWorkerRunning */
+
+async function waitForServiceWorkerStopped(workerText, document) {
+  return _waitForServiceWorkerStatus(workerText, "Stopped", document);
+}
+/* exported waitForServiceWorkerStopped */
+
+async function waitForServiceWorkerRunning(workerText, document) {
+  return _waitForServiceWorkerStatus(workerText, "Running", document);
+}
+/* exported waitForServiceWorkerRunning */
+
+async function waitForServiceWorkerRegistering(workerText, document) {
+  return _waitForServiceWorkerStatus(workerText, "Registering", document);
+}
+/* exported waitForServiceWorkerRegistering */
+
+async function waitForRegistration(tab) {
+  info("Wait until the registration appears on the window");
+  const swBrowser = tab.linkedBrowser;
+  await asyncWaitUntil(async () =>
+    SpecialPowers.spawn(swBrowser, [], async function () {
+      return !!(await content.wrappedJSObject.getRegistration());
+    })
+  );
+}
+/* exported waitForRegistration */
+
+/**
+ * Unregister the service worker from the content page. The content page should define
+ * `getRegistration` to allow this helper to retrieve the service worker registration that
+ * should be unregistered.
+ *
+ * @param {Tab} tab
+ *        The tab on which the service worker should be removed.
+ */
+async function unregisterServiceWorker(tab) {
+  return SpecialPowers.spawn(tab.linkedBrowser, [], function () {
+    const win = content.wrappedJSObject;
+    // Check that the content page defines getRegistration.
+    is(
+      typeof win.getRegistration,
+      "function",
+      "getRegistration is a valid function"
+    );
+    win.getRegistration().unregister();
+  });
+}
+/* exported unregisterServiceWorker */
diff --git a/devtools/client/aboutdebugging/test/browser/helper-telemetry.js b/devtools/client/aboutdebugging/test/browser/helper-telemetry.js
new file mode 100644
index 0000000000..ecb09fb241
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/helper-telemetry.js
@@ -0,0 +1,116 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from head.js */
+
+/**
+ * Reset all telemetry events.
+ */
+function setupTelemetryTest() {
+  // Let's reset the counts.
+  Services.telemetry.clearEvents();
+
+  // Ensure no events have been logged
+  const ALL_CHANNELS = Ci.nsITelemetry.DATASET_ALL_CHANNELS;
+  const snapshot = Services.telemetry.snapshotEvents(ALL_CHANNELS, true);
+  ok(!snapshot.parent, "No events have been logged for the main process");
+}
+/* exported setupTelemetryTest */
+
+/**
+ * Check that the logged telemetry events exactly match the array of expected events.
+ * Will compare the number of events, the event methods, and the event extras including
+ * the about:debugging session id.
+ */
+function checkTelemetryEvents(expectedEvents, expectedSessionId) {
+  const evts = readAboutDebuggingEvents();
+  is(evts.length, expectedEvents.length, "Expected number of events");
+
+  function _eventHasExpectedExtras(e, expectedEvent) {
+    const expectedExtras = Object.keys(expectedEvent.extras);
+    return expectedExtras.every(extra => {
+      return e.extras[extra] === expectedEvent.extras[extra];
+    });
+  }
+
+  for (const expectedEvent of expectedEvents) {
+    const sameMethodEvents = evts.filter(
+      e => e.method === expectedEvent.method
+    );
+    ok(
+      !!sameMethodEvents.length,
+      "Found event for method: " + expectedEvent.method
+    );
+
+    const sameExtrasEvents = sameMethodEvents.filter(e =>
+      _eventHasExpectedExtras(e, expectedEvent)
+    );
+    Assert.strictEqual(
+      sameExtrasEvents.length,
+      1,
+      "Found exactly one event matching the expected extras"
+    );
+    if (sameExtrasEvents.length === 0) {
+      info(JSON.stringify(sameMethodEvents));
+    }
+    is(
+      sameExtrasEvents[0].extras.session_id,
+      expectedSessionId,
+      "Select page event has the expected session"
+    );
+  }
+
+  return evts;
+}
+/* exported checkTelemetryEvents */
+
+/**
+ * Retrieve the session id from an "open" event.
+ * Note that calling this will "clear" all the events.
+ */
+function getOpenEventSessionId() {
+  const openEvents = readAboutDebuggingEvents().filter(
+    e => e.method === "open_adbg"
+  );
+  ok(!!openEvents[0], "Found an about:debugging open event");
+  return openEvents[0].extras.session_id;
+}
+/* exported getOpenEventSessionId */
+
+/**
+ * Read all the pending events that have "aboutdebugging" as their object property.
+ * WARNING: Calling this method also flushes/clears the events.
+ */
+function readAboutDebuggingEvents() {
+  const ALL_CHANNELS = Ci.nsITelemetry.DATASET_ALL_CHANNELS;
+  // Retrieve and clear telemetry events.
+  const snapshot = Services.telemetry.snapshotEvents(ALL_CHANNELS, true);
+  // about:debugging events are logged in the parent process
+  const parentEvents = snapshot.parent || [];
+
+  return parentEvents
+    .map(_toEventObject)
+    .filter(e => e.object === "aboutdebugging");
+}
+/* exported getLoggedEvents */
+
+/**
+ * The telemetry event data structure is simply an array. This helper remaps the array to
+ * an object with more user friendly properties.
+ */
+function _toEventObject(rawEvent) {
+  return {
+    // Category is typically devtools.main for us.
+    category: rawEvent[1],
+    // Method is the event's name (eg open, select_page etc...)
+    method: rawEvent[2],
+    // Object will usually be aboutdebugging for our tests
+    object: rawEvent[3],
+    // Value is usually empty for devtools events
+    value: rawEvent[4],
+    // Extras contain all the details of the event, including the session_id.
+    extras: rawEvent[5],
+  };
+}
diff --git a/devtools/client/aboutdebugging/test/browser/mocks/helper-adb-mock.js b/devtools/client/aboutdebugging/test/browser/mocks/helper-adb-mock.js
new file mode 100644
index 0000000000..f02ca02ee3
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/mocks/helper-adb-mock.js
@@ -0,0 +1,137 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Setup the loader to return the provided mock object instead of the regular adb module.
+ *
+ * @param {Object}
+ *        mock should implement the following methods:
+ *        - registerListener(listener)
+ *        - getRuntimes()
+ *        - getDevices()
+ *        - updateRuntimes()
+ *        - unregisterListener(listener)
+ */
+function enableAdbMock(mock) {
+  const {
+    setMockedModule,
+  } = require("resource://devtools/shared/loader/browser-loader-mocks.js");
+  setMockedModule(mock, "devtools/client/shared/remote-debugging/adb/adb");
+}
+/* exported enableAdbMock */
+
+/**
+ * Update the loader to clear the mock entry for the adb module.
+ */
+function disableAdbMock() {
+  const {
+    removeMockedModule,
+  } = require("resource://devtools/shared/loader/browser-loader-mocks.js");
+  removeMockedModule("devtools/client/shared/remote-debugging/adb/adb");
+}
+/* exported disableAdbMock */
+
+/**
+ * Creates a simple mock version for adb, implementing all the expected methods
+ * with empty placeholders.
+ */
+function createAdbMock() {
+  const adbMock = {};
+  adbMock.registerListener = function (listener) {
+    console.log("MOCKED METHOD registerListener");
+  };
+
+  adbMock.getRuntimes = function () {
+    console.log("MOCKED METHOD getRuntimes");
+  };
+
+  adbMock.getDevices = function () {
+    console.log("MOCKED METHOD getDevices");
+  };
+
+  adbMock.updateRuntimes = function () {
+    console.log("MOCKED METHOD updateRuntimes");
+  };
+
+  adbMock.unregisterListener = function (listener) {
+    console.log("MOCKED METHOD unregisterListener");
+  };
+
+  adbMock.once = function () {
+    console.log("MOCKED METHOD once");
+  };
+
+  adbMock.isProcessStarted = function () {
+    console.log("MOCKED METHOD isProcessStarted");
+  };
+
+  return { adb: adbMock };
+}
+/* exported createAdbMock */
+
+/**
+ * The adb module allows to observe runtime updates. To simulate this behaviour
+ * the easiest is to use an EventEmitter-decorated object that can accept listeners and
+ * can emit events from the test.
+ *
+ * This method will update the registerListener method of the provided
+ * usbRuntimesMock in order to add listeners to a mockObserver, and returns said observer
+ * so that the test can emit "runtime-list-updated" when needed.
+ */
+function addObserverMock(adbMock) {
+  const EventEmitter = require("resource://devtools/shared/event-emitter.js");
+
+  const observerMock = {};
+  EventEmitter.decorate(observerMock);
+  adbMock.registerListener = function (listener) {
+    console.log("MOCKED METHOD registerListener with mock scanner");
+    observerMock.on("runtime-list-updated", listener);
+  };
+
+  // NOTE FOR REVIEW: Instead of emitting "runtime-list-updated" events in the test,
+  // this mock could have a emitObservedEvent method, that would just emit the correct
+  // event. This way if the event name changes, everything remains contained in this
+  // method.
+
+  return observerMock;
+}
+/* exported addObserverMock */
+
+function createAdbProcessMock() {
+  const EventEmitter = require("resource://devtools/shared/event-emitter.js");
+
+  const mock = {};
+  EventEmitter.decorate(mock);
+
+  mock.ready = false;
+
+  mock.start = async () => {
+    console.log("MOCKED METHOD start");
+    mock.ready = true;
+    mock.emit("adb-ready");
+  };
+
+  return { adbProcess: mock };
+}
+/* exported createAdbProcessMock */
+
+function enableAdbProcessMock(mock) {
+  const {
+    setMockedModule,
+  } = require("resource://devtools/shared/loader/browser-loader-mocks.js");
+  setMockedModule(
+    mock,
+    "devtools/client/shared/remote-debugging/adb/adb-process"
+  );
+}
+/* exported enableAdbProcessMock */
+
+function disableAdbProcessMock() {
+  const {
+    removeMockedModule,
+  } = require("resource://devtools/shared/loader/browser-loader-mocks.js");
+  removeMockedModule("devtools/client/shared/remote-debugging/adb/adb-process");
+}
+/* exported disableAdbProcessMock */
diff --git a/devtools/client/aboutdebugging/test/browser/mocks/helper-client-wrapper-mock.js b/devtools/client/aboutdebugging/test/browser/mocks/helper-client-wrapper-mock.js
new file mode 100644
index 0000000000..5748904bff
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/mocks/helper-client-wrapper-mock.js
@@ -0,0 +1,138 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict"; // defined in head.js
+
+/* global CHROME_URL_ROOT */
+
+// This head file contains helpers to create mock versions of the ClientWrapper class
+// defined at devtools/client/aboutdebugging/src/modules/client-wrapper.js .
+
+const {
+  RUNTIME_PREFERENCE,
+} = require("resource://devtools/client/aboutdebugging/src/constants.js");
+
+// Sensible default values for runtime preferences that should be usable in most
+// situations
+const DEFAULT_PREFERENCES = {
+  [RUNTIME_PREFERENCE.CONNECTION_PROMPT]: true,
+  [RUNTIME_PREFERENCE.PERMANENT_PRIVATE_BROWSING]: false,
+  [RUNTIME_PREFERENCE.SERVICE_WORKERS_ENABLED]: true,
+};
+
+// Creates a simple mock ClientWrapper.
+function createClientMock() {
+  const EventEmitter = require("resource://devtools/shared/event-emitter.js");
+  const eventEmitter = {};
+  EventEmitter.decorate(eventEmitter);
+
+  return {
+    // add a reference to the internal event emitter so that consumers can fire client
+    // events.
+    _eventEmitter: eventEmitter,
+    _preferences: {},
+    contentProcessFronts: [],
+    serviceWorkerRegistrationFronts: [],
+    once: (evt, listener) => {
+      eventEmitter.once(evt, listener);
+    },
+    on: (evt, listener) => {
+      eventEmitter.on(evt, listener);
+    },
+    off: (evt, listener) => {
+      eventEmitter.off(evt, listener);
+    },
+    client: {
+      once: (evt, listener) => {
+        eventEmitter.once(evt, listener);
+      },
+      on: (evt, listener) => {
+        eventEmitter.on(evt, listener);
+      },
+      off: (evt, listener) => {
+        eventEmitter.off(evt, listener);
+      },
+    },
+    // no-op
+    close: () => {},
+    // client is not closed
+    isClosed: () => false,
+    // no-op
+    connect: () => {},
+    // no-op
+    getDeviceDescription: () => {},
+    // Return default preference value or null if no match.
+    getPreference(prefName) {
+      if (prefName in this._preferences) {
+        return this._preferences[prefName];
+      }
+      if (prefName in DEFAULT_PREFERENCES) {
+        return DEFAULT_PREFERENCES[prefName];
+      }
+      return null;
+    },
+    // no-op
+    createRootResourceCommand: () => {
+      return {
+        watchResources: () => new Promise(r => r()),
+        unwatchResources: () => {},
+      };
+    },
+    // Empty array of addons
+    listAddons: () => [],
+    // Empty array of processes
+    listProcesses: () => [],
+    // Empty array of tabs
+    listTabs: () => [],
+    // Empty arrays of workers
+    listWorkers: () => ({
+      otherWorkers: [],
+      serviceWorkers: [],
+      sharedWorkers: [],
+    }),
+    // no-op
+    getMainProcess: () => {},
+    // no-op
+    getFront: () => {},
+    // stores the preference locally (doesn't update about:config)
+    setPreference(prefName, value) {
+      this._preferences[prefName] = value;
+    },
+    getPerformancePanelUrl: () => CHROME_URL_ROOT + "empty.html",
+    loadPerformanceProfiler: () => {},
+    // Valid compatibility report
+    checkVersionCompatibility: () => {
+      const {
+        COMPATIBILITY_STATUS,
+      } = require("resource://devtools/client/shared/remote-debugging/version-checker.js");
+      return { status: COMPATIBILITY_STATUS.COMPATIBLE };
+    },
+    // No traits by default but allow updates.
+    traits: {},
+  };
+}
+
+// Create a ClientWrapper mock that can be used to replace the this-firefox runtime.
+function createThisFirefoxClientMock() {
+  const mockThisFirefoxDescription = {
+    name: "Firefox",
+    channel: "nightly",
+    version: "63.0",
+  };
+
+  // Create a fake about:debugging tab because our test helper openAboutDebugging
+  // waits until about:debugging is displayed in the list of tabs.
+  const mockAboutDebuggingTab = {
+    retrieveFavicon: () => {},
+    outerWindowID: 0,
+    traits: {},
+    url: "about:debugging",
+  };
+
+  const mockThisFirefoxClient = createClientMock();
+  mockThisFirefoxClient.listTabs = () => [mockAboutDebuggingTab];
+  mockThisFirefoxClient.getDeviceDescription = () => mockThisFirefoxDescription;
+
+  return mockThisFirefoxClient;
+}
+/* exported createThisFirefoxClientMock */
diff --git a/devtools/client/aboutdebugging/test/browser/mocks/helper-runtime-client-factory-mock.js b/devtools/client/aboutdebugging/test/browser/mocks/helper-runtime-client-factory-mock.js
new file mode 100644
index 0000000000..b74c229fcf
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/mocks/helper-runtime-client-factory-mock.js
@@ -0,0 +1,76 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Setup the loader to return the provided mock object instead of the regular
+ * runtime-client-factory module.
+ *
+ * @param {Object}
+ *        mock should implement the following methods:
+ *        - createClientForRuntime(runtime)
+ */
+function enableRuntimeClientFactoryMock(mock) {
+  const {
+    setMockedModule,
+  } = require("resource://devtools/shared/loader/browser-loader-mocks.js");
+  setMockedModule(
+    mock,
+    "devtools/client/aboutdebugging/src/modules/runtime-client-factory"
+  );
+
+  // When using a mocked client, we should not attempt to check default
+  // preferences.
+  mockRuntimeDefaultPreferences();
+}
+/* exported enableRuntimeClientFactoryMock */
+
+const mockRuntimeDefaultPreferences = function () {
+  const {
+    removeMockedModule,
+    setMockedModule,
+  } = require("resource://devtools/shared/loader/browser-loader-mocks.js");
+
+  const mock = {
+    setDefaultPreferencesIfNeeded: () => {},
+    DEFAULT_PREFERENCES: [],
+  };
+  setMockedModule(
+    mock,
+    "devtools/client/aboutdebugging/src/modules/runtime-default-preferences"
+  );
+
+  registerCleanupFunction(() => {
+    removeMockedModule(
+      "devtools/client/aboutdebugging/src/modules/runtime-default-preferences"
+    );
+  });
+};
+
+/**
+ * Update the loader to clear the mock entry for the runtime-client-factory module.
+ */
+function disableRuntimeClientFactoryMock() {
+  const {
+    removeMockedModule,
+  } = require("resource://devtools/shared/loader/browser-loader-mocks.js");
+  removeMockedModule(
+    "devtools/client/aboutdebugging/src/modules/runtime-client-factory"
+  );
+}
+/* exported disableRuntimeClientFactoryMock */
+
+/**
+ * Creates a simple mock version for runtime-client-factory, implementing all the expected
+ * methods with empty placeholders.
+ */
+function createRuntimeClientFactoryMock() {
+  const RuntimeClientFactoryMock = {};
+  RuntimeClientFactoryMock.createClientForRuntime = function (runtime) {
+    console.log("MOCKED METHOD createClientForRuntime");
+  };
+
+  return RuntimeClientFactoryMock;
+}
+/* exported createRuntimeClientFactoryMock */
diff --git a/devtools/client/aboutdebugging/test/browser/resources/bad-extensions/invalid-json/manifest.json b/devtools/client/aboutdebugging/test/browser/resources/bad-extensions/invalid-json/manifest.json
new file mode 100644
index 0000000000..4ab10b4de7
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/bad-extensions/invalid-json/manifest.json
@@ -0,0 +1 @@
+this is not valid json
diff --git a/devtools/client/aboutdebugging/test/browser/resources/bad-extensions/invalid-property/manifest.json b/devtools/client/aboutdebugging/test/browser/resources/bad-extensions/invalid-property/manifest.json
new file mode 100644
index 0000000000..992818bd77
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/bad-extensions/invalid-property/manifest.json
@@ -0,0 +1,23 @@
+{
+  "manifest_version": 2,
+  "name": "test-invalid-extension",
+  "version": "1",
+  "description": "the name says it all",
+  "permissions": ["*://*.foo.com/*", "alarms", "notifications", "tabs"],
+  "background": {
+    "scripts": ["background.js"]
+  },
+  "content_scripts": [
+    {
+      "matches": "*://*.foo.com/*",
+      "js": ["content.js"]
+    }
+  ],
+  "browser_action": {
+    "default_icon": {
+      "32": "home.svg"
+    },
+    "default_title": "foobarbaz (v1)",
+    "browser_style": true
+  }
+}
diff --git a/devtools/client/aboutdebugging/test/browser/resources/doc_aboutdebugging_devtoolstoolbox_breakpoint.html b/devtools/client/aboutdebugging/test/browser/resources/doc_aboutdebugging_devtoolstoolbox_breakpoint.html
new file mode 100644
index 0000000000..bb28556775
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/doc_aboutdebugging_devtoolstoolbox_breakpoint.html
@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>BREAKPOINT TEST PAGE</title>
+</head>
+<body>
+  <script type="text/javascript" src="script_aboutdebugging_devtoolstoolbox_breakpoint.js"></script>
+</body>
+</html>
diff --git a/devtools/client/aboutdebugging/test/browser/resources/packaged-extension/packaged-extension.xpi b/devtools/client/aboutdebugging/test/browser/resources/packaged-extension/packaged-extension.xpi
new file mode 100644
index 0000000000..c1c7af9600
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/packaged-extension/packaged-extension.xpi
diff --git a/devtools/client/aboutdebugging/test/browser/resources/real/usb-runtimes-sample.json b/devtools/client/aboutdebugging/test/browser/resources/real/usb-runtimes-sample.json
new file mode 100644
index 0000000000..bce334e95a
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/real/usb-runtimes-sample.json
@@ -0,0 +1,14 @@
+[
+  {
+    "sidebarInfo": {
+      "deviceName": "Pixel 2",
+      "shortName": "Firefox Nightly"
+    },
+    "runtimeDetails": {
+      "info": {
+        "name": "Mozilla Nightly",
+        "version": "64.0a1"
+      }
+    }
+  }
+]
diff --git a/devtools/client/aboutdebugging/test/browser/resources/script_aboutdebugging_devtoolstoolbox_breakpoint.js b/devtools/client/aboutdebugging/test/browser/resources/script_aboutdebugging_devtoolstoolbox_breakpoint.js
new file mode 100644
index 0000000000..99401016e4
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/script_aboutdebugging_devtoolstoolbox_breakpoint.js
@@ -0,0 +1,12 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Random method on which a breakpoint will be set from the DevTools UI in the
+// test.
+window.testMethod = function () {
+  const a = 1;
+  const b = 2;
+  return a + b;
+};
diff --git a/devtools/client/aboutdebugging/test/browser/resources/service-workers/controlled-sw.html b/devtools/client/aboutdebugging/test/browser/resources/service-workers/controlled-sw.html
new file mode 100644
index 0000000000..98d3bffd95
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/service-workers/controlled-sw.html
@@ -0,0 +1,38 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="UTF-8">
+  <title>Service worker controlled</title>
+</head>
+<body>
+<script type="text/javascript">
+
+"use strict";
+
+let registration;
+
+const registerServiceWorker = async function() {
+  try {
+    registration = await navigator.serviceWorker.register("controlled-sw.js");
+    dump("Controlled service worker registered\n");
+  } catch (e) {
+    dump("Controlled service worker not registered: " + e + "\n");
+  }
+};
+
+// Helper called from helper-serviceworker.js to unregister the service worker.
+window.getRegistration = function() {
+  return registration;
+};
+
+// Called from browser_aboutdebugging_serviceworker_status.js
+window.installServiceWorker = function() {
+  registration.installing.postMessage("install-service-worker");
+};
+
+// Register the service worker.
+registerServiceWorker();
+
+</script>
+</body>
+</html>
diff --git a/devtools/client/aboutdebugging/test/browser/resources/service-workers/controlled-sw.js b/devtools/client/aboutdebugging/test/browser/resources/service-workers/controlled-sw.js
new file mode 100644
index 0000000000..0a6d9cfdc6
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/service-workers/controlled-sw.js
@@ -0,0 +1,31 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* eslint-env worker */
+
+"use strict";
+
+// Copied from shared-head.js
+function waitUntil(predicate, interval = 10) {
+  if (predicate()) {
+    return Promise.resolve(true);
+  }
+  return new Promise(resolve => {
+    setTimeout(function () {
+      waitUntil(predicate, interval).then(() => resolve(true));
+    }, interval);
+  });
+}
+
+// This flag will be flipped from controlled-sw.html::installServiceWorker()
+let canInstall = false;
+self.addEventListener("message", function (event) {
+  if (event.data === "install-service-worker") {
+    canInstall = true;
+  }
+});
+
+// Wait for the canInstall flag to be flipped before completing the install.
+self.addEventListener("install", function (event) {
+  event.waitUntil(waitUntil(() => canInstall));
+});
diff --git a/devtools/client/aboutdebugging/test/browser/resources/service-workers/empty-sw.html b/devtools/client/aboutdebugging/test/browser/resources/service-workers/empty-sw.html
new file mode 100644
index 0000000000..ab862743a7
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/service-workers/empty-sw.html
@@ -0,0 +1,30 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="UTF-8">
+  <title>Service worker test</title>
+</head>
+<body>
+<script type="text/javascript">
+"use strict";
+
+let registration;
+
+const registerServiceWorker = async function() {
+  try {
+    registration = await navigator.serviceWorker.register("empty-sw.js");
+    dump("Empty service worker registered\n");
+  } catch (e) {
+    dump("Empty service worker not registered: " + e + "\n");
+  }
+};
+
+// Helper called from helper-serviceworker.js to unregister the service worker.
+window.getRegistration = function() {
+  return registration;
+};
+// Register the service worker.
+registerServiceWorker();
+</script>
+</body>
+</html>
diff --git a/devtools/client/aboutdebugging/test/browser/resources/service-workers/empty-sw.js b/devtools/client/aboutdebugging/test/browser/resources/service-workers/empty-sw.js
new file mode 100644
index 0000000000..1e7226402c
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/service-workers/empty-sw.js
@@ -0,0 +1 @@
+// Empty, just test registering.
diff --git a/devtools/client/aboutdebugging/test/browser/resources/service-workers/fetch-sw.html b/devtools/client/aboutdebugging/test/browser/resources/service-workers/fetch-sw.html
new file mode 100644
index 0000000000..a1bb218341
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/service-workers/fetch-sw.html
@@ -0,0 +1,30 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="UTF-8">
+  <title>Service worker test</title>
+</head>
+<body>
+<script type="text/javascript">
+"use strict";
+
+let registration;
+
+const registerServiceWorker = async function() {
+  try {
+    registration = await navigator.serviceWorker.register("fetch-sw.js");
+    dump("Empty service worker registered\n");
+  } catch (e) {
+    dump("Empty service worker not registered: " + e + "\n");
+  }
+};
+
+// Helper called from helper-serviceworker.js to unregister the service worker.
+window.getRegistration = function() {
+  return registration;
+};
+// Register the service worker.
+registerServiceWorker();
+</script>
+</body>
+</html>
diff --git a/devtools/client/aboutdebugging/test/browser/resources/service-workers/fetch-sw.js b/devtools/client/aboutdebugging/test/browser/resources/service-workers/fetch-sw.js
new file mode 100644
index 0000000000..de6ee1fb32
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/service-workers/fetch-sw.js
@@ -0,0 +1,6 @@
+"use strict";
+
+// Bug 1328293
+self.onfetch = function (event) {
+  // do nothing.
+};
diff --git a/devtools/client/aboutdebugging/test/browser/resources/service-workers/push-sw.html b/devtools/client/aboutdebugging/test/browser/resources/service-workers/push-sw.html
new file mode 100644
index 0000000000..bf5b0b0b0a
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/service-workers/push-sw.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="UTF-8">
+  <title>Service worker push test</title>
+</head>
+<body>
+<script type="text/javascript">
+
+"use strict";
+
+let registration;
+let subscription;
+
+const registerServiceWorker = async function() {
+  const perm = { type: "desktop-notification", allow: true, context: document };
+  await SpecialPowers.pushPermissions([perm]);
+
+  try {
+    registration = await navigator.serviceWorker.register("push-sw.js");
+    dump("Push service worker registered\n");
+  } catch (e) {
+    dump("Push service worker not registered: " + e + "\n");
+  }
+};
+
+// Helper called from helper-serviceworker.js to unregister the service worker.
+window.getRegistration = function() {
+  return registration;
+};
+
+// Helper called from browser_aboutdebugging_serviceworker_pushservice_url.js
+window.subscribeToPush = async function() {
+  try {
+    subscription = await registration.pushManager.subscribe();
+    dump("SW subscribed to push: " + subscription.endpoint + "\n");
+  } catch (e) {
+    dump("SW not subscribed to push: " + e + "\n");
+  }
+};
+
+// Helper called from browser_aboutdebugging_serviceworker_pushservice_url.js
+window.unsubscribeToPush = async function() {
+  subscription.unsubscribe();
+};
+
+// Expose a promise to wait until the service worker is claimed.
+window.onSwClaimed = new Promise(resolve => {
+  navigator.serviceWorker.addEventListener("message", function(event) {
+    if (event.data == "sw-claimed") {
+      resolve();
+    }
+  });
+});
+
+// Register the service worker.
+registerServiceWorker();
+
+</script>
+</body>
+</html>
diff --git a/devtools/client/aboutdebugging/test/browser/resources/service-workers/push-sw.js b/devtools/client/aboutdebugging/test/browser/resources/service-workers/push-sw.js
new file mode 100644
index 0000000000..1231697ddd
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/service-workers/push-sw.js
@@ -0,0 +1,35 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* eslint-env worker */
+/* global clients */
+
+"use strict";
+
+// Send a message to all controlled windows.
+function postMessage(message) {
+  return clients.matchAll().then(function (clientlist) {
+    clientlist.forEach(function (client) {
+      client.postMessage(message);
+    });
+  });
+}
+
+// Don't wait for the next page load to become the active service worker.
+self.addEventListener("install", function (event) {
+  event.waitUntil(self.skipWaiting());
+});
+
+// Claim control over the currently open test page when activating.
+self.addEventListener("activate", function (event) {
+  event.waitUntil(
+    self.clients.claim().then(function () {
+      return postMessage("sw-claimed");
+    })
+  );
+});
+
+// Forward all "push" events to the controlled window.
+self.addEventListener("push", function (event) {
+  event.waitUntil(postMessage("sw-pushed"));
+});
diff --git a/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-linux.xpi b/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-linux.xpi
new file mode 100644
index 0000000000..56054c341c
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-linux.xpi
diff --git a/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-linux64.xpi b/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-linux64.xpi
new file mode 100644
index 0000000000..9cd737b017
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-linux64.xpi
diff --git a/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-mac64.xpi b/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-mac64.xpi
new file mode 100644
index 0000000000..5af9bc963d
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-mac64.xpi
diff --git a/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-win32.xpi b/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-win32.xpi
new file mode 100644
index 0000000000..0c10c8502c
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/test-adb-extension/adb-extension-win32.xpi
diff --git a/devtools/client/aboutdebugging/test/browser/resources/test-temporary-extension/manifest.json b/devtools/client/aboutdebugging/test/browser/resources/test-temporary-extension/manifest.json
new file mode 100644
index 0000000000..c62b2ddbd6
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/test-temporary-extension/manifest.json
@@ -0,0 +1,13 @@
+{
+  "manifest_version": 2,
+  "name": "test-temporary-extension",
+  "version": "1.0",
+  "browser_specific_settings": {
+    "gecko": {
+      "id": "test-temporary-extension@mozilla.org"
+    }
+  },
+  "background": {
+    "scripts": ["script.js"]
+  }
+}
diff --git a/devtools/client/aboutdebugging/test/browser/resources/test-temporary-extension/script.js b/devtools/client/aboutdebugging/test/browser/resources/test-temporary-extension/script.js
new file mode 100644
index 0000000000..02d5604c3a
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/resources/test-temporary-extension/script.js
@@ -0,0 +1,8 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* eslint-env browser */
+
+"use strict";
+
+document.body.innerText = "Background Page Body Test Content";
diff --git a/devtools/client/aboutdebugging/test/browser/test-tab-favicons.html b/devtools/client/aboutdebugging/test/browser/test-tab-favicons.html
new file mode 100644
index 0000000000..35954f67a1
--- /dev/null
+++ b/devtools/client/aboutdebugging/test/browser/test-tab-favicons.html
@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <title>Favicon tab</title>
+    <link rel="icon" type="image/png" href="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAAATklEQVRYhe3SIQ4AIBADwf7/04elBAtrVlSduGnSTDJ7cuT1PQJwwO+Hl7sAGAA07gjAAfgIBeAAoHFHAA7ARygABwCNOwJwAD5CATRgAYXh+kypw86nAAAAAElFTkSuQmCC">
+  <head>
+  <body>Some page with a favicon</body>
+</html>