Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

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

43 files changed, 10971 insertions, 0 deletions

diff --git a/comm/mail/components/extensions/test/xpcshell/.eslintrc.js b/comm/mail/components/extensions/test/xpcshell/.eslintrc.js
new file mode 100644
index 0000000000..60d784b53c
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/.eslintrc.js
@@ -0,0 +1,13 @@
+"use strict";
+
+module.exports = {
+  env: {
+    // The tests in this folder are testing based on WebExtensions, so lets
+    // just define the webextensions environment here.
+    webextensions: true,
+    // Many parts of WebExtensions test definitions (e.g. content scripts) also
+    // interact with the browser environment, so define that here as we don't
+    // have an easy way to handle per-function/scope usage yet.
+    browser: true,
+  },
+};
diff --git a/comm/mail/components/extensions/test/xpcshell/data/utils.js b/comm/mail/components/extensions/test/xpcshell/data/utils.js
new file mode 100644
index 0000000000..9025982e33
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/data/utils.js
@@ -0,0 +1,124 @@
+/* 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/. */
+
+// Functions for extensions to use, so that we avoid repeating ourselves.
+
+function assertDeepEqual(
+  expected,
+  actual,
+  description = "Values should be equal",
+  options = {}
+) {
+  let ok;
+  let strict = !!options?.strict;
+  try {
+    ok = assertDeepEqualNested(expected, actual, strict);
+  } catch (e) {
+    ok = false;
+  }
+  if (!ok) {
+    browser.test.fail(
+      `Deep equal test. \n Expected value: ${JSON.stringify(
+        expected
+      )} \n Actual value: ${JSON.stringify(actual)},
+      ${description}`
+    );
+  }
+}
+
+function assertDeepEqualNested(expected, actual, strict) {
+  if (expected === null) {
+    browser.test.assertTrue(actual === null);
+    return actual === null;
+  }
+
+  if (expected === undefined) {
+    browser.test.assertTrue(actual === undefined);
+    return actual === undefined;
+  }
+
+  if (["boolean", "number", "string"].includes(typeof expected)) {
+    browser.test.assertEq(typeof expected, typeof actual);
+    browser.test.assertEq(expected, actual);
+    return typeof expected == typeof actual && expected == actual;
+  }
+
+  if (Array.isArray(expected)) {
+    browser.test.assertTrue(Array.isArray(actual));
+    browser.test.assertEq(expected.length, actual.length);
+    let ok = 0;
+    let all = 0;
+    for (let i = 0; i < expected.length; i++) {
+      all++;
+      if (assertDeepEqualNested(expected[i], actual[i], strict)) {
+        ok++;
+      }
+    }
+    return (
+      Array.isArray(actual) && expected.length == actual.length && all == ok
+    );
+  }
+
+  let expectedKeys = Object.keys(expected);
+  let actualKeys = Object.keys(actual);
+  // Ignore any extra keys on the actual object in non-strict mode (default).
+  let lengthOk = strict
+    ? expectedKeys.length == actualKeys.length
+    : expectedKeys.length <= actualKeys.length;
+  browser.test.assertTrue(lengthOk);
+
+  let ok = 0;
+  let all = 0;
+  for (let key of expectedKeys) {
+    all++;
+    browser.test.assertTrue(actualKeys.includes(key), `Key ${key} exists`);
+    if (assertDeepEqualNested(expected[key], actual[key], strict)) {
+      ok++;
+    }
+  }
+  return all == ok && lengthOk;
+}
+
+function waitForMessage() {
+  return waitForEvent("test.onMessage");
+}
+
+function waitForEvent(eventName) {
+  let [namespace, name] = eventName.split(".");
+  return new Promise(resolve => {
+    browser[namespace][name].addListener(function listener(...args) {
+      browser[namespace][name].removeListener(listener);
+      resolve(args);
+    });
+  });
+}
+
+async function waitForCondition(condition, msg, interval = 100, maxTries = 50) {
+  let conditionPassed = false;
+  let tries = 0;
+  for (; tries < maxTries && !conditionPassed; tries++) {
+    await new Promise(resolve =>
+      // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+      window.setTimeout(resolve, interval)
+    );
+    try {
+      conditionPassed = await condition();
+    } catch (e) {
+      throw Error(`${msg} - threw exception: ${e}`);
+    }
+  }
+  if (conditionPassed) {
+    browser.test.succeed(
+      `waitForCondition succeeded after ${tries} retries - ${msg}`
+    );
+  } else {
+    browser.test.fail(`${msg} - timed out after ${maxTries} retries`);
+  }
+}
+
+function sendMessage(...args) {
+  let replyPromise = waitForMessage();
+  browser.test.sendMessage(...args);
+  return replyPromise;
+}
diff --git a/comm/mail/components/extensions/test/xpcshell/head-imap.js b/comm/mail/components/extensions/test/xpcshell/head-imap.js
new file mode 100644
index 0000000000..ac85c52b64
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/head-imap.js
@@ -0,0 +1,12 @@
+/* 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/. */
+
+/* import-globals-from head.js */
+
+var IS_IMAP = true;
+
+let wrappedCreateAccount = createAccount;
+createAccount = function (type = "imap") {
+  return wrappedCreateAccount(type);
+};
diff --git a/comm/mail/components/extensions/test/xpcshell/head-nntp.js b/comm/mail/components/extensions/test/xpcshell/head-nntp.js
new file mode 100644
index 0000000000..0b4a56d0dc
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/head-nntp.js
@@ -0,0 +1,12 @@
+/* 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/. */
+
+/* import-globals-from head.js */
+
+var IS_NNTP = true;
+
+let wrappedCreateAccount = createAccount;
+createAccount = function (type = "nntp") {
+  return wrappedCreateAccount(type);
+};
diff --git a/comm/mail/components/extensions/test/xpcshell/head.js b/comm/mail/components/extensions/test/xpcshell/head.js
new file mode 100644
index 0000000000..f8c0c0e7b9
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/head.js
@@ -0,0 +1,298 @@
+/* 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/. */
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { MailServices } = ChromeUtils.import(
+  "resource:///modules/MailServices.jsm"
+);
+var { mailTestUtils } = ChromeUtils.import(
+  "resource://testing-common/mailnews/MailTestUtils.jsm"
+);
+var { MessageGenerator } = ChromeUtils.import(
+  "resource://testing-common/mailnews/MessageGenerator.jsm"
+);
+var { fsDebugAll, gThreadManager, nsMailServer } = ChromeUtils.import(
+  "resource://testing-common/mailnews/Maild.jsm"
+);
+var { PromiseTestUtils } = ChromeUtils.import(
+  "resource://testing-common/mailnews/PromiseTestUtils.jsm"
+);
+
+// Persistent Listener test functionality
+var { assertPersistentListeners } = ExtensionTestUtils.testAssertions;
+
+ExtensionTestUtils.init(this);
+
+var IS_IMAP = false;
+var IS_NNTP = false;
+
+function formatVCard(strings, ...values) {
+  let arr = [];
+  for (let str of strings) {
+    arr.push(str);
+    arr.push(values.shift());
+  }
+  let lines = arr.join("").split("\n");
+  let indent = lines[1].length - lines[1].trimLeft().length;
+  let outLines = [];
+  for (let line of lines) {
+    if (line.length > 0) {
+      outLines.push(line.substring(indent) + "\r\n");
+    }
+  }
+  return outLines.join("");
+}
+
+function createAccount(type = "none") {
+  let account;
+
+  if (type == "local") {
+    MailServices.accounts.createLocalMailAccount();
+    account = MailServices.accounts.FindAccountForServer(
+      MailServices.accounts.localFoldersServer
+    );
+  } else {
+    account = MailServices.accounts.createAccount();
+    account.incomingServer = MailServices.accounts.createIncomingServer(
+      `${account.key}user`,
+      "localhost",
+      type
+    );
+  }
+
+  if (type == "imap") {
+    IMAPServer.open();
+    account.incomingServer.port = IMAPServer.port;
+    account.incomingServer.username = "user";
+    account.incomingServer.password = "password";
+  }
+
+  if (type == "nntp") {
+    NNTPServer.open();
+    account.incomingServer.port = NNTPServer.port;
+  }
+  info(`Created account ${account.toString()}`);
+  return account;
+}
+
+function cleanUpAccount(account) {
+  let serverKey = account.incomingServer.key;
+  let serverType = account.incomingServer.type;
+  info(
+    `Cleaning up ${serverType} account ${account.key} and server ${serverKey}`
+  );
+  MailServices.accounts.removeAccount(account, true);
+
+  try {
+    let server = MailServices.accounts.getIncomingServer(serverKey);
+    if (server) {
+      info(`Cleaning up leftover ${serverType} server ${serverKey}`);
+      MailServices.accounts.removeIncomingServer(server, false);
+    }
+  } catch (e) {}
+}
+
+registerCleanupFunction(() => {
+  MailServices.accounts.accounts.forEach(cleanUpAccount);
+});
+
+function addIdentity(account, email = "xpcshell@localhost") {
+  let identity = MailServices.accounts.createIdentity();
+  identity.email = email;
+  account.addIdentity(identity);
+  if (!account.defaultIdentity) {
+    account.defaultIdentity = identity;
+  }
+  info(`Created identity ${identity.toString()}`);
+  return identity;
+}
+
+async function createSubfolder(parent, name) {
+  if (parent.server.type == "nntp") {
+    createNewsgroup(name);
+    let account = MailServices.accounts.FindAccountForServer(parent.server);
+    subscribeNewsgroup(account, name);
+    return parent.getChildNamed(name);
+  }
+
+  let promiseAdded = PromiseTestUtils.promiseFolderAdded(name);
+  parent.createSubfolder(name, null);
+  await promiseAdded;
+  return parent.getChildNamed(name);
+}
+
+function createMessages(folder, makeMessagesArg) {
+  if (typeof makeMessagesArg == "number") {
+    makeMessagesArg = { count: makeMessagesArg };
+  }
+  if (!createMessages.messageGenerator) {
+    createMessages.messageGenerator = new MessageGenerator();
+  }
+
+  let messages = createMessages.messageGenerator.makeMessages(makeMessagesArg);
+  return addGeneratedMessages(folder, messages);
+}
+
+class FakeGeneratedMessage {
+  constructor(msg) {
+    this.msg = msg;
+  }
+  toMessageString() {
+    return this.msg;
+  }
+  toMboxString() {
+    // A cheap hack. It works for existing uses but may not work for future uses.
+    let fromAddress = this.msg.match(/From: .* <(.*@.*)>/)[0];
+    let mBoxString = `From ${fromAddress}\r\n${this.msg}`;
+    // Ensure a trailing empty line.
+    if (!mBoxString.endsWith("\r\n")) {
+      mBoxString = mBoxString + "\r\n";
+    }
+    return mBoxString;
+  }
+}
+
+async function createMessageFromFile(folder, path) {
+  let message = await IOUtils.readUTF8(path);
+  return addGeneratedMessages(folder, [new FakeGeneratedMessage(message)]);
+}
+
+async function createMessageFromString(folder, message) {
+  return addGeneratedMessages(folder, [new FakeGeneratedMessage(message)]);
+}
+
+async function addGeneratedMessages(folder, messages) {
+  if (folder.server.type == "imap") {
+    return IMAPServer.addMessages(folder, messages);
+  }
+  if (folder.server.type == "nntp") {
+    return NNTPServer.addMessages(folder, messages);
+  }
+
+  let messageStrings = messages.map(message => message.toMboxString());
+  folder.QueryInterface(Ci.nsIMsgLocalMailFolder);
+  folder.addMessageBatch(messageStrings);
+  folder.callFilterPlugins(null);
+  return Promise.resolve();
+}
+
+async function getUtilsJS() {
+  return IOUtils.readUTF8(do_get_file("data/utils.js").path);
+}
+
+var IMAPServer = {
+  open() {
+    let { ImapDaemon, ImapMessage, IMAP_RFC3501_handler } = ChromeUtils.import(
+      "resource://testing-common/mailnews/Imapd.jsm"
+    );
+    IMAPServer.ImapMessage = ImapMessage;
+
+    this.daemon = new ImapDaemon();
+    this.server = new nsMailServer(
+      daemon => new IMAP_RFC3501_handler(daemon),
+      this.daemon
+    );
+    this.server.start();
+
+    registerCleanupFunction(() => this.close());
+  },
+  close() {
+    this.server.stop();
+  },
+  get port() {
+    return this.server.port;
+  },
+
+  addMessages(folder, messages) {
+    let fakeFolder = IMAPServer.daemon.getMailbox(folder.name);
+    messages.forEach(message => {
+      if (typeof message != "string") {
+        message = message.toMessageString();
+      }
+      let msgURI = Services.io.newURI(
+        "data:text/plain;base64," + btoa(message)
+      );
+      let imapMsg = new IMAPServer.ImapMessage(
+        msgURI.spec,
+        fakeFolder.uidnext++,
+        []
+      );
+      fakeFolder.addMessage(imapMsg);
+    });
+
+    return new Promise(resolve =>
+      mailTestUtils.updateFolderAndNotify(folder, resolve)
+    );
+  },
+};
+
+function subscribeNewsgroup(account, group) {
+  account.incomingServer.QueryInterface(Ci.nsINntpIncomingServer);
+  account.incomingServer.subscribeToNewsgroup(group);
+  account.incomingServer.maximumConnectionsNumber = 1;
+}
+
+function createNewsgroup(group) {
+  if (!NNTPServer.hasGroup(group)) {
+    NNTPServer.addGroup(group);
+  }
+}
+
+var NNTPServer = {
+  open() {
+    let { NNTP_RFC977_handler, NntpDaemon } = ChromeUtils.import(
+      "resource://testing-common/mailnews/Nntpd.jsm"
+    );
+
+    this.daemon = new NntpDaemon();
+    this.server = new nsMailServer(
+      daemon => new NNTP_RFC977_handler(daemon),
+      this.daemon
+    );
+    this.server.start();
+
+    registerCleanupFunction(() => this.close());
+  },
+
+  close() {
+    this.server.stop();
+  },
+  get port() {
+    return this.server.port;
+  },
+
+  addGroup(group) {
+    return this.daemon.addGroup(group);
+  },
+
+  hasGroup(group) {
+    return this.daemon.getGroup(group) != null;
+  },
+
+  addMessages(folder, messages) {
+    let { NewsArticle } = ChromeUtils.import(
+      "resource://testing-common/mailnews/Nntpd.jsm"
+    );
+
+    let group = folder.name;
+    messages.forEach(message => {
+      if (typeof message != "string") {
+        message = message.toMessageString();
+      }
+      // The NNTP daemon needs a trailing empty line.
+      if (!message.endsWith("\r\n")) {
+        message = message + "\r\n";
+      }
+      let article = new NewsArticle(message);
+      article.groups = [group];
+      this.daemon.addArticle(article);
+    });
+
+    return new Promise(resolve => {
+      mailTestUtils.updateFolderAndNotify(folder, resolve);
+    });
+  },
+};
diff --git a/comm/mail/components/extensions/test/xpcshell/images/redPixel.png b/comm/mail/components/extensions/test/xpcshell/images/redPixel.png
new file mode 100644
index 0000000000..abda018027
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/images/redPixel.png
diff --git a/comm/mail/components/extensions/test/xpcshell/images/whitePixel.png b/comm/mail/components/extensions/test/xpcshell/images/whitePixel.png
new file mode 100644
index 0000000000..5514ad40e9
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/images/whitePixel.png
diff --git a/comm/mail/components/extensions/test/xpcshell/messages/alternative.eml b/comm/mail/components/extensions/test/xpcshell/messages/alternative.eml
new file mode 100644
index 0000000000..11de6a87d6
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/alternative.eml
@@ -0,0 +1,23 @@
+Message-ID: <alternative.eml@mime.sample>

+Date: Fri, 19 May 2000 00:29:55 -0400

+To: Heinz <mueller@example.com>, Karl <friedrich@example.com>

+From: Doug Sauder <dwsauder@example.com>

+Subject: Default content-types

+Mime-Version: 1.0

+Content-Type: multipart/alternative;

+	boundary="=====================_714967308==_.ALT"

+

+This message is in MIME format.  The first part should be readable text,

+while the remaining parts are likely unreadable without MIME-aware tools.

+

+--=====================_714967308==_.ALT

+Content-Transfer-Encoding: quoted-printable

+

+I am TEXT!

+

+--=====================_714967308==_.ALT

+Content-Type: text/html

+

+<html><body>I <b>am</b> HTML!</body></html>

+

+--=====================_714967308==_.ALT--

diff --git a/comm/mail/components/extensions/test/xpcshell/messages/attachedMessageWithMissingHeaders.eml b/comm/mail/components/extensions/test/xpcshell/messages/attachedMessageWithMissingHeaders.eml
new file mode 100644
index 0000000000..85a54b66c5
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/attachedMessageWithMissingHeaders.eml
@@ -0,0 +1,35 @@
+Message-ID: <sample.eml@mime.sample>

+Date: Fri, 20 May 2000 00:29:55 -0400

+To: Heinz <mueller@example.com>

+From: Batman <bruce@example.com>

+Subject: Attached message without subject

+Mime-Version: 1.0

+Content-Type: multipart/mixed;

+  boundary="------------49CVLb1N6p6Spdka4qq7Naeg"

+

+This is a multi-part message in MIME format.

+--------------49CVLb1N6p6Spdka4qq7Naeg

+Content-Type: text/html; charset=UTF-8

+Content-Transfer-Encoding: 7bit

+

+<html>

+  <head>

+

+    <meta http-equiv="content-type" content="text/html; charset=UTF-8">

+  </head>

+  <body>

+    <p>This message has one email attachment with missing headers.<br>

+    </p>

+  </body>

+</html>

+--------------49CVLb1N6p6Spdka4qq7Naeg

+Content-Type: message/rfc822; charset=UTF-8; name="message1.eml"

+Content-Disposition: attachment; filename="message1.eml"

+Content-Transfer-Encoding: 7bit

+

+Message-ID: <sample-attached.eml@mime.sample>

+MIME-Version: 1.0

+

+This is my body

+

+--------------49CVLb1N6p6Spdka4qq7Naeg--

diff --git a/comm/mail/components/extensions/test/xpcshell/messages/nestedMessages.eml b/comm/mail/components/extensions/test/xpcshell/messages/nestedMessages.eml
new file mode 100644
index 0000000000..5ced639ff8
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/nestedMessages.eml
@@ -0,0 +1,127 @@
+Message-ID: <sample.eml@mime.sample>
+Date: Fri, 20 May 2000 00:29:55 -0400
+To: Heinz <mueller@example.com>
+Cc: Robin <damian@wayne-enterprises.com>
+From: Batman <bruce@wayne-enterprises.com>
+Subject: Attached message with attachments
+Mime-Version: 1.0
+Content-Type: multipart/mixed; 
+  boundary="------------49CVLb1N6p6Spdka4qq7Naeg"
+
+This is a multi-part message in MIME format.
+--------------49CVLb1N6p6Spdka4qq7Naeg
+Content-Type: text/html; charset=UTF-8
+Content-Transfer-Encoding: 7bit
+
+<html>
+  <head>
+
+    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
+  </head>
+  <body>
+    <p>This message has one normal attachment and one email attachment,
+      which itself has 3 attachments.<br>
+    </p>
+  </body>
+</html>
+--------------49CVLb1N6p6Spdka4qq7Naeg
+Content-Type: message/rfc822; charset=UTF-8; name="message1.eml"
+Content-Disposition: attachment; filename="message1.eml"
+Content-Transfer-Encoding: 7bit
+
+Message-ID: <sample-attached.eml@mime.sample>
+From: Superman <clark.kent@dailyplanet.com>
+To: Jimmy <jimmy.olsen@dailyplanet.com>
+Subject: Test message 1
+Date: Wed, 17 May 2000 19:32:47 -0400
+MIME-Version: 1.0
+Content-Type: multipart/mixed;
+	boundary="----=_NextPart_000_0002_01BFC036.AE309650"
+
+This is a multi-part message in MIME format.
+
+------=_NextPart_000_0002_01BFC036.AE309650
+Content-Type: text/plain;
+	charset="iso-8859-1"
+Content-Transfer-Encoding: 7bit
+
+Message with multiple attachments.
+
+------=_NextPart_000_0002_01BFC036.AE309650
+Content-Type: image/png;
+	name="whitePixel.png"
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+	filename="whitePixel.png"
+
+iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnn
+AAAAAElFTkSuQmCC
+
+------=_NextPart_000_0002_01BFC036.AE309650
+Content-Type: image/png;
+	name="greenPixel.png"
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment
+
+iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAAXNSR0IArs4c6QAAAARnQU1BAACx
+jwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAMSURBVBhXY+C76AoAAhUBJel4xsMAAAAASUVO
+RK5CYII=
+
+------=_NextPart_000_0002_01BFC036.AE309650
+Content-Type: image/png
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+	filename="redPixel.png"
+
+iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAAXNSR0IArs4c6QAAAARnQU1BAACx
+jwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAMSURBVBhXY+hgkAYAAbcApOp/9LEAAAAASUVO
+RK5CYII=
+
+------=_NextPart_000_0002_01BFC036.AE309650
+Content-Type: message/rfc822; charset=UTF-8; name="message2.eml"
+Content-Disposition: attachment; filename="message2.eml"
+Content-Transfer-Encoding: 7bit
+
+Message-ID: <sample-nested-attached.eml@mime.sample>
+From: Jimmy <jimmy.olsen@dailyplanet.com>
+To: Superman <clark.kent@dailyplanet.com>
+Subject: Test message 2
+Date: Wed, 16 May 2000 19:32:47 -0400
+MIME-Version: 1.0
+Content-Type: multipart/mixed;
+  boundary="----=_NextPart_000_0003_01BFC036.AE309650"
+
+This is a multi-part message in MIME format.
+
+------=_NextPart_000_0003_01BFC036.AE309650
+Content-Type: text/plain;
+  charset="iso-8859-1"
+Content-Transfer-Encoding: 7bit
+
+This message has an attachment
+
+------=_NextPart_000_0003_01BFC036.AE309650
+Content-Type: image/png;
+  name="whitePixel.png"
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+  filename="whitePixel.png"
+
+iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnn
+AAAAAElFTkSuQmCC
+
+------=_NextPart_000_0003_01BFC036.AE309650--
+
+------=_NextPart_000_0002_01BFC036.AE309650--
+
+--------------49CVLb1N6p6Spdka4qq7Naeg
+Content-Type: image/png;
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+  filename="yellowPixel.png"
+
+iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAAXNSR0IArs4c6QAAAARnQU1B
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+AAAASUVORK5CYII=
+
+--------------49CVLb1N6p6Spdka4qq7Naeg--
diff --git a/comm/mail/components/extensions/test/xpcshell/messages/sample01.eml b/comm/mail/components/extensions/test/xpcshell/messages/sample01.eml
new file mode 100644
index 0000000000..f7ac14a07d
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/sample01.eml
@@ -0,0 +1,11 @@
+From: Bug Reporter <new@thunderbird.bug>

+Newsgroups: gmane.comp.mozilla.thundebird.user

+Subject: =?UTF-8?B?zrHOu8+GzqzOss63z4TOvw==?=

+Date: Thu, 27 May 2021 21:23:35 +0100

+Message-ID: <01.eml@mime.sample>

+MIME-Version: 1.0

+Content-Type: text/plain; charset=utf-8;

+Content-Transfer-Encoding: base64

+Content-Disposition: inline

+

+zobOu8+GzrEK

diff --git a/comm/mail/components/extensions/test/xpcshell/messages/sample02.eml b/comm/mail/components/extensions/test/xpcshell/messages/sample02.eml
new file mode 100644
index 0000000000..74b60b5665
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/sample02.eml
@@ -0,0 +1,121 @@
+From: "Doug Sauder" <doug@example.com>

+To: =?iso-8859-1?Q?Heinz_M=FCller?= <mueller@example.com>

+Subject: Test message from Microsoft Outlook 00

+Date: Wed, 17 May 2000 19:32:47 -0400

+Message-ID: <02.eml@mime.sample>

+MIME-Version: 1.0

+Content-Type: multipart/mixed;

+	boundary="----=_NextPart_000_0002_01BFC036.AE309650"

+X-Priority: 3 (Normal)

+X-MSMail-Priority: Normal

+X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)

+Importance: Normal

+X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2314.1300

+

+This is a multi-part message in MIME format.

+

+------=_NextPart_000_0002_01BFC036.AE309650

+Content-Type: text/plain;

+	charset="iso-8859-1"

+Content-Transfer-Encoding: quoted-printable

+

+

+Die Hasen und die Fr=F6sche=20

+=20

+

+------=_NextPart_000_0002_01BFC036.AE309650

+Content-Type: image/png;

+	name="blueball1.png"

+Content-Transfer-Encoding: base64

+Content-Disposition: attachment;

+	filename="blueball2.png"

+

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+O7wAAAAASUVORK5CYII=

+

+------=_NextPart_000_0002_01BFC036.AE309650

+Content-Type: image/png;

+	name="greenball.png"

+Content-Transfer-Encoding: base64

+Content-Disposition: attachment

+

+iVBORw0KGgoAAAANSUhEUgAAABsAAAAbCAMAAAC6CgRnAAADAFBMVEX///8AAAAAEAAAGAAAIQAA

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+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

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+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

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+------=_NextPart_000_0002_01BFC036.AE309650

+Content-Type: image/png

+Content-Transfer-Encoding: base64

+Content-Disposition: attachment;

+	filename="redball.png"

+

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+

+------=_NextPart_000_0002_01BFC036.AE309650--

diff --git a/comm/mail/components/extensions/test/xpcshell/messages/sample03.eml b/comm/mail/components/extensions/test/xpcshell/messages/sample03.eml
new file mode 100644
index 0000000000..3eb8e06802
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/sample03.eml
@@ -0,0 +1,43 @@
+From: =?iso-8859-1?Q?Heinz_M=FCller?= <mueller@example.com>

+To: "Joe Blow" <jblow@example.com>

+Subject: Test message from Microsoft Outlook 00

+Date: Wed, 17 May 2000 19:35:05 -0400

+Message-ID: <03.eml@mime.sample>

+MIME-Version: 1.0

+Content-Type: image/png;

+	name="doubelspace  ball.png"

+Content-Transfer-Encoding: base64

+Content-Disposition: attachment;

+	filename="doubelspace  ball.png"

+X-Priority: 3 (Normal)

+X-MSMail-Priority: Normal

+X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)

+Importance: Normal

+X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2314.1300

+

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diff --git a/comm/mail/components/extensions/test/xpcshell/messages/sample04.eml b/comm/mail/components/extensions/test/xpcshell/messages/sample04.eml
new file mode 100644
index 0000000000..6dd2a94b56
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/sample04.eml
@@ -0,0 +1,10 @@
+Newsgroups: gmane.comp.mozilla.thundebird.user

+From: Bug Reporter <new@thunderbird.bug>

+Subject: =?koi8-r?B?4czGwdfJ1Ao=?=

+Date: Sun, 27 May 2001 21:23:35 +0100

+MIME-Version: 1.0

+Message-ID: <04.eml@mime.sample>

+Content-Type: text/plain; charset=koi8-r;

+Content-Transfer-Encoding: base64

+

+98/Q0s/TCg==
\ No newline at end of file
diff --git a/comm/mail/components/extensions/test/xpcshell/messages/sample05.eml b/comm/mail/components/extensions/test/xpcshell/messages/sample05.eml
new file mode 100644
index 0000000000..6e70eee744
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/sample05.eml
@@ -0,0 +1,10 @@
+Newsgroups: gmane.comp.mozilla.thundebird.user

+From: Bug Reporter <new@thunderbird.bug>

+Subject: =?windows-1251?B?wOv04OLo8go=?=

+Date: Sun, 27 May 2001 21:23:35 +0100

+MIME-Version: 1.0

+Message-ID: <05.eml@mime.sample>

+Content-Type: text/plain; charset=windows-1251;

+Content-Transfer-Encoding: base64

+

+wu7v8O7xCg==
\ No newline at end of file
diff --git a/comm/mail/components/extensions/test/xpcshell/messages/sample06.eml b/comm/mail/components/extensions/test/xpcshell/messages/sample06.eml
new file mode 100644
index 0000000000..a5b3a40ac5
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/sample06.eml
@@ -0,0 +1,8 @@
+Newsgroups: gmane.comp.mozilla.thundebird.user

+From: Bug Reporter <new@thunderbird.bug>

+Subject: I have no content type

+Date: Sun, 27 May 2001 21:23:35 +0100

+MIME-Version: 1.0

+Message-ID: <06.eml@mime.sample>

+

+No content type

diff --git a/comm/mail/components/extensions/test/xpcshell/messages/sample07.eml b/comm/mail/components/extensions/test/xpcshell/messages/sample07.eml
new file mode 100644
index 0000000000..29283b2ce0
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/messages/sample07.eml
@@ -0,0 +1,24 @@
+Message-ID: <07.eml@mime.sample>

+Date: Fri, 19 May 2000 00:29:55 -0400

+To: Heinz <mueller@example.com>

+From: Doug Sauder <dwsauder@example.com>

+Subject: Default content-types

+Mime-Version: 1.0

+Content-Type: multipart/alternative;

+	boundary="=====================_714967308==_.ALT"

+

+This message is in MIME format.  The first part should be readable text,

+while the remaining parts are likely unreadable without MIME-aware tools.

+

+--=====================_714967308==_.ALT

+Content-Transfer-Encoding: quoted-printable

+

+Die Hasen

+

+--=====================_714967308==_.ALT

+Content-Type: text/html

+

+<html><body><b>Die Hasen</b></body></html>

+

+--=====================_714967308==_.ALT--

+

diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_accounts.js b/comm/mail/components/extensions/test/xpcshell/test_ext_accounts.js
new file mode 100644
index 0000000000..ac6f5482ce
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_accounts.js
@@ -0,0 +1,1089 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+add_task(async function test_accounts() {
+  // Here all the accounts are local but the first account will behave as
+  // an actual local account and will be kept last always.
+  let files = {
+    "background.js": async () => {
+      let [account1Id, account1Name] = await window.waitForMessage();
+
+      let defaultAccount = await browser.accounts.getDefault();
+      browser.test.assertEq(
+        null,
+        defaultAccount,
+        "The default account should be null, as none is defined."
+      );
+
+      let result1 = await browser.accounts.list();
+      browser.test.assertEq(1, result1.length);
+      window.assertDeepEqual(
+        {
+          id: account1Id,
+          name: account1Name,
+          type: "none",
+          folders: [
+            {
+              accountId: account1Id,
+              name: "Trash",
+              path: "/Trash",
+              type: "trash",
+            },
+            {
+              accountId: account1Id,
+              name: "Outbox",
+              path: "/Unsent Messages",
+              type: "outbox",
+            },
+          ],
+        },
+        result1[0]
+      );
+
+      // Test that excluding folders works.
+      let result1WithOutFolders = await browser.accounts.list(false);
+      for (let account of result1WithOutFolders) {
+        browser.test.assertEq(null, account.folders, "Folders not included");
+      }
+
+      let [account2Id, account2Name] = await window.sendMessage(
+        "create account 2"
+      );
+      // The new account is defined as default and should be returned first.
+      let result2 = await browser.accounts.list();
+      browser.test.assertEq(2, result2.length);
+      window.assertDeepEqual(
+        [
+          {
+            id: account2Id,
+            name: account2Name,
+            type: "imap",
+            folders: [
+              {
+                accountId: account2Id,
+                name: "Inbox",
+                path: "/INBOX",
+                type: "inbox",
+              },
+            ],
+          },
+          {
+            id: account1Id,
+            name: account1Name,
+            type: "none",
+            folders: [
+              {
+                accountId: account1Id,
+                name: "Trash",
+                path: "/Trash",
+                type: "trash",
+              },
+              {
+                accountId: account1Id,
+                name: "Outbox",
+                path: "/Unsent Messages",
+                type: "outbox",
+              },
+            ],
+          },
+        ],
+        result2
+      );
+
+      let result3 = await browser.accounts.get(account1Id);
+      window.assertDeepEqual(result1[0], result3);
+      let result4 = await browser.accounts.get(account2Id);
+      window.assertDeepEqual(result2[0], result4);
+
+      let result3WithoutFolders = await browser.accounts.get(account1Id, false);
+      browser.test.assertEq(
+        null,
+        result3WithoutFolders.folders,
+        "Folders not included"
+      );
+      let result4WithoutFolders = await browser.accounts.get(account2Id, false);
+      browser.test.assertEq(
+        null,
+        result4WithoutFolders.folders,
+        "Folders not included"
+      );
+
+      await window.sendMessage("create folders");
+      let result5 = await browser.accounts.get(account1Id);
+      let platformInfo = await browser.runtime.getPlatformInfo();
+      window.assertDeepEqual(
+        [
+          {
+            accountId: account1Id,
+            name: "Trash",
+            path: "/Trash",
+            subFolders: [
+              {
+                accountId: account1Id,
+                name: "%foo %test% 'bar'(!)+",
+                path: "/Trash/%foo %test% 'bar'(!)+",
+              },
+              {
+                accountId: account1Id,
+                name: "Ϟ",
+                // This character is not supported on Windows, so it gets hashed,
+                // by NS_MsgHashIfNecessary.
+                path: platformInfo.os == "win" ? "/Trash/b52bc214" : "/Trash/Ϟ",
+              },
+            ],
+            type: "trash",
+          },
+          {
+            accountId: account1Id,
+            name: "Outbox",
+            path: "/Unsent Messages",
+            type: "outbox",
+          },
+        ],
+        result5.folders
+      );
+
+      // Check we can access the folders through folderPathToURI.
+      for (let folder of result5.folders) {
+        await browser.messages.list(folder);
+      }
+
+      let result6 = await browser.accounts.get(account2Id);
+      window.assertDeepEqual(
+        [
+          {
+            accountId: account2Id,
+            name: "Inbox",
+            path: "/INBOX",
+            subFolders: [
+              {
+                accountId: account2Id,
+                name: "%foo %test% 'bar'(!)+",
+                path: "/INBOX/%foo %test% 'bar'(!)+",
+              },
+              {
+                accountId: account2Id,
+                name: "Ϟ",
+                path: "/INBOX/&A94-",
+              },
+            ],
+            type: "inbox",
+          },
+          {
+            // The trash folder magically appears at this point.
+            // It wasn't here before.
+            accountId: "account2",
+            name: "Trash",
+            path: "/Trash",
+            type: "trash",
+          },
+        ],
+        result6.folders
+      );
+
+      // Check we can access the folders through folderPathToURI.
+      for (let folder of result6.folders) {
+        await browser.messages.list(folder);
+      }
+
+      defaultAccount = await browser.accounts.getDefault();
+      browser.test.assertEq(result2[0].id, defaultAccount.id);
+
+      browser.test.notifyPass("finished");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "accountsIdentities", "messagesRead"],
+    },
+  });
+
+  await extension.startup();
+  let account1 = createAccount();
+  extension.sendMessage(account1.key, account1.incomingServer.prettyName);
+
+  await extension.awaitMessage("create account 2");
+  let account2 = createAccount("imap");
+  IMAPServer.open();
+  account2.incomingServer.port = IMAPServer.port;
+  account2.incomingServer.username = "user";
+  account2.incomingServer.password = "password";
+  MailServices.accounts.defaultAccount = account2;
+  extension.sendMessage(account2.key, account2.incomingServer.prettyName);
+
+  await extension.awaitMessage("create folders");
+  let inbox1 = account1.incomingServer.rootFolder.subFolders[0];
+  // Test our code can handle characters that might be escaped.
+  inbox1.createSubfolder("%foo %test% 'bar'(!)+", null);
+  inbox1.createSubfolder("Ϟ", null); // Test our code can handle unicode.
+
+  let inbox2 = account2.incomingServer.rootFolder.subFolders[0];
+  inbox2.QueryInterface(Ci.nsIMsgImapMailFolder).hierarchyDelimiter = "/";
+  // Test our code can handle characters that might be escaped.
+  inbox2.createSubfolder("%foo %test% 'bar'(!)+", null);
+  await PromiseTestUtils.promiseFolderAdded("%foo %test% 'bar'(!)+");
+  inbox2.createSubfolder("Ϟ", null); // Test our code can handle unicode.
+  await PromiseTestUtils.promiseFolderAdded("Ϟ");
+
+  extension.sendMessage();
+
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  cleanUpAccount(account1);
+  cleanUpAccount(account2);
+});
+
+add_task(async function test_identities() {
+  let account1 = createAccount();
+  let account2 = createAccount("imap");
+  let identity0 = addIdentity(account1, "id0@invalid");
+  let identity1 = addIdentity(account1, "id1@invalid");
+  let identity2 = addIdentity(account1, "id2@invalid");
+  let identity3 = addIdentity(account2, "id3@invalid");
+  addIdentity(account2, "id4@invalid");
+  identity2.label = "A label";
+  identity2.fullName = "Identity 2!";
+  identity2.organization = "Dis Organization";
+  identity2.replyTo = "reply@invalid";
+  identity2.composeHtml = true;
+  identity2.htmlSigText = "This is me. And this is my Dog.";
+  identity2.htmlSigFormat = false;
+
+  equal(account1.defaultIdentity.key, identity0.key);
+  equal(account2.defaultIdentity.key, identity3.key);
+  let files = {
+    "background.js": async () => {
+      let accounts = await browser.accounts.list();
+      browser.test.assertEq(2, accounts.length);
+
+      const localAccount = accounts.find(account => account.type == "none");
+      const imapAccount = accounts.find(account => account.type == "imap");
+
+      // Register event listener.
+      let onCreatedLog = [];
+      browser.identities.onCreated.addListener((id, created) => {
+        onCreatedLog.push({ id, created });
+      });
+      let onUpdatedLog = [];
+      browser.identities.onUpdated.addListener((id, changed) => {
+        onUpdatedLog.push({ id, changed });
+      });
+      let onDeletedLog = [];
+      browser.identities.onDeleted.addListener(id => {
+        onDeletedLog.push(id);
+      });
+
+      const { id: accountId, identities } = localAccount;
+      const identityIds = identities.map(i => i.id);
+      browser.test.assertEq(3, identities.length);
+
+      browser.test.assertEq(accountId, identities[0].accountId);
+      browser.test.assertEq("id0@invalid", identities[0].email);
+      browser.test.assertEq(accountId, identities[1].accountId);
+      browser.test.assertEq("id1@invalid", identities[1].email);
+      browser.test.assertEq(accountId, identities[2].accountId);
+      browser.test.assertEq("id2@invalid", identities[2].email);
+      browser.test.assertEq("A label", identities[2].label);
+      browser.test.assertEq("Identity 2!", identities[2].name);
+      browser.test.assertEq("Dis Organization", identities[2].organization);
+      browser.test.assertEq("reply@invalid", identities[2].replyTo);
+      browser.test.assertEq(true, identities[2].composeHtml);
+      browser.test.assertEq(
+        "This is me. And this is my Dog.",
+        identities[2].signature
+      );
+      browser.test.assertEq(true, identities[2].signatureIsPlainText);
+
+      // Testing browser.identities.list().
+
+      let allIdentities = await browser.identities.list();
+      browser.test.assertEq(5, allIdentities.length);
+
+      let localIdentities = await browser.identities.list(localAccount.id);
+      browser.test.assertEq(
+        3,
+        localIdentities.length,
+        "number of local identities is correct"
+      );
+      for (let i = 0; i < 2; i++) {
+        browser.test.assertEq(
+          localAccount.identities[i].id,
+          localIdentities[i].id,
+          "returned local identity is correct"
+        );
+      }
+
+      let imapIdentities = await browser.identities.list(imapAccount.id);
+      browser.test.assertEq(
+        2,
+        imapIdentities.length,
+        "number of imap identities is correct"
+      );
+      for (let i = 0; i < 1; i++) {
+        browser.test.assertEq(
+          imapAccount.identities[i].id,
+          imapIdentities[i].id,
+          "returned imap identity is correct"
+        );
+      }
+
+      // Testing browser.identities.get().
+
+      let badIdentity = await browser.identities.get("funny");
+      browser.test.assertEq(null, badIdentity);
+
+      for (let identity of identities) {
+        let testIdentity = await browser.identities.get(identity.id);
+        for (let prop of Object.keys(identity)) {
+          browser.test.assertEq(
+            identity[prop],
+            testIdentity[prop],
+            `Testing identity.${prop}`
+          );
+        }
+      }
+
+      // Testing browser.identities.delete().
+
+      let imapDefaultIdentity = await browser.identities.getDefault(
+        imapAccount.id
+      );
+      let imapNonDefaultIdentity = imapIdentities.find(
+        identity => identity.id != imapDefaultIdentity.id
+      );
+
+      await browser.identities.delete(imapNonDefaultIdentity.id);
+      imapIdentities = await browser.identities.list(imapAccount.id);
+      browser.test.assertEq(
+        1,
+        imapIdentities.length,
+        "number of imap identities after delete is correct"
+      );
+      browser.test.assertEq(
+        imapDefaultIdentity.id,
+        imapIdentities[0].id,
+        "leftover identity after delete is correct"
+      );
+
+      await browser.test.assertRejects(
+        browser.identities.delete(imapDefaultIdentity.id),
+        `Identity ${imapDefaultIdentity.id} is the default identity of account ${imapAccount.id} and cannot be deleted`,
+        "browser.identities.delete threw exception"
+      );
+
+      await browser.test.assertRejects(
+        browser.identities.delete("somethingInvalid"),
+        "Identity not found: somethingInvalid",
+        "browser.identities.delete threw exception"
+      );
+
+      // Testing browser.identities.create().
+
+      let createTests = [
+        {
+          // Set all.
+          accountId: imapAccount.id,
+          details: {
+            email: "id0+test@invalid",
+            label: "TestLabel",
+            name: "Mr. Test",
+            organization: "MZLA",
+            replyTo: "id0+test@invalid",
+            signature: "This is Bruce. And this is my Cat.",
+            composeHtml: true,
+            signatureIsPlainText: false,
+          },
+        },
+        {
+          // Set some.
+          accountId: imapAccount.id,
+          details: {
+            email: "id0+work@invalid",
+            replyTo: "",
+            signature: "I am Batman.",
+            composeHtml: false,
+          },
+        },
+        {
+          // Set none.
+          accountId: imapAccount.id,
+          details: {},
+        },
+        {
+          // Set some on an invalid account.
+          accountId: "somethingInvalid",
+          details: {
+            email: "id0+work@invalid",
+            replyTo: "",
+            signature: "I am Batman.",
+            composeHtml: false,
+          },
+          expectedThrow: `Account not found: somethingInvalid`,
+        },
+        {
+          // Try to set a protected property.
+          accountId: imapAccount.id,
+          details: {
+            accountId: "accountId5",
+          },
+          expectedThrow: `Setting the accountId property of a MailIdentity is not supported.`,
+        },
+        {
+          // Try to set a protected property together with others.
+          accountId: imapAccount.id,
+          details: {
+            id: "id8",
+            email: "id0+work@invalid",
+            label: "TestLabel",
+            name: "Mr. Test",
+            organization: "MZLA",
+            replyTo: "",
+            signature: "I am Batman.",
+            composeHtml: false,
+            signatureIsPlainText: false,
+          },
+          expectedThrow: `Setting the id property of a MailIdentity is not supported.`,
+        },
+      ];
+      for (let createTest of createTests) {
+        if (createTest.expectedThrow) {
+          await browser.test.assertRejects(
+            browser.identities.create(createTest.accountId, createTest.details),
+            createTest.expectedThrow,
+            `It rejects as expected: ${createTest.expectedThrow}.`
+          );
+        } else {
+          let createPromise = new Promise(resolve => {
+            const callback = (id, identity) => {
+              browser.identities.onCreated.removeListener(callback);
+              resolve(identity);
+            };
+            browser.identities.onCreated.addListener(callback);
+          });
+          let createdIdentity = await browser.identities.create(
+            createTest.accountId,
+            createTest.details
+          );
+          let createdIdentity2 = await createPromise;
+
+          let expected = createTest.details;
+          for (let prop of Object.keys(expected)) {
+            browser.test.assertEq(
+              expected[prop],
+              createdIdentity[prop],
+              `Testing created identity.${prop}`
+            );
+            browser.test.assertEq(
+              expected[prop],
+              createdIdentity2[prop],
+              `Testing created identity.${prop}`
+            );
+          }
+          await browser.identities.delete(createdIdentity.id);
+        }
+
+        let foundIdentities = await browser.identities.list(imapAccount.id);
+        browser.test.assertEq(
+          1,
+          foundIdentities.length,
+          "number of imap identities after create/delete is correct"
+        );
+      }
+
+      // Testing browser.identities.update().
+
+      let updateTests = [
+        {
+          // Set all.
+          identityId: identities[2].id,
+          details: {
+            email: "id0+test@invalid",
+            label: "TestLabel",
+            name: "Mr. Test",
+            organization: "MZLA",
+            replyTo: "id0+test@invalid",
+            signature: "This is Bruce. And this is my Cat.",
+            composeHtml: true,
+            signatureIsPlainText: false,
+          },
+        },
+        {
+          // Set some.
+          identityId: identities[2].id,
+          details: {
+            email: "id0+work@invalid",
+            replyTo: "",
+            signature: "I am Batman.",
+            composeHtml: false,
+          },
+          expected: {
+            email: "id0+work@invalid",
+            label: "TestLabel",
+            name: "Mr. Test",
+            organization: "MZLA",
+            replyTo: "",
+            signature: "I am Batman.",
+            composeHtml: false,
+            signatureIsPlainText: false,
+          },
+        },
+        {
+          // Clear.
+          identityId: identities[2].id,
+          details: {
+            email: "",
+            label: "",
+            name: "",
+            organization: "",
+            replyTo: "",
+            signature: "",
+            composeHtml: false,
+            signatureIsPlainText: true,
+          },
+        },
+        {
+          // Try to update an invalid identity.
+          identityId: "somethingInvalid",
+          details: {
+            email: "id0+work@invalid",
+            replyTo: "",
+            signature: "I am Batman.",
+            composeHtml: false,
+          },
+          expectedThrow: "Identity not found: somethingInvalid",
+        },
+        {
+          // Try to update a protected property.
+          identityId: identities[2].id,
+          details: {
+            accountId: "accountId5",
+          },
+          expectedThrow:
+            "Setting the accountId property of a MailIdentity is not supported.",
+        },
+        {
+          // Try to update another protected property together with others.
+          identityId: identities[2].id,
+          details: {
+            id: "id8",
+            email: "id0+work@invalid",
+            label: "TestLabel",
+            name: "Mr. Test",
+            organization: "MZLA",
+            replyTo: "",
+            signature: "I am Batman.",
+            composeHtml: false,
+            signatureIsPlainText: false,
+          },
+          expectedThrow:
+            "Setting the id property of a MailIdentity is not supported.",
+        },
+      ];
+      for (let updateTest of updateTests) {
+        if (updateTest.expectedThrow) {
+          await browser.test.assertRejects(
+            browser.identities.update(
+              updateTest.identityId,
+              updateTest.details
+            ),
+            updateTest.expectedThrow,
+            `It rejects as expected: ${updateTest.expectedThrow}.`
+          );
+          continue;
+        }
+
+        let updatePromise = new Promise(resolve => {
+          const callback = (id, changed) => {
+            browser.identities.onUpdated.removeListener(callback);
+            resolve(changed);
+          };
+          browser.identities.onUpdated.addListener(callback);
+        });
+        let updatedIdentity = await browser.identities.update(
+          updateTest.identityId,
+          updateTest.details
+        );
+        await updatePromise;
+
+        let returnedIdentity = await browser.identities.get(
+          updateTest.identityId
+        );
+
+        let expected = updateTest.expected || updateTest.details;
+        for (let prop of Object.keys(expected)) {
+          browser.test.assertEq(
+            expected[prop],
+            updatedIdentity[prop],
+            `Testing updated identity.${prop}`
+          );
+          browser.test.assertEq(
+            expected[prop],
+            returnedIdentity[prop],
+            `Testing returned identity.${prop}`
+          );
+        }
+      }
+
+      // Testing getDefault().
+
+      let defaultIdentity = await browser.identities.getDefault(accountId);
+      browser.test.assertEq(identities[0].id, defaultIdentity.id);
+
+      await browser.identities.setDefault(accountId, identityIds[2]);
+      defaultIdentity = await browser.identities.getDefault(accountId);
+      browser.test.assertEq(identities[2].id, defaultIdentity.id);
+
+      let { identities: newIdentities } = await browser.accounts.get(accountId);
+      browser.test.assertEq(3, newIdentities.length);
+      browser.test.assertEq(identityIds[2], newIdentities[0].id);
+      browser.test.assertEq(identityIds[0], newIdentities[1].id);
+      browser.test.assertEq(identityIds[1], newIdentities[2].id);
+
+      await browser.identities.setDefault(accountId, identityIds[1]);
+      defaultIdentity = await browser.identities.getDefault(accountId);
+      browser.test.assertEq(identities[1].id, defaultIdentity.id);
+
+      ({ identities: newIdentities } = await browser.accounts.get(accountId));
+      browser.test.assertEq(3, newIdentities.length);
+      browser.test.assertEq(identityIds[1], newIdentities[0].id);
+      browser.test.assertEq(identityIds[2], newIdentities[1].id);
+      browser.test.assertEq(identityIds[0], newIdentities[2].id);
+
+      // Check event listeners.
+      window.assertDeepEqual(
+        onCreatedLog,
+        [
+          {
+            id: "id6",
+            created: {
+              accountId: "account4",
+              id: "id6",
+              label: "TestLabel",
+              name: "Mr. Test",
+              email: "id0+test@invalid",
+              replyTo: "id0+test@invalid",
+              organization: "MZLA",
+              composeHtml: true,
+              signature: "This is Bruce. And this is my Cat.",
+              signatureIsPlainText: false,
+            },
+          },
+          {
+            id: "id7",
+            created: {
+              accountId: "account4",
+              id: "id7",
+              label: "",
+              name: "",
+              email: "id0+work@invalid",
+              replyTo: "",
+              organization: "",
+              composeHtml: false,
+              signature: "I am Batman.",
+              signatureIsPlainText: true,
+            },
+          },
+          {
+            id: "id8",
+            created: {
+              accountId: "account4",
+              id: "id8",
+              label: "",
+              name: "",
+              email: "",
+              replyTo: "",
+              organization: "",
+              composeHtml: true,
+              signature: "",
+              signatureIsPlainText: true,
+            },
+          },
+        ],
+        "captured onCreated events are correct"
+      );
+      window.assertDeepEqual(
+        onUpdatedLog,
+        [
+          {
+            id: "id3",
+            changed: {
+              label: "TestLabel",
+              name: "Mr. Test",
+              email: "id0+test@invalid",
+              replyTo: "id0+test@invalid",
+              organization: "MZLA",
+              signature: "This is Bruce. And this is my Cat.",
+              signatureIsPlainText: false,
+              accountId: "account3",
+              id: "id3",
+            },
+          },
+          {
+            id: "id3",
+            changed: {
+              email: "id0+work@invalid",
+              replyTo: "",
+              composeHtml: false,
+              signature: "I am Batman.",
+              accountId: "account3",
+              id: "id3",
+            },
+          },
+          {
+            id: "id3",
+            changed: {
+              label: "",
+              name: "",
+              email: "",
+              organization: "",
+              signature: "",
+              signatureIsPlainText: true,
+              accountId: "account3",
+              id: "id3",
+            },
+          },
+        ],
+        "captured onUpdated events are correct"
+      );
+      window.assertDeepEqual(
+        onDeletedLog,
+        ["id5", "id6", "id7", "id8"],
+        "captured onDeleted events are correct"
+      );
+
+      browser.test.notifyPass("finished");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "accountsIdentities"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  equal(account1.defaultIdentity.key, identity1.key);
+
+  cleanUpAccount(account1);
+  cleanUpAccount(account2);
+});
+
+add_task(async function test_identities_without_write_permissions() {
+  let account = createAccount();
+  let identity0 = addIdentity(account, "id0@invalid");
+
+  equal(account.defaultIdentity.key, identity0.key);
+
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      let accounts = await browser.accounts.list();
+      browser.test.assertEq(1, accounts.length);
+
+      const [{ identities }] = accounts;
+      browser.test.assertEq(1, identities.length);
+
+      // Testing browser.identities.update().
+
+      await browser.test.assertThrows(
+        () => browser.identities.update(identities[0].id, {}),
+        "browser.identities.update is not a function",
+        "It rejects for a missing permission."
+      );
+
+      // Testing browser.identities.delete().
+
+      await browser.test.assertThrows(
+        () => browser.identities.delete(identities[0].id),
+        "browser.identities.delete is not a function",
+        "It rejects for a missing permission."
+      );
+
+      browser.test.notifyPass("finished");
+    },
+    manifest: {
+      permissions: ["accountsRead"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  cleanUpAccount(account);
+});
+
+add_task(async function test_accounts_events() {
+  let account1 = createAccount();
+  addIdentity(account1, "id1@invalid");
+
+  let files = {
+    "background.js": async () => {
+      // Register event listener.
+      let onCreatedLog = [];
+      let onUpdatedLog = [];
+      let onDeletedLog = [];
+
+      let createListener = (id, created) => {
+        onCreatedLog.push({ id, created });
+      };
+      let updateListener = (id, changed) => {
+        onUpdatedLog.push({ id, changed });
+      };
+      let deleteListener = id => {
+        onDeletedLog.push(id);
+      };
+
+      await browser.accounts.onCreated.addListener(createListener);
+      await browser.accounts.onUpdated.addListener(updateListener);
+      await browser.accounts.onDeleted.addListener(deleteListener);
+
+      // Create accounts.
+      let imapAccountKey = await window.sendMessage("createAccount", {
+        type: "imap",
+        identity: "user@invalidImap",
+      });
+      let localAccountKey = await window.sendMessage("createAccount", {
+        type: "none",
+        identity: "user@invalidLocal",
+      });
+      let popAccountKey = await window.sendMessage("createAccount", {
+        type: "pop3",
+        identity: "user@invalidPop",
+      });
+
+      // Update account identities.
+      let accounts = await browser.accounts.list();
+      let imapAccount = accounts.find(a => a.id == imapAccountKey);
+      let localAccount = accounts.find(a => a.id == localAccountKey);
+      let popAccount = accounts.find(a => a.id == popAccountKey);
+
+      let id1 = await browser.identities.create(imapAccount.id, {
+        composeHtml: true,
+        email: "user1@inter.net",
+        name: "user1",
+      });
+      let id2 = await browser.identities.create(localAccount.id, {
+        composeHtml: false,
+        email: "user2@inter.net",
+        name: "user2",
+      });
+      let id3 = await browser.identities.create(popAccount.id, {
+        composeHtml: false,
+        email: "user3@inter.net",
+        name: "user3",
+      });
+
+      await browser.identities.setDefault(imapAccount.id, id1.id);
+      browser.test.assertEq(
+        id1.id,
+        (await browser.identities.getDefault(imapAccount.id)).id
+      );
+      await browser.identities.setDefault(localAccount.id, id2.id);
+      browser.test.assertEq(
+        id2.id,
+        (await browser.identities.getDefault(localAccount.id)).id
+      );
+      await browser.identities.setDefault(popAccount.id, id3.id);
+      browser.test.assertEq(
+        id3.id,
+        (await browser.identities.getDefault(popAccount.id)).id
+      );
+
+      // Update account names.
+      await window.sendMessage("updateAccountName", {
+        accountKey: imapAccountKey,
+        name: "Test1",
+      });
+      await window.sendMessage("updateAccountName", {
+        accountKey: localAccountKey,
+        name: "Test2",
+      });
+      await window.sendMessage("updateAccountName", {
+        accountKey: popAccountKey,
+        name: "Test3",
+      });
+
+      // Delete accounts.
+      await window.sendMessage("removeAccount", {
+        accountKey: imapAccountKey,
+      });
+      await window.sendMessage("removeAccount", {
+        accountKey: localAccountKey,
+      });
+      await window.sendMessage("removeAccount", {
+        accountKey: popAccountKey,
+      });
+
+      await browser.accounts.onCreated.removeListener(createListener);
+      await browser.accounts.onUpdated.removeListener(updateListener);
+      await browser.accounts.onDeleted.removeListener(deleteListener);
+
+      // Check event listeners.
+      browser.test.assertEq(3, onCreatedLog.length);
+      window.assertDeepEqual(
+        [
+          {
+            id: "account7",
+            created: {
+              id: "account7",
+              type: "imap",
+              identities: [],
+              name: "Mail for account7user@localhost",
+              folders: null,
+            },
+          },
+          {
+            id: "account8",
+            created: {
+              id: "account8",
+              type: "none",
+              identities: [],
+              name: "account8user on localhost",
+              folders: null,
+            },
+          },
+          {
+            id: "account9",
+            created: {
+              id: "account9",
+              type: "pop3",
+              identities: [],
+              name: "account9user on localhost",
+              folders: null,
+            },
+          },
+        ],
+        onCreatedLog,
+        "captured onCreated events are correct"
+      );
+      window.assertDeepEqual(
+        [
+          {
+            id: "account7",
+            changed: { id: "account7", name: "Mail for user@localhost" },
+          },
+          {
+            id: "account7",
+            changed: {
+              id: "account7",
+              defaultIdentity: { id: "id11" },
+            },
+          },
+          {
+            id: "account8",
+            changed: {
+              id: "account8",
+              defaultIdentity: { id: "id12" },
+            },
+          },
+          {
+            id: "account9",
+            changed: {
+              id: "account9",
+              defaultIdentity: { id: "id13" },
+            },
+          },
+          {
+            id: "account7",
+            changed: {
+              id: "account7",
+              defaultIdentity: { id: "id14" },
+            },
+          },
+          {
+            id: "account8",
+            changed: {
+              id: "account8",
+              defaultIdentity: { id: "id15" },
+            },
+          },
+          {
+            id: "account9",
+            changed: {
+              id: "account9",
+              defaultIdentity: { id: "id16" },
+            },
+          },
+          {
+            id: "account7",
+            changed: {
+              id: "account7",
+              name: "Test1",
+            },
+          },
+          {
+            id: "account8",
+            changed: {
+              id: "account8",
+              name: "Test2",
+            },
+          },
+          {
+            id: "account9",
+            changed: {
+              id: "account9",
+              name: "Test3",
+            },
+          },
+        ],
+        onUpdatedLog,
+        "captured onUpdated events are correct"
+      );
+      window.assertDeepEqual(
+        ["account7", "account8", "account9"],
+        onDeletedLog,
+        "captured onDeleted events are correct"
+      );
+
+      // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+      await new Promise(r => window.setTimeout(r, 250));
+      browser.test.notifyPass("finished");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "accountsIdentities"],
+    },
+  });
+
+  extension.onMessage("createAccount", details => {
+    let account = createAccount(details.type);
+    addIdentity(account, details.identity);
+    extension.sendMessage(account.key);
+  });
+  extension.onMessage("updateAccountName", details => {
+    let account = MailServices.accounts.getAccount(details.accountKey);
+    account.incomingServer.prettyName = details.name;
+    extension.sendMessage();
+  });
+  extension.onMessage("removeAccount", details => {
+    let account = MailServices.accounts.getAccount(details.accountKey);
+    cleanUpAccount(account);
+    extension.sendMessage();
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  cleanUpAccount(account1);
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_accounts_mv3_event_pages.js b/comm/mail/components/extensions/test/xpcshell/test_ext_accounts_mv3_event_pages.js
new file mode 100644
index 0000000000..0ac4394f40
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_accounts_mv3_event_pages.js
@@ -0,0 +1,220 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+var { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+
+ExtensionTestUtils.mockAppInfo();
+AddonTestUtils.maybeInit(this);
+
+add_task(async function test_accounts_MV3_event_pages() {
+  await AddonTestUtils.promiseStartupManager();
+
+  let files = {
+    "background.js": async () => {
+      // Whenever the extension starts or wakes up, the eventCounter is reset and
+      // allows to observe the order of events fired. In case of a wake-up, the
+      // first observed event is the one that woke up the background.
+      let eventCounter = 0;
+
+      for (let eventName of ["onCreated", "onUpdated", "onDeleted"]) {
+        browser.accounts[eventName].addListener(async (...args) => {
+          browser.test.sendMessage(`${eventName} event received`, {
+            eventCount: ++eventCounter,
+            args,
+          });
+        });
+      }
+
+      browser.test.sendMessage("background started");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      manifest_version: 3,
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "accountsIdentities"],
+    },
+  });
+
+  function checkPersistentListeners({ primed }) {
+    // A persistent event is referenced by its moduleName as defined in
+    // ext-mails.json, not by its actual namespace.
+    const persistent_events = [
+      "accounts.onCreated",
+      "accounts.onUpdated",
+      "accounts.onDeleted",
+    ];
+
+    for (let event of persistent_events) {
+      let [moduleName, eventName] = event.split(".");
+      assertPersistentListeners(extension, moduleName, eventName, {
+        primed,
+      });
+    }
+  }
+
+  let testData = [
+    {
+      type: "imap",
+      identity: "user@invalidImap",
+      expectedUpdate: true,
+      expectedName: accountKey => `Mail for ${accountKey}user@localhost`,
+      expectedType: "imap",
+      updatedName: "Test1",
+    },
+    {
+      type: "pop3",
+      identity: "user@invalidPop",
+      expectedUpdate: false,
+      expectedName: accountKey => `${accountKey}user on localhost`,
+      expectedType: "pop3",
+      updatedName: "Test2",
+    },
+    {
+      type: "none",
+      identity: "user@invalidLocal",
+      expectedUpdate: false,
+      expectedName: accountKey => `${accountKey}user on localhost`,
+      expectedType: "none",
+      updatedName: "Test3",
+    },
+    {
+      type: "local",
+      identity: "user@invalidLocal",
+      expectedUpdate: false,
+      expectedName: accountKey => "Local Folders",
+      expectedType: "none",
+      updatedName: "Test4",
+    },
+  ];
+
+  await extension.startup();
+  await extension.awaitMessage("background started");
+
+  // Verify persistent listener, not yet primed.
+  checkPersistentListeners({ primed: false });
+
+  // Create.
+
+  for (let details of testData) {
+    await extension.terminateBackground({ disableResetIdleForTest: true });
+    // Verify the primed persistent listeners.
+    checkPersistentListeners({ primed: true });
+
+    let account = createAccount(details.type);
+    details.account = account;
+
+    {
+      let rv = await extension.awaitMessage("onCreated event received");
+      Assert.deepEqual(
+        {
+          eventCount: 1,
+          args: [
+            details.account.key,
+            {
+              id: details.account.key,
+              name: details.expectedName(account.key),
+              type: details.expectedType,
+              folders: null,
+              identities: [],
+            },
+          ],
+        },
+        rv,
+        "The primed onCreated event should return the correct values"
+      );
+    }
+
+    if (details.expectedUpdate) {
+      let rv = await extension.awaitMessage("onUpdated event received");
+      Assert.deepEqual(
+        {
+          eventCount: 2,
+          args: [
+            details.account.key,
+            { id: details.account.key, name: "Mail for user@localhost" },
+          ],
+        },
+        rv,
+        "The non-primed onUpdated event should return the correct values"
+      );
+    }
+
+    // The background should have been restarted.
+    await extension.awaitMessage("background started");
+    // The listener should no longer be primed.
+    checkPersistentListeners({ primed: false });
+  }
+
+  // Update.
+
+  for (let details of testData) {
+    await extension.terminateBackground({ disableResetIdleForTest: true });
+    // Verify the primed persistent listeners.
+    checkPersistentListeners({ primed: true });
+
+    let account = MailServices.accounts.getAccount(details.account.key);
+    account.incomingServer.prettyName = details.updatedName;
+    let rv = await extension.awaitMessage("onUpdated event received");
+
+    Assert.deepEqual(
+      {
+        eventCount: 1,
+        args: [
+          details.account.key,
+          {
+            id: details.account.key,
+            name: details.updatedName,
+          },
+        ],
+      },
+      rv,
+      "The primed onUpdated event should return the correct values"
+    );
+
+    // The background should have been restarted.
+    await extension.awaitMessage("background started");
+    // The listener should no longer be primed.
+    checkPersistentListeners({ primed: false });
+  }
+
+  // Delete.
+
+  for (let details of testData) {
+    await extension.terminateBackground({ disableResetIdleForTest: true });
+    // Verify the primed persistent listeners.
+    checkPersistentListeners({ primed: true });
+
+    cleanUpAccount(details.account);
+    let rv = await extension.awaitMessage("onDeleted event received");
+
+    Assert.deepEqual(
+      {
+        eventCount: 1,
+        args: [details.account.key],
+      },
+      rv,
+      "The primed onDeleted event should return the correct values"
+    );
+
+    // The background should have been restarted.
+    await extension.awaitMessage("background started");
+    // The listener should no longer be primed.
+    checkPersistentListeners({ primed: false });
+  }
+
+  await extension.unload();
+
+  await AddonTestUtils.promiseShutdownManager();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook.js b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook.js
new file mode 100644
index 0000000000..8fcc3ca14f
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook.js
@@ -0,0 +1,2043 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+var { XPCOMUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/XPCOMUtils.sys.mjs"
+);
+
+XPCOMUtils.defineLazyModuleGetters(this, {
+  AddrBookCard: "resource:///modules/AddrBookCard.jsm",
+  AddrBookUtils: "resource:///modules/AddrBookUtils.jsm",
+});
+
+var { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+
+ExtensionTestUtils.mockAppInfo();
+AddonTestUtils.maybeInit(this);
+
+add_setup(async () => {
+  Services.prefs.setIntPref("ldap_2.servers.osx.dirType", -1);
+
+  registerCleanupFunction(() => {
+    // Make sure any open database is given a chance to close.
+    Services.startup.advanceShutdownPhase(
+      Services.startup.SHUTDOWN_PHASE_APPSHUTDOWNCONFIRMED
+    );
+  });
+});
+
+add_task(async function test_addressBooks() {
+  async function background() {
+    let firstBookId, secondBookId, newContactId;
+
+    let events = [];
+    let eventPromise;
+    let eventPromiseResolve;
+    for (let eventNamespace of ["addressBooks", "contacts", "mailingLists"]) {
+      for (let eventName of [
+        "onCreated",
+        "onUpdated",
+        "onDeleted",
+        "onMemberAdded",
+        "onMemberRemoved",
+      ]) {
+        if (eventName in browser[eventNamespace]) {
+          browser[eventNamespace][eventName].addListener((...args) => {
+            events.push({ namespace: eventNamespace, name: eventName, args });
+            if (eventPromiseResolve) {
+              let resolve = eventPromiseResolve;
+              eventPromiseResolve = null;
+              resolve();
+            }
+          });
+        }
+      }
+    }
+
+    let outsideEvent = function (action, ...args) {
+      eventPromise = new Promise(resolve => {
+        eventPromiseResolve = resolve;
+      });
+      return window.sendMessage("outsideEventsTest", action, ...args);
+    };
+    let checkEvents = async function (...expectedEvents) {
+      if (eventPromiseResolve) {
+        await eventPromise;
+      }
+
+      browser.test.assertEq(
+        expectedEvents.length,
+        events.length,
+        "Correct number of events"
+      );
+
+      if (expectedEvents.length != events.length) {
+        for (let event of events) {
+          let args = event.args.join(", ");
+          browser.test.log(`${event.namespace}.${event.name}(${args})`);
+        }
+        throw new Error("Wrong number of events, stopping.");
+      }
+
+      for (let [namespace, name, ...expectedArgs] of expectedEvents) {
+        let event = events.shift();
+        browser.test.assertEq(
+          namespace,
+          event.namespace,
+          "Event namespace is correct"
+        );
+        browser.test.assertEq(name, event.name, "Event type is correct");
+        browser.test.assertEq(
+          expectedArgs.length,
+          event.args.length,
+          "Argument count is correct"
+        );
+        window.assertDeepEqual(expectedArgs, event.args);
+        if (expectedEvents.length == 1) {
+          return event.args;
+        }
+      }
+
+      return null;
+    };
+
+    async function addressBookTest() {
+      browser.test.log("Starting addressBookTest");
+      let list = await browser.addressBooks.list();
+      browser.test.assertEq(2, list.length);
+      for (let b of list) {
+        browser.test.assertEq(5, Object.keys(b).length);
+        browser.test.assertEq(36, b.id.length);
+        browser.test.assertEq("addressBook", b.type);
+        browser.test.assertTrue("name" in b);
+        browser.test.assertFalse(b.readOnly);
+        browser.test.assertFalse(b.remote);
+      }
+
+      let completeList = await browser.addressBooks.list(true);
+      browser.test.assertEq(2, completeList.length);
+      for (let b of completeList) {
+        browser.test.assertEq(7, Object.keys(b).length);
+      }
+
+      firstBookId = list[0].id;
+      secondBookId = list[1].id;
+
+      let firstBook = await browser.addressBooks.get(firstBookId);
+      browser.test.assertEq(5, Object.keys(firstBook).length);
+
+      let secondBook = await browser.addressBooks.get(secondBookId, true);
+      browser.test.assertEq(7, Object.keys(secondBook).length);
+      browser.test.assertTrue(Array.isArray(secondBook.contacts));
+      browser.test.assertEq(0, secondBook.contacts.length);
+      browser.test.assertTrue(Array.isArray(secondBook.mailingLists));
+      browser.test.assertEq(0, secondBook.mailingLists.length);
+      let newBookId = await browser.addressBooks.create({ name: "test name" });
+      browser.test.assertEq(36, newBookId.length);
+      await checkEvents([
+        "addressBooks",
+        "onCreated",
+        { type: "addressBook", id: newBookId },
+      ]);
+
+      list = await browser.addressBooks.list();
+      browser.test.assertEq(3, list.length);
+
+      let newBook = await browser.addressBooks.get(newBookId);
+      browser.test.assertEq(newBookId, newBook.id);
+      browser.test.assertEq("addressBook", newBook.type);
+      browser.test.assertEq("test name", newBook.name);
+
+      await browser.addressBooks.update(newBookId, { name: "new name" });
+      await checkEvents([
+        "addressBooks",
+        "onUpdated",
+        { type: "addressBook", id: newBookId },
+      ]);
+      let updatedBook = await browser.addressBooks.get(newBookId);
+      browser.test.assertEq("new name", updatedBook.name);
+
+      list = await browser.addressBooks.list();
+      browser.test.assertEq(3, list.length);
+
+      await browser.addressBooks.delete(newBookId);
+      await checkEvents(["addressBooks", "onDeleted", newBookId]);
+
+      list = await browser.addressBooks.list();
+      browser.test.assertEq(2, list.length);
+
+      for (let operation of ["get", "update", "delete"]) {
+        let args = [newBookId];
+        if (operation == "update") {
+          args.push({ name: "" });
+        }
+
+        try {
+          await browser.addressBooks[operation].apply(
+            browser.addressBooks,
+            args
+          );
+          browser.test.fail(
+            `Calling ${operation} on a non-existent address book should throw`
+          );
+        } catch (ex) {
+          browser.test.assertEq(
+            `addressBook with id=${newBookId} could not be found.`,
+            ex.message,
+            `browser.addressBooks.${operation} threw exception`
+          );
+        }
+      }
+
+      // Test the prevention of creating new address book with an empty name
+      await browser.test.assertRejects(
+        browser.addressBooks.create({ name: "" }),
+        "An unexpected error occurred",
+        "browser.addressBooks.create threw exception"
+      );
+
+      browser.test.assertEq(0, events.length, "No events left unconsumed");
+      browser.test.log("Completed addressBookTest");
+    }
+
+    async function contactsTest() {
+      browser.test.log("Starting contactsTest");
+      let contacts = await browser.contacts.list(firstBookId);
+      browser.test.assertTrue(Array.isArray(contacts));
+      browser.test.assertEq(0, contacts.length);
+
+      newContactId = await browser.contacts.create(firstBookId, {
+        FirstName: "first",
+        LastName: "last",
+        Notes: "Notes",
+        SomethingCustom: "Custom property",
+      });
+      browser.test.assertEq(36, newContactId.length);
+      await checkEvents([
+        "contacts",
+        "onCreated",
+        { type: "contact", parentId: firstBookId, id: newContactId },
+      ]);
+
+      contacts = await browser.contacts.list(firstBookId);
+      browser.test.assertEq(1, contacts.length, "Contact added to first book.");
+      browser.test.assertEq(contacts[0].id, newContactId);
+
+      contacts = await browser.contacts.list(secondBookId);
+      browser.test.assertEq(
+        0,
+        contacts.length,
+        "Contact not added to second book."
+      );
+
+      let newContact = await browser.contacts.get(newContactId);
+      browser.test.assertEq(6, Object.keys(newContact).length);
+      browser.test.assertEq(newContactId, newContact.id);
+      browser.test.assertEq(firstBookId, newContact.parentId);
+      browser.test.assertEq("contact", newContact.type);
+      browser.test.assertEq(false, newContact.readOnly);
+      browser.test.assertEq(false, newContact.remote);
+      browser.test.assertEq(5, Object.keys(newContact.properties).length);
+      browser.test.assertEq("first", newContact.properties.FirstName);
+      browser.test.assertEq("last", newContact.properties.LastName);
+      browser.test.assertEq("Notes", newContact.properties.Notes);
+      browser.test.assertEq(
+        "Custom property",
+        newContact.properties.SomethingCustom
+      );
+      browser.test.assertEq(
+        `BEGIN:VCARD\r\nVERSION:4.0\r\nNOTE:Notes\r\nN:last;first;;;\r\nUID:${newContactId}\r\nEND:VCARD\r\n`,
+        newContact.properties.vCard
+      );
+
+      // Changing the UID should throw.
+      try {
+        await browser.contacts.update(newContactId, {
+          vCard: `BEGIN:VCARD\r\nVERSION:4.0\r\nN:;first;;;\r\nEMAIL;PREF=1:first@last\r\nUID:SomethingNew\r\nEND:VCARD\r\n`,
+        });
+        browser.test.fail(
+          `Updating a contact with a vCard with a differnt UID should throw`
+        );
+      } catch (ex) {
+        browser.test.assertEq(
+          `The card's UID ${newContactId} may not be changed: BEGIN:VCARD\r\nVERSION:4.0\r\nN:;first;;;\r\nEMAIL;PREF=1:first@last\r\nUID:SomethingNew\r\nEND:VCARD\r\n.`,
+          ex.message,
+          `browser.contacts.update threw exception`
+        );
+      }
+
+      // Test Custom1.
+      {
+        await browser.contacts.update(newContactId, {
+          vCard: `BEGIN:VCARD\r\nVERSION:4.0\r\nNOTE:Notes\r\nN:last;first;;;\r\nX-CUSTOM1;VALUE=TEXT:Original custom value\r\nEND:VCARD`,
+        });
+        await checkEvents([
+          "contacts",
+          "onUpdated",
+          { type: "contact", parentId: firstBookId, id: newContactId },
+          {
+            Custom1: { oldValue: null, newValue: "Original custom value" },
+          },
+        ]);
+        let updContact1 = await browser.contacts.get(newContactId);
+        browser.test.assertEq(
+          "Original custom value",
+          updContact1.properties.Custom1
+        );
+
+        await browser.contacts.update(newContactId, {
+          Custom1: "Updated custom value",
+        });
+        await checkEvents([
+          "contacts",
+          "onUpdated",
+          { type: "contact", parentId: firstBookId, id: newContactId },
+          {
+            Custom1: {
+              oldValue: "Original custom value",
+              newValue: "Updated custom value",
+            },
+          },
+        ]);
+        let updContact2 = await browser.contacts.get(newContactId);
+        browser.test.assertEq(
+          "Updated custom value",
+          updContact2.properties.Custom1
+        );
+        browser.test.assertTrue(
+          updContact2.properties.vCard.includes(
+            "X-CUSTOM1;VALUE=TEXT:Updated custom value"
+          ),
+          "vCard should include the correct x-custom1 entry"
+        );
+      }
+
+      // If a vCard and legacy properties are given, vCard must win.
+      await browser.contacts.update(newContactId, {
+        vCard: `BEGIN:VCARD\r\nVERSION:4.0\r\nN:;first;;;\r\nEMAIL;PREF=1:first@last\r\nUID:${newContactId}\r\nEND:VCARD\r\n`,
+        FirstName: "Superman",
+        PrimaryEmail: "c.kent@dailyplanet.com",
+        PreferDisplayName: "0",
+        OtherCustom: "Yet another custom property",
+        Notes: "Ignored Notes",
+      });
+      await checkEvents([
+        "contacts",
+        "onUpdated",
+        { type: "contact", parentId: firstBookId, id: newContactId },
+        {
+          PrimaryEmail: { oldValue: null, newValue: "first@last" },
+          LastName: { oldValue: "last", newValue: null },
+          OtherCustom: {
+            oldValue: null,
+            newValue: "Yet another custom property",
+          },
+          PreferDisplayName: { oldValue: null, newValue: "0" },
+          Custom1: { oldValue: "Updated custom value", newValue: null },
+        },
+      ]);
+
+      let updatedContact = await browser.contacts.get(newContactId);
+      browser.test.assertEq(6, Object.keys(updatedContact.properties).length);
+      browser.test.assertEq("first", updatedContact.properties.FirstName);
+      browser.test.assertEq(
+        "first@last",
+        updatedContact.properties.PrimaryEmail
+      );
+      browser.test.assertTrue(!("LastName" in updatedContact.properties));
+      browser.test.assertTrue(
+        !("Notes" in updatedContact.properties),
+        "The vCard is not specifying Notes and the specified Notes property should be ignored."
+      );
+      browser.test.assertEq(
+        "Custom property",
+        updatedContact.properties.SomethingCustom,
+        "Untouched custom properties should not be changed by updating the vCard"
+      );
+      browser.test.assertEq(
+        "Yet another custom property",
+        updatedContact.properties.OtherCustom,
+        "Custom properties should be added even while updating a vCard"
+      );
+      browser.test.assertEq(
+        "0",
+        updatedContact.properties.PreferDisplayName,
+        "Setting non-banished properties parallel to a vCard should update"
+      );
+      browser.test.assertEq(
+        `BEGIN:VCARD\r\nVERSION:4.0\r\nN:;first;;;\r\nEMAIL;PREF=1:first@last\r\nUID:${newContactId}\r\nEND:VCARD\r\n`,
+        updatedContact.properties.vCard
+      );
+
+      // Manually Remove properties.
+      await browser.contacts.update(newContactId, {
+        LastName: "lastname",
+        PrimaryEmail: null,
+        SecondEmail: "test@invalid.de",
+        SomethingCustom: null,
+        OtherCustom: null,
+      });
+      await checkEvents([
+        "contacts",
+        "onUpdated",
+        { type: "contact", parentId: firstBookId, id: newContactId },
+        {
+          LastName: { oldValue: null, newValue: "lastname" },
+          // It is how it is. Defining a 2nd email with no 1st, will make it the first.
+          PrimaryEmail: { oldValue: "first@last", newValue: "test@invalid.de" },
+          SomethingCustom: { oldValue: "Custom property", newValue: null },
+          OtherCustom: {
+            oldValue: "Yet another custom property",
+            newValue: null,
+          },
+        },
+      ]);
+
+      updatedContact = await browser.contacts.get(newContactId);
+      browser.test.assertEq(5, Object.keys(updatedContact.properties).length);
+      // LastName and FirstName are stored in the same multi field property and changing LastName should not change FirstName.
+      browser.test.assertEq("first", updatedContact.properties.FirstName);
+      browser.test.assertEq("lastname", updatedContact.properties.LastName);
+      browser.test.assertEq(
+        "test@invalid.de",
+        updatedContact.properties.PrimaryEmail
+      );
+      browser.test.assertTrue(
+        !("SomethingCustom" in updatedContact.properties)
+      );
+      browser.test.assertTrue(!("OtherCustom" in updatedContact.properties));
+      browser.test.assertEq(
+        `BEGIN:VCARD\r\nVERSION:4.0\r\nN:lastname;first;;;\r\nEMAIL:test@invalid.de\r\nUID:${newContactId}\r\nEND:VCARD\r\n`,
+        updatedContact.properties.vCard
+      );
+
+      // Add an email address, going from 1 to 2.Also remove FirstName, LastName should stay.
+      await browser.contacts.update(newContactId, {
+        FirstName: null,
+        PrimaryEmail: "new1@invalid.de",
+        SecondEmail: "new2@invalid.de",
+      });
+      await checkEvents([
+        "contacts",
+        "onUpdated",
+        { type: "contact", parentId: firstBookId, id: newContactId },
+        {
+          PrimaryEmail: {
+            oldValue: "test@invalid.de",
+            newValue: "new1@invalid.de",
+          },
+          SecondEmail: { oldValue: null, newValue: "new2@invalid.de" },
+          FirstName: { oldValue: "first", newValue: null },
+        },
+      ]);
+
+      updatedContact = await browser.contacts.get(newContactId);
+      browser.test.assertEq(5, Object.keys(updatedContact.properties).length);
+      browser.test.assertEq("lastname", updatedContact.properties.LastName);
+      browser.test.assertEq(
+        "new1@invalid.de",
+        updatedContact.properties.PrimaryEmail
+      );
+      browser.test.assertEq(
+        "new2@invalid.de",
+        updatedContact.properties.SecondEmail
+      );
+      browser.test.assertEq(
+        `BEGIN:VCARD\r\nVERSION:4.0\r\nN:lastname;;;;\r\nEMAIL;PREF=1:new1@invalid.de\r\nUID:${newContactId}\r\nEMAIL:new2@invalid.de\r\nEND:VCARD\r\n`,
+        updatedContact.properties.vCard
+      );
+
+      // Remove and email address, going from 2 to 1.
+      await browser.contacts.update(newContactId, {
+        SecondEmail: null,
+      });
+      await checkEvents([
+        "contacts",
+        "onUpdated",
+        { type: "contact", parentId: firstBookId, id: newContactId },
+        {
+          SecondEmail: { oldValue: "new2@invalid.de", newValue: null },
+        },
+      ]);
+
+      updatedContact = await browser.contacts.get(newContactId);
+      browser.test.assertEq(4, Object.keys(updatedContact.properties).length);
+      browser.test.assertEq("lastname", updatedContact.properties.LastName);
+      browser.test.assertEq(
+        "new1@invalid.de",
+        updatedContact.properties.PrimaryEmail
+      );
+      browser.test.assertEq(
+        `BEGIN:VCARD\r\nVERSION:4.0\r\nN:lastname;;;;\r\nEMAIL;PREF=1:new1@invalid.de\r\nUID:${newContactId}\r\nEND:VCARD\r\n`,
+        updatedContact.properties.vCard
+      );
+
+      // Set a fixed UID.
+      let fixedContactId = await browser.contacts.create(
+        firstBookId,
+        "this is a test",
+        {
+          FirstName: "a",
+          LastName: "test",
+        }
+      );
+      browser.test.assertEq("this is a test", fixedContactId);
+      await checkEvents([
+        "contacts",
+        "onCreated",
+        { type: "contact", parentId: firstBookId, id: "this is a test" },
+      ]);
+
+      let fixedContact = await browser.contacts.get("this is a test");
+      browser.test.assertEq("this is a test", fixedContact.id);
+
+      await browser.contacts.delete("this is a test");
+      await checkEvents([
+        "contacts",
+        "onDeleted",
+        firstBookId,
+        "this is a test",
+      ]);
+
+      try {
+        await browser.contacts.create(firstBookId, newContactId, {
+          FirstName: "uh",
+          LastName: "oh",
+        });
+        browser.test.fail(`Adding a contact with a duplicate id should throw`);
+      } catch (ex) {
+        browser.test.assertEq(
+          `Duplicate contact id: ${newContactId}`,
+          ex.message,
+          `browser.contacts.create threw exception`
+        );
+      }
+
+      browser.test.assertEq(0, events.length, "No events left unconsumed");
+      browser.test.log("Completed contactsTest");
+    }
+
+    async function mailingListsTest() {
+      browser.test.log("Starting mailingListsTest");
+      let mailingLists = await browser.mailingLists.list(firstBookId);
+      browser.test.assertTrue(Array.isArray(mailingLists));
+      browser.test.assertEq(0, mailingLists.length);
+
+      let newMailingListId = await browser.mailingLists.create(firstBookId, {
+        name: "name",
+      });
+      browser.test.assertEq(36, newMailingListId.length);
+      await checkEvents([
+        "mailingLists",
+        "onCreated",
+        { type: "mailingList", parentId: firstBookId, id: newMailingListId },
+      ]);
+
+      mailingLists = await browser.mailingLists.list(firstBookId);
+      browser.test.assertEq(
+        1,
+        mailingLists.length,
+        "List added to first book."
+      );
+
+      mailingLists = await browser.mailingLists.list(secondBookId);
+      browser.test.assertEq(
+        0,
+        mailingLists.length,
+        "List not added to second book."
+      );
+
+      let newAddressList = await browser.mailingLists.get(newMailingListId);
+      browser.test.assertEq(8, Object.keys(newAddressList).length);
+      browser.test.assertEq(newMailingListId, newAddressList.id);
+      browser.test.assertEq(firstBookId, newAddressList.parentId);
+      browser.test.assertEq("mailingList", newAddressList.type);
+      browser.test.assertEq("name", newAddressList.name);
+      browser.test.assertEq("", newAddressList.nickName);
+      browser.test.assertEq("", newAddressList.description);
+      browser.test.assertEq(false, newAddressList.readOnly);
+      browser.test.assertEq(false, newAddressList.remote);
+
+      // Test that a valid name is ensured for an existing mail list
+      await browser.test.assertRejects(
+        browser.mailingLists.update(newMailingListId, {
+          name: "",
+        }),
+        "An unexpected error occurred",
+        "browser.mailingLists.update threw exception"
+      );
+
+      await browser.test.assertRejects(
+        browser.mailingLists.update(newMailingListId, {
+          name: "Two  spaces invalid name",
+        }),
+        "An unexpected error occurred",
+        "browser.mailingLists.update threw exception"
+      );
+
+      await browser.test.assertRejects(
+        browser.mailingLists.update(newMailingListId, {
+          name: "><<<",
+        }),
+        "An unexpected error occurred",
+        "browser.mailingLists.update threw exception"
+      );
+
+      await browser.mailingLists.update(newMailingListId, {
+        name: "name!",
+        nickName: "nickname!",
+        description: "description!",
+      });
+      await checkEvents([
+        "mailingLists",
+        "onUpdated",
+        { type: "mailingList", parentId: firstBookId, id: newMailingListId },
+      ]);
+
+      let updatedMailingList = await browser.mailingLists.get(newMailingListId);
+      browser.test.assertEq("name!", updatedMailingList.name);
+      browser.test.assertEq("nickname!", updatedMailingList.nickName);
+      browser.test.assertEq("description!", updatedMailingList.description);
+
+      await browser.mailingLists.addMember(newMailingListId, newContactId);
+      await checkEvents([
+        "mailingLists",
+        "onMemberAdded",
+        { type: "contact", parentId: newMailingListId, id: newContactId },
+      ]);
+
+      let listMembers = await browser.mailingLists.listMembers(
+        newMailingListId
+      );
+      browser.test.assertTrue(Array.isArray(listMembers));
+      browser.test.assertEq(1, listMembers.length);
+
+      let anotherContactId = await browser.contacts.create(firstBookId, {
+        FirstName: "second",
+        LastName: "last",
+        PrimaryEmail: "em@il",
+      });
+      await checkEvents([
+        "contacts",
+        "onCreated",
+        {
+          type: "contact",
+          parentId: firstBookId,
+          id: anotherContactId,
+          readOnly: false,
+        },
+      ]);
+
+      await browser.mailingLists.addMember(newMailingListId, anotherContactId);
+      await checkEvents([
+        "mailingLists",
+        "onMemberAdded",
+        { type: "contact", parentId: newMailingListId, id: anotherContactId },
+      ]);
+
+      listMembers = await browser.mailingLists.listMembers(newMailingListId);
+      browser.test.assertEq(2, listMembers.length);
+
+      await browser.contacts.delete(anotherContactId);
+      await checkEvents(
+        ["contacts", "onDeleted", firstBookId, anotherContactId],
+        ["mailingLists", "onMemberRemoved", newMailingListId, anotherContactId]
+      );
+      listMembers = await browser.mailingLists.listMembers(newMailingListId);
+      browser.test.assertEq(1, listMembers.length);
+
+      await browser.mailingLists.removeMember(newMailingListId, newContactId);
+      await checkEvents([
+        "mailingLists",
+        "onMemberRemoved",
+        newMailingListId,
+        newContactId,
+      ]);
+      listMembers = await browser.mailingLists.listMembers(newMailingListId);
+      browser.test.assertEq(0, listMembers.length);
+
+      await browser.mailingLists.delete(newMailingListId);
+      await checkEvents([
+        "mailingLists",
+        "onDeleted",
+        firstBookId,
+        newMailingListId,
+      ]);
+
+      mailingLists = await browser.mailingLists.list(firstBookId);
+      browser.test.assertEq(0, mailingLists.length);
+
+      for (let operation of [
+        "get",
+        "update",
+        "delete",
+        "listMembers",
+        "addMember",
+        "removeMember",
+      ]) {
+        let args = [newMailingListId];
+        switch (operation) {
+          case "update":
+            args.push({ name: "" });
+            break;
+          case "addMember":
+          case "removeMember":
+            args.push(newContactId);
+            break;
+        }
+
+        try {
+          await browser.mailingLists[operation].apply(
+            browser.mailingLists,
+            args
+          );
+          browser.test.fail(
+            `Calling ${operation} on a non-existent mailing list should throw`
+          );
+        } catch (ex) {
+          browser.test.assertEq(
+            `mailingList with id=${newMailingListId} could not be found.`,
+            ex.message,
+            `browser.mailingLists.${operation} threw exception`
+          );
+        }
+      }
+
+      // Test that a valid name is ensured for a new mail list
+      await browser.test.assertRejects(
+        browser.mailingLists.create(firstBookId, {
+          name: "",
+        }),
+        "An unexpected error occurred",
+        "browser.mailingLists.update threw exception"
+      );
+
+      await browser.test.assertRejects(
+        browser.mailingLists.create(firstBookId, {
+          name: "Two  spaces invalid name",
+        }),
+        "An unexpected error occurred",
+        "browser.mailingLists.update threw exception"
+      );
+
+      await browser.test.assertRejects(
+        browser.mailingLists.create(firstBookId, {
+          name: "><<<",
+        }),
+        "An unexpected error occurred",
+        "browser.mailingLists.update threw exception"
+      );
+
+      browser.test.assertEq(0, events.length, "No events left unconsumed");
+      browser.test.log("Completed mailingListsTest");
+    }
+
+    async function contactRemovalTest() {
+      browser.test.log("Starting contactRemovalTest");
+      await browser.contacts.delete(newContactId);
+      await checkEvents(["contacts", "onDeleted", firstBookId, newContactId]);
+
+      for (let operation of ["get", "update", "delete"]) {
+        let args = [newContactId];
+        if (operation == "update") {
+          args.push({});
+        }
+
+        try {
+          await browser.contacts[operation].apply(browser.contacts, args);
+          browser.test.fail(
+            `Calling ${operation} on a non-existent contact should throw`
+          );
+        } catch (ex) {
+          browser.test.assertEq(
+            `contact with id=${newContactId} could not be found.`,
+            ex.message,
+            `browser.contacts.${operation} threw exception`
+          );
+        }
+      }
+
+      let contacts = await browser.contacts.list(firstBookId);
+      browser.test.assertEq(0, contacts.length);
+
+      browser.test.assertEq(0, events.length, "No events left unconsumed");
+      browser.test.log("Completed contactRemovalTest");
+    }
+
+    async function outsideEventsTest() {
+      browser.test.log("Starting outsideEventsTest");
+      let [bookId, newBookPrefId] = await outsideEvent("createAddressBook");
+      let [newBook] = await checkEvents([
+        "addressBooks",
+        "onCreated",
+        { type: "addressBook", id: bookId },
+      ]);
+      browser.test.assertEq("external add", newBook.name);
+
+      await outsideEvent("updateAddressBook", newBookPrefId);
+      let [updatedBook] = await checkEvents([
+        "addressBooks",
+        "onUpdated",
+        { type: "addressBook", id: bookId },
+      ]);
+      browser.test.assertEq("external edit", updatedBook.name);
+
+      await outsideEvent("deleteAddressBook", newBookPrefId);
+      await checkEvents(["addressBooks", "onDeleted", bookId]);
+
+      let [parentId1, contactId] = await outsideEvent("createContact");
+      let [newContact] = await checkEvents([
+        "contacts",
+        "onCreated",
+        { type: "contact", parentId: parentId1, id: contactId },
+      ]);
+      browser.test.assertEq("external", newContact.properties.FirstName);
+      browser.test.assertEq("add", newContact.properties.LastName);
+      browser.test.assertTrue(
+        newContact.properties.vCard.includes("VERSION:4.0"),
+        "vCard should be version 4.0"
+      );
+
+      // Update the contact from outside.
+      await outsideEvent("updateContact", contactId);
+      let [updatedContact] = await checkEvents([
+        "contacts",
+        "onUpdated",
+        { type: "contact", parentId: parentId1, id: contactId },
+        { LastName: { oldValue: "add", newValue: "edit" } },
+      ]);
+      browser.test.assertEq("external", updatedContact.properties.FirstName);
+      browser.test.assertEq("edit", updatedContact.properties.LastName);
+
+      let [parentId2, listId] = await outsideEvent("createMailingList");
+      let [newList] = await checkEvents([
+        "mailingLists",
+        "onCreated",
+        { type: "mailingList", parentId: parentId2, id: listId },
+      ]);
+      browser.test.assertEq("external add", newList.name);
+
+      await outsideEvent("updateMailingList", listId);
+      let [updatedList] = await checkEvents([
+        "mailingLists",
+        "onUpdated",
+        { type: "mailingList", parentId: parentId2, id: listId },
+      ]);
+      browser.test.assertEq("external edit", updatedList.name);
+
+      await outsideEvent("addMailingListMember", listId, contactId);
+      await checkEvents([
+        "mailingLists",
+        "onMemberAdded",
+        { type: "contact", parentId: listId, id: contactId },
+      ]);
+      let listMembers = await browser.mailingLists.listMembers(listId);
+      browser.test.assertEq(1, listMembers.length);
+
+      await outsideEvent("removeMailingListMember", listId, contactId);
+      await checkEvents(["mailingLists", "onMemberRemoved", listId, contactId]);
+
+      await outsideEvent("deleteMailingList", listId);
+      await checkEvents(["mailingLists", "onDeleted", parentId2, listId]);
+
+      await outsideEvent("deleteContact", contactId);
+      await checkEvents(["contacts", "onDeleted", parentId1, contactId]);
+
+      browser.test.log("Completed outsideEventsTest");
+    }
+
+    await addressBookTest();
+    await contactsTest();
+    await mailingListsTest();
+    await contactRemovalTest();
+    await outsideEventsTest();
+
+    browser.test.notifyPass("addressBooks");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    files: {
+      "background.js": background,
+      "utils.js": await getUtilsJS(),
+    },
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["addressBooks"],
+    },
+  });
+
+  let parent = MailServices.ab.getDirectory("jsaddrbook://abook.sqlite");
+  function findContact(id) {
+    for (let child of parent.childCards) {
+      if (child.UID == id) {
+        return child;
+      }
+    }
+    return null;
+  }
+  function findMailingList(id) {
+    for (let list of parent.childNodes) {
+      if (list.UID == id) {
+        return list;
+      }
+    }
+    return null;
+  }
+
+  extension.onMessage("outsideEventsTest", async (action, ...args) => {
+    switch (action) {
+      case "createAddressBook": {
+        let dirPrefId = MailServices.ab.newAddressBook(
+          "external add",
+          "",
+          Ci.nsIAbManager.JS_DIRECTORY_TYPE
+        );
+        let book = MailServices.ab.getDirectoryFromId(dirPrefId);
+        extension.sendMessage(book.UID, dirPrefId);
+        return;
+      }
+      case "updateAddressBook": {
+        let book = MailServices.ab.getDirectoryFromId(args[0]);
+        book.dirName = "external edit";
+        extension.sendMessage();
+        return;
+      }
+      case "deleteAddressBook": {
+        let book = MailServices.ab.getDirectoryFromId(args[0]);
+        MailServices.ab.deleteAddressBook(book.URI);
+        extension.sendMessage();
+        return;
+      }
+      case "createContact": {
+        let contact = new AddrBookCard();
+        contact.firstName = "external";
+        contact.lastName = "add";
+        contact.primaryEmail = "test@invalid";
+
+        let newContact = parent.addCard(contact);
+        extension.sendMessage(parent.UID, newContact.UID);
+        return;
+      }
+      case "updateContact": {
+        let contact = findContact(args[0]);
+        if (contact) {
+          contact.firstName = "external";
+          contact.lastName = "edit";
+          parent.modifyCard(contact);
+          extension.sendMessage();
+          return;
+        }
+        break;
+      }
+      case "deleteContact": {
+        let contact = findContact(args[0]);
+        if (contact) {
+          parent.deleteCards([contact]);
+          extension.sendMessage();
+          return;
+        }
+        break;
+      }
+      case "createMailingList": {
+        let list = Cc[
+          "@mozilla.org/addressbook/directoryproperty;1"
+        ].createInstance(Ci.nsIAbDirectory);
+        list.isMailList = true;
+        list.dirName = "external add";
+
+        let newList = parent.addMailList(list);
+        extension.sendMessage(parent.UID, newList.UID);
+        return;
+      }
+      case "updateMailingList": {
+        let list = findMailingList(args[0]);
+        if (list) {
+          list.dirName = "external edit";
+          list.editMailListToDatabase(null);
+          extension.sendMessage();
+          return;
+        }
+        break;
+      }
+      case "deleteMailingList": {
+        let list = findMailingList(args[0]);
+        if (list) {
+          parent.deleteDirectory(list);
+          extension.sendMessage();
+          return;
+        }
+        break;
+      }
+      case "addMailingListMember": {
+        let list = findMailingList(args[0]);
+        let contact = findContact(args[1]);
+
+        if (list && contact) {
+          list.addCard(contact);
+          equal(1, list.childCards.length);
+          extension.sendMessage();
+          return;
+        }
+        break;
+      }
+      case "removeMailingListMember": {
+        let list = findMailingList(args[0]);
+        let contact = findContact(args[1]);
+
+        if (list && contact) {
+          list.deleteCards([contact]);
+          equal(0, list.childCards.length);
+          ok(findContact(args[1]), "Contact was not removed");
+          extension.sendMessage();
+          return;
+        }
+        break;
+      }
+    }
+    throw new Error(
+      `Message "${action}" passed to handler didn't do anything.`
+    );
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("addressBooks");
+  await extension.unload();
+});
+
+add_task(async function test_addressBooks_MV3_event_pages() {
+  await AddonTestUtils.promiseStartupManager();
+
+  let files = {
+    "background.js": async () => {
+      // Whenever the extension starts or wakes up, hasFired is set to false. In
+      // case of a wake-up, the first fired event is the one that woke up the background.
+      let hasFired = false;
+
+      // Create and register event listener.
+      for (let event of [
+        "addressBooks.onCreated",
+        "addressBooks.onUpdated",
+        "addressBooks.onDeleted",
+        "contacts.onCreated",
+        "contacts.onUpdated",
+        "contacts.onDeleted",
+        "mailingLists.onCreated",
+        "mailingLists.onUpdated",
+        "mailingLists.onDeleted",
+        "mailingLists.onMemberAdded",
+        "mailingLists.onMemberRemoved",
+      ]) {
+        let [apiName, eventName] = event.split(".");
+        browser[apiName][eventName].addListener((...args) => {
+          // Only send the first event after background wake-up, this should be
+          // the only one expected.
+          if (!hasFired) {
+            hasFired = true;
+            browser.test.sendMessage(`${apiName}.${eventName} received`, args);
+          }
+        });
+      }
+
+      browser.test.sendMessage("background started");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      manifest_version: 3,
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["addressBooks"],
+      browser_specific_settings: { gecko: { id: "addressbook@xpcshell.test" } },
+    },
+  });
+
+  let parent = MailServices.ab.getDirectory("jsaddrbook://abook.sqlite");
+  function findContact(id) {
+    for (let child of parent.childCards) {
+      if (child.UID == id) {
+        return child;
+      }
+    }
+    return null;
+  }
+  function findMailingList(id) {
+    for (let list of parent.childNodes) {
+      if (list.UID == id) {
+        return list;
+      }
+    }
+    return null;
+  }
+  function outsideEvent(action, ...args) {
+    switch (action) {
+      case "createAddressBook": {
+        let dirPrefId = MailServices.ab.newAddressBook(
+          "external add",
+          "",
+          Ci.nsIAbManager.JS_DIRECTORY_TYPE
+        );
+        let book = MailServices.ab.getDirectoryFromId(dirPrefId);
+        return [book, dirPrefId];
+      }
+      case "updateAddressBook": {
+        let book = MailServices.ab.getDirectoryFromId(args[0]);
+        book.dirName = "external edit";
+        return [];
+      }
+      case "deleteAddressBook": {
+        let book = MailServices.ab.getDirectoryFromId(args[0]);
+        MailServices.ab.deleteAddressBook(book.URI);
+        return [];
+      }
+      case "createContact": {
+        let contact = new AddrBookCard();
+        contact.firstName = "external";
+        contact.lastName = "add";
+        contact.primaryEmail = "test@invalid";
+
+        let newContact = parent.addCard(contact);
+        return [parent.UID, newContact.UID];
+      }
+      case "updateContact": {
+        let contact = findContact(args[0]);
+        if (contact) {
+          contact.firstName = "external";
+          contact.lastName = "edit";
+          parent.modifyCard(contact);
+          return [];
+        }
+        break;
+      }
+      case "deleteContact": {
+        let contact = findContact(args[0]);
+        if (contact) {
+          parent.deleteCards([contact]);
+          return [];
+        }
+        break;
+      }
+      case "createMailingList": {
+        let list = Cc[
+          "@mozilla.org/addressbook/directoryproperty;1"
+        ].createInstance(Ci.nsIAbDirectory);
+        list.isMailList = true;
+        list.dirName = "external add";
+
+        let newList = parent.addMailList(list);
+        return [parent.UID, newList.UID];
+      }
+      case "updateMailingList": {
+        let list = findMailingList(args[0]);
+        if (list) {
+          list.dirName = "external edit";
+          list.editMailListToDatabase(null);
+          return [];
+        }
+        break;
+      }
+      case "deleteMailingList": {
+        let list = findMailingList(args[0]);
+        if (list) {
+          parent.deleteDirectory(list);
+          return [];
+        }
+        break;
+      }
+      case "addMailingListMember": {
+        let list = findMailingList(args[0]);
+        let contact = findContact(args[1]);
+
+        if (list && contact) {
+          list.addCard(contact);
+          equal(1, list.childCards.length);
+          return [];
+        }
+        break;
+      }
+      case "removeMailingListMember": {
+        let list = findMailingList(args[0]);
+        let contact = findContact(args[1]);
+
+        if (list && contact) {
+          list.deleteCards([contact]);
+          equal(0, list.childCards.length);
+          ok(findContact(args[1]), "Contact was not removed");
+          return [];
+        }
+        break;
+      }
+    }
+    throw new Error(
+      `Message "${action}" passed to handler didn't do anything.`
+    );
+  }
+
+  function checkPersistentListeners({ primed }) {
+    // A persistent event is referenced by its moduleName as defined in
+    // ext-mails.json, not by its actual namespace.
+    const persistent_events = [
+      "addressBook.onAddressBookCreated",
+      "addressBook.onAddressBookUpdated",
+      "addressBook.onAddressBookDeleted",
+      "addressBook.onContactCreated",
+      "addressBook.onContactUpdated",
+      "addressBook.onContactDeleted",
+      "addressBook.onMailingListCreated",
+      "addressBook.onMailingListUpdated",
+      "addressBook.onMailingListDeleted",
+      "addressBook.onMemberAdded",
+      "addressBook.onMemberRemoved",
+    ];
+
+    for (let event of persistent_events) {
+      let [moduleName, eventName] = event.split(".");
+      assertPersistentListeners(extension, moduleName, eventName, {
+        primed,
+      });
+    }
+  }
+
+  await extension.startup();
+  await extension.awaitMessage("background started");
+  checkPersistentListeners({ primed: false });
+
+  // addressBooks.onCreated.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  let [newBook, dirPrefId] = outsideEvent("createAddressBook");
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  Assert.deepEqual(
+    [
+      {
+        id: newBook.UID,
+        type: "addressBook",
+        name: "external add",
+        readOnly: false,
+        remote: false,
+      },
+    ],
+    await extension.awaitMessage("addressBooks.onCreated received"),
+    "The primed addressBooks.onCreated event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // addressBooks.onUpdated.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  outsideEvent("updateAddressBook", dirPrefId);
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  Assert.deepEqual(
+    [
+      {
+        id: newBook.UID,
+        type: "addressBook",
+        name: "external edit",
+        readOnly: false,
+        remote: false,
+      },
+    ],
+    await extension.awaitMessage("addressBooks.onUpdated received"),
+    "The primed addressBooks.onUpdated event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // addressBooks.onDeleted.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  outsideEvent("deleteAddressBook", dirPrefId);
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  Assert.deepEqual(
+    [newBook.UID],
+    await extension.awaitMessage("addressBooks.onDeleted received"),
+    "The primed addressBooks.onDeleted event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // contacts.onCreated.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  let [parentId1, contactId] = outsideEvent("createContact");
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  let [createdNode] = await extension.awaitMessage(
+    "contacts.onCreated received"
+  );
+  Assert.deepEqual(
+    {
+      type: "contact",
+      parentId: parentId1,
+      id: contactId,
+    },
+    {
+      type: createdNode.type,
+      parentId: createdNode.parentId,
+      id: createdNode.id,
+    },
+    "The primed contacts.onCreated event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // contacts.onUpdated.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  outsideEvent("updateContact", contactId);
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  let [updatedNode, changedProperties] = await extension.awaitMessage(
+    "contacts.onUpdated received"
+  );
+  Assert.deepEqual(
+    [
+      { type: "contact", parentId: parentId1, id: contactId },
+      { LastName: { oldValue: "add", newValue: "edit" } },
+    ],
+    [
+      {
+        type: updatedNode.type,
+        parentId: updatedNode.parentId,
+        id: updatedNode.id,
+      },
+      changedProperties,
+    ],
+    "The primed contacts.onUpdated event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // mailingLists.onCreated.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  let [parentId2, listId] = outsideEvent("createMailingList");
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  Assert.deepEqual(
+    [
+      {
+        type: "mailingList",
+        parentId: parentId2,
+        id: listId,
+        name: "external add",
+        nickName: "",
+        description: "",
+        readOnly: false,
+        remote: false,
+      },
+    ],
+    await extension.awaitMessage("mailingLists.onCreated received"),
+    "The primed mailingLists.onCreated event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // mailingList.onUpdated.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  outsideEvent("updateMailingList", listId);
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  Assert.deepEqual(
+    [
+      {
+        type: "mailingList",
+        parentId: parentId2,
+        id: listId,
+        name: "external edit",
+        nickName: "",
+        description: "",
+        readOnly: false,
+        remote: false,
+      },
+    ],
+    await extension.awaitMessage("mailingLists.onUpdated received"),
+    "The primed mailingLists.onUpdated event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // mailingList.onMemberAdded.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  outsideEvent("addMailingListMember", listId, contactId);
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  let [addedNode] = await extension.awaitMessage(
+    "mailingLists.onMemberAdded received"
+  );
+  Assert.deepEqual(
+    { type: "contact", parentId: listId, id: contactId },
+    { type: addedNode.type, parentId: addedNode.parentId, id: addedNode.id },
+    "The primed mailingLists.onMemberAdded event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // mailingList.onMemberRemoved.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  outsideEvent("removeMailingListMember", listId, contactId);
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  Assert.deepEqual(
+    [listId, contactId],
+    await extension.awaitMessage("mailingLists.onMemberRemoved received"),
+    "The primed mailingLists.onMemberRemoved event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // mailingList.onDeleted.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  outsideEvent("deleteMailingList", listId);
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  Assert.deepEqual(
+    [parentId2, listId],
+    await extension.awaitMessage("mailingLists.onDeleted received"),
+    "The primed mailingLists.onDeleted event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  // contacts.onDeleted.
+
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  checkPersistentListeners({ primed: true });
+  outsideEvent("deleteContact", contactId);
+  // The event should have restarted the background.
+  await extension.awaitMessage("background started");
+  Assert.deepEqual(
+    [parentId1, contactId],
+    await extension.awaitMessage("contacts.onDeleted received"),
+    "The primed contacts.onDeleted event should return the correct values"
+  );
+  checkPersistentListeners({ primed: false });
+
+  await extension.unload();
+
+  await AddonTestUtils.promiseShutdownManager();
+});
+
+add_task(async function test_photos() {
+  async function background() {
+    let events = [];
+    let eventPromise;
+    let eventPromiseResolve;
+    for (let eventNamespace of ["addressBooks", "contacts"]) {
+      for (let eventName of ["onCreated", "onUpdated", "onDeleted"]) {
+        if (eventName in browser[eventNamespace]) {
+          browser[eventNamespace][eventName].addListener((...args) => {
+            events.push({ namespace: eventNamespace, name: eventName, args });
+            if (eventPromiseResolve) {
+              let resolve = eventPromiseResolve;
+              eventPromiseResolve = null;
+              resolve();
+            }
+          });
+        }
+      }
+    }
+
+    let getDataUrl = function (file) {
+      return new Promise((resolve, reject) => {
+        var reader = new FileReader();
+        reader.readAsDataURL(file);
+        reader.onload = function () {
+          resolve(reader.result);
+        };
+        reader.onerror = function (error) {
+          reject(new Error(error));
+        };
+      });
+    };
+
+    let updateAndVerifyPhoto = async function (
+      parentId,
+      id,
+      photoFile,
+      photoData
+    ) {
+      eventPromise = new Promise(resolve => {
+        eventPromiseResolve = resolve;
+      });
+      await browser.contacts.setPhoto(id, photoFile);
+
+      await checkEvents([
+        "contacts",
+        "onUpdated",
+        { type: "contact", parentId, id },
+        {},
+      ]);
+      let updatedPhoto = await browser.contacts.getPhoto(id);
+      // eslint-disable-next-line mozilla/use-isInstance
+      browser.test.assertTrue(updatedPhoto instanceof File);
+      browser.test.assertEq("image/png", updatedPhoto.type);
+      browser.test.assertEq(`${id}.png`, updatedPhoto.name);
+      browser.test.assertEq(photoData, await getDataUrl(updatedPhoto));
+    };
+    let normalizeVCard = function (vCard) {
+      return vCard
+        .replaceAll("\r\n", "")
+        .replaceAll("\n", "")
+        .replaceAll(" ", "");
+    };
+    let outsideEvent = function (action, ...args) {
+      eventPromise = new Promise(resolve => {
+        eventPromiseResolve = resolve;
+      });
+      return window.sendMessage("outsideEventsTest", action, ...args);
+    };
+    let checkEvents = async function (...expectedEvents) {
+      if (eventPromiseResolve) {
+        await eventPromise;
+      }
+
+      browser.test.assertEq(
+        expectedEvents.length,
+        events.length,
+        "Correct number of events"
+      );
+
+      if (expectedEvents.length != events.length) {
+        for (let event of events) {
+          let args = event.args.join(", ");
+          browser.test.log(`${event.namespace}.${event.name}(${args})`);
+        }
+        throw new Error("Wrong number of events, stopping.");
+      }
+
+      for (let [namespace, name, ...expectedArgs] of expectedEvents) {
+        let event = events.shift();
+        browser.test.assertEq(
+          namespace,
+          event.namespace,
+          "Event namespace is correct"
+        );
+        browser.test.assertEq(name, event.name, "Event type is correct");
+        browser.test.assertEq(
+          expectedArgs.length,
+          event.args.length,
+          "Argument count is correct"
+        );
+        window.assertDeepEqual(expectedArgs, event.args);
+        if (expectedEvents.length == 1) {
+          return event.args;
+        }
+      }
+
+      return null;
+    };
+
+    let whitePixelData =
+      "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQmCC";
+    let bluePixelData =
+      "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQg==";
+    let greenPixelData =
+      "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAMSURBVBhXY5CeYAMAAbEA6ASxSWcAAAAASUVORK5CYII=";
+    let redPixelData =
+      "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAMSURBVBhXY3growIAAycBLhVrvukAAAAASUVORK5CYII=";
+    let vCard3WhitePixel =
+      "PHOTO;ENCODING=B;TYPE=PNG:iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQmCC";
+    let vCard4WhitePixel =
+      "PHOTO;VALUE=URL:data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQmCC";
+    let vCard4BluePixel =
+      "PHOTO;VALUE=URL:data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQg==";
+
+    // Create a photo file, which is linked to a local file to simulate a file
+    // opened through a filepicker.
+    let [redPixelRealFile] = await window.sendMessage("getRedPixelFile");
+
+    // Create a photo file, which is a simple data blob.
+    let greenPixelFile = await fetch(greenPixelData)
+      .then(res => res.arrayBuffer())
+      .then(buf => new File([buf], "greenPixel.png", { type: "image/png" }));
+
+    // -------------------------------------------------------------------------
+    // Test vCard v4 with a photoName set.
+    // -------------------------------------------------------------------------
+
+    let [parentId1, contactId1, photoName1] = await outsideEvent(
+      "createV4ContactWithPhotoName"
+    );
+    let [newContact] = await checkEvents([
+      "contacts",
+      "onCreated",
+      { type: "contact", parentId: parentId1, id: contactId1 },
+    ]);
+    browser.test.assertEq("external", newContact.properties.FirstName);
+    browser.test.assertEq("add", newContact.properties.LastName);
+    browser.test.assertTrue(
+      newContact.properties.vCard.includes("VERSION:4.0"),
+      "vCard should be version 4.0"
+    );
+    browser.test.assertTrue(
+      normalizeVCard(newContact.properties.vCard).includes(vCard4WhitePixel),
+      `vCard should include the correct Photo property [${normalizeVCard(
+        newContact.properties.vCard
+      )}] vs [${vCard4WhitePixel}]`
+    );
+    // Check internal photoUrl is the correct fileUrl.
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId1,
+      `^file:.*?${photoName1}$`
+    );
+
+    // Test if we can get the photo through the API.
+
+    let photo = await browser.contacts.getPhoto(contactId1);
+    // eslint-disable-next-line mozilla/use-isInstance
+    browser.test.assertTrue(photo instanceof File);
+    browser.test.assertEq("image/png", photo.type);
+    browser.test.assertEq(`${contactId1}.png`, photo.name);
+    browser.test.assertEq(
+      whitePixelData,
+      await getDataUrl(photo),
+      "vCard 4.0 contact with photo from internal fileUrl from photoName should return the correct photo file"
+    );
+    // Re-check internal photoUrl.
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId1,
+      `^file:.*?${photoName1}$`
+    );
+
+    // Test if we can update the photo through the API by providing a file which
+    // is linked to a local file. Since this vCard had only a photoName set and
+    // its photo stored as a local file, the updated photo should also be stored
+    // as a local file.
+
+    await updateAndVerifyPhoto(
+      parentId1,
+      contactId1,
+      redPixelRealFile,
+      redPixelData
+    );
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId1,
+      `^file:.*?${contactId1}\.png$`
+    );
+
+    // Test if we can update the photo through the API, by providing a pure data
+    // blob (decoupled from a local file, without file.mozFullPath set).
+
+    await updateAndVerifyPhoto(
+      parentId1,
+      contactId1,
+      greenPixelFile,
+      greenPixelData
+    );
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId1,
+      `^file:.*?${contactId1}-1\.png$`
+    );
+
+    // Test if we get the correct photo if it is updated by the user, storing the
+    // photo in its vCard (outside of the API).
+
+    await outsideEvent("updateV4ContactWithBluePixel", contactId1);
+    let [updatedContact1] = await checkEvents([
+      "contacts",
+      "onUpdated",
+      { type: "contact", parentId: parentId1, id: contactId1 },
+      { LastName: { oldValue: "add", newValue: "edit" } },
+    ]);
+    browser.test.assertEq("external", updatedContact1.properties.FirstName);
+    browser.test.assertEq("edit", updatedContact1.properties.LastName);
+    let updatedPhoto1 = await browser.contacts.getPhoto(contactId1);
+    // eslint-disable-next-line mozilla/use-isInstance
+    browser.test.assertTrue(updatedPhoto1 instanceof File);
+    browser.test.assertEq("image/png", updatedPhoto1.type);
+    browser.test.assertEq(`${contactId1}.png`, updatedPhoto1.name);
+    browser.test.assertEq(bluePixelData, await getDataUrl(updatedPhoto1));
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId1,
+      bluePixelData
+    );
+
+    // -------------------------------------------------------------------------
+    // Test vCard v4 with a photoName and also a photo in its vCard.
+    // -------------------------------------------------------------------------
+
+    let [parentId2, contactId2] = await outsideEvent(
+      "createV4ContactWithBothPhotoProps"
+    );
+    let [newContact2] = await checkEvents([
+      "contacts",
+      "onCreated",
+      { type: "contact", parentId: parentId2, id: contactId2 },
+    ]);
+    browser.test.assertEq("external", newContact2.properties.FirstName);
+    browser.test.assertEq("add", newContact2.properties.LastName);
+    browser.test.assertTrue(
+      newContact2.properties.vCard.includes("VERSION:4.0"),
+      "vCard should be version 4.0"
+    );
+    // The card should not include vCard4WhitePixel (which photoName points to),
+    // but the value of vCard4BluePixel stored in the vCard photo property.
+    browser.test.assertTrue(
+      normalizeVCard(newContact2.properties.vCard).includes(vCard4BluePixel),
+      `vCard should include the correct Photo property [${normalizeVCard(
+        newContact2.properties.vCard
+      )}] vs [${vCard4BluePixel}]`
+    );
+    // Check internal photoUrl is the correct dataUrl.
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId2,
+      bluePixelData
+    );
+
+    // Test if we can get the correct photo through the API.
+
+    let photo3 = await browser.contacts.getPhoto(contactId2);
+    // eslint-disable-next-line mozilla/use-isInstance
+    browser.test.assertTrue(photo3 instanceof File);
+    browser.test.assertEq("image/png", photo3.type);
+    browser.test.assertEq(`${contactId2}.png`, photo3.name);
+    browser.test.assertEq(
+      bluePixelData,
+      await getDataUrl(photo3),
+      "vCard 4.0 contact with photo from internal dataUrl from vCard (vCard wins over photoName) should return the correct photo file"
+    );
+    // Re-check internal photoUrl.
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId2,
+      bluePixelData
+    );
+
+    // Test if we can update the photo through the API by providing a file which
+    // is linked to a local file. Since this vCard had its photo stored as dataUrl
+    // in the vCard, the updated photo should be stored as a dataUrl as well.
+
+    await updateAndVerifyPhoto(
+      parentId2,
+      contactId2,
+      redPixelRealFile,
+      redPixelData
+    );
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId2,
+      redPixelData
+    );
+
+    // Test if we can update the photo through the API, by providing a pure data
+    // blob (decoupled from a local file, without file.mozFullPath set).
+
+    await updateAndVerifyPhoto(
+      parentId2,
+      contactId2,
+      greenPixelFile,
+      greenPixelData
+    );
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId2,
+      greenPixelData
+    );
+
+    // -------------------------------------------------------------------------
+    // Test vCard v3 with a photoName set.
+    // -------------------------------------------------------------------------
+
+    let [parentId3, contactId3, photoName4] = await outsideEvent(
+      "createV3ContactWithPhotoName"
+    );
+    let [newContact4] = await checkEvents([
+      "contacts",
+      "onCreated",
+      { type: "contact", parentId: parentId3, id: contactId3 },
+    ]);
+    browser.test.assertEq("external", newContact4.properties.FirstName);
+    browser.test.assertEq("add", newContact4.properties.LastName);
+    browser.test.assertTrue(
+      newContact4.properties.vCard.includes("VERSION:3.0"),
+      "vCard should be version 3.0"
+    );
+    browser.test.assertTrue(
+      normalizeVCard(newContact4.properties.vCard).includes(vCard3WhitePixel),
+      `vCard should include the correct Photo property [${normalizeVCard(
+        newContact4.properties.vCard
+      )}] vs [${vCard3WhitePixel}]`
+    );
+    // Check internal photoUrl is the correct fileUrl.
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId3,
+      `^file:.*?${photoName4}$`
+    );
+    let photo4 = await browser.contacts.getPhoto(contactId3);
+    // eslint-disable-next-line mozilla/use-isInstance
+    browser.test.assertTrue(photo4 instanceof File);
+    browser.test.assertEq("image/png", photo4.type);
+    browser.test.assertEq(`${contactId3}.png`, photo4.name);
+    browser.test.assertEq(
+      whitePixelData,
+      await getDataUrl(photo4),
+      "vCard 3.0 contact with photo from internal fileUrl from photoName should return the correct photo file"
+    );
+    // Re-check internal photoUrl.
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId3,
+      `^file:.*?${photoName4}$`
+    );
+
+    // Test if we can update the photo through the API by providing a file which
+    // is linked to a local file. Since this vCard had only a photoName set and
+    // its photo stored as a local file, the updated photo should also be stored
+    // as a local file.
+
+    await updateAndVerifyPhoto(
+      parentId3,
+      contactId3,
+      redPixelRealFile,
+      redPixelData
+    );
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId3,
+      `^file:.*?${contactId3}\.png$`
+    );
+
+    // Test if we can update the photo through the API, by providing a pure data
+    // blob (decoupled from a local file, without file.mozFullPath set).
+
+    await updateAndVerifyPhoto(
+      parentId3,
+      contactId3,
+      greenPixelFile,
+      greenPixelData
+    );
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId3,
+      `^file:.*?${contactId3}-1\.png$`
+    );
+
+    // Test if we get the correct photo if it is updated by the user, storing the
+    // photo in its vCard (outside of the API).
+
+    await outsideEvent("updateV3ContactWithBluePixel", contactId3);
+    let [updatedContact3] = await checkEvents([
+      "contacts",
+      "onUpdated",
+      { type: "contact", parentId: parentId3, id: contactId3 },
+      { LastName: { oldValue: "add", newValue: "edit" } },
+    ]);
+    browser.test.assertEq("external", updatedContact3.properties.FirstName);
+    browser.test.assertEq("edit", updatedContact3.properties.LastName);
+    let updatedPhoto3 = await browser.contacts.getPhoto(contactId3);
+    // eslint-disable-next-line mozilla/use-isInstance
+    browser.test.assertTrue(updatedPhoto3 instanceof File);
+    browser.test.assertEq("image/png", updatedPhoto3.type);
+    browser.test.assertEq(`${contactId3}.png`, updatedPhoto3.name);
+    browser.test.assertEq(bluePixelData, await getDataUrl(updatedPhoto3));
+    await window.sendMessage(
+      "verifyInternalPhotoUrl",
+      contactId3,
+      bluePixelData
+    );
+
+    // Cleanup. Delete all created contacts.
+
+    await outsideEvent("deleteContact", contactId1);
+    await checkEvents(["contacts", "onDeleted", parentId1, contactId1]);
+    await outsideEvent("deleteContact", contactId2);
+    await checkEvents(["contacts", "onDeleted", parentId2, contactId2]);
+    await outsideEvent("deleteContact", contactId3);
+    await checkEvents(["contacts", "onDeleted", parentId3, contactId3]);
+    browser.test.notifyPass("addressBooksPhotos");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    files: {
+      "background.js": background,
+      "utils.js": await getUtilsJS(),
+    },
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["addressBooks"],
+    },
+  });
+
+  let parent = MailServices.ab.getDirectory("jsaddrbook://abook.sqlite");
+  function findContact(id) {
+    for (let child of parent.childCards) {
+      if (child.UID == id) {
+        return child;
+      }
+    }
+    return null;
+  }
+
+  async function getUniqueWhitePixelFile() {
+    // Copy photo file into the required Photos subfolder of the profile folder.
+    let photoName = `${AddrBookUtils.newUID()}.png`;
+    await IOUtils.copy(
+      do_get_file("images/whitePixel.png").path,
+      PathUtils.join(PathUtils.profileDir, "Photos", photoName)
+    );
+    return photoName;
+  }
+
+  extension.onMessage("getRedPixelFile", async () => {
+    let redPixelFile = await File.createFromNsIFile(
+      do_get_file("images/redPixel.png")
+    );
+    extension.sendMessage(redPixelFile);
+  });
+
+  extension.onMessage("verifyInternalPhotoUrl", (id, expected) => {
+    let contact = findContact(id);
+    let photoUrl = contact.photoURL;
+    if (expected.startsWith("data:")) {
+      Assert.equal(expected, photoUrl, `photoURL should be correct`);
+    } else {
+      let regExp = new RegExp(expected);
+      Assert.ok(
+        regExp.test(photoUrl),
+        `photoURL <${photoUrl}> should match expected regExp <${expected}>`
+      );
+    }
+    extension.sendMessage();
+  });
+
+  extension.onMessage("outsideEventsTest", async (action, ...args) => {
+    switch (action) {
+      case "createV4ContactWithPhotoName": {
+        let photoName = await getUniqueWhitePixelFile();
+        let contact = new AddrBookCard();
+        contact.firstName = "external";
+        contact.lastName = "add";
+        contact.primaryEmail = "test@invalid";
+        contact.setProperty("PhotoName", photoName);
+
+        let newContact = parent.addCard(contact);
+        extension.sendMessage(parent.UID, newContact.UID, photoName);
+        return;
+      }
+      case "createV4ContactWithBothPhotoProps": {
+        // This contact has whitePixel as file but bluePixel in the vCard.
+        let photoName = await getUniqueWhitePixelFile();
+        let contact = new AddrBookCard();
+        contact.setProperty("PhotoName", photoName);
+        contact.setProperty(
+          "_vCard",
+          formatVCard`
+            BEGIN:VCARD
+            VERSION:4.0
+            EMAIL;PREF=1:test@invalid
+            N:add;external;;;
+            UID:fd9aecf9-2453-4ba1-bec6-574a15bb380b
+            PHOTO;VALUE=URL:data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAA
+             ACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQg==
+            END:VCARD
+          `
+        );
+        let newContact = parent.addCard(contact);
+        extension.sendMessage(parent.UID, newContact.UID, photoName);
+        return;
+      }
+      case "updateV4ContactWithBluePixel": {
+        let contact = findContact(args[0]);
+        if (contact) {
+          contact.setProperty(
+            "_vCard",
+            formatVCard`
+              BEGIN:VCARD
+              VERSION:4.0
+              EMAIL;PREF=1:test@invalid
+              N:edit;external;;;
+              PHOTO;VALUE=URL:data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAA
+               ACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQg==
+              END:VCARD
+            `
+          );
+          parent.modifyCard(contact);
+          extension.sendMessage();
+          return;
+        }
+        break;
+      }
+      case "createV3ContactWithPhotoName": {
+        let photoName = await getUniqueWhitePixelFile();
+        let contact = new AddrBookCard();
+        contact.setProperty("PhotoName", photoName);
+        contact.setProperty(
+          "_vCard",
+          formatVCard`
+            BEGIN:VCARD
+            VERSION:3.0
+            EMAIL:test@invalid
+            N:add;external
+            UID:fd9aecf9-2453-4ba1-bec6-574a15bb380c
+            END:VCARD
+          `
+        );
+        let newContact = parent.addCard(contact);
+        extension.sendMessage(parent.UID, newContact.UID, photoName);
+        return;
+      }
+      case "updateV3ContactWithBluePixel": {
+        let contact = findContact(args[0]);
+        if (contact) {
+          contact.setProperty(
+            "_vCard",
+            formatVCard`
+              BEGIN:VCARD
+              VERSION:3.0
+              EMAIL:test@invalid
+              N:edit;external
+              PHOTO;ENCODING=b;TYPE=PNG:iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAD
+               ElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQg==
+              END:VCARD
+            `
+          );
+          parent.modifyCard(contact);
+          extension.sendMessage();
+          return;
+        }
+        break;
+      }
+      case "deleteContact": {
+        let contact = findContact(args[0]);
+        if (contact) {
+          parent.deleteCards([contact]);
+          extension.sendMessage();
+          return;
+        }
+        break;
+      }
+    }
+    throw new Error(
+      `Message "${action}" passed to handler didn't do anything.`
+    );
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("addressBooksPhotos");
+  await extension.unload();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_provider.js b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_provider.js
new file mode 100644
index 0000000000..a09540dcbe
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_provider.js
@@ -0,0 +1,139 @@
+/* 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/. */
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+add_task(async function () {
+  let extension = ExtensionTestUtils.loadExtension({
+    background: async () => {
+      let id = "9b9074ff-8fa4-4c58-9c3b-bc9ea2e17db1";
+      let dummy = async (node, searchString, query) => {
+        await browser.test.assertTrue(
+          false,
+          "Should have removed this address book"
+        );
+      };
+      await browser.addressBooks.provider.onSearchRequest.addListener(dummy, {
+        addressBookName: "dummy",
+        isSecure: false,
+        id,
+      });
+      await browser.addressBooks.provider.onSearchRequest.removeListener(dummy);
+      id = "00e1d9af-a846-4ef5-a6ac-15e8926bf6d3";
+      await browser.addressBooks.provider.onSearchRequest.addListener(
+        async (node, searchString, query) => {
+          await browser.test.assertEq(
+            id,
+            node.id,
+            "Addressbook should have the id we requested"
+          );
+          return {
+            results: [
+              {
+                DisplayName: searchString,
+                PrimaryEmail: searchString + "@example.com",
+              },
+            ],
+            isCompleteResult: true,
+          };
+        },
+        {
+          addressBookName: "xpcshell",
+          isSecure: false,
+          id,
+        }
+      );
+      await browser.addressBooks.provider.onSearchRequest.addListener(
+        async (node, searchString, query) => {
+          await browser.test.assertTrue(
+            false,
+            "Should not have created a duplicate address book"
+          );
+        },
+        {
+          addressBookName: "xpcshell",
+          isSecure: false,
+          id,
+        }
+      );
+    },
+    manifest: { permissions: ["addressBooks"] },
+  });
+
+  await extension.startup();
+
+  const dummyUID = "9b9074ff-8fa4-4c58-9c3b-bc9ea2e17db1";
+  let searchBook = MailServices.ab.getDirectoryFromUID(dummyUID);
+  ok(searchBook == null, "Dummy directory was removed by extension");
+
+  const UID = "00e1d9af-a846-4ef5-a6ac-15e8926bf6d3";
+  searchBook = MailServices.ab.getDirectoryFromUID(UID);
+  ok(searchBook != null, "Extension registered an async directory");
+
+  let foundCards = 0;
+  await new Promise(resolve => {
+    searchBook.search(null, "test", {
+      onSearchFoundCard(card) {
+        ok(card != null, "A card was found.");
+        equal(card.directoryUID, UID, "The card comes from the directory.");
+        equal(
+          card.primaryEmail,
+          "test@example.com",
+          "The card has the correct email address."
+        );
+        equal(
+          card.displayName,
+          "test",
+          "The card has the correct display name."
+        );
+        foundCards++;
+      },
+      onSearchFinished(status, isCompleteResult) {
+        ok(Components.isSuccessCode(status), "Search finished successfully.");
+        equal(foundCards, 1, "One card was found.");
+        ok(isCompleteResult, "A full result set was received.");
+        resolve();
+      },
+    });
+  });
+
+  let autoCompleteSearch = Cc[
+    "@mozilla.org/autocomplete/search;1?name=addrbook"
+  ].createInstance(Ci.nsIAutoCompleteSearch);
+  await new Promise(resolve => {
+    autoCompleteSearch.startSearch("test", null, null, {
+      onSearchResult(aSearch, aResult) {
+        equal(aSearch, autoCompleteSearch, "This is our search.");
+        if (aResult.searchResult == Ci.nsIAutoCompleteResult.RESULT_SUCCESS) {
+          equal(aResult.matchCount, 1, "One match was found.");
+          equal(
+            aResult.getValueAt(0),
+            "test <test@example.com>",
+            "The match had the expected value."
+          );
+          resolve();
+        } else {
+          equal(
+            aResult.searchResult,
+            Ci.nsIAutoCompleteResult.RESULT_NOMATCH_ONGOING,
+            "We should be waiting for the extension's results."
+          );
+        }
+      },
+    });
+  });
+
+  await extension.unload();
+  searchBook = MailServices.ab.getDirectoryFromUID(UID);
+  ok(searchBook == null, "Extension directory removed after unload");
+});
+
+registerCleanupFunction(() => {
+  // Make sure any open database is given a chance to close.
+  Services.startup.advanceShutdownPhase(
+    Services.startup.SHUTDOWN_PHASE_APPSHUTDOWNCONFIRMED
+  );
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_quickSearch.js b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_quickSearch.js
new file mode 100644
index 0000000000..9a6bbd8f4e
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_quickSearch.js
@@ -0,0 +1,238 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { LDAPServer } = ChromeUtils.import(
+  "resource://testing-common/LDAPServer.jsm"
+);
+
+add_setup(async () => {
+  Services.prefs.setIntPref("ldap_2.servers.osx.dirType", -1);
+
+  registerCleanupFunction(() => {
+    LDAPServer.close();
+    // Make sure any open database is given a chance to close.
+    Services.startup.advanceShutdownPhase(
+      Services.startup.SHUTDOWN_PHASE_APPSHUTDOWNCONFIRMED
+    );
+  });
+});
+
+add_task(async function test_quickSearch() {
+  async function background() {
+    let book1 = await browser.addressBooks.create({ name: "book1" });
+    let book2 = await browser.addressBooks.create({ name: "book2" });
+
+    let book1contacts = {
+      charlie: await browser.contacts.create(book1, { FirstName: "charlie" }),
+      juliet: await browser.contacts.create(book1, { FirstName: "juliet" }),
+      mike: await browser.contacts.create(book1, { FirstName: "mike" }),
+      oscar: await browser.contacts.create(book1, { FirstName: "oscar" }),
+      papa: await browser.contacts.create(book1, { FirstName: "papa" }),
+      romeo: await browser.contacts.create(book1, { FirstName: "romeo" }),
+      victor: await browser.contacts.create(book1, { FirstName: "victor" }),
+    };
+
+    let book2contacts = {
+      bigBird: await browser.contacts.create(book2, {
+        FirstName: "Big",
+        LastName: "Bird",
+      }),
+      cookieMonster: await browser.contacts.create(book2, {
+        FirstName: "Cookie",
+        LastName: "Monster",
+      }),
+      elmo: await browser.contacts.create(book2, { FirstName: "Elmo" }),
+      grover: await browser.contacts.create(book2, { FirstName: "Grover" }),
+      oscarTheGrouch: await browser.contacts.create(book2, {
+        FirstName: "Oscar",
+        LastName: "The Grouch",
+      }),
+    };
+
+    // A search string without a match in either book.
+    let results = await browser.contacts.quickSearch(book1, "snuffleupagus");
+    browser.test.assertEq(0, results.length);
+
+    // A search string with a match in the book we're searching.
+    results = await browser.contacts.quickSearch(book1, "mike");
+    browser.test.assertEq(1, results.length);
+    browser.test.assertEq(book1contacts.mike, results[0].id);
+
+    // A search string passed via queryInfo
+    results = await browser.contacts.quickSearch(book1, {
+      searchString: "mike",
+    });
+    browser.test.assertEq(1, results.length);
+    browser.test.assertEq(book1contacts.mike, results[0].id);
+
+    // A search string with a match in the book we're not searching.
+    results = await browser.contacts.quickSearch(book1, "elmo");
+    browser.test.assertEq(0, results.length);
+
+    // A search string with a match in both books.
+    results = await browser.contacts.quickSearch(book1, "oscar");
+    browser.test.assertEq(1, results.length);
+    browser.test.assertEq(book1contacts.oscar, results[0].id);
+
+    // A search string with a match in both books. Looking in all books.
+    results = await browser.contacts.quickSearch("oscar");
+    browser.test.assertEq(2, results.length);
+    browser.test.assertEq(book1contacts.oscar, results[0].id);
+    browser.test.assertEq(book2contacts.oscarTheGrouch, results[1].id);
+
+    // No valid search strings.
+    results = await browser.contacts.quickSearch("  ");
+    browser.test.assertEq(0, results.length);
+
+    await browser.addressBooks.delete(book1);
+    await browser.addressBooks.delete(book2);
+
+    browser.test.notifyPass("addressBooks");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: { permissions: ["addressBooks"] },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("addressBooks");
+  await extension.unload();
+});
+
+add_task(async function test_quickSearch_types() {
+  // If nsIAbLDAPDirectory doesn't exist in our build options, someone has
+  // specified --disable-ldap
+  if (!("nsIAbLDAPDirectory" in Ci)) {
+    return;
+  }
+
+  // Add a card to the personal AB.
+  let personaAB = MailServices.ab.getDirectory("jsaddrbook://abook.sqlite");
+
+  let contact = Cc["@mozilla.org/addressbook/cardproperty;1"].createInstance(
+    Ci.nsIAbCard
+  );
+  contact.UID = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx";
+  contact.displayName = "personal contact";
+  contact.firstName = "personal";
+  contact.lastName = "contact";
+  contact.primaryEmail = "personal@invalid";
+  contact = personaAB.addCard(contact);
+
+  // Set up the history AB as read-only.
+  let historyAB = MailServices.ab.getDirectory("jsaddrbook://history.sqlite");
+
+  contact = Cc["@mozilla.org/addressbook/cardproperty;1"].createInstance(
+    Ci.nsIAbCard
+  );
+  contact.UID = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxy";
+  contact.displayName = "history contact";
+  contact.firstName = "history";
+  contact.lastName = "contact";
+  contact.primaryEmail = "history@invalid";
+  contact = historyAB.addCard(contact);
+
+  historyAB.setBoolValue("readOnly", true);
+
+  Assert.ok(historyAB.readOnly);
+
+  // Set up an LDAP address book.
+  LDAPServer.open();
+
+  // Create an LDAP directory
+  MailServices.ab.newAddressBook(
+    "test",
+    `ldap://localhost:${LDAPServer.port}/people??sub?(objectclass=*)`,
+    Ci.nsIAbManager.LDAP_DIRECTORY_TYPE
+  );
+
+  async function background() {
+    function checkCards(cards, expectedNames) {
+      browser.test.assertEq(expectedNames.length, cards.length);
+      let expected = new Set(expectedNames);
+      for (let card of cards) {
+        expected.delete(card.properties.FirstName);
+      }
+      browser.test.assertEq(
+        0,
+        expected.size,
+        "Should have seen all expected cards"
+      );
+    }
+    // No arguments should get cards from all address books.
+    let results = await browser.contacts.quickSearch("contact");
+    checkCards(results, ["personal", "history", "LDAP"]);
+
+    // An empty argument should get cards from all address books.
+    results = await browser.contacts.quickSearch({ searchString: "contact" });
+    checkCards(results, ["personal", "history", "LDAP"]);
+
+    // Skip remote address books.
+    results = await browser.contacts.quickSearch({
+      searchString: "contact",
+      includeRemote: false,
+    });
+    checkCards(results, ["personal", "history"]);
+
+    // Skip local address books.
+    results = await browser.contacts.quickSearch({
+      searchString: "contact",
+      includeLocal: false,
+    });
+    checkCards(results, ["LDAP"]);
+
+    // Skip read-only address books.
+    results = await browser.contacts.quickSearch({
+      searchString: "contact",
+      includeReadOnly: false,
+    });
+    checkCards(results, ["personal"]);
+
+    // Skip read-write address books.
+    results = await browser.contacts.quickSearch({
+      searchString: "contact",
+      includeReadWrite: false,
+    });
+    checkCards(results, ["LDAP", "history"]);
+
+    browser.test.notifyPass("addressBooks");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: { permissions: ["addressBooks"] },
+  });
+
+  let startupPromise = extension.startup();
+
+  // This for loop handles returning responses for LDAP. It should run once
+  // for each test that queries the remote address book.
+  for (let i = 0; i < 4; i++) {
+    await LDAPServer.read(LDAPServer.BindRequest);
+    LDAPServer.writeBindResponse();
+
+    await LDAPServer.read(LDAPServer.SearchRequest);
+    LDAPServer.writeSearchResultEntry({
+      dn: "uid=ldap,dc=contact,dc=invalid",
+      attributes: {
+        objectClass: "person",
+        cn: "LDAP contact",
+        givenName: "LDAP",
+        mail: "eurus@contact.invalid",
+        sn: "contact",
+      },
+    });
+    LDAPServer.writeSearchResultDone();
+  }
+
+  await startupPromise;
+  await extension.awaitFinish("addressBooks");
+  await extension.unload();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_readonly.js b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_readonly.js
new file mode 100644
index 0000000000..3b40dc67a2
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_readonly.js
@@ -0,0 +1,148 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+add_setup(async () => {
+  Services.prefs.setIntPref("ldap_2.servers.osx.dirType", -1);
+
+  registerCleanupFunction(() => {
+    // Make sure any open database is given a chance to close.
+    Services.startup.advanceShutdownPhase(
+      Services.startup.SHUTDOWN_PHASE_APPSHUTDOWNCONFIRMED
+    );
+  });
+
+  let historyAB = MailServices.ab.getDirectory("jsaddrbook://history.sqlite");
+
+  let contact1 = Cc["@mozilla.org/addressbook/cardproperty;1"].createInstance(
+    Ci.nsIAbCard
+  );
+  contact1.UID = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx";
+  contact1.displayName = "contact number one";
+  contact1.firstName = "contact";
+  contact1.lastName = "one";
+  contact1.primaryEmail = "contact1@invalid";
+  contact1 = historyAB.addCard(contact1);
+
+  let mailList = Cc[
+    "@mozilla.org/addressbook/directoryproperty;1"
+  ].createInstance(Ci.nsIAbDirectory);
+  mailList.isMailList = true;
+  mailList.dirName = "Mailing";
+  mailList.listNickName = "Mailing";
+  mailList.description = "";
+
+  historyAB.addMailList(mailList);
+  historyAB.setBoolValue("readOnly", true);
+
+  Assert.ok(historyAB.readOnly);
+});
+
+add_task(async function test_addressBooks_readonly() {
+  async function background() {
+    let list = await browser.addressBooks.list();
+
+    // The read only AB should be in the list.
+    let readOnlyAB = list.find(ab => ab.name == "Collected Addresses");
+    browser.test.assertTrue(!!readOnlyAB, "Should have found the address book");
+
+    browser.test.assertTrue(
+      readOnlyAB.readOnly,
+      "Should have marked the address book as read-only"
+    );
+
+    let card = await browser.contacts.get(
+      "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+    );
+    browser.test.assertTrue(!!card, "Should have found the card");
+
+    browser.test.assertTrue(
+      card.readOnly,
+      "Should have marked the card as read-only"
+    );
+
+    await browser.test.assertRejects(
+      browser.contacts.create(readOnlyAB.id, {
+        email: "test@example.com",
+      }),
+      "Cannot create a contact in a read-only address book",
+      "Should reject creating an address book card"
+    );
+
+    await browser.test.assertRejects(
+      browser.contacts.update(card.id, card.properties),
+      "Cannot modify a contact in a read-only address book",
+      "Should reject modifying an address book card"
+    );
+
+    await browser.test.assertRejects(
+      browser.contacts.delete(card.id),
+      "Cannot delete a contact in a read-only address book",
+      "Should reject deleting an address book card"
+    );
+
+    // Mailing List
+
+    let mailingLists = await browser.mailingLists.list(readOnlyAB.id);
+    let readOnlyML = mailingLists[0];
+    browser.test.assertTrue(!!readOnlyAB, "Should have found the mailing list");
+
+    browser.test.assertTrue(
+      readOnlyML.readOnly,
+      "Should have marked the mailing list as read-only"
+    );
+
+    await browser.test.assertRejects(
+      browser.mailingLists.create(readOnlyAB.id, { name: "Test" }),
+      "Cannot create a mailing list in a read-only address book",
+      "Should reject creating a mailing list"
+    );
+
+    await browser.test.assertRejects(
+      browser.mailingLists.update(readOnlyML.id, { name: "newTest" }),
+      "Cannot modify a mailing list in a read-only address book",
+      "Should reject modifying a mailing list"
+    );
+
+    await browser.test.assertRejects(
+      browser.mailingLists.delete(readOnlyML.id),
+      "Cannot delete a mailing list in a read-only address book",
+      "Should reject deleting a mailing list"
+    );
+
+    await browser.test.assertRejects(
+      browser.mailingLists.addMember(readOnlyML.id, card.id),
+      "Cannot add to a mailing list in a read-only address book",
+      "Should reject deleting a mailing list"
+    );
+
+    await browser.test.assertRejects(
+      browser.mailingLists.removeMember(readOnlyML.id, card.id),
+      "Cannot remove from a mailing list in a read-only address book",
+      "Should reject deleting a mailing list"
+    );
+
+    browser.test.notifyPass("addressBooks");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    files: {
+      "background.js": background,
+      "utils.js": await getUtilsJS(),
+    },
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["addressBooks"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("addressBooks");
+  await extension.unload();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_remote.js b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_remote.js
new file mode 100644
index 0000000000..7a34c8ce86
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_addressBook_remote.js
@@ -0,0 +1,101 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { LDAPServer } = ChromeUtils.import(
+  "resource://testing-common/LDAPServer.jsm"
+);
+
+add_setup(async () => {
+  // If nsIAbLDAPDirectory doesn't exist in our build options, someone has
+  // specified --disable-ldap.
+  if (!("nsIAbLDAPDirectory" in Ci)) {
+    return;
+  }
+  Services.prefs.setIntPref("ldap_2.servers.osx.dirType", -1);
+
+  LDAPServer.open();
+
+  // Create an LDAP directory.
+  MailServices.ab.newAddressBook(
+    "test",
+    `ldap://localhost:${LDAPServer.port}/people??sub?(objectclass=*)`,
+    Ci.nsIAbManager.LDAP_DIRECTORY_TYPE
+  );
+
+  registerCleanupFunction(() => {
+    LDAPServer.close();
+    // Make sure any open database is given a chance to close.
+    Services.startup.advanceShutdownPhase(
+      Services.startup.SHUTDOWN_PHASE_APPSHUTDOWNCONFIRMED
+    );
+  });
+});
+
+add_task(async function test_addressBooks_remote() {
+  async function background() {
+    let list = await browser.addressBooks.list();
+
+    // The remote AB should be in the list.
+    let remoteAB = list.find(ab => ab.name == "test");
+    browser.test.assertTrue(!!remoteAB, "Should have found the address book");
+
+    browser.test.assertTrue(
+      remoteAB.remote,
+      "Should have marked the address book as remote"
+    );
+
+    let cards = await browser.contacts.quickSearch("eurus");
+    browser.test.assertTrue(
+      cards.length,
+      "Should have found at least one card"
+    );
+
+    browser.test.assertTrue(
+      cards[0].remote,
+      "Should have marked the card as remote"
+    );
+
+    // Mailing lists are not supported for LDAP address books.
+
+    browser.test.notifyPass("addressBooks");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    files: {
+      "background.js": background,
+      "utils.js": await getUtilsJS(),
+    },
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["addressBooks"],
+    },
+  });
+
+  let startupPromise = extension.startup();
+
+  await LDAPServer.read(LDAPServer.BindRequest);
+  LDAPServer.writeBindResponse();
+
+  await LDAPServer.read(LDAPServer.SearchRequest);
+  LDAPServer.writeSearchResultEntry({
+    dn: "uid=eurus,dc=bakerstreet,dc=invalid",
+    attributes: {
+      objectClass: "person",
+      cn: "Eurus Holmes",
+      givenName: "Eurus",
+      mail: "eurus@bakerstreet.invalid",
+      sn: "Holmes",
+    },
+  });
+  LDAPServer.writeSearchResultDone();
+
+  await startupPromise;
+  await extension.awaitFinish("addressBooks");
+  await extension.unload();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_alias.js b/comm/mail/components/extensions/test/xpcshell/test_ext_alias.js
new file mode 100644
index 0000000000..3fff1e0e08
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_alias.js
@@ -0,0 +1,123 @@
+/* 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/. */
+
+var { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+AddonTestUtils.maybeInit(this);
+const server = AddonTestUtils.createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write(
+    "<!DOCTYPE html><html><head><meta charset='utf8'></head><body></body></html>"
+  );
+});
+
+add_task(async function test_alias() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background: async () => {
+      let pending = new Set(["contentscript", "webscript"]);
+
+      browser.runtime.onMessage.addListener(message => {
+        if (message == "contentscript") {
+          pending.delete(message);
+          browser.test.succeed("Content script has completed");
+        } else if (message == "webscript") {
+          pending.delete(message);
+          browser.test.succeed("Web accessible script has completed");
+        }
+
+        if (pending.size == 0) {
+          browser.test.notifyPass("ext_alias");
+        }
+      });
+
+      browser.test.assertEq(
+        "object",
+        typeof browser,
+        "Background script has browser object"
+      );
+      browser.test.assertEq(
+        "object",
+        typeof messenger,
+        "Background script has messenger object"
+      );
+      browser.test.assertEq(
+        "alias@xpcshell",
+        messenger.runtime.getManifest().applications.gecko.id, // eslint-disable-line no-undef
+        "Background script can access the manifest"
+      );
+    },
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/dummy"],
+          js: ["content.js"],
+        },
+      ],
+
+      applications: { gecko: { id: "alias@xpcshell" } },
+      web_accessible_resources: ["web.html", "web.js"],
+    },
+    files: {
+      "content.js": `
+        browser.test.assertEq("object", typeof browser, "Content script has browser object");
+        browser.test.assertEq("object", typeof messenger, "Content script has messenger object");
+        browser.test.assertEq(
+          "alias@xpcshell",
+          messenger.runtime.getManifest().applications.gecko.id,
+          "Content script can access manifest"
+        );
+
+        // Unprivileged content in a frame
+        let frame = document.createElement("iframe");
+        frame.src = browser.runtime.getURL("web.html");
+        document.body.appendChild(frame);
+
+        browser.runtime.sendMessage("contentscript");
+      `,
+      "web.html": `
+        <!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset='utf8'>
+            <script src="web.js"></script>
+          </head>
+          <body>
+          </body>
+        </html>
+      `,
+      "web.js": `
+        browser.test.assertEq("object", typeof browser, "Web accessible script has browser object");
+        browser.test.assertEq("object", typeof messenger, "Web accessible script has messenger object");
+        browser.test.assertEq(
+          "alias@xpcshell",
+          messenger.runtime.getManifest().applications.gecko.id,
+          "Web accessible script can access manifest"
+        );
+
+        browser.runtime.sendMessage("webscript");
+      `,
+    },
+  });
+
+  await extension.startup();
+
+  const contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+  await extension.awaitFinish("ext_alias");
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_browserAction_unifiedtoolbar_restart.js b/comm/mail/components/extensions/test/xpcshell/test_ext_browserAction_unifiedtoolbar_restart.js
new file mode 100644
index 0000000000..ef2687af68
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_browserAction_unifiedtoolbar_restart.js
@@ -0,0 +1,350 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+var { getCachedAllowedSpaces, setCachedAllowedSpaces } = ChromeUtils.import(
+  "resource:///modules/ExtensionToolbarButtons.jsm"
+);
+var { storeState, getState } = ChromeUtils.importESModule(
+  "resource:///modules/CustomizationState.mjs"
+);
+const { AddonManager } = ChromeUtils.importESModule(
+  "resource://gre/modules/AddonManager.sys.mjs"
+);
+var { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+const { TestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TestUtils.sys.mjs"
+);
+
+const {
+  createAppInfo,
+  createHttpServer,
+  createTempXPIFile,
+  promiseRestartManager,
+  promiseShutdownManager,
+  promiseStartupManager,
+  promiseCompleteAllInstalls,
+  promiseFindAddonUpdates,
+} = AddonTestUtils;
+
+// Prepare test environment to be able to load add-on updates.
+const PREF_EM_CHECK_UPDATE_SECURITY = "extensions.checkUpdateSecurity";
+Services.prefs.setBoolPref(PREF_EM_CHECK_UPDATE_SECURITY, false);
+
+let gProfD = do_get_profile();
+let profileDir = gProfD.clone();
+profileDir.append("extensions");
+const stageDir = profileDir.clone();
+stageDir.append("staged");
+
+let server = createHttpServer({
+  hosts: ["example.com"],
+});
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "102");
+
+async function enforceState(state) {
+  const stateChangeObserved = TestUtils.topicObserved(
+    "unified-toolbar-state-change"
+  );
+  storeState(state);
+  await stateChangeObserved;
+}
+
+function check(testType, expectedCache, expectedMail, expectedCalendar) {
+  let extensionId = `browser_action_spaces_${testType}@mochi.test`;
+
+  Assert.equal(
+    getCachedAllowedSpaces().has(extensionId),
+    expectedCache != null,
+    "CachedAllowedSpaces should include the test extension"
+  );
+  if (expectedCache != null) {
+    Assert.deepEqual(
+      getCachedAllowedSpaces().get(extensionId),
+      expectedCache,
+      "CachedAllowedSpaces should be correct"
+    );
+  }
+  Assert.equal(
+    getState().mail.includes(`ext-${extensionId}`),
+    expectedMail,
+    "The mail state should include the action button of the test extension"
+  );
+  Assert.equal(
+    getState().calendar.includes(`ext-${extensionId}`),
+    expectedCalendar,
+    "The calendar state should include the action button of the test extension"
+  );
+}
+
+function addXPI(testType, thisVersion, nextVersion, browser_action) {
+  server.registerFile(
+    `/addons/${testType}_v${thisVersion}.xpi`,
+    createTempXPIFile({
+      "manifest.json": {
+        manifest_version: 2,
+        name: testType,
+        version: `${thisVersion}.0`,
+        background: { scripts: ["background.js"] },
+        applications: {
+          gecko: {
+            id: `browser_action_spaces_${testType}@mochi.test`,
+            update_url: nextVersion
+              ? `http://example.com/${testType}_updates_v${nextVersion}.json`
+              : null,
+          },
+        },
+        browser_action,
+      },
+      "background.js": `
+          if (browser.runtime.getManifest().name == "delayed") {
+              browser.runtime.onUpdateAvailable.addListener(details => {
+                  browser.test.sendMessage("update postponed by ${thisVersion}");
+              });
+          }
+          browser.test.log(" ===== ready ${testType} ${thisVersion}");
+          browser.test.sendMessage("ready ${thisVersion}");`,
+    })
+  );
+  if (nextVersion) {
+    addUpdateJSON(testType, nextVersion);
+  }
+}
+
+function addUpdateJSON(testType, nextVersion) {
+  let extensionId = `browser_action_spaces_${testType}@mochi.test`;
+
+  AddonTestUtils.registerJSON(
+    server,
+    `/${testType}_updates_v${nextVersion}.json`,
+    {
+      addons: {
+        [extensionId]: {
+          updates: [
+            {
+              version: `${nextVersion}.0`,
+              update_link: `http://example.com/addons/${testType}_v${nextVersion}.xpi`,
+              applications: {
+                gecko: {
+                  strict_min_version: "1",
+                },
+              },
+            },
+          ],
+        },
+      },
+    }
+  );
+}
+
+async function checkForExtensionUpdate(testType, extension) {
+  let update = await promiseFindAddonUpdates(extension.addon);
+  let install = update.updateAvailable;
+  await promiseCompleteAllInstalls([install]);
+
+  if (testType == "normal") {
+    Assert.equal(
+      install.state,
+      AddonManager.STATE_INSTALLED,
+      "Update should have been installed"
+    );
+  } else {
+    Assert.equal(
+      install.state,
+      AddonManager.STATE_POSTPONED,
+      "Update should have been postponed"
+    );
+  }
+}
+
+async function runTest(testType) {
+  // Simulate starting up the app.
+  await promiseStartupManager();
+
+  // Set a customized state for the spaces we are working with in this test.
+  await enforceState({
+    mail: ["spacer", "search-bar", "spacer"],
+    calendar: ["spacer", "search-bar", "spacer"],
+  });
+
+  // Check conditions before installing the add-on.
+  check(testType, null, false, false);
+
+  // Add the required update JSON to our test server, to be able to update to v2.
+  addUpdateJSON(testType, 2);
+  // Install addon v1 without a browserAction.
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    files: {
+      "background.js": function () {
+        if (browser.runtime.getManifest().name == "delayed") {
+          function handleUpdateAvailable(details) {
+            browser.test.sendMessage("update postponed by 1");
+          }
+          browser.runtime.onUpdateAvailable.addListener(handleUpdateAvailable);
+        }
+        browser.test.sendMessage("ready 1");
+      },
+    },
+    manifest: {
+      background: { scripts: ["background.js"] },
+      version: "1.0",
+      name: testType,
+      applications: {
+        gecko: {
+          id: `browser_action_spaces_${testType}@mochi.test`,
+          update_url: `http://example.com/${testType}_updates_v2.json`,
+        },
+      },
+    },
+  });
+  await extension.startup();
+  await extension.awaitMessage("ready 1");
+
+  // State should not have changed.
+  check(testType, null, false, false);
+
+  // v2 will add the mail space and the default space.
+  addXPI(testType, 2, 3, { allowed_spaces: ["mail", "default"] });
+  await checkForExtensionUpdate(testType, extension);
+
+  if (testType == "delayed") {
+    await extension.awaitMessage("update postponed by 1");
+    // Restart to install the update v2.
+    await promiseRestartManager();
+  }
+
+  await extension.awaitStartup();
+  await extension.awaitMessage("ready 2");
+
+  // The button should have been added to the mail space.
+  check(testType, ["mail", "default"], true, false);
+
+  // Remove our extension button from all customized states.
+  await enforceState({
+    mail: ["spacer", "search-bar", "spacer"],
+    calendar: ["spacer", "search-bar", "spacer"],
+  });
+
+  // Simulate restarting the app.
+  await promiseRestartManager();
+  await extension.awaitStartup();
+  await extension.awaitMessage("ready 2");
+
+  // The button should not be re-added to any space after the restart.
+  check(testType, ["mail", "default"], false, false);
+
+  // v3 will add the calendar space.
+  addXPI(testType, 3, 4, {
+    allowed_spaces: ["mail", "calendar", "default"],
+  });
+  await checkForExtensionUpdate(testType, extension);
+
+  if (testType == "delayed") {
+    await extension.awaitMessage("update postponed by 2");
+    // Restart to install the update v3.
+    await promiseRestartManager();
+  }
+
+  await extension.awaitStartup();
+  await extension.awaitMessage("ready 3");
+
+  // The button should have been added to the calendar space.
+  check(testType, ["mail", "calendar", "default"], false, true);
+
+  // Simulate restarting the app.
+  await promiseRestartManager();
+  await extension.awaitStartup();
+  await extension.awaitMessage("ready 3");
+
+  // Should not have changed.
+  check(testType, ["mail", "calendar", "default"], false, true);
+
+  // v4 will remove the calendar space again.
+  addXPI(testType, 4, 5, { allowed_spaces: ["mail", "default"] });
+  await checkForExtensionUpdate(testType, extension);
+
+  if (testType == "delayed") {
+    await extension.awaitMessage("update postponed by 3");
+    // Restart to install the update v4.
+    await promiseRestartManager();
+  }
+
+  await extension.awaitStartup();
+  await extension.awaitMessage("ready 4");
+
+  // The calendar space should no longer be known and the button should be removed
+  // from the calendar space.
+  check(testType, ["mail", "default"], false, false);
+
+  // Simulate restarting the app.
+  await promiseRestartManager();
+  await extension.awaitStartup();
+  await extension.awaitMessage("ready 4");
+
+  // Should not have changed.
+  check(testType, ["mail", "default"], false, false);
+
+  // v5 will remove the entire browser_action. Testing the onUpdate code path in
+  // ext-browserAction.
+  addXPI(testType, 5, 6, null);
+  await checkForExtensionUpdate(testType, extension);
+
+  if (testType == "delayed") {
+    await extension.awaitMessage("update postponed by 4");
+    // Restart to install the update v5.
+    await promiseRestartManager();
+  }
+
+  await extension.awaitStartup();
+  await extension.awaitMessage("ready 5");
+
+  // There should no longer be a cached entry for any known spaces.
+  check(testType, null, false, false);
+
+  // Simulate restarting the app.
+  await promiseRestartManager();
+  await extension.awaitStartup();
+  await extension.awaitMessage("ready 5");
+
+  // Should not have changed.
+  check(testType, null, false, false);
+
+  // v6 will add the mail space again.
+  addXPI(testType, 6, null, { allowed_spaces: ["mail", "default"] });
+  await checkForExtensionUpdate(testType, extension);
+
+  if (testType == "delayed") {
+    await extension.awaitMessage("update postponed by 5");
+    // Restart to install the update v6.
+    await promiseRestartManager();
+  }
+
+  await extension.awaitStartup();
+  await extension.awaitMessage("ready 6");
+
+  // The button should have been added to the mail space.
+  check(testType, ["mail", "default"], true, false);
+
+  // Unload the extension. Testing the onUninstall code path in ext-browserAction.
+  await extension.unload();
+
+  // There should no longer be a cached entry for any known spaces.
+  check(testType, null, false, false);
+
+  await promiseShutdownManager();
+}
+
+add_task(async function test_normal_updates() {
+  await runTest("normal");
+});
+
+add_task(async function test_delayed_updates() {
+  await runTest("delayed");
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_experiments.js b/comm/mail/components/extensions/test/xpcshell/test_ext_experiments.js
new file mode 100644
index 0000000000..d8ccd58da6
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_experiments.js
@@ -0,0 +1,279 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+add_task(async function test_managers() {
+  let account = createAccount();
+  let folder = await createSubfolder(
+    account.incomingServer.rootFolder,
+    "test1"
+  );
+  await createMessages(folder, 5);
+
+  let files = {
+    "background.js": async () => {
+      let [testAccount] = await browser.accounts.list();
+      let testFolder = testAccount.folders.find(f => f.name == "test1");
+      let {
+        messages: [testMessage],
+      } = await browser.messages.list(testFolder);
+
+      let messageCount = await browser.testapi.testCanGetFolder(testFolder);
+      browser.test.assertEq(5, messageCount);
+
+      let convertedFolder = await browser.testapi.testCanConvertFolder();
+      browser.test.assertEq(testFolder.accountId, convertedFolder.accountId);
+      browser.test.assertEq(testFolder.path, convertedFolder.path);
+
+      let subject = await browser.testapi.testCanGetMessage(testMessage.id);
+      browser.test.assertEq(testMessage.subject, subject);
+
+      let convertedMessage = await browser.testapi.testCanConvertMessage();
+      browser.test.log(JSON.stringify(convertedMessage));
+      browser.test.assertEq(testMessage.id, convertedMessage.id);
+      browser.test.assertEq(testMessage.subject, convertedMessage.subject);
+
+      let messageList = await browser.testapi.testCanStartMessageList();
+      browser.test.assertEq(36, messageList.id.length);
+      browser.test.assertEq(4, messageList.messages.length);
+      browser.test.assertEq(
+        testMessage.subject,
+        messageList.messages[0].subject
+      );
+
+      messageList = await browser.messages.continueList(messageList.id);
+      browser.test.assertEq(null, messageList.id);
+      browser.test.assertEq(1, messageList.messages.length);
+      browser.test.assertTrue(
+        testMessage.subject != messageList.messages[0].subject
+      );
+
+      let [bookUID, contactUID, listUID] = await window.sendMessage("get UIDs");
+      let [foundBook, foundContact, foundList] =
+        await browser.testapi.testCanFindAddressBookItems(
+          bookUID,
+          contactUID,
+          listUID
+        );
+      browser.test.assertEq("new book", foundBook.name);
+      browser.test.assertEq("new contact", foundContact.properties.DisplayName);
+      browser.test.assertEq("new list", foundList.name);
+
+      browser.test.notifyPass("finished");
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files: {
+      ...files,
+      "schema.json": [
+        {
+          namespace: "testapi",
+          functions: [
+            {
+              name: "testCanGetFolder",
+              type: "function",
+              async: true,
+              parameters: [
+                {
+                  name: "folder",
+                  $ref: "folders.MailFolder",
+                },
+              ],
+            },
+            {
+              name: "testCanConvertFolder",
+              type: "function",
+              async: true,
+              parameters: [],
+            },
+            {
+              name: "testCanGetMessage",
+              type: "function",
+              async: true,
+              parameters: [
+                {
+                  name: "messageId",
+                  type: "integer",
+                },
+              ],
+            },
+            {
+              name: "testCanConvertMessage",
+              type: "function",
+              async: true,
+              parameters: [],
+            },
+            {
+              name: "testCanStartMessageList",
+              type: "function",
+              async: true,
+              parameters: [],
+            },
+            {
+              name: "testCanFindAddressBookItems",
+              type: "function",
+              async: true,
+              parameters: [
+                { name: "bookUID", type: "string" },
+                { name: "contactUID", type: "string" },
+                { name: "listUID", type: "string" },
+              ],
+            },
+          ],
+        },
+      ],
+      "implementation.js": () => {
+        var { ExtensionCommon } = ChromeUtils.importESModule(
+          "resource://gre/modules/ExtensionCommon.sys.mjs"
+        );
+        var { MailServices } = ChromeUtils.import(
+          "resource:///modules/MailServices.jsm"
+        );
+        this.testapi = class extends ExtensionCommon.ExtensionAPI {
+          getAPI(context) {
+            return {
+              testapi: {
+                async testCanGetFolder({ accountId, path }) {
+                  let realFolder = context.extension.folderManager.get(
+                    accountId,
+                    path
+                  );
+                  return realFolder.getTotalMessages(false);
+                },
+                async testCanConvertFolder() {
+                  let realFolder = MailServices.accounts.allFolders.find(
+                    f => f.name == "test1"
+                  );
+                  return context.extension.folderManager.convert(realFolder);
+                },
+                async testCanGetMessage(messageId) {
+                  let realMessage =
+                    context.extension.messageManager.get(messageId);
+                  return realMessage.subject;
+                },
+                async testCanConvertMessage() {
+                  let realFolder = MailServices.accounts.allFolders.find(
+                    f => f.name == "test1"
+                  );
+                  let realMessage = [...realFolder.messages][0];
+                  return context.extension.messageManager.convert(realMessage);
+                },
+                async testCanStartMessageList() {
+                  let realFolder = MailServices.accounts.allFolders.find(
+                    f => f.name == "test1"
+                  );
+                  return context.extension.messageManager.startMessageList(
+                    realFolder.messages
+                  );
+                },
+                async testCanFindAddressBookItems(
+                  bookUID,
+                  contactUID,
+                  listUID
+                ) {
+                  let foundBook =
+                    context.extension.addressBookManager.findAddressBookById(
+                      bookUID
+                    );
+                  let foundContact =
+                    context.extension.addressBookManager.findContactById(
+                      contactUID
+                    );
+                  let foundList =
+                    context.extension.addressBookManager.findMailingListById(
+                      listUID
+                    );
+
+                  return [
+                    await context.extension.addressBookManager.convert(
+                      foundBook
+                    ),
+                    await context.extension.addressBookManager.convert(
+                      foundContact
+                    ),
+                    await context.extension.addressBookManager.convert(
+                      foundList
+                    ),
+                  ];
+                },
+              },
+            };
+          }
+        };
+      },
+      "utils.js": await getUtilsJS(),
+    },
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "addressBooks", "messagesRead"],
+      experiment_apis: {
+        testapi: {
+          schema: "schema.json",
+          parent: {
+            scopes: ["addon_parent"],
+            paths: [["testapi"]],
+            script: "implementation.js",
+          },
+        },
+      },
+    },
+  });
+
+  let dirPrefId = MailServices.ab.newAddressBook(
+    "new book",
+    "",
+    Ci.nsIAbManager.JS_DIRECTORY_TYPE
+  );
+  let book = MailServices.ab.getDirectoryFromId(dirPrefId);
+
+  let contact = Cc["@mozilla.org/addressbook/cardproperty;1"].createInstance(
+    Ci.nsIAbCard
+  );
+  contact.displayName = "new contact";
+  contact.firstName = "new";
+  contact.lastName = "contact";
+  contact.primaryEmail = "new.contact@invalid";
+  contact = book.addCard(contact);
+
+  let list = Cc["@mozilla.org/addressbook/directoryproperty;1"].createInstance(
+    Ci.nsIAbDirectory
+  );
+  list.isMailList = true;
+  list.dirName = "new list";
+  list = book.addMailList(list);
+  list.addCard(contact);
+
+  Services.prefs.setIntPref("extensions.webextensions.messagesPerPage", 4);
+
+  await extension.startup();
+  await extension.awaitMessage("get UIDs");
+  extension.sendMessage(book.UID, contact.UID, list.UID);
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  Services.prefs.clearUserPref("extensions.webextensions.messagesPerPage");
+
+  await new Promise(resolve => {
+    let observer = {
+      observe() {
+        Services.obs.removeObserver(observer, "addrbook-directory-deleted");
+        resolve();
+      },
+    };
+    Services.obs.addObserver(observer, "addrbook-directory-deleted");
+    MailServices.ab.deleteAddressBook(book.URI);
+  });
+});
+
+registerCleanupFunction(() => {
+  // Make sure any open database is given a chance to close.
+  Services.startup.advanceShutdownPhase(
+    Services.startup.SHUTDOWN_PHASE_APPSHUTDOWNCONFIRMED
+  );
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_folders.js b/comm/mail/components/extensions/test/xpcshell/test_ext_folders.js
new file mode 100644
index 0000000000..39a8d63016
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_folders.js
@@ -0,0 +1,560 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_folders() {
+    let files = {
+      "background.js": async () => {
+        let [accountId, IS_IMAP] = await window.waitForMessage();
+
+        let account = await browser.accounts.get(accountId);
+        browser.test.assertEq(3, account.folders.length);
+
+        // Test create.
+
+        let onCreatedPromise = window.waitForEvent("folders.onCreated");
+        let folder1 = await browser.folders.create(account, "folder1");
+        let [createdFolder] = await onCreatedPromise;
+        for (let folder of [folder1, createdFolder]) {
+          browser.test.assertEq(accountId, folder.accountId);
+          browser.test.assertEq("folder1", folder.name);
+          browser.test.assertEq("/folder1", folder.path);
+        }
+
+        account = await browser.accounts.get(accountId);
+        // Check order of the returned folders being correct (new folder not last).
+        browser.test.assertEq(4, account.folders.length);
+        if (IS_IMAP) {
+          browser.test.assertEq("Inbox", account.folders[0].name);
+          browser.test.assertEq("Trash", account.folders[1].name);
+        } else {
+          browser.test.assertEq("Trash", account.folders[0].name);
+          browser.test.assertEq("Outbox", account.folders[1].name);
+        }
+        browser.test.assertEq("folder1", account.folders[2].name);
+        browser.test.assertEq("unused", account.folders[3].name);
+
+        let folder2 = await browser.folders.create(folder1, "folder+2");
+        browser.test.assertEq(accountId, folder2.accountId);
+        browser.test.assertEq("folder+2", folder2.name);
+        browser.test.assertEq("/folder1/folder+2", folder2.path);
+
+        account = await browser.accounts.get(accountId);
+        browser.test.assertEq(4, account.folders.length);
+        browser.test.assertEq(1, account.folders[2].subFolders.length);
+        browser.test.assertEq(
+          "/folder1/folder+2",
+          account.folders[2].subFolders[0].path
+        );
+
+        // Test reject on creating already existing folder.
+        await browser.test.assertRejects(
+          browser.folders.create(folder1, "folder+2"),
+          `folders.create() failed, because folder+2 already exists in /folder1`,
+          "browser.folders.create threw exception"
+        );
+
+        // Test rename.
+
+        {
+          let onRenamedPromise = window.waitForEvent("folders.onRenamed");
+          let folder3 = await browser.folders.rename(
+            { accountId, path: "/folder1/folder+2" },
+            "folder3"
+          );
+          let [originalFolder, renamedFolder] = await onRenamedPromise;
+          // Test the original folder.
+          browser.test.assertEq(accountId, originalFolder.accountId);
+          browser.test.assertEq("folder+2", originalFolder.name);
+          browser.test.assertEq("/folder1/folder+2", originalFolder.path);
+          // Test the renamed folder.
+          for (let folder of [folder3, renamedFolder]) {
+            browser.test.assertEq(accountId, folder.accountId);
+            browser.test.assertEq("folder3", folder.name);
+            browser.test.assertEq("/folder1/folder3", folder.path);
+          }
+
+          account = await browser.accounts.get(accountId);
+          browser.test.assertEq(4, account.folders.length);
+          browser.test.assertEq(1, account.folders[2].subFolders.length);
+          browser.test.assertEq(
+            "/folder1/folder3",
+            account.folders[2].subFolders[0].path
+          );
+
+          // Test reject on renaming absolute root.
+          await browser.test.assertRejects(
+            browser.folders.rename({ accountId, path: "/" }, "UhhOh"),
+            `folders.rename() failed, because it cannot rename the root of the account`,
+            "browser.folders.rename threw exception"
+          );
+
+          // Test reject on renaming to existing folder.
+          await browser.test.assertRejects(
+            browser.folders.rename(
+              { accountId, path: "/folder1/folder3" },
+              "folder3"
+            ),
+            `folders.rename() failed, because folder3 already exists in /folder1`,
+            "browser.folders.rename threw exception"
+          );
+        }
+
+        // Test delete (and onMoved).
+
+        {
+          // The delete request will trigger an onDelete event for IMAP and an
+          // onMoved event for local folders.
+          let deletePromise = window.waitForEvent(
+            `folders.${IS_IMAP ? "onDeleted" : "onMoved"}`
+          );
+          await browser.folders.delete({ accountId, path: "/folder1/folder3" });
+          // The onMoved event returns the original/deleted and the new folder.
+          // The onDeleted event returns just the original/deleted folder.
+          let [originalFolder, folderMovedToTrash] = await deletePromise;
+
+          // Test the originalFolder folder.
+          browser.test.assertEq(accountId, originalFolder.accountId);
+          browser.test.assertEq("folder3", originalFolder.name);
+          browser.test.assertEq("/folder1/folder3", originalFolder.path);
+
+          // Check if it really is in trash folder.
+          account = await browser.accounts.get(accountId);
+          browser.test.assertEq(4, account.folders.length);
+          let trashFolder = account.folders.find(f => f.name == "Trash");
+          browser.test.assertTrue(trashFolder);
+          browser.test.assertEq("/Trash", trashFolder.path);
+          browser.test.assertEq(1, trashFolder.subFolders.length);
+          browser.test.assertEq(
+            "/Trash/folder3",
+            trashFolder.subFolders[0].path
+          );
+          browser.test.assertEq("/folder1", account.folders[2].path);
+
+          if (!IS_IMAP) {
+            // For non IMAP folders, the delete request has triggered an onMoved
+            // event, check if that has reported moving the folder to trash.
+            browser.test.assertEq(accountId, folderMovedToTrash.accountId);
+            browser.test.assertEq("folder3", folderMovedToTrash.name);
+            browser.test.assertEq("/Trash/folder3", folderMovedToTrash.path);
+
+            // Delete the folder from trash.
+            let onDeletedPromise = window.waitForEvent("folders.onDeleted");
+            await browser.folders.delete({ accountId, path: "/Trash/folder3" });
+            let [deletedFolder] = await onDeletedPromise;
+            browser.test.assertEq(accountId, deletedFolder.accountId);
+            browser.test.assertEq("folder3", deletedFolder.name);
+            browser.test.assertEq("/Trash/folder3", deletedFolder.path);
+            // Check if the folder is gone.
+            let trashSubfolders = await browser.folders.getSubFolders(
+              trashFolder,
+              false
+            );
+            browser.test.assertEq(
+              0,
+              trashSubfolders.length,
+              "Folder has been deleted from trash."
+            );
+          } else {
+            // The IMAP test server signals success for the delete request, but
+            // keeps the folder. Testing for this broken behavior to get notified
+            // via test fails, if this behaviour changes.
+            await browser.folders.delete({ accountId, path: "/Trash/folder3" });
+            let trashSubfolders = await browser.folders.getSubFolders(
+              trashFolder,
+              false
+            );
+            browser.test.assertEq(
+              "/Trash/folder3",
+              trashSubfolders[0].path,
+              "IMAP test server cannot delete from trash, the folder is still there."
+            );
+          }
+
+          // Test reject on deleting non-existing folder.
+          await browser.test.assertRejects(
+            browser.folders.delete({ accountId, path: "/folder1/folder5" }),
+            `Folder not found: /folder1/folder5`,
+            "browser.folders.delete threw exception"
+          );
+
+          account = await browser.accounts.get(accountId);
+          browser.test.assertEq(4, account.folders.length);
+          browser.test.assertEq("/folder1", account.folders[2].path);
+        }
+
+        // Test move.
+
+        {
+          await browser.folders.create(folder1, "folder4");
+          let onMovedPromise = window.waitForEvent("folders.onMoved");
+          let folder4_moved = await browser.folders.move(
+            { accountId, path: "/folder1/folder4" },
+            { accountId, path: "/" }
+          );
+          let [originalFolder, movedFolder] = await onMovedPromise;
+          // Test the original folder.
+          browser.test.assertEq(accountId, originalFolder.accountId);
+          browser.test.assertEq("folder4", originalFolder.name);
+          browser.test.assertEq("/folder1/folder4", originalFolder.path);
+          // Test the moved folder.
+          for (let folder of [folder4_moved, movedFolder]) {
+            browser.test.assertEq(accountId, folder.accountId);
+            browser.test.assertEq("folder4", folder.name);
+            browser.test.assertEq("/folder4", folder.path);
+          }
+
+          account = await browser.accounts.get(accountId);
+          browser.test.assertEq(5, account.folders.length);
+          browser.test.assertEq("/folder4", account.folders[3].path);
+
+          // Test reject on moving to already existing folder.
+          await browser.test.assertRejects(
+            browser.folders.move(folder4_moved, account),
+            `folders.move() failed, because folder4 already exists in /`,
+            "browser.folders.move threw exception"
+          );
+        }
+
+        // Test copy.
+
+        {
+          let onCopiedPromise = window.waitForEvent("folders.onCopied");
+          let folder4_copied = await browser.folders.copy(
+            { accountId, path: "/folder4" },
+            { accountId, path: "/folder1" }
+          );
+          let [originalFolder, copiedFolder] = await onCopiedPromise;
+          // Test the original folder.
+          browser.test.assertEq(accountId, originalFolder.accountId);
+          browser.test.assertEq("folder4", originalFolder.name);
+          browser.test.assertEq("/folder4", originalFolder.path);
+          // Test the copied folder.
+          for (let folder of [folder4_copied, copiedFolder]) {
+            browser.test.assertEq(accountId, folder.accountId);
+            browser.test.assertEq("folder4", folder.name);
+            browser.test.assertEq("/folder1/folder4", folder.path);
+          }
+
+          account = await browser.accounts.get(accountId);
+          browser.test.assertEq(5, account.folders.length);
+          browser.test.assertEq(1, account.folders[2].subFolders.length);
+          browser.test.assertEq("/folder4", account.folders[3].path);
+          browser.test.assertEq(
+            "/folder1/folder4",
+            account.folders[2].subFolders[0].path
+          );
+
+          // Test reject on copy to already existing folder.
+          await browser.test.assertRejects(
+            browser.folders.copy(folder4_copied, folder1),
+            `folders.copy() failed, because folder4 already exists in /folder1`,
+            "browser.folders.copy threw exception"
+          );
+        }
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead", "accountsFolders", "messagesDelete"],
+      },
+    });
+
+    let account = createAccount();
+    // Not all folders appear immediately on IMAP. Creating a new one causes them to appear.
+    await createSubfolder(account.incomingServer.rootFolder, "unused");
+
+    // We should now have three folders. For IMAP accounts they are Inbox, Trash,
+    // and unused. Otherwise they are Trash, Unsent Messages and unused.
+
+    await extension.startup();
+    extension.sendMessage(account.key, IS_IMAP);
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_without_delete_permission() {
+    let files = {
+      "background.js": async () => {
+        let [accountId] = await window.waitForMessage();
+
+        // Test reject on delete without messagesDelete permission.
+        await browser.test.assertRejects(
+          browser.folders.delete({ accountId, path: "/unused" }),
+          `Using folders.delete() requires the "accountsFolders" and the "messagesDelete" permission`,
+          "It rejects for a missing permission."
+        );
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead", "accountsFolders"],
+      },
+    });
+
+    let account = createAccount();
+    // Not all folders appear immediately on IMAP. Creating a new one causes them to appear.
+    await createSubfolder(account.incomingServer.rootFolder, "unused");
+
+    // We should now have three folders. For IMAP accounts they are Inbox,
+    // Trash, and unused. Otherwise they are Trash, Unsent Messages and unused.
+    await extension.startup();
+    extension.sendMessage(account.key);
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
+
+add_task(async function test_getParentFolders_getSubFolders() {
+  let files = {
+    "background.js": async () => {
+      let [accountId] = await window.waitForMessage();
+      let account = await browser.accounts.get(accountId);
+
+      async function createSubFolder(folderOrAccount, name) {
+        let subFolder = await browser.folders.create(folderOrAccount, name);
+        let basePath = folderOrAccount.path || "/";
+        if (!basePath.endsWith("/")) {
+          basePath = basePath + "/";
+        }
+        browser.test.assertEq(accountId, subFolder.accountId);
+        browser.test.assertEq(name, subFolder.name);
+        browser.test.assertEq(`${basePath}${name}`, subFolder.path);
+        return subFolder;
+      }
+
+      // Create a new root folder in the account.
+      let root = await createSubFolder(account, "MyRoot");
+
+      // Build a flat list of newly created nested folders in MyRoot.
+      let flatFolders = [root];
+      for (let i = 0; i < 10; i++) {
+        flatFolders.push(await createSubFolder(flatFolders[i], `level${i}`));
+      }
+
+      // Test getParentFolders().
+
+      // Pop out the last child folder and get its parents.
+      let lastChild = flatFolders.pop();
+      let parentsWithSubDefault = await browser.folders.getParentFolders(
+        lastChild
+      );
+      let parentsWithSubFalse = await browser.folders.getParentFolders(
+        lastChild,
+        false
+      );
+      let parentsWithSubTrue = await browser.folders.getParentFolders(
+        lastChild,
+        true
+      );
+
+      browser.test.assertEq(10, parentsWithSubDefault.length, "Correct depth.");
+      browser.test.assertEq(10, parentsWithSubFalse.length, "Correct depth.");
+      browser.test.assertEq(10, parentsWithSubTrue.length, "Correct depth.");
+
+      // Reverse the flatFolders array, to match the expected return value of
+      // getParentFolders().
+      flatFolders.reverse();
+
+      // Build expected nested subfolder structure.
+      lastChild.subFolders = [];
+      let flatFoldersWithSub = [];
+      for (let i = 0; i < 10; i++) {
+        let f = {};
+        Object.assign(f, flatFolders[i]);
+        if (i == 0) {
+          f.subFolders = [lastChild];
+        } else {
+          f.subFolders = [flatFoldersWithSub[i - 1]];
+        }
+        flatFoldersWithSub.push(f);
+      }
+
+      // Test return values of getParentFolders(). The way the flatFolder array
+      // has been created, its entries do not have subFolder properties.
+      for (let i = 0; i < 10; i++) {
+        window.assertDeepEqual(parentsWithSubFalse[i], flatFolders[i]);
+        window.assertDeepEqual(flatFolders[i], parentsWithSubFalse[i]);
+
+        window.assertDeepEqual(parentsWithSubTrue[i], flatFoldersWithSub[i]);
+        window.assertDeepEqual(flatFoldersWithSub[i], parentsWithSubTrue[i]);
+
+        // Default = false
+        window.assertDeepEqual(parentsWithSubDefault[i], flatFolders[i]);
+        window.assertDeepEqual(flatFolders[i], parentsWithSubDefault[i]);
+      }
+
+      // Test getSubFolders().
+
+      let expectedSubsWithSub = [flatFoldersWithSub[8]];
+      let expectedSubsWithoutSub = [flatFolders[8]];
+
+      // Test excluding subfolders (so only the direct subfolder are reported).
+      let subsWithSubFalse = await browser.folders.getSubFolders(root, false);
+      window.assertDeepEqual(expectedSubsWithoutSub, subsWithSubFalse);
+      window.assertDeepEqual(subsWithSubFalse, expectedSubsWithoutSub);
+
+      // Test including all subfolders.
+      let subsWithSubTrue = await browser.folders.getSubFolders(root, true);
+      window.assertDeepEqual(expectedSubsWithSub, subsWithSubTrue);
+      window.assertDeepEqual(subsWithSubTrue, expectedSubsWithSub);
+
+      // Test default subfolder handling of getSubFolders (= true).
+      let subsWithSubDefault = await browser.folders.getSubFolders(root);
+      window.assertDeepEqual(subsWithSubDefault, subsWithSubTrue);
+      window.assertDeepEqual(subsWithSubTrue, subsWithSubDefault);
+
+      browser.test.notifyPass("finished");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "accountsFolders"],
+    },
+  });
+
+  let account = createAccount();
+  // Not all folders appear immediately on IMAP. Creating a new one causes them to appear.
+  await createSubfolder(account.incomingServer.rootFolder, "unused");
+
+  // We should now have three folders. For IMAP accounts they are Inbox,
+  // Trash, and unused. Otherwise they are Trash, Unsent Messages and unused.
+  await extension.startup();
+  extension.sendMessage(account.key);
+  await extension.awaitFinish("finished");
+  await extension.unload();
+});
+
+add_task(async function test_getFolderInfo() {
+  let files = {
+    "background.js": async () => {
+      let [accountId, IS_NNTP] = await window.waitForMessage();
+
+      let account = await browser.accounts.get(accountId);
+      browser.test.assertEq(IS_NNTP ? 1 : 3, account.folders.length);
+      let folders = await browser.folders.getSubFolders(account, false);
+      let InfoTestFolder = folders.find(f => f.name == "InfoTest");
+
+      // Verify initial state.
+      let info = await browser.folders.getFolderInfo(InfoTestFolder);
+      window.assertDeepEqual(
+        { totalMessageCount: 12, unreadMessageCount: 12, favorite: false },
+        info
+      );
+
+      // Test flipping favorite to true and marking all messages as read.
+      let onFolderInfoChangedPromise = window.waitForEvent(
+        "folders.onFolderInfoChanged"
+      );
+      await window.sendMessage("markAllAsRead");
+      await window.sendMessage("setFavorite", true);
+      let [mailFolder, mailFolderInfo] = await onFolderInfoChangedPromise;
+      window.assertDeepEqual(
+        { unreadMessageCount: 0, favorite: true },
+        mailFolderInfo
+      );
+      browser.test.assertEq(InfoTestFolder.path, mailFolder.path);
+
+      info = await browser.folders.getFolderInfo(InfoTestFolder);
+      window.assertDeepEqual(
+        { totalMessageCount: 12, unreadMessageCount: 0, favorite: true },
+        info
+      );
+
+      // Test flipping favorite back to false.
+      onFolderInfoChangedPromise = window.waitForEvent(
+        "folders.onFolderInfoChanged"
+      );
+      await window.sendMessage("setFavorite", false);
+      [mailFolder, mailFolderInfo] = await onFolderInfoChangedPromise;
+      window.assertDeepEqual({ favorite: false }, mailFolderInfo);
+      browser.test.assertEq(InfoTestFolder.path, mailFolder.path);
+
+      // Test setting some messages back to unread.
+      onFolderInfoChangedPromise = window.waitForEvent(
+        "folders.onFolderInfoChanged"
+      );
+      await window.sendMessage("markSomeAsUnread", 5);
+      [mailFolder, mailFolderInfo] = await onFolderInfoChangedPromise;
+      window.assertDeepEqual({ unreadMessageCount: 5 }, mailFolderInfo);
+
+      browser.test.notifyPass("finished");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "accountsFolders", "messagesDelete"],
+    },
+  });
+
+  let account = createAccount();
+  // Not all folders appear immediately on IMAP. Creating a new one causes them to appear.
+  let InfoTestFolder = await createSubfolder(
+    account.incomingServer.rootFolder,
+    "InfoTest"
+  );
+  await createMessages(InfoTestFolder, 12);
+
+  extension.onMessage("markAllAsRead", () => {
+    InfoTestFolder.markAllMessagesRead(null);
+    extension.sendMessage();
+  });
+
+  extension.onMessage("markSomeAsUnread", count => {
+    let messages = InfoTestFolder.messages;
+    while (messages.hasMoreElements() && count > 0) {
+      let msg = messages.getNext();
+      msg.markRead(false);
+      count--;
+    }
+    extension.sendMessage();
+  });
+
+  extension.onMessage("setFavorite", value => {
+    if (value) {
+      InfoTestFolder.setFlag(Ci.nsMsgFolderFlags.Favorite);
+    } else {
+      InfoTestFolder.clearFlag(Ci.nsMsgFolderFlags.Favorite);
+    }
+    extension.sendMessage();
+  });
+
+  // We should now have three folders. For IMAP accounts they are Inbox, Trash,
+  // and InfoTest. Otherwise they are Trash, Unsent Messages and InfoTest.
+
+  await extension.startup();
+  extension.sendMessage(account.key, IS_NNTP);
+  await extension.awaitFinish("finished");
+  await extension.unload();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_folders_mv3_event_pages.js b/comm/mail/components/extensions/test/xpcshell/test_ext_folders_mv3_event_pages.js
new file mode 100644
index 0000000000..eac947cda8
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_folders_mv3_event_pages.js
@@ -0,0 +1,374 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+var { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+
+ExtensionTestUtils.mockAppInfo();
+AddonTestUtils.maybeInit(this);
+
+registerCleanupFunction(async () => {
+  // Remove the temporary MozillaMailnews folder, which is not deleted in time when
+  // the cleanupFunction registered by AddonTestUtils.maybeInit() checks for left over
+  // files in the temp folder.
+  // Note: PathUtils.tempDir points to the system temp folder, which is different.
+  let path = PathUtils.join(
+    Services.dirsvc.get("TmpD", Ci.nsIFile).path,
+    "MozillaMailnews"
+  );
+  await IOUtils.remove(path, { recursive: true });
+});
+
+// Test events and persistent events for Manifest V3 for onCreated, onRenamed,
+// onMoved, onCopied and onDeleted.
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_folders_MV3_event_pages() {
+    await AddonTestUtils.promiseStartupManager();
+
+    let account = createAccount();
+    let rootFolder = account.incomingServer.rootFolder;
+    addIdentity(account, "id1@invalid");
+
+    let files = {
+      "background.js": () => {
+        for (let eventName of [
+          "onCreated",
+          "onDeleted",
+          "onCopied",
+          "onRenamed",
+          "onMoved",
+        ]) {
+          browser.folders[eventName].addListener(async (...args) => {
+            browser.test.log(`${eventName} received: ${JSON.stringify(args)}`);
+            browser.test.sendMessage(`${eventName} received`, args);
+          });
+        }
+
+        browser.test.sendMessage("background started");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        manifest_version: 3,
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead"],
+      },
+    });
+
+    // Function to start an event page extension (MV3), which can be called whenever
+    // the main test is about to trigger an event. The extension terminates its
+    // background and listens for that single event, verifying it is waking up correctly.
+    async function event_page_extension(eventName, actionCallback) {
+      let ext = ExtensionTestUtils.loadExtension({
+        files: {
+          "background.js": async () => {
+            // Whenever the extension starts or wakes up, hasFired is set to false. In
+            // case of a wake-up, the first fired event is the one that woke up the background.
+            let hasFired = false;
+            let _eventName = browser.runtime.getManifest().description;
+
+            browser.folders[_eventName].addListener(async (...args) => {
+              // Only send the first event after background wake-up, this should
+              // be the only one expected.
+              if (!hasFired) {
+                hasFired = true;
+                browser.test.sendMessage(`${_eventName} received`, args);
+              }
+            });
+
+            browser.test.sendMessage("background started");
+          },
+        },
+        manifest: {
+          manifest_version: 3,
+          description: eventName,
+          background: { scripts: ["background.js"] },
+          permissions: ["accountsRead"],
+        },
+      });
+      await ext.startup();
+      await ext.awaitMessage("background started");
+      // The listener should be persistent, but not primed.
+      assertPersistentListeners(ext, "folders", eventName, { primed: false });
+
+      await ext.terminateBackground({ disableResetIdleForTest: true });
+      // Verify the primed persistent listener.
+      assertPersistentListeners(ext, "folders", eventName, { primed: true });
+
+      await actionCallback();
+      let rv = await ext.awaitMessage(`${eventName} received`);
+      await ext.awaitMessage("background started");
+      // The listener should be persistent, but not primed.
+      assertPersistentListeners(ext, "folders", eventName, { primed: false });
+
+      await ext.unload();
+      return rv;
+    }
+
+    await extension.startup();
+    await extension.awaitMessage("background started");
+
+    // Create a test folder before terminating the background script, to make sure
+    // everything is sane.
+
+    rootFolder.createSubfolder("TestFolder", null);
+    await extension.awaitMessage("onCreated received");
+    if (IS_IMAP) {
+      // IMAP creates a default Trash folder on the fly.
+      await extension.awaitMessage("onCreated received");
+    }
+
+    // Create SubFolder1.
+
+    {
+      rootFolder.createSubfolder("SubFolder1", null);
+      let createData = await extension.awaitMessage("onCreated received");
+      Assert.deepEqual(
+        [
+          {
+            accountId: account.key,
+            name: "SubFolder1",
+            path: "/SubFolder1",
+          },
+        ],
+        createData,
+        "The onCreated event should return the correct values"
+      );
+    }
+
+    // Create SubFolder2 (used for primed onFolderInfoChanged).
+
+    {
+      let primedChangeData = await event_page_extension(
+        "onFolderInfoChanged",
+        () => {
+          rootFolder.createSubfolder("SubFolder3", null);
+        }
+      );
+      let createData = await extension.awaitMessage("onCreated received");
+      Assert.deepEqual(
+        [
+          {
+            accountId: account.key,
+            name: "SubFolder3",
+            path: "/SubFolder3",
+          },
+        ],
+        createData,
+        "The onCreated event should return the correct values"
+      );
+      // Testing for onFolderInfoChanged is difficult, because it may not be for
+      // the last created folder, but for one of the folders created earlier. We
+      // therefore do not check the folder, but only the value.
+      Assert.deepEqual(
+        { totalMessageCount: 0, unreadMessageCount: 0 },
+        primedChangeData[1],
+        "The primed onFolderInfoChanged event should return the correct values"
+      );
+    }
+
+    // Copy.
+
+    {
+      let primedCopyData = await event_page_extension("onCopied", () => {
+        MailServices.copy.copyFolder(
+          rootFolder.getChildNamed("SubFolder3"),
+          rootFolder.getChildNamed("SubFolder1"),
+          false,
+          null,
+          null
+        );
+      });
+      let copyData = await extension.awaitMessage("onCopied received");
+      Assert.deepEqual(
+        primedCopyData,
+        copyData,
+        "The primed onCopied event should return the correct values"
+      );
+      Assert.deepEqual(
+        [
+          {
+            accountId: account.key,
+            name: "SubFolder3",
+            path: "/SubFolder3",
+          },
+          {
+            accountId: account.key,
+            name: "SubFolder3",
+            path: "/SubFolder1/SubFolder3",
+          },
+        ],
+        copyData,
+        "The onCopied event should return the correct values"
+      );
+
+      if (IS_IMAP) {
+        // IMAP fires an additional create event.
+        let createData = await extension.awaitMessage("onCreated received");
+        Assert.deepEqual(
+          [
+            {
+              accountId: account.key,
+              name: "SubFolder3",
+              path: "/SubFolder1/SubFolder3",
+            },
+          ],
+          createData,
+          "The onCreated event should return the correct MailFolder values."
+        );
+      }
+    }
+
+    // Move.
+
+    {
+      let primedMoveData = await event_page_extension("onMoved", () => {
+        MailServices.copy.copyFolder(
+          rootFolder.getChildNamed("SubFolder1").getChildNamed("SubFolder3"),
+          rootFolder.getChildNamed("SubFolder3"),
+          true,
+          null,
+          null
+        );
+      });
+
+      let moveData = await extension.awaitMessage("onMoved received");
+      Assert.deepEqual(
+        primedMoveData,
+        moveData,
+        "The primed onMoved event should return the correct values"
+      );
+      Assert.deepEqual(
+        [
+          {
+            accountId: account.key,
+            name: "SubFolder3",
+            path: "/SubFolder1/SubFolder3",
+          },
+          {
+            accountId: account.key,
+            name: "SubFolder3",
+            path: "/SubFolder3/SubFolder3",
+          },
+        ],
+        moveData,
+        "The onMoved event should return the correct values"
+      );
+
+      if (IS_IMAP) {
+        // IMAP fires additional rename and delete events.
+        let renameData = await extension.awaitMessage("onRenamed received");
+        Assert.deepEqual(
+          [
+            {
+              accountId: account.key,
+              name: "SubFolder3",
+              path: "/SubFolder1/SubFolder3",
+            },
+            {
+              accountId: account.key,
+              name: "SubFolder3",
+              path: "/SubFolder3/SubFolder3",
+            },
+          ],
+          renameData,
+          "The onRenamed event should return the correct MailFolder values."
+        );
+        let deleteData = await extension.awaitMessage("onDeleted received");
+        Assert.deepEqual(
+          [
+            {
+              accountId: account.key,
+              name: "SubFolder3",
+              path: "/SubFolder1/SubFolder3",
+            },
+          ],
+          deleteData,
+          "The onDeleted event should return the correct MailFolder values."
+        );
+      }
+    }
+
+    // Delete.
+
+    {
+      let primedDeleteData = await event_page_extension("onDeleted", () => {
+        let subFolder1 = rootFolder.getChildNamed("SubFolder3");
+        subFolder1.propagateDelete(
+          subFolder1.getChildNamed("SubFolder3"),
+          true
+        );
+      });
+      let deleteData = await extension.awaitMessage("onDeleted received");
+      Assert.deepEqual(
+        primedDeleteData,
+        deleteData,
+        "The primed onDeleted event should return the correct values"
+      );
+      Assert.deepEqual(
+        [
+          {
+            accountId: account.key,
+            name: "SubFolder3",
+            path: "/SubFolder3/SubFolder3",
+          },
+        ],
+        deleteData,
+        "The onDeleted event should return the correct values"
+      );
+    }
+
+    // Rename.
+
+    {
+      let primedRenameData = await event_page_extension("onRenamed", () => {
+        rootFolder.getChildNamed("TestFolder").rename("TestFolder2", null);
+      });
+      let renameData = await extension.awaitMessage("onRenamed received");
+      Assert.deepEqual(
+        primedRenameData,
+        renameData,
+        "The primed onRenamed event should return the correct values"
+      );
+      if (IS_IMAP) {
+        // IMAP server sends an additional onDeleted and onCreated.
+        await extension.awaitMessage("onDeleted received");
+        await extension.awaitMessage("onCreated received");
+      }
+      Assert.deepEqual(
+        [
+          {
+            accountId: account.key,
+            name: "TestFolder",
+            path: "/TestFolder",
+          },
+          {
+            accountId: account.key,
+            name: "TestFolder2",
+            path: "/TestFolder2",
+          },
+        ],
+        renameData,
+        "The onRenamed event should return the correct values"
+      );
+    }
+
+    await extension.unload();
+
+    cleanUpAccount(account);
+    await AddonTestUtils.promiseShutdownManager();
+  }
+);
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_identities_mv3_event_pages.js b/comm/mail/components/extensions/test/xpcshell/test_ext_identities_mv3_event_pages.js
new file mode 100644
index 0000000000..0b12f8ca1c
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_identities_mv3_event_pages.js
@@ -0,0 +1,146 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+var { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+
+ExtensionTestUtils.mockAppInfo();
+AddonTestUtils.maybeInit(this);
+
+add_task(async function test_identities_MV3_event_pages() {
+  await AddonTestUtils.promiseStartupManager();
+
+  let account1 = createAccount();
+  addIdentity(account1, "id1@invalid");
+
+  let files = {
+    "background.js": async () => {
+      // Whenever the extension starts or wakes up, hasFired is set to false. In
+      // case of a wake-up, the first fired event is the one that woke up the background.
+      let hasFired = false;
+
+      for (let eventName of ["onCreated", "onUpdated", "onDeleted"]) {
+        browser.identities[eventName].addListener((...args) => {
+          // Only send the first event after background wake-up, this should be the
+          // only one expected.
+          if (!hasFired) {
+            hasFired = true;
+            browser.test.sendMessage(`${eventName} received`, args);
+          }
+        });
+      }
+
+      browser.test.sendMessage("background started");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      manifest_version: 3,
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "accountsIdentities"],
+      browser_specific_settings: { gecko: { id: "identities@xpcshell.test" } },
+    },
+  });
+
+  function checkPersistentListeners({ primed }) {
+    // A persistent event is referenced by its moduleName as defined in
+    // ext-mails.json, not by its actual namespace.
+    const persistent_events = [
+      "identities.onCreated",
+      "identities.onUpdated",
+      "identities.onDeleted",
+    ];
+
+    for (let event of persistent_events) {
+      let [moduleName, eventName] = event.split(".");
+      assertPersistentListeners(extension, moduleName, eventName, {
+        primed,
+      });
+    }
+  }
+
+  await extension.startup();
+
+  await extension.awaitMessage("background started");
+  // Verify persistent listener, not yet primed.
+  checkPersistentListeners({ primed: false });
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  // Verify the primed persistent listeners.
+  checkPersistentListeners({ primed: true });
+
+  // Create.
+
+  let id2 = addIdentity(account1, "id2@invalid");
+  let createData = await extension.awaitMessage("onCreated received");
+  Assert.deepEqual(
+    [
+      "id2",
+      {
+        accountId: "account1",
+        id: "id2",
+        label: "",
+        name: "",
+        email: "id2@invalid",
+        replyTo: "",
+        organization: "",
+        composeHtml: true,
+        signature: "",
+        signatureIsPlainText: true,
+      },
+    ],
+    createData,
+    "The primed onCreated event should return the correct values"
+  );
+
+  await extension.awaitMessage("background started");
+  // Verify persistent listener, not yet primed.
+  checkPersistentListeners({ primed: false });
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  // Verify the primed persistent listeners.
+  checkPersistentListeners({ primed: true });
+
+  // Update
+
+  id2.fullName = "Updated Name";
+  let updateData = await extension.awaitMessage("onUpdated received");
+  Assert.deepEqual(
+    ["id2", { name: "Updated Name", accountId: "account1", id: "id2" }],
+    updateData,
+    "The primed onUpdated event should return the correct values"
+  );
+  await extension.awaitMessage("background started");
+  // Verify persistent listener, not yet primed.
+  checkPersistentListeners({ primed: false });
+  await extension.terminateBackground({ disableResetIdleForTest: true });
+  // Verify the primed persistent listeners.
+  checkPersistentListeners({ primed: true });
+
+  // Delete
+
+  account1.removeIdentity(id2);
+  let deleteData = await extension.awaitMessage("onDeleted received");
+  Assert.deepEqual(
+    ["id2"],
+    deleteData,
+    "The primed onDeleted event should return the correct values"
+  );
+  // The background should have been restarted.
+  await extension.awaitMessage("background started");
+  // The listener should no longer be primed.
+  checkPersistentListeners({ primed: false });
+
+  await extension.unload();
+
+  cleanUpAccount(account1);
+  await AddonTestUtils.promiseShutdownManager();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_messages.js b/comm/mail/components/extensions/test/xpcshell/test_ext_messages.js
new file mode 100644
index 0000000000..24b2cb1484
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_messages.js
@@ -0,0 +1,730 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { ExtensionsUI } = ChromeUtils.import(
+  "resource:///modules/ExtensionsUI.jsm"
+);
+
+let account, rootFolder, subFolders;
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function setup() {
+    account = createAccount();
+    rootFolder = account.incomingServer.rootFolder;
+    subFolders = {
+      test3: await createSubfolder(rootFolder, "test3"),
+      test4: await createSubfolder(rootFolder, "test4"),
+      trash: rootFolder.getChildNamed("Trash"),
+    };
+    await createMessages(subFolders.trash, 99);
+    await createMessages(subFolders.test4, 1);
+  }
+);
+
+add_task(async function non_canonical_permission_description_mapping() {
+  let { msgs } = ExtensionsUI._buildStrings({
+    addon: { name: "FakeExtension" },
+    permissions: {
+      origins: [],
+      permissions: ["accountsRead", "messagesMove"],
+    },
+  });
+  equal(2, msgs.length, "Correct amount of descriptions");
+  equal(
+    "See your mail accounts, their identities and their folders",
+    msgs[0],
+    "Correct description for accountsRead"
+  );
+  equal(
+    "Copy or move your email messages (including moving them to the trash folder)",
+    msgs[1],
+    "Correct description for messagesMove"
+  );
+});
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_pagination() {
+    let files = {
+      "background.js": async () => {
+        // Test a response of 99 messages at 10 messages per page.
+        let [folder] = await window.waitForMessage();
+        let page = await browser.messages.list(folder);
+        browser.test.assertEq(36, page.id.length);
+        browser.test.assertEq(10, page.messages.length);
+
+        let originalPageId = page.id;
+        let numPages = 1;
+        let numMessages = 10;
+        while (page.id) {
+          page = await browser.messages.continueList(page.id);
+          browser.test.assertTrue(page.messages.length > 0);
+          numPages++;
+          numMessages += page.messages.length;
+          if (numMessages < 99) {
+            browser.test.assertEq(originalPageId, page.id);
+          } else {
+            browser.test.assertEq(null, page.id);
+          }
+        }
+        browser.test.assertEq(10, numPages);
+        browser.test.assertEq(99, numMessages);
+
+        browser.test.assertRejects(
+          browser.messages.continueList(originalPageId),
+          /No message list for id .*\. Have you reached the end of a list\?/
+        );
+
+        await window.sendMessage("setPref");
+
+        // Do the same test, but with the default 100 messages per page.
+        page = await browser.messages.list(folder);
+        browser.test.assertEq(null, page.id);
+        browser.test.assertEq(99, page.messages.length);
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead", "messagesRead"],
+      },
+    });
+
+    Services.prefs.setIntPref("extensions.webextensions.messagesPerPage", 10);
+
+    await extension.startup();
+    extension.sendMessage({ accountId: account.key, path: "/Trash" });
+
+    await extension.awaitMessage("setPref");
+    Services.prefs.clearUserPref("extensions.webextensions.messagesPerPage");
+    extension.sendMessage();
+
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_delete_without_permission() {
+    let files = {
+      "background.js": async () => {
+        let [accountId] = await window.waitForMessage();
+        let { folders } = await browser.accounts.get(accountId);
+        let testFolder4 = folders.find(f => f.name == "test4");
+
+        let { messages: folder4Messages } = await browser.messages.list(
+          testFolder4
+        );
+
+        // Try to delete a message.
+        await browser.test.assertThrows(
+          () => browser.messages.delete([folder4Messages[0].id], true),
+          `browser.messages.delete is not a function`,
+          "Should reject deleting without proper permission"
+        );
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        browser_specific_settings: {
+          gecko: { id: "messages.delete@mochi.test" },
+        },
+        permissions: ["accountsRead", "messagesMove", "messagesRead"],
+      },
+    });
+
+    await extension.startup();
+    extension.sendMessage(account.key);
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_move_and_copy_without_permission() {
+    let files = {
+      "background.js": async () => {
+        let [accountId] = await window.waitForMessage();
+        let { folders } = await browser.accounts.get(accountId);
+        let testFolder4 = folders.find(f => f.name == "test4");
+        let testFolder3 = folders.find(f => f.name == "test3");
+
+        let { messages: folder4Messages } = await browser.messages.list(
+          testFolder4
+        );
+
+        // Try to move a message.
+        await browser.test.assertRejects(
+          browser.messages.move([folder4Messages[0].id], testFolder3),
+          `Using messages.move() requires the "accountsRead" and the "messagesMove" permission`,
+          "Should reject move without proper permission"
+        );
+
+        // Try to copy a message.
+        await browser.test.assertRejects(
+          browser.messages.copy([folder4Messages[0].id], testFolder3),
+          `Using messages.copy() requires the "accountsRead" and the "messagesMove" permission`,
+          "Should reject copy without proper permission"
+        );
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        browser_specific_settings: {
+          gecko: { id: "messages.move@mochi.test" },
+        },
+        permissions: ["messagesRead", "accountsRead"],
+      },
+    });
+
+    await extension.startup();
+    extension.sendMessage(account.key);
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_tags() {
+    let files = {
+      "background.js": async () => {
+        let [accountId] = await window.waitForMessage();
+        let { folders } = await browser.accounts.get(accountId);
+        let testFolder4 = folders.find(f => f.name == "test4");
+        let { messages: folder4Messages } = await browser.messages.list(
+          testFolder4
+        );
+
+        let tags1 = await browser.messages.listTags();
+        window.assertDeepEqual(
+          [
+            {
+              key: "$label1",
+              tag: "Important",
+              color: "#FF0000",
+              ordinal: "",
+            },
+            {
+              key: "$label2",
+              tag: "Work",
+              color: "#FF9900",
+              ordinal: "",
+            },
+            {
+              key: "$label3",
+              tag: "Personal",
+              color: "#009900",
+              ordinal: "",
+            },
+            {
+              key: "$label4",
+              tag: "To Do",
+              color: "#3333FF",
+              ordinal: "",
+            },
+            {
+              key: "$label5",
+              tag: "Later",
+              color: "#993399",
+              ordinal: "",
+            },
+          ],
+          tags1
+        );
+
+        // Test some allowed special chars and that the key is created as lower
+        // case.
+        let goodKeys = [
+          "TestKey",
+          "Test_Key",
+          "Test\\Key",
+          "Test}Key",
+          "Test&Key",
+          "Test!Key",
+          "Test§Key",
+          "Test$Key",
+          "Test=Key",
+          "Test?Key",
+        ];
+        for (let key of goodKeys) {
+          await browser.messages.createTag(key, "Test Tag", "#123456");
+          let goodTags = await browser.messages.listTags();
+          window.assertDeepEqual(
+            [
+              {
+                key: "$label1",
+                tag: "Important",
+                color: "#FF0000",
+                ordinal: "",
+              },
+              {
+                key: "$label2",
+                tag: "Work",
+                color: "#FF9900",
+                ordinal: "",
+              },
+              {
+                key: "$label3",
+                tag: "Personal",
+                color: "#009900",
+                ordinal: "",
+              },
+              {
+                key: "$label4",
+                tag: "To Do",
+                color: "#3333FF",
+                ordinal: "",
+              },
+              {
+                key: "$label5",
+                tag: "Later",
+                color: "#993399",
+                ordinal: "",
+              },
+              {
+                key: key.toLowerCase(),
+                tag: "Test Tag",
+                color: "#123456",
+                ordinal: "",
+              },
+            ],
+            goodTags
+          );
+          await browser.messages.deleteTag(key.toLowerCase());
+        }
+
+        await browser.messages.createTag("custom_tag", "Custom Tag", "#123456");
+        let tags2 = await browser.messages.listTags();
+        window.assertDeepEqual(
+          [
+            {
+              key: "$label1",
+              tag: "Important",
+              color: "#FF0000",
+              ordinal: "",
+            },
+            {
+              key: "$label2",
+              tag: "Work",
+              color: "#FF9900",
+              ordinal: "",
+            },
+            {
+              key: "$label3",
+              tag: "Personal",
+              color: "#009900",
+              ordinal: "",
+            },
+            {
+              key: "$label4",
+              tag: "To Do",
+              color: "#3333FF",
+              ordinal: "",
+            },
+            {
+              key: "$label5",
+              tag: "Later",
+              color: "#993399",
+              ordinal: "",
+            },
+            {
+              key: "custom_tag",
+              tag: "Custom Tag",
+              color: "#123456",
+              ordinal: "",
+            },
+          ],
+          tags2
+        );
+
+        await browser.messages.updateTag("$label5", {
+          tag: "Much Later",
+          color: "#225599",
+        });
+        let tags3 = await browser.messages.listTags();
+        window.assertDeepEqual(
+          [
+            {
+              key: "$label1",
+              tag: "Important",
+              color: "#FF0000",
+              ordinal: "",
+            },
+            {
+              key: "$label2",
+              tag: "Work",
+              color: "#FF9900",
+              ordinal: "",
+            },
+            {
+              key: "$label3",
+              tag: "Personal",
+              color: "#009900",
+              ordinal: "",
+            },
+            {
+              key: "$label4",
+              tag: "To Do",
+              color: "#3333FF",
+              ordinal: "",
+            },
+            {
+              key: "$label5",
+              tag: "Much Later",
+              color: "#225599",
+              ordinal: "",
+            },
+            {
+              key: "custom_tag",
+              tag: "Custom Tag",
+              color: "#123456",
+              ordinal: "",
+            },
+          ],
+          tags3
+        );
+
+        // Test rejects for createTag().
+        let badKeys = [
+          "Bad Key",
+          "Bad%Key",
+          "Bad/Key",
+          "Bad*Key",
+          'Bad"Key',
+          "Bad{Key}",
+          "Bad(Key)",
+          "Bad<Key>",
+        ];
+        for (let badKey of badKeys) {
+          await browser.test.assertThrows(
+            () =>
+              browser.messages.createTag(badKey, "Important Stuff", "#223344"),
+            /Type error for parameter key/,
+            `Should reject creating an invalid key: ${badKey}`
+          );
+        }
+
+        await browser.test.assertThrows(
+          () =>
+            browser.messages.createTag(
+              "GoodKeyBadColor",
+              "Important Stuff",
+              "#223"
+            ),
+          /Type error for parameter color /,
+          "Should reject creating a key using an invalid short color"
+        );
+
+        await browser.test.assertThrows(
+          () =>
+            browser.messages.createTag(
+              "GoodKeyBadColor",
+              "Important Stuff",
+              "123223"
+            ),
+          /Type error for parameter color /,
+          "Should reject creating a key using an invalid color without leading #"
+        );
+
+        await browser.test.assertRejects(
+          browser.messages.createTag("$label5", "Important Stuff", "#223344"),
+          `Specified key already exists: $label5`,
+          "Should reject creating a key which exists already"
+        );
+
+        await browser.test.assertRejects(
+          browser.messages.createTag(
+            "Custom_Tag",
+            "Important Stuff",
+            "#223344"
+          ),
+          `Specified key already exists: custom_tag`,
+          "Should reject creating a key which exists already"
+        );
+
+        await browser.test.assertRejects(
+          browser.messages.createTag("GoodKey", "Important", "#223344"),
+          `Specified tag already exists: Important`,
+          "Should reject creating a key using a tag which exists already"
+        );
+
+        // Test rejects for updateTag();
+        await browser.test.assertThrows(
+          () => browser.messages.updateTag("Bad Key", { tag: "Much Later" }),
+          /Type error for parameter key/,
+          "Should reject updating an invalid key"
+        );
+
+        await browser.test.assertThrows(
+          () =>
+            browser.messages.updateTag("GoodKeyBadColor", { color: "123223" }),
+          /Error processing color/,
+          "Should reject updating a key using an invalid color"
+        );
+
+        await browser.test.assertRejects(
+          browser.messages.updateTag("$label50", { tag: "Much Later" }),
+          `Specified key does not exist: $label50`,
+          "Should reject updating an unknown key"
+        );
+
+        await browser.test.assertRejects(
+          browser.messages.updateTag("$label5", { tag: "Important" }),
+          `Specified tag already exists: Important`,
+          "Should reject updating a key using a tag which exists already"
+        );
+
+        // Test rejects for deleteTag();
+        await browser.test.assertThrows(
+          () => browser.messages.deleteTag("Bad Key"),
+          /Type error for parameter key/,
+          "Should reject deleting an invalid key"
+        );
+
+        await browser.test.assertRejects(
+          browser.messages.deleteTag("$label50"),
+          `Specified key does not exist: $label50`,
+          "Should reject deleting an unknown key"
+        );
+
+        // Test tagging messages, deleting tag and re-creating tag.
+        await browser.messages.update(folder4Messages[0].id, {
+          tags: ["custom_tag"],
+        });
+        let message1 = await browser.messages.get(folder4Messages[0].id);
+        window.assertDeepEqual(["custom_tag"], message1.tags);
+
+        await browser.messages.deleteTag("custom_tag");
+        let message2 = await browser.messages.get(folder4Messages[0].id);
+        window.assertDeepEqual([], message2.tags);
+
+        await browser.messages.createTag("custom_tag", "Custom Tag", "#123456");
+        let message3 = await browser.messages.get(folder4Messages[0].id);
+        window.assertDeepEqual(["custom_tag"], message3.tags);
+
+        // Test deleting built-in tag.
+        await browser.messages.deleteTag("$label5");
+        let tags4 = await browser.messages.listTags();
+        window.assertDeepEqual(
+          [
+            {
+              key: "$label1",
+              tag: "Important",
+              color: "#FF0000",
+              ordinal: "",
+            },
+            {
+              key: "$label2",
+              tag: "Work",
+              color: "#FF9900",
+              ordinal: "",
+            },
+            {
+              key: "$label3",
+              tag: "Personal",
+              color: "#009900",
+              ordinal: "",
+            },
+            {
+              key: "$label4",
+              tag: "To Do",
+              color: "#3333FF",
+              ordinal: "",
+            },
+            {
+              key: "custom_tag",
+              tag: "Custom Tag",
+              color: "#123456",
+              ordinal: "",
+            },
+          ],
+          tags4
+        );
+
+        // Clean up.
+        await browser.messages.update(folder4Messages[0].id, { tags: [] });
+        await browser.messages.deleteTag("custom_tag");
+        await browser.messages.createTag("$label5", "Later", "#993399");
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["messagesRead", "accountsRead", "messagesTags"],
+      },
+    });
+
+    await extension.startup();
+    extension.sendMessage(account.key);
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_tags_no_permission() {
+    let files = {
+      "background.js": async () => {
+        await browser.test.assertThrows(
+          () =>
+            browser.messages.createTag(
+              "custom_tag",
+              "Important Stuff",
+              "#223344"
+            ),
+          /browser.messages.createTag is not a function/,
+          "Should reject creating tags without messagesTags permission"
+        );
+
+        await browser.test.assertThrows(
+          () => browser.messages.updateTag("$label5", { tag: "Much Later" }),
+          /browser.messages.updateTag is not a function/,
+          "Should reject updating tags without messagesTags permission"
+        );
+
+        await browser.test.assertThrows(
+          () => browser.messages.deleteTag("$label5"),
+          /browser.messages.deleteTag is not a function/,
+          "Should reject deleting tags without messagesTags permission"
+        );
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["messagesRead", "accountsRead"],
+      },
+    });
+
+    await extension.startup();
+    extension.sendMessage(account.key);
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
+
+// The IMAP fakeserver just can't handle this.
+add_task({ skip_if: () => IS_IMAP || IS_NNTP }, async function test_archive() {
+  let account2 = createAccount();
+  account2.addIdentity(MailServices.accounts.createIdentity());
+  let inbox2 = await createSubfolder(
+    account2.incomingServer.rootFolder,
+    "test"
+  );
+  await createMessages(inbox2, 15);
+
+  let month = 10;
+  for (let message of inbox2.messages) {
+    message.date = new Date(2018, month++, 15) * 1000;
+  }
+
+  let files = {
+    "background.js": async () => {
+      let [accountId] = await window.waitForMessage();
+
+      let accountBefore = await browser.accounts.get(accountId);
+      browser.test.assertEq(3, accountBefore.folders.length);
+      browser.test.assertEq("/test", accountBefore.folders[2].path);
+
+      let messagesBefore = await browser.messages.list(
+        accountBefore.folders[2]
+      );
+      browser.test.assertEq(15, messagesBefore.messages.length);
+      await browser.messages.archive(messagesBefore.messages.map(m => m.id));
+
+      let accountAfter = await browser.accounts.get(accountId);
+      browser.test.assertEq(4, accountAfter.folders.length);
+      browser.test.assertEq("/test", accountAfter.folders[3].path);
+      browser.test.assertEq("/Archives", accountAfter.folders[0].path);
+      browser.test.assertEq(3, accountAfter.folders[0].subFolders.length);
+      browser.test.assertEq(
+        "/Archives/2018",
+        accountAfter.folders[0].subFolders[0].path
+      );
+      browser.test.assertEq(
+        "/Archives/2019",
+        accountAfter.folders[0].subFolders[1].path
+      );
+      browser.test.assertEq(
+        "/Archives/2020",
+        accountAfter.folders[0].subFolders[2].path
+      );
+
+      let messagesAfter = await browser.messages.list(accountAfter.folders[3]);
+      browser.test.assertEq(0, messagesAfter.messages.length);
+
+      let messages2018 = await browser.messages.list(
+        accountAfter.folders[0].subFolders[0]
+      );
+      browser.test.assertEq(2, messages2018.messages.length);
+
+      let messages2019 = await browser.messages.list(
+        accountAfter.folders[0].subFolders[1]
+      );
+      browser.test.assertEq(12, messages2019.messages.length);
+
+      let messages2020 = await browser.messages.list(
+        accountAfter.folders[0].subFolders[2]
+      );
+      browser.test.assertEq(1, messages2020.messages.length);
+
+      browser.test.notifyPass("finished");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "messagesMove", "messagesRead"],
+    },
+  });
+
+  await extension.startup();
+  extension.sendMessage(account2.key);
+  await extension.awaitFinish("finished");
+  await extension.unload();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_messages_attachments.js b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_attachments.js
new file mode 100644
index 0000000000..e46e35afe7
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_attachments.js
@@ -0,0 +1,499 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { TestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TestUtils.sys.mjs"
+);
+
+add_task(
+  {
+    skip_if: () => IS_IMAP,
+  },
+  async function test_setup() {
+    let _account = createAccount();
+    let _testFolder = await createSubfolder(
+      _account.incomingServer.rootFolder,
+      "test1"
+    );
+
+    let textAttachment = {
+      body: "textAttachment",
+      filename: "test.txt",
+      contentType: "text/plain",
+    };
+    let binaryAttachment = {
+      body: btoa("binaryAttachment"),
+      filename: "test",
+      contentType: "application/octet-stream",
+      encoding: "base64",
+    };
+
+    await createMessages(_testFolder, {
+      count: 1,
+      subject: "0 attachments",
+    });
+    await createMessages(_testFolder, {
+      count: 1,
+      subject: "1 text attachment",
+      attachments: [textAttachment],
+    });
+    await createMessages(_testFolder, {
+      count: 1,
+      subject: "1 binary attachment",
+      attachments: [binaryAttachment],
+    });
+    await createMessages(_testFolder, {
+      count: 1,
+      subject: "2 attachments",
+      attachments: [binaryAttachment, textAttachment],
+    });
+    await createMessageFromFile(
+      _testFolder,
+      do_get_file("messages/nestedMessages.eml").path
+    );
+  }
+);
+
+add_task(
+  {
+    skip_if: () => IS_IMAP,
+  },
+  async function test_attachments() {
+    let extension = ExtensionTestUtils.loadExtension({
+      files: {
+        "background.js": async () => {
+          let [account] = await browser.accounts.list();
+          let testFolder = account.folders.find(f => f.name == "test1");
+          let { messages } = await browser.messages.list(testFolder);
+          browser.test.assertEq(5, messages.length);
+
+          let attachments, attachment, file;
+
+          // "0 attachments" message.
+
+          attachments = await browser.messages.listAttachments(messages[0].id);
+          browser.test.assertEq("0 attachments", messages[0].subject);
+          browser.test.assertEq(0, attachments.length);
+
+          // "1 text attachment" message.
+
+          attachments = await browser.messages.listAttachments(messages[1].id);
+          browser.test.assertEq("1 text attachment", messages[1].subject);
+          browser.test.assertEq(1, attachments.length);
+
+          attachment = attachments[0];
+          browser.test.assertEq("text/plain", attachment.contentType);
+          browser.test.assertEq("test.txt", attachment.name);
+          browser.test.assertEq("1.2", attachment.partName);
+          browser.test.assertEq(14, attachment.size);
+
+          file = await browser.messages.getAttachmentFile(
+            messages[1].id,
+            attachment.partName
+          );
+          // eslint-disable-next-line mozilla/use-isInstance
+          browser.test.assertTrue(file instanceof File);
+          browser.test.assertEq("test.txt", file.name);
+          browser.test.assertEq(14, file.size);
+
+          browser.test.assertEq("textAttachment", await file.text());
+
+          let reader = new FileReader();
+          let data = await new Promise(resolve => {
+            reader.onload = e => resolve(e.target.result);
+            reader.readAsDataURL(file);
+          });
+
+          browser.test.assertEq(
+            "data:text/plain;base64,dGV4dEF0dGFjaG1lbnQ=",
+            data
+          );
+
+          // "1 binary attachment" message.
+
+          attachments = await browser.messages.listAttachments(messages[2].id);
+          browser.test.assertEq("1 binary attachment", messages[2].subject);
+          browser.test.assertEq(1, attachments.length);
+
+          attachment = attachments[0];
+          browser.test.assertEq(
+            attachment.contentType,
+            "application/octet-stream"
+          );
+          browser.test.assertEq("test", attachment.name);
+          browser.test.assertEq("1.2", attachment.partName);
+          browser.test.assertEq(16, attachment.size);
+
+          file = await browser.messages.getAttachmentFile(
+            messages[2].id,
+            attachment.partName
+          );
+          // eslint-disable-next-line mozilla/use-isInstance
+          browser.test.assertTrue(file instanceof File);
+          browser.test.assertEq("test", file.name);
+          browser.test.assertEq(16, file.size);
+
+          browser.test.assertEq("binaryAttachment", await file.text());
+
+          reader = new FileReader();
+          data = await new Promise(resolve => {
+            reader.onload = e => resolve(e.target.result);
+            reader.readAsDataURL(file);
+          });
+
+          browser.test.assertEq(
+            "data:application/octet-stream;base64,YmluYXJ5QXR0YWNobWVudA==",
+            data
+          );
+
+          // "2 attachments" message.
+
+          attachments = await browser.messages.listAttachments(messages[3].id);
+          browser.test.assertEq("2 attachments", messages[3].subject);
+          browser.test.assertEq(2, attachments.length);
+
+          attachment = attachments[0];
+          browser.test.assertEq(
+            attachment.contentType,
+            "application/octet-stream"
+          );
+          browser.test.assertEq("test", attachment.name);
+          browser.test.assertEq("1.2", attachment.partName);
+          browser.test.assertEq(16, attachment.size);
+
+          file = await browser.messages.getAttachmentFile(
+            messages[3].id,
+            attachment.partName
+          );
+          // eslint-disable-next-line mozilla/use-isInstance
+          browser.test.assertTrue(file instanceof File);
+          browser.test.assertEq("test", file.name);
+          browser.test.assertEq(16, file.size);
+
+          browser.test.assertEq("binaryAttachment", await file.text());
+
+          attachment = attachments[1];
+          browser.test.assertEq("text/plain", attachment.contentType);
+          browser.test.assertEq("test.txt", attachment.name);
+          browser.test.assertEq("1.3", attachment.partName);
+          browser.test.assertEq(14, attachment.size);
+
+          file = await browser.messages.getAttachmentFile(
+            messages[3].id,
+            attachment.partName
+          );
+          // eslint-disable-next-line mozilla/use-isInstance
+          browser.test.assertTrue(file instanceof File);
+          browser.test.assertEq("test.txt", file.name);
+          browser.test.assertEq(14, file.size);
+
+          browser.test.assertEq("textAttachment", await file.text());
+
+          await browser.test.assertRejects(
+            browser.messages.listAttachments(0),
+            /^Message not found: \d+\.$/,
+            "Bad message ID should throw"
+          );
+          await browser.test.assertRejects(
+            browser.messages.getAttachmentFile(0, "1.2"),
+            /^Message not found: \d+\.$/,
+            "Bad message ID should throw"
+          );
+          browser.test.assertThrows(
+            () => browser.messages.getAttachmentFile(messages[3].id, "silly"),
+            /^Type error for parameter partName .* for messages\.getAttachmentFile\.$/,
+            "Bad part name should throw"
+          );
+          await browser.test.assertRejects(
+            browser.messages.getAttachmentFile(messages[3].id, "1.42"),
+            /Part 1.42 not found in message \d+\./,
+            "Non-existent part should throw"
+          );
+
+          browser.test.notifyPass("finished");
+        },
+        "utils.js": await getUtilsJS(),
+      },
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead", "messagesRead"],
+      },
+    });
+
+    await extension.startup();
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
+
+add_task(
+  {
+    skip_if: () => IS_IMAP,
+  },
+  async function test_messages_as_attachments() {
+    let extension = ExtensionTestUtils.loadExtension({
+      files: {
+        "background.js": async () => {
+          let [account] = await browser.accounts.list();
+          let testFolder = account.folders.find(f => f.name == "test1");
+          let { messages } = await browser.messages.list(testFolder);
+          browser.test.assertEq(5, messages.length);
+          let message = messages[4];
+
+          function validateMessage(msg, expectedValues) {
+            for (let expectedValueName in expectedValues) {
+              let value = msg[expectedValueName];
+              let expected = expectedValues[expectedValueName];
+              if (Array.isArray(expected)) {
+                browser.test.assertTrue(
+                  Array.isArray(value),
+                  `Value for ${expectedValueName} should be an Array.`
+                );
+                browser.test.assertEq(
+                  expected.length,
+                  value.length,
+                  `Value for ${expectedValueName} should have the correct Array size.`
+                );
+                for (let i = 0; i < expected.length; i++) {
+                  browser.test.assertEq(
+                    expected[i],
+                    value[i],
+                    `Value for ${expectedValueName}[${i}] should be correct.`
+                  );
+                }
+              } else if (expected instanceof Date) {
+                browser.test.assertTrue(
+                  value instanceof Date,
+                  `Value for ${expectedValueName} should be a Date.`
+                );
+                browser.test.assertEq(
+                  expected.getTime(),
+                  value.getTime(),
+                  `Date value for ${expectedValueName} should be correct.`
+                );
+              } else {
+                browser.test.assertEq(
+                  expected,
+                  value,
+                  `Value for ${expectedValueName} should be correct.`
+                );
+              }
+            }
+          }
+
+          // Request attachments.
+          let attachments = await browser.messages.listAttachments(message.id);
+          browser.test.assertEq(2, attachments.length);
+          browser.test.assertEq("1.2", attachments[0].partName);
+          browser.test.assertEq("1.3", attachments[1].partName);
+
+          browser.test.assertEq("message1.eml", attachments[0].name);
+          browser.test.assertEq("yellowPixel.png", attachments[1].name);
+
+          // Validate the returned MessageHeader for attached message1.eml.
+          let subMessage = attachments[0].message;
+          browser.test.assertTrue(
+            subMessage.id != message.id,
+            `Id of attached SubMessage (${subMessage.id}) should be different from the id of the outer message (${message.id})`
+          );
+          validateMessage(subMessage, {
+            date: new Date(958606367000),
+            author: "Superman <clark.kent@dailyplanet.com>",
+            recipients: ["Jimmy <jimmy.olsen@dailyplanet.com>"],
+            ccList: [],
+            bccList: [],
+            subject: "Test message 1",
+            new: false,
+            headersOnly: false,
+            flagged: false,
+            junk: false,
+            junkScore: 0,
+            headerMessageId: "sample-attached.eml@mime.sample",
+            size: 0,
+            tags: [],
+            external: true,
+          });
+
+          // Get attachments of sub-message messag1.eml.
+          let subAttachments = await browser.messages.listAttachments(
+            subMessage.id
+          );
+          browser.test.assertEq(4, subAttachments.length);
+          browser.test.assertEq("1.2.1.2", subAttachments[0].partName);
+          browser.test.assertEq("1.2.1.3", subAttachments[1].partName);
+          browser.test.assertEq("1.2.1.4", subAttachments[2].partName);
+          browser.test.assertEq("1.2.1.5", subAttachments[3].partName);
+
+          browser.test.assertEq("whitePixel.png", subAttachments[0].name);
+          browser.test.assertEq("greenPixel.png", subAttachments[1].name);
+          browser.test.assertEq("redPixel.png", subAttachments[2].name);
+          browser.test.assertEq("message2.eml", subAttachments[3].name);
+
+          // Validate the returned MessageHeader for sub-message message2.eml
+          // attached to sub-message message1.eml.
+          let subSubMessage = subAttachments[3].message;
+          browser.test.assertTrue(
+            ![message.id, subMessage.id].includes(subSubMessage.id),
+            `Id of attached SubSubMessage (${subSubMessage.id}) should be different from the id of the outer message (${message.id}) and from the SubMessage (${subMessage.id})`
+          );
+          validateMessage(subSubMessage, {
+            date: new Date(958519967000),
+            author: "Jimmy <jimmy.olsen@dailyplanet.com>",
+            recipients: ["Superman <clark.kent@dailyplanet.com>"],
+            ccList: [],
+            bccList: [],
+            subject: "Test message 2",
+            new: false,
+            headersOnly: false,
+            flagged: false,
+            junk: false,
+            junkScore: 0,
+            headerMessageId: "sample-nested-attached.eml@mime.sample",
+            size: 0,
+            tags: [],
+            external: true,
+          });
+
+          // Test getAttachmentFile().
+          // Note: This function has x-ray vision into sub-messages and can get
+          // any part inside the message, even if - technically - the attachments
+          // belong to subMessages. There is no difference between requesting
+          // part 1.2.1.2 from the main message or from message1.eml (part 1.2).
+          // X-ray vision from a sub-message back into a parent is not allowed.
+          let platform = await browser.runtime.getPlatformInfo();
+          let fileTests = [
+            {
+              partName: "1.2",
+              name: "message1.eml",
+              size:
+                platform.os != "win" &&
+                (account.type == "none" || account.type == "nntp")
+                  ? 2517
+                  : 2601,
+              text: "Message-ID: <sample-attached.eml@mime.sample>",
+            },
+            {
+              partName: "1.2.1.2",
+              name: "whitePixel.png",
+              size: 69,
+              data: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQmCC",
+            },
+            {
+              partName: "1.2.1.3",
+              name: "greenPixel.png",
+              size: 119,
+              data: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAMSURBVBhXY+C76AoAAhUBJel4xsMAAAAASUVORK5CYII=",
+            },
+            {
+              partName: "1.2.1.4",
+              name: "redPixel.png",
+              size: 119,
+              data: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAMSURBVBhXY+hgkAYAAbcApOp/9LEAAAAASUVORK5CYII=",
+            },
+            {
+              partName: "1.2.1.5",
+              name: "message2.eml",
+              size:
+                platform.os != "win" &&
+                (account.type == "none" || account.type == "nntp")
+                  ? 838
+                  : 867,
+              text: "Message-ID: <sample-nested-attached.eml@mime.sample>",
+            },
+            {
+              partName: "1.2.1.5.1.2",
+              name: "whitePixel.png",
+              size: 69,
+              data: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVQI12P4//8/AAX+Av7czFnnAAAAAElFTkSuQmCC",
+            },
+            {
+              partName: "1.3",
+              name: "yellowPixel.png",
+              size: 119,
+              data: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAMSURBVBhXY/j/iQEABOUB8pypNlQAAAAASUVORK5CYII=",
+            },
+          ];
+          let testMessages = [
+            {
+              id: message.id,
+              expectedFileCounts: 7,
+            },
+            {
+              id: subMessage.id,
+              subPart: "1.2.",
+              expectedFileCounts: 5,
+            },
+            {
+              id: subSubMessage.id,
+              subPart: "1.2.1.5.",
+              expectedFileCounts: 1,
+            },
+          ];
+          for (let msg of testMessages) {
+            let fileCounts = 0;
+            for (let test of fileTests) {
+              if (msg.subPart && !test.partName.startsWith(msg.subPart)) {
+                await browser.test.assertRejects(
+                  browser.messages.getAttachmentFile(msg.id, test.partName),
+                  `Part ${test.partName} not found in message ${msg.id}.`,
+                  "Sub-message should not be able to get parts from parent message"
+                );
+                continue;
+              }
+              fileCounts++;
+
+              let file = await browser.messages.getAttachmentFile(
+                msg.id,
+                test.partName
+              );
+
+              // eslint-disable-next-line mozilla/use-isInstance
+              browser.test.assertTrue(file instanceof File);
+              browser.test.assertEq(test.name, file.name);
+              browser.test.assertEq(test.size, file.size);
+
+              if (test.text) {
+                browser.test.assertTrue(
+                  (await file.text()).startsWith(test.text)
+                );
+              }
+
+              if (test.data) {
+                let reader = new FileReader();
+                let data = await new Promise(resolve => {
+                  reader.onload = e => resolve(e.target.result);
+                  reader.readAsDataURL(file);
+                });
+                browser.test.assertEq(
+                  test.data,
+                  data.replaceAll("\r\n", "\n").trim()
+                );
+              }
+            }
+            browser.test.assertEq(
+              msg.expectedFileCounts,
+              fileCounts,
+              "Should have requested to correct amount of attachment files."
+            );
+          }
+          browser.test.notifyPass("finished");
+        },
+        "utils.js": await getUtilsJS(),
+      },
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead", "messagesRead"],
+      },
+    });
+
+    await extension.startup();
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_messages_get.js b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_get.js
new file mode 100644
index 0000000000..2872a2141f
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_get.js
@@ -0,0 +1,1073 @@
+/* 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";
+
+var { FileUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/FileUtils.sys.mjs"
+);
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { OpenPGPTestUtils } = ChromeUtils.import(
+  "resource://testing-common/mozmill/OpenPGPTestUtils.jsm"
+);
+
+const OPENPGP_TEST_DIR = do_get_file("../../../../test/browser/openpgp");
+const OPENPGP_KEY_PATH = PathUtils.join(
+  OPENPGP_TEST_DIR.path,
+  "data",
+  "keys",
+  "alice@openpgp.example-0xf231550c4f47e38e-secret.asc"
+);
+
+/**
+ * Test the messages.getRaw and messages.getFull functions. Since each message
+ * is unique and there are minor differences between the account
+ * implementations, we don't compare exactly with a reference message.
+ */
+add_task(async function test_plain_mv2() {
+  let _account = createAccount();
+  let _folder = await createSubfolder(
+    _account.incomingServer.rootFolder,
+    "test1"
+  );
+  await createMessages(_folder, 1);
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: async () => {
+      let accounts = await browser.accounts.list();
+      browser.test.assertEq(1, accounts.length);
+
+      for (let account of accounts) {
+        let folder = account.folders.find(f => f.name == "test1");
+        let { messages } = await browser.messages.list(folder);
+        browser.test.assertEq(1, messages.length);
+
+        let [message] = messages;
+
+        // Expected message content:
+        // -------------------------
+        // From andy@anway.invalid
+        // Content-Type: text/plain; charset=ISO-8859-1; format=flowed
+        // Subject: Big Meeting Today
+        // From: "Andy Anway" <andy@anway.invalid>
+        // To: "Bob Bell" <bob@bell.invalid>
+        // Message-Id: <0@made.up.invalid>
+        // Date: Wed, 06 Nov 2019 22:37:40 +1300
+        //
+        // Hello Bob Bell!
+        //
+
+        browser.test.assertEq("Big Meeting Today", message.subject);
+        browser.test.assertEq(
+          '"Andy Anway" <andy@anway.invalid>',
+          message.author
+        );
+
+        // The msgHdr of NNTP messages have no recipients.
+        if (account.type != "nntp") {
+          browser.test.assertEq(
+            "Bob Bell <bob@bell.invalid>",
+            message.recipients[0]
+          );
+        }
+
+        let strMessage_1 = await browser.messages.getRaw(message.id);
+        browser.test.assertEq("string", typeof strMessage_1);
+        let strMessage_2 = await browser.messages.getRaw(message.id, {
+          data_format: "BinaryString",
+        });
+        browser.test.assertEq("string", typeof strMessage_2);
+        let fileMessage_3 = await browser.messages.getRaw(message.id, {
+          data_format: "File",
+        });
+        // eslint-disable-next-line mozilla/use-isInstance
+        browser.test.assertTrue(fileMessage_3 instanceof File);
+        // Since we do not have utf-8 chars in the test message, the returned BinaryString is
+        // identical to the return value of File.text().
+        let strMessage_3 = await fileMessage_3.text();
+
+        for (let strMessage of [strMessage_1, strMessage_2, strMessage_3]) {
+          // Fold Windows line-endings \r\n to \n.
+          strMessage = strMessage.replace(/\r/g, "");
+          browser.test.assertTrue(
+            strMessage.includes("Subject: Big Meeting Today\n")
+          );
+          browser.test.assertTrue(
+            strMessage.includes('From: "Andy Anway" <andy@anway.invalid>\n')
+          );
+          browser.test.assertTrue(
+            strMessage.includes('To: "Bob Bell" <bob@bell.invalid>\n')
+          );
+          browser.test.assertTrue(strMessage.includes("Hello Bob Bell!"));
+        }
+
+        // {
+        //   "contentType": "message/rfc822",
+        //   "headers": {
+        //     "content-type": ["text/plain; charset=ISO-8859-1; format=flowed"],
+        //     "subject": ["Big Meeting Today"],
+        //     "from": ["\"Andy Anway\" <andy@anway.invalid>"],
+        //     "to": ["\"Bob Bell\" <bob@bell.invalid>"],
+        //     "message-id": ["<0@made.up.invalid>"],
+        //     "date": ["Wed, 06 Nov 2019 22:37:40 +1300"]
+        //   },
+        //   "partName": "",
+        //   "size": 17,
+        //   "parts": [
+        //     {
+        //       "body": "Hello Bob Bell!\n\n",
+        //       "contentType": "text/plain",
+        //       "headers": {
+        //         "content-type": ["text/plain; charset=ISO-8859-1; format=flowed"]
+        //       },
+        //       "partName": "1",
+        //       "size": 17
+        //     }
+        //   ]
+        // }
+
+        let fullMessage = await browser.messages.getFull(message.id);
+        browser.test.log(JSON.stringify(fullMessage));
+        browser.test.assertEq("object", typeof fullMessage);
+        browser.test.assertEq("message/rfc822", fullMessage.contentType);
+
+        browser.test.assertEq("object", typeof fullMessage.headers);
+        for (let header of [
+          "content-type",
+          "date",
+          "from",
+          "message-id",
+          "subject",
+          "to",
+        ]) {
+          browser.test.assertTrue(Array.isArray(fullMessage.headers[header]));
+          browser.test.assertEq(1, fullMessage.headers[header].length);
+        }
+        browser.test.assertEq(
+          "Big Meeting Today",
+          fullMessage.headers.subject[0]
+        );
+        browser.test.assertEq(
+          '"Andy Anway" <andy@anway.invalid>',
+          fullMessage.headers.from[0]
+        );
+        browser.test.assertEq(
+          '"Bob Bell" <bob@bell.invalid>',
+          fullMessage.headers.to[0]
+        );
+
+        browser.test.assertTrue(Array.isArray(fullMessage.parts));
+        browser.test.assertEq(1, fullMessage.parts.length);
+        browser.test.assertEq("object", typeof fullMessage.parts[0]);
+        browser.test.assertEq(
+          "Hello Bob Bell!",
+          fullMessage.parts[0].body.trimRight()
+        );
+      }
+
+      browser.test.notifyPass("finished");
+    },
+    manifest: { permissions: ["accountsRead", "messagesRead"] },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  cleanUpAccount(_account);
+});
+
+add_task(async function test_plain_mv3() {
+  let _account = createAccount();
+  let _folder = await createSubfolder(
+    _account.incomingServer.rootFolder,
+    "test1"
+  );
+  await createMessages(_folder, 1);
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: async () => {
+      let accounts = await browser.accounts.list();
+      browser.test.assertEq(1, accounts.length);
+
+      for (let account of accounts) {
+        let folder = account.folders.find(f => f.name == "test1");
+        let { messages } = await browser.messages.list(folder);
+        browser.test.assertEq(1, messages.length);
+
+        let [message] = messages;
+
+        // Expected message content:
+        // -------------------------
+        // From chris@clarke.invalid
+        // Content-Type: text/plain; charset=ISO-8859-1; format=flowed
+        // Subject: Small Party Tomorrow
+        // From: "Chris Clarke" <chris@clarke.invalid>
+        // To: "David Davol" <david@davol.invalid>
+        // Message-Id: <1@made.up.invalid>
+        // Date: Tue, 01 Feb 2000 01:00:00 +0100
+        //
+        // Hello David Davol!
+        //
+
+        browser.test.assertEq("Small Party Tomorrow", message.subject);
+        browser.test.assertEq(
+          '"Chris Clarke" <chris@clarke.invalid>',
+          message.author
+        );
+
+        // The msgHdr of NNTP messages have no recipients.
+        if (account.type != "nntp") {
+          browser.test.assertEq(
+            "David Davol <david@davol.invalid>",
+            message.recipients[0]
+          );
+        }
+
+        let fileMessage_1 = await browser.messages.getRaw(message.id);
+        // eslint-disable-next-line mozilla/use-isInstance
+        browser.test.assertTrue(fileMessage_1 instanceof File);
+        // Since we do not have utf-8 chars in the test message, the returned
+        // BinaryString is identical to the return value of File.text().
+        let strMessage_1 = await fileMessage_1.text();
+
+        let strMessage_2 = await browser.messages.getRaw(message.id, {
+          data_format: "BinaryString",
+        });
+        browser.test.assertEq("string", typeof strMessage_2);
+
+        let fileMessage_3 = await browser.messages.getRaw(message.id, {
+          data_format: "File",
+        });
+        // eslint-disable-next-line mozilla/use-isInstance
+        browser.test.assertTrue(fileMessage_3 instanceof File);
+        let strMessage_3 = await fileMessage_3.text();
+
+        for (let strMessage of [strMessage_1, strMessage_2, strMessage_3]) {
+          // Fold Windows line-endings \r\n to \n.
+          strMessage = strMessage.replace(/\r/g, "");
+          browser.test.assertTrue(
+            strMessage.includes("Subject: Small Party Tomorrow\n")
+          );
+          browser.test.assertTrue(
+            strMessage.includes('From: "Chris Clarke" <chris@clarke.invalid>\n')
+          );
+          browser.test.assertTrue(
+            strMessage.includes('To: "David Davol" <david@davol.invalid>\n')
+          );
+          browser.test.assertTrue(strMessage.includes("Hello David Davol!"));
+        }
+
+        // {
+        //   "contentType": "message/rfc822",
+        //   "headers": {
+        //     "content-type": ["text/plain; charset=ISO-8859-1; format=flowed"],
+        //     "subject": ["Small Party Tomorrow"],
+        //     "from": ["\"Chris Clarke\" <chris@clarke.invalid>"],
+        //     "to": ["\"David Davol\" <David Davol>"],
+        //     "message-id": ["<1@made.up.invalid>"],
+        //     "date": ["Tue, 01 Feb 2000 01:00:00 +0100"]
+        //   },
+        //   "partName": "",
+        //   "size": 20,
+        //   "parts": [
+        //     {
+        //       "body": "David Davol!\n\n",
+        //       "contentType": "text/plain",
+        //       "headers": {
+        //         "content-type": ["text/plain; charset=ISO-8859-1; format=flowed"]
+        //       },
+        //       "partName": "1",
+        //       "size": 20
+        //     }
+        //   ]
+        // }
+
+        let fullMessage = await browser.messages.getFull(message.id);
+        browser.test.log(JSON.stringify(fullMessage));
+        browser.test.assertEq("object", typeof fullMessage);
+        browser.test.assertEq("message/rfc822", fullMessage.contentType);
+
+        browser.test.assertEq("object", typeof fullMessage.headers);
+        for (let header of [
+          "content-type",
+          "date",
+          "from",
+          "message-id",
+          "subject",
+          "to",
+        ]) {
+          browser.test.assertTrue(Array.isArray(fullMessage.headers[header]));
+          browser.test.assertEq(1, fullMessage.headers[header].length);
+        }
+        browser.test.assertEq(
+          "Small Party Tomorrow",
+          fullMessage.headers.subject[0]
+        );
+        browser.test.assertEq(
+          '"Chris Clarke" <chris@clarke.invalid>',
+          fullMessage.headers.from[0]
+        );
+        browser.test.assertEq(
+          '"David Davol" <david@davol.invalid>',
+          fullMessage.headers.to[0]
+        );
+
+        browser.test.assertTrue(Array.isArray(fullMessage.parts));
+        browser.test.assertEq(1, fullMessage.parts.length);
+        browser.test.assertEq("object", typeof fullMessage.parts[0]);
+        browser.test.assertEq(
+          "Hello David Davol!",
+          fullMessage.parts[0].body.trimRight()
+        );
+      }
+
+      browser.test.notifyPass("finished");
+    },
+    manifest: {
+      manifest_version: 3,
+      permissions: ["accountsRead", "messagesRead"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  cleanUpAccount(_account);
+});
+
+/**
+ * Test that mime parsers for all message types retrieve the correctly decoded
+ * headers and bodies. Bodies should no not be returned, if it is an attachment.
+ * Sizes are not checked for.
+ */
+add_task(async function test_encoding() {
+  let _account = createAccount();
+  let _folder = await createSubfolder(
+    _account.incomingServer.rootFolder,
+    "test1"
+  );
+
+  // Main body with disposition inline, base64 encoded,
+  // subject is UTF-8 encoded word.
+  await createMessageFromFile(
+    _folder,
+    do_get_file("messages/sample01.eml").path
+  );
+  // A multipart/mixed mime message, to header is iso-8859-1 encoded word,
+  // body is quoted printable with iso-8859-1, attachments with different names
+  // and filenames.
+  await createMessageFromFile(
+    _folder,
+    do_get_file("messages/sample02.eml").path
+  );
+  // Message with attachment only, From header is iso-8859-1 encoded word.
+  await createMessageFromFile(
+    _folder,
+    do_get_file("messages/sample03.eml").path
+  );
+  // Message with koi8-r + base64 encoded body, subject is koi8-r encoded word.
+  await createMessageFromFile(
+    _folder,
+    do_get_file("messages/sample04.eml").path
+  );
+  // Message with windows-1251 + base64 encoded body, subject is windows-1251
+  // encoded word.
+  await createMessageFromFile(
+    _folder,
+    do_get_file("messages/sample05.eml").path
+  );
+  // Message without plain/text content-type.
+  await createMessageFromFile(
+    _folder,
+    do_get_file("messages/sample06.eml").path
+  );
+  // A multipart/alternative message without plain/text content-type.
+  await createMessageFromFile(
+    _folder,
+    do_get_file("messages/sample07.eml").path
+  );
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: async () => {
+      let accounts = await browser.accounts.list();
+      browser.test.assertEq(1, accounts.length);
+
+      let expectedData = {
+        "01.eml@mime.sample": {
+          msgHeaders: {
+            subject: "αλφάβητο",
+            author: "Bug Reporter <new@thunderbird.bug>",
+          },
+          msgParts: {
+            contentType: "message/rfc822",
+            partName: "",
+            size: 0,
+            headers: {
+              from: ["Bug Reporter <new@thunderbird.bug>"],
+              newsgroups: ["gmane.comp.mozilla.thundebird.user"],
+              subject: ["αλφάβητο"],
+              date: ["Thu, 27 May 2021 21:23:35 +0100"],
+              "message-id": ["<01.eml@mime.sample>"],
+              "mime-version": ["1.0"],
+              "content-type": ["text/plain; charset=utf-8;"],
+              "content-transfer-encoding": ["base64"],
+              "content-disposition": ["inline"],
+            },
+            parts: [
+              {
+                contentType: "text/plain",
+                partName: "1",
+                size: 0,
+                body: "Άλφα\n",
+                headers: {
+                  "content-type": ["text/plain; charset=utf-8;"],
+                },
+              },
+            ],
+          },
+        },
+        "02.eml@mime.sample": {
+          msgHeaders: {
+            subject: "Test message from Microsoft Outlook 00",
+            author: '"Doug Sauder" <doug@example.com>',
+          },
+          msgParts: {
+            contentType: "message/rfc822",
+            partName: "",
+            size: 0,
+            headers: {
+              from: ['"Doug Sauder" <doug@example.com>'],
+              to: ["Heinz Müller <mueller@example.com>"],
+              subject: ["Test message from Microsoft Outlook 00"],
+              date: ["Wed, 17 May 2000 19:32:47 -0400"],
+              "message-id": ["<02.eml@mime.sample>"],
+              "mime-version": ["1.0"],
+              "content-type": [
+                'multipart/mixed; boundary="----=_NextPart_000_0002_01BFC036.AE309650"',
+              ],
+              "x-priority": ["3 (Normal)"],
+              "x-msmail-priority": ["Normal"],
+              "x-mailer": [
+                "Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)",
+              ],
+              importance: ["Normal"],
+              "x-mimeole": ["Produced By Microsoft MimeOLE V5.00.2314.1300"],
+            },
+            parts: [
+              {
+                contentType: "multipart/mixed",
+                partName: "1",
+                size: 0,
+                headers: {
+                  "content-type": [
+                    'multipart/mixed; boundary="----=_NextPart_000_0002_01BFC036.AE309650"',
+                  ],
+                },
+                parts: [
+                  {
+                    contentType: "text/plain",
+                    partName: "1.1",
+                    size: 0,
+                    body: `\nDie Hasen und die Frösche \n \n`,
+                    headers: {
+                      "content-type": ['text/plain; charset="iso-8859-1"'],
+                    },
+                  },
+                  {
+                    contentType: "image/png",
+                    partName: "1.2",
+                    size: 0,
+                    name: "blueball2.png",
+                    headers: {
+                      "content-type": ['image/png; name="blueball1.png"'],
+                    },
+                  },
+                  {
+                    contentType: "image/png",
+                    partName: "1.3",
+                    size: 0,
+                    name: "greenball.png",
+                    headers: {
+                      "content-type": ['image/png; name="greenball.png"'],
+                    },
+                  },
+                  {
+                    contentType: "image/png",
+                    partName: "1.4",
+                    size: 0,
+                    name: "redball.png",
+                    headers: {
+                      "content-type": ["image/png"],
+                    },
+                  },
+                ],
+              },
+            ],
+          },
+        },
+        "03.eml@mime.sample": {
+          msgHeaders: {
+            subject: "Test message from Microsoft Outlook 00",
+            author: "Heinz Müller <mueller@example.com>",
+          },
+          msgParts: {
+            contentType: "message/rfc822",
+            partName: "",
+            size: 0,
+            headers: {
+              from: ["Heinz Müller <mueller@example.com>"],
+              to: ['"Joe Blow" <jblow@example.com>'],
+              subject: ["Test message from Microsoft Outlook 00"],
+              date: ["Wed, 17 May 2000 19:35:05 -0400"],
+              "message-id": ["<03.eml@mime.sample>"],
+              "mime-version": ["1.0"],
+              "content-type": ['image/png; name="doubelspace  ball.png"'],
+              "content-transfer-encoding": ["base64"],
+              "content-disposition": [
+                'attachment; filename="doubelspace  ball.png"',
+              ],
+              "x-priority": ["3 (Normal)"],
+              "x-msmail-priority": ["Normal"],
+              "x-mailer": [
+                "Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)",
+              ],
+              importance: ["Normal"],
+              "x-mimeole": ["Produced By Microsoft MimeOLE V5.00.2314.1300"],
+            },
+            parts: [
+              {
+                contentType: "image/png",
+                name: "doubelspace  ball.png",
+                partName: "1",
+                size: 0,
+                headers: {
+                  "content-type": ['image/png; name="doubelspace  ball.png"'],
+                },
+              },
+            ],
+          },
+        },
+        "04.eml@mime.sample": {
+          msgHeaders: {
+            subject: "Алфавит",
+            author: "Bug Reporter <new@thunderbird.bug>",
+          },
+          msgParts: {
+            contentType: "message/rfc822",
+            partName: "",
+            size: 0,
+            headers: {
+              from: ["Bug Reporter <new@thunderbird.bug>"],
+              newsgroups: ["gmane.comp.mozilla.thundebird.user"],
+              subject: ["Алфавит"],
+              date: ["Sun, 27 May 2001 21:23:35 +0100"],
+              "message-id": ["<04.eml@mime.sample>"],
+              "mime-version": ["1.0"],
+              "content-type": ["text/plain; charset=koi8-r;"],
+              "content-transfer-encoding": ["base64"],
+            },
+            parts: [
+              {
+                contentType: "text/plain",
+                partName: "1",
+                size: 0,
+                body: "Вопрос\n",
+                headers: {
+                  "content-type": ["text/plain; charset=koi8-r;"],
+                },
+              },
+            ],
+          },
+        },
+        "05.eml@mime.sample": {
+          msgHeaders: {
+            subject: "Алфавит",
+            author: "Bug Reporter <new@thunderbird.bug>",
+          },
+          msgParts: {
+            contentType: "message/rfc822",
+            partName: "",
+            size: 0,
+            headers: {
+              from: ["Bug Reporter <new@thunderbird.bug>"],
+              newsgroups: ["gmane.comp.mozilla.thundebird.user"],
+              subject: ["Алфавит"],
+              date: ["Sun, 27 May 2001 21:23:35 +0100"],
+              "message-id": ["<05.eml@mime.sample>"],
+              "mime-version": ["1.0"],
+              "content-type": ["text/plain; charset=windows-1251;"],
+              "content-transfer-encoding": ["base64"],
+            },
+            parts: [
+              {
+                contentType: "text/plain",
+                partName: "1",
+                size: 0,
+                body: "Вопрос\n",
+                headers: {
+                  "content-type": ["text/plain; charset=windows-1251;"],
+                },
+              },
+            ],
+          },
+        },
+        "06.eml@mime.sample": {
+          msgHeaders: {
+            subject: "I have no content type",
+            author: "Bug Reporter <new@thunderbird.bug>",
+          },
+          msgParts: {
+            contentType: "message/rfc822",
+            partName: "",
+            size: 0,
+            headers: {
+              from: ["Bug Reporter <new@thunderbird.bug>"],
+              newsgroups: ["gmane.comp.mozilla.thundebird.user"],
+              subject: ["I have no content type"],
+              date: ["Sun, 27 May 2001 21:23:35 +0100"],
+              "message-id": ["<06.eml@mime.sample>"],
+              "mime-version": ["1.0"],
+            },
+            parts: [
+              {
+                contentType: "text/plain",
+                partName: "1",
+                size: 0,
+                body: "No content type\n",
+                headers: {
+                  "content-type": ["text/plain"],
+                },
+              },
+            ],
+          },
+        },
+        "07.eml@mime.sample": {
+          msgHeaders: {
+            subject: "Default content-types",
+            author: "Doug Sauder <dwsauder@example.com>",
+          },
+          msgParts: {
+            contentType: "message/rfc822",
+            partName: "",
+            size: 0,
+            headers: {
+              from: ["Doug Sauder <dwsauder@example.com>"],
+              to: ["Heinz <mueller@example.com>"],
+              subject: ["Default content-types"],
+              date: ["Fri, 19 May 2000 00:29:55 -0400"],
+              "message-id": ["<07.eml@mime.sample>"],
+              "mime-version": ["1.0"],
+              "content-type": [
+                'multipart/alternative; boundary="=====================_714967308==_.ALT"',
+              ],
+            },
+            parts: [
+              {
+                contentType: "multipart/alternative",
+                partName: "1",
+                size: 0,
+                headers: {
+                  "content-type": [
+                    'multipart/alternative; boundary="=====================_714967308==_.ALT"',
+                  ],
+                },
+                parts: [
+                  {
+                    contentType: "text/plain",
+                    partName: "1.1",
+                    size: 0,
+                    body: "Die Hasen\n",
+                    headers: {
+                      "content-type": ["text/plain"],
+                    },
+                  },
+                  {
+                    contentType: "text/html",
+                    partName: "1.2",
+                    size: 0,
+                    body: "<html><body><b>Die Hasen</b></body></html>\n",
+                    headers: {
+                      "content-type": ["text/html"],
+                    },
+                  },
+                ],
+              },
+            ],
+          },
+        },
+      };
+
+      function checkMsgHeaders(expected, actual) {
+        // Check if all expected properties are there.
+        for (let property of Object.keys(expected)) {
+          browser.test.assertEq(
+            expected.hasOwnProperty(property),
+            actual.hasOwnProperty(property),
+            `expected property ${property} is present`
+          );
+          // Check property content.
+          browser.test.assertEq(
+            expected[property],
+            actual[property],
+            `property ${property} is correct`
+          );
+        }
+      }
+
+      function checkMsgParts(expected, actual) {
+        // Check if all expected properties are there.
+        for (let property of Object.keys(expected)) {
+          browser.test.assertEq(
+            expected.hasOwnProperty(property),
+            actual.hasOwnProperty(property),
+            `expected property ${property} is present`
+          );
+          if (
+            ["parts", "headers", "size"].includes(property) ||
+            (["body"].includes(property) && expected[property] == "")
+          ) {
+            continue;
+          }
+          // Check property content.
+          browser.test.assertEq(
+            JSON.stringify(expected[property].replaceAll("\r\n", "\n")),
+            JSON.stringify(actual[property].replaceAll("\r\n", "\n")),
+            `property ${property} is correct`
+          );
+        }
+
+        // Check for unexpected properties.
+        for (let property of Object.keys(actual)) {
+          browser.test.assertEq(
+            expected.hasOwnProperty(property),
+            actual.hasOwnProperty(property),
+            `property ${property} is expected`
+          );
+        }
+
+        // Check if all expected headers are there.
+        if (expected.headers) {
+          for (let header of Object.keys(expected.headers)) {
+            browser.test.assertEq(
+              expected.headers.hasOwnProperty(header),
+              actual.headers.hasOwnProperty(header),
+              `expected header ${header} is present`
+            );
+            // Check header content.
+            // Note: jsmime does not eat TABs after a CLRF.
+            browser.test.assertEq(
+              expected.headers[header].toString().replaceAll("\t", " "),
+              actual.headers[header].toString().replaceAll("\t", " "),
+              `header ${header} is correct`
+            );
+          }
+          // Check for unexpected headers.
+          for (let header of Object.keys(actual.headers)) {
+            browser.test.assertEq(
+              expected.headers.hasOwnProperty(header),
+              actual.headers.hasOwnProperty(header),
+              `header ${header} is expected`
+            );
+          }
+        }
+
+        // Check sub-parts.
+        browser.test.assertEq(
+          Array.isArray(expected.parts),
+          Array.isArray(actual.parts),
+          `has sub-parts`
+        );
+        if (Array.isArray(expected.parts)) {
+          browser.test.assertEq(
+            expected.parts.length,
+            actual.parts.length,
+            "number of parts"
+          );
+          for (let i in expected.parts) {
+            checkMsgParts(expected.parts[i], actual.parts[i]);
+          }
+        }
+      }
+
+      for (let account of accounts) {
+        let folder = account.folders.find(f => f.name == "test1");
+        let { messages } = await browser.messages.list(folder);
+        browser.test.assertEq(7, messages.length);
+
+        for (let message of messages) {
+          let fullMessage = await browser.messages.getFull(message.id);
+          browser.test.assertEq("object", typeof fullMessage);
+
+          let expected = expectedData[message.headerMessageId];
+          checkMsgHeaders(expected.msgHeaders, message);
+          checkMsgParts(expected.msgParts, fullMessage);
+        }
+      }
+
+      browser.test.notifyPass("finished");
+    },
+    manifest: { permissions: ["accountsRead", "messagesRead"] },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  cleanUpAccount(_account);
+});
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_openpgp() {
+    let _account = createAccount();
+    let _identity = addIdentity(_account);
+    let _folder = await createSubfolder(
+      _account.incomingServer.rootFolder,
+      "test1"
+    );
+
+    // Load an encrypted message.
+
+    let messagePath = PathUtils.join(
+      OPENPGP_TEST_DIR.path,
+      "data",
+      "eml",
+      "unsigned-encrypted-to-0xf231550c4f47e38e-from-0xfbfcc82a015e7330.eml"
+    );
+    await createMessageFromFile(_folder, messagePath);
+
+    let extension = ExtensionTestUtils.loadExtension({
+      files: {
+        "background.js": async () => {
+          let [account] = await browser.accounts.list();
+          let folder = account.folders.find(f => f.name == "test1");
+
+          // Read the message, without the key set up. The headers should be
+          // readable, but not the message itself.
+
+          let { messages } = await browser.messages.list(folder);
+          browser.test.assertEq(1, messages.length);
+
+          let [message] = messages;
+          browser.test.assertEq("...", message.subject);
+          browser.test.assertEq(
+            "Bob Babbage <bob@openpgp.example>",
+            message.author
+          );
+          browser.test.assertEq("alice@openpgp.example", message.recipients[0]);
+
+          let fullMessage = await browser.messages.getFull(message.id);
+          browser.test.log(JSON.stringify(fullMessage));
+          browser.test.assertEq("object", typeof fullMessage);
+          browser.test.assertEq("message/rfc822", fullMessage.contentType);
+
+          browser.test.assertEq("object", typeof fullMessage.headers);
+          for (let header of [
+            "content-type",
+            "date",
+            "from",
+            "message-id",
+            "subject",
+            "to",
+          ]) {
+            browser.test.assertTrue(Array.isArray(fullMessage.headers[header]));
+            browser.test.assertEq(1, fullMessage.headers[header].length);
+          }
+          browser.test.assertEq("...", fullMessage.headers.subject[0]);
+          browser.test.assertEq(
+            "Bob Babbage <bob@openpgp.example>",
+            fullMessage.headers.from[0]
+          );
+          browser.test.assertEq(
+            "alice@openpgp.example",
+            fullMessage.headers.to[0]
+          );
+
+          browser.test.assertTrue(Array.isArray(fullMessage.parts));
+          browser.test.assertEq(1, fullMessage.parts.length);
+
+          let part = fullMessage.parts[0];
+          browser.test.assertEq("object", typeof part);
+          browser.test.assertEq("multipart/encrypted", part.contentType);
+          browser.test.assertEq(undefined, part.parts);
+
+          // Now set up the key and read the message again. It should all be
+          // there this time.
+
+          await window.sendMessage("load key");
+
+          ({ messages } = await browser.messages.list(folder));
+          browser.test.assertEq(1, messages.length);
+          [message] = messages;
+          browser.test.assertEq("...", message.subject);
+          browser.test.assertEq(
+            "Bob Babbage <bob@openpgp.example>",
+            message.author
+          );
+          browser.test.assertEq("alice@openpgp.example", message.recipients[0]);
+
+          fullMessage = await browser.messages.getFull(message.id);
+          browser.test.log(JSON.stringify(fullMessage));
+          browser.test.assertEq("object", typeof fullMessage);
+          browser.test.assertEq("message/rfc822", fullMessage.contentType);
+
+          browser.test.assertEq("object", typeof fullMessage.headers);
+          for (let header of [
+            "content-type",
+            "date",
+            "from",
+            "message-id",
+            "subject",
+            "to",
+          ]) {
+            browser.test.assertTrue(Array.isArray(fullMessage.headers[header]));
+            browser.test.assertEq(1, fullMessage.headers[header].length);
+          }
+          browser.test.assertEq("...", fullMessage.headers.subject[0]);
+          browser.test.assertEq(
+            "Bob Babbage <bob@openpgp.example>",
+            fullMessage.headers.from[0]
+          );
+          browser.test.assertEq(
+            "alice@openpgp.example",
+            fullMessage.headers.to[0]
+          );
+
+          browser.test.assertTrue(Array.isArray(fullMessage.parts));
+          browser.test.assertEq(1, fullMessage.parts.length);
+
+          part = fullMessage.parts[0];
+          browser.test.assertEq("object", typeof part);
+          browser.test.assertEq("multipart/encrypted", part.contentType);
+          browser.test.assertTrue(Array.isArray(part.parts));
+          browser.test.assertEq(1, part.parts.length);
+
+          part = part.parts[0];
+          browser.test.assertEq("object", typeof part);
+          browser.test.assertEq("multipart/fake-container", part.contentType);
+          browser.test.assertTrue(Array.isArray(part.parts));
+          browser.test.assertEq(1, part.parts.length);
+
+          part = part.parts[0];
+          browser.test.assertEq("object", typeof part);
+          browser.test.assertEq("text/plain", part.contentType);
+          browser.test.assertEq(
+            "Sundays are nothing without callaloo.",
+            part.body.trimRight()
+          );
+
+          browser.test.notifyPass("finished");
+        },
+        "utils.js": await getUtilsJS(),
+      },
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead", "messagesRead"],
+      },
+    });
+
+    await extension.startup();
+
+    await extension.awaitMessage("load key");
+    info(`Adding key from ${OPENPGP_KEY_PATH}`);
+    await OpenPGPTestUtils.initOpenPGP();
+    let [id] = await OpenPGPTestUtils.importPrivateKey(
+      null,
+      new FileUtils.File(OPENPGP_KEY_PATH)
+    );
+    _identity.setUnicharAttribute("openpgp_key_id", id);
+    extension.sendMessage();
+
+    await extension.awaitFinish("finished");
+    await extension.unload();
+
+    cleanUpAccount(_account);
+  }
+);
+
+add_task(async function test_attached_message_with_missing_headers() {
+  let _account = createAccount();
+  let _folder = await createSubfolder(
+    _account.incomingServer.rootFolder,
+    "test1"
+  );
+
+  await createMessageFromFile(
+    _folder,
+    do_get_file("messages/attachedMessageWithMissingHeaders.eml").path
+  );
+
+  let extension = ExtensionTestUtils.loadExtension({
+    files: {
+      "background.js": async () => {
+        let accounts = await browser.accounts.list();
+        browser.test.assertEq(1, accounts.length);
+
+        for (let account of accounts) {
+          let folder = account.folders.find(f => f.name == "test1");
+          let { messages } = await browser.messages.list(folder);
+          browser.test.assertEq(1, messages.length);
+
+          let msg = messages[0];
+          let attachments = await browser.messages.listAttachments(msg.id);
+          browser.test.assertEq(
+            attachments.length,
+            1,
+            "Should have found the correct number of attachments"
+          );
+
+          let attachedMessage = attachments[0].message;
+          browser.test.assertTrue(
+            !!attachedMessage,
+            "Should have found an attached message"
+          );
+          browser.test.assertEq(
+            attachedMessage.date.getTime(),
+            0,
+            "The date should be correct"
+          );
+          browser.test.assertEq(
+            attachedMessage.subject,
+            "",
+            "The subject should be empty"
+          );
+          browser.test.assertEq(
+            attachedMessage.author,
+            "",
+            "The author should be empty"
+          );
+          browser.test.assertEq(
+            attachedMessage.headerMessageId,
+            "sample-attached.eml@mime.sample",
+            "The headerMessageId should be correct"
+          );
+          window.assertDeepEqual(
+            attachedMessage.recipients,
+            [],
+            "The recipients should be correct"
+          );
+        }
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    },
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "messagesRead"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  cleanUpAccount(_account);
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_messages_id.js b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_id.js
new file mode 100644
index 0000000000..dac01fa514
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_id.js
@@ -0,0 +1,256 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var subFolders;
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function setup() {
+    let account = createAccount();
+    let rootFolder = account.incomingServer.rootFolder;
+    subFolders = {
+      test1: await createSubfolder(rootFolder, "test1"),
+      test2: await createSubfolder(rootFolder, "test2"),
+      test3: await createSubfolder(rootFolder, "test3"),
+      attachment: await createSubfolder(rootFolder, "attachment"),
+    };
+    await createMessages(subFolders.test1, 5);
+    let textAttachment = {
+      body: "textAttachment",
+      filename: "test.txt",
+      contentType: "text/plain",
+    };
+    await createMessages(subFolders.attachment, {
+      count: 1,
+      subject: "Msg with text attachment",
+      attachments: [textAttachment],
+    });
+  }
+);
+
+// In this test we'll move and copy some messages around between
+// folders. Every operation should result in the message's id property
+// changing to a never-seen-before value.
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_identifiers() {
+    let extension = ExtensionTestUtils.loadExtension({
+      files: {
+        "background.js": async () => {
+          let [{ folders }] = await browser.accounts.list();
+          let testFolder1 = folders.find(f => f.name == "test1");
+          let testFolder2 = folders.find(f => f.name == "test2");
+          let testFolder3 = folders.find(f => f.name == "test3");
+
+          let { messages } = await browser.messages.list(testFolder1);
+          browser.test.assertEq(
+            5,
+            messages.length,
+            "message count in testFolder1"
+          );
+          browser.test.assertEq(1, messages[0].id);
+          browser.test.assertEq(2, messages[1].id);
+          browser.test.assertEq(3, messages[2].id);
+          browser.test.assertEq(4, messages[3].id);
+          browser.test.assertEq(5, messages[4].id);
+
+          let subjects = messages.map(m => m.subject);
+
+          // Move two messages. We could do this in one operation, but to be
+          // sure of the order, do it in separate operations.
+
+          await browser.messages.move([1], testFolder2);
+          await browser.messages.move([3], testFolder2);
+
+          ({ messages } = await browser.messages.list(testFolder1));
+          browser.test.assertEq(
+            3,
+            messages.length,
+            "message count in testFolder1"
+          );
+          browser.test.assertEq(2, messages[0].id);
+          browser.test.assertEq(4, messages[1].id);
+          browser.test.assertEq(5, messages[2].id);
+          browser.test.assertEq(subjects[1], messages[0].subject);
+          browser.test.assertEq(subjects[3], messages[1].subject);
+          browser.test.assertEq(subjects[4], messages[2].subject);
+
+          ({ messages } = await browser.messages.list(testFolder2));
+          browser.test.assertEq(
+            2,
+            messages.length,
+            "message count in testFolder2"
+          );
+          browser.test.assertEq(6, messages[0].id, "new id created");
+          browser.test.assertEq(7, messages[1].id, "new id created");
+          browser.test.assertEq(subjects[0], messages[0].subject);
+          browser.test.assertEq(subjects[2], messages[1].subject);
+
+          // Copy one message.
+
+          await browser.messages.copy([6], testFolder3);
+
+          ({ messages } = await browser.messages.list(testFolder2));
+          browser.test.assertEq(
+            2,
+            messages.length,
+            "message count in testFolder2"
+          );
+          browser.test.assertEq(6, messages[0].id);
+          browser.test.assertEq(7, messages[1].id);
+          browser.test.assertEq(subjects[0], messages[0].subject);
+          browser.test.assertEq(subjects[2], messages[1].subject);
+
+          ({ messages } = await browser.messages.list(testFolder3));
+          browser.test.assertEq(
+            1,
+            messages.length,
+            "message count in testFolder3"
+          );
+          browser.test.assertEq(8, messages[0].id, "new id created");
+          browser.test.assertEq(subjects[0], messages[0].subject);
+
+          // Move the copied message back to the previous folder. There should
+          // now be two copies there, each with their own ID.
+
+          await browser.messages.move([8], testFolder2);
+
+          ({ messages } = await browser.messages.list(testFolder2));
+          browser.test.assertEq(
+            3,
+            messages.length,
+            "message count in testFolder2"
+          );
+          browser.test.assertEq(6, messages[0].id);
+          browser.test.assertEq(7, messages[1].id);
+          browser.test.assertEq(
+            9,
+            messages[2].id,
+            "new id created, not a duplicate"
+          );
+          browser.test.assertEq(subjects[0], messages[0].subject);
+          browser.test.assertEq(subjects[2], messages[1].subject);
+          browser.test.assertEq(
+            subjects[0],
+            messages[2].subject,
+            "same message as another in this folder"
+          );
+
+          browser.test.notifyPass("finished");
+        },
+        "utils.js": await getUtilsJS(),
+      },
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead", "messagesMove", "messagesRead"],
+      },
+    });
+
+    await extension.startup();
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
+
+// In this test we'll remove an attachment from a message and its id property
+// should not change. (Bug 1645595). Test does not work with IMAP test server,
+// which has issues with attachments.
+add_task(
+  {
+    skip_if: () => IS_NNTP || IS_IMAP,
+  },
+  async function test_attachments() {
+    let extension = ExtensionTestUtils.loadExtension({
+      files: {
+        "background.js": async () => {
+          let id;
+
+          browser.test.onMessage.addListener(async () => {
+            // This listener gets called once the attachment has been removed.
+            // Make sure we still get the message and it no longer has the
+            // attachment.
+            let modifiedMessage = await browser.messages.getFull(id);
+            browser.test.assertEq(
+              "Msg with text attachment",
+              modifiedMessage.headers.subject[0]
+            );
+            browser.test.assertEq(
+              "text/x-moz-deleted",
+              modifiedMessage.parts[0].parts[1].contentType
+            );
+            browser.test.assertEq(
+              "Deleted: test.txt",
+              modifiedMessage.parts[0].parts[1].name
+            );
+            browser.test.notifyPass("finished");
+          });
+
+          let [{ folders }] = await browser.accounts.list();
+          let testFolder = folders.find(f => f.name == "attachment");
+          let { messages } = await browser.messages.list(testFolder);
+          browser.test.assertEq(1, messages.length);
+          id = messages[0].id;
+
+          let originalMessage = await browser.messages.getFull(id);
+          browser.test.assertEq(
+            "Msg with text attachment",
+            originalMessage.headers.subject[0]
+          );
+          browser.test.assertEq(
+            "text/plain",
+            originalMessage.parts[0].parts[1].contentType
+          );
+          browser.test.assertEq(
+            "test.txt",
+            originalMessage.parts[0].parts[1].name
+          );
+          browser.test.sendMessage("removeAttachment", id);
+        },
+        "utils.js": await getUtilsJS(),
+      },
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead", "messagesRead"],
+      },
+    });
+
+    let observer = {
+      observe(aSubject, aTopic, aData) {
+        if (aTopic == "attachment-delete-msgkey-changed") {
+          extension.sendMessage();
+        }
+      },
+    };
+    Services.obs.addObserver(observer, "attachment-delete-msgkey-changed");
+
+    extension.onMessage("removeAttachment", () => {
+      let msgHdr = subFolders.attachment.messages.getNext();
+      let msgUri = msgHdr.folder.getUriForMsg(msgHdr);
+      let messenger = Cc["@mozilla.org/messenger;1"].createInstance(
+        Ci.nsIMessenger
+      );
+      messenger.detachAttachment(
+        "text/plain",
+        `${msgUri}?part=1.2&filename=test.txt`,
+        "test.txt",
+        msgUri,
+        false /* do not save */,
+        true /* do not ask */
+      );
+    });
+
+    await extension.startup();
+    await extension.awaitFinish("finished");
+    await extension.unload();
+  }
+);
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_messages_import.js b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_import.js
new file mode 100644
index 0000000000..c3bef58835
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_import.js
@@ -0,0 +1,121 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { FileUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/FileUtils.sys.mjs"
+);
+var { MailStringUtils } = ChromeUtils.import(
+  "resource:///modules/MailStringUtils.jsm"
+);
+
+add_task(async function test_import() {
+  let _account = createAccount();
+  await createSubfolder(_account.incomingServer.rootFolder, "test1");
+  await createSubfolder(_account.incomingServer.rootFolder, "test2");
+  await createSubfolder(_account.incomingServer.rootFolder, "test3");
+
+  let extension = ExtensionTestUtils.loadExtension({
+    files: {
+      "background.js": async () => {
+        async function do_import(expected, file, folder, options) {
+          let msg = await browser.messages.import(file, folder, options);
+          browser.test.assertEq(
+            "alternative.eml@mime.sample",
+            msg.headerMessageId,
+            "should find the correct message after import"
+          );
+          let { messages } = await browser.messages.list(folder);
+          browser.test.assertEq(
+            1,
+            messages.length,
+            "should find the imported message in the destination folder"
+          );
+          for (let [propName, value] of Object.entries(expected)) {
+            window.assertDeepEqual(
+              value,
+              messages[0][propName],
+              `Property ${propName} should be correct`
+            );
+          }
+        }
+
+        let accounts = await browser.accounts.list();
+        browser.test.assertEq(1, accounts.length);
+        let [account] = accounts;
+        let folder1 = account.folders.find(f => f.name == "test1");
+        let folder2 = account.folders.find(f => f.name == "test2");
+        let folder3 = account.folders.find(f => f.name == "test3");
+        browser.test.assertTrue(folder1, "Test folder should exist");
+        browser.test.assertTrue(folder2, "Test folder should exist");
+        browser.test.assertTrue(folder3, "Test folder should exist");
+
+        let [emlFileContent] = await window.sendMessage(
+          "getFileContent",
+          "messages/alternative.eml"
+        );
+        let file = new File([emlFileContent], "test.eml");
+
+        if (account.type == "nntp" || account.type == "imap") {
+          // nsIMsgCopyService.copyFileMessage() not implemented for NNTP.
+          // offline/online behavior of IMAP nsIMsgCopyService.copyFileMessage()
+          // is too erratic to be supported ATM.
+          await browser.test.assertRejects(
+            browser.messages.import(file, folder1),
+            `browser.messenger.import() is not supported for ${account.type} accounts`,
+            "Should throw for unsupported accounts"
+          );
+        } else {
+          await do_import(
+            {
+              new: false,
+              read: false,
+              flagged: false,
+            },
+            file,
+            folder1
+          );
+          await do_import(
+            {
+              new: true,
+              read: true,
+              flagged: true,
+              tags: ["$label1"],
+            },
+            file,
+            folder2,
+            {
+              new: true,
+              read: true,
+              flagged: true,
+              tags: ["$label1"],
+            }
+          );
+        }
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    },
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "messagesRead", "messagesImport"],
+    },
+  });
+
+  extension.onMessage("getFileContent", async path => {
+    let raw = await IOUtils.read(do_get_file(path).path);
+    extension.sendMessage(MailStringUtils.uint8ArrayToByteString(raw));
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("finished");
+  await extension.unload();
+
+  cleanUpAccount(_account);
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_messages_move_copy_delete.js b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_move_copy_delete.js
new file mode 100644
index 0000000000..81011374e3
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_move_copy_delete.js
@@ -0,0 +1,656 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { TestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TestUtils.sys.mjs"
+);
+var { ExtensionsUI } = ChromeUtils.import(
+  "resource:///modules/ExtensionsUI.jsm"
+);
+var { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+var { PromiseTestUtils } = ChromeUtils.import(
+  "resource://testing-common/mailnews/PromiseTestUtils.jsm"
+);
+
+ExtensionTestUtils.mockAppInfo();
+AddonTestUtils.maybeInit(this);
+
+Services.prefs.setBoolPref(
+  "mail.server.server1.autosync_offline_stores",
+  false
+);
+
+registerCleanupFunction(async () => {
+  // Remove the temporary MozillaMailnews folder, which is not deleted in time when
+  // the cleanupFunction registered by AddonTestUtils.maybeInit() checks for left over
+  // files in the temp folder.
+  // Note: PathUtils.tempDir points to the system temp folder, which is different.
+  let path = PathUtils.join(
+    Services.dirsvc.get("TmpD", Ci.nsIFile).path,
+    "MozillaMailnews"
+  );
+  await IOUtils.remove(path, { recursive: true });
+});
+
+// Function to start an event page extension (MV3), which can be called whenever
+// the main test is about to trigger an event. The extension terminates its
+// background and listens for that single event, verifying it is waking up correctly.
+async function event_page_extension(eventName, actionCallback) {
+  let ext = ExtensionTestUtils.loadExtension({
+    files: {
+      "background.js": async () => {
+        // Whenever the extension starts or wakes up, hasFired is set to false. In
+        // case of a wake-up, the first fired event is the one that woke up the background.
+        let hasFired = false;
+        let _eventName = browser.runtime.getManifest().description;
+
+        browser.messages[_eventName].addListener(async (...args) => {
+          // Only send the first event after background wake-up, this should
+          // be the only one expected.
+          if (!hasFired) {
+            hasFired = true;
+            browser.test.sendMessage(`${_eventName} received`, args);
+          }
+        });
+        browser.test.sendMessage("background started");
+      },
+    },
+    manifest: {
+      manifest_version: 3,
+      description: eventName,
+      background: { scripts: ["background.js"] },
+      browser_specific_settings: {
+        gecko: { id: "event_page_extension@mochi.test" },
+      },
+      permissions: ["accountsRead", "messagesRead", "messagesMove"],
+    },
+  });
+  await ext.startup();
+  await ext.awaitMessage("background started");
+  // The listener should be persistent, but not primed.
+  assertPersistentListeners(ext, "messages", eventName, { primed: false });
+
+  await ext.terminateBackground({ disableResetIdleForTest: true });
+  // Verify the primed persistent listener.
+  assertPersistentListeners(ext, "messages", eventName, { primed: true });
+
+  await actionCallback();
+  let rv = await ext.awaitMessage(`${eventName} received`);
+  await ext.awaitMessage("background started");
+  // The listener should be persistent, but not primed.
+  assertPersistentListeners(ext, "messages", eventName, { primed: false });
+
+  await ext.unload();
+  return rv;
+}
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_move_copy_delete() {
+    await AddonTestUtils.promiseStartupManager();
+
+    let account = createAccount();
+    let rootFolder = account.incomingServer.rootFolder;
+    let subFolders = {
+      test1: await createSubfolder(rootFolder, "test1"),
+      test2: await createSubfolder(rootFolder, "test2"),
+      test3: await createSubfolder(rootFolder, "test3"),
+      trash: rootFolder.getChildNamed("Trash"),
+    };
+    await createMessages(subFolders.trash, 4);
+    // 4 messages must be created before this line or test_move_copy_delete will break.
+    await createMessages(subFolders.test1, 5);
+
+    let files = {
+      "background.js": async () => {
+        async function capturePrimedEvent(eventName, callback) {
+          let eventPageExtensionReadyPromise = window.waitForMessage();
+          browser.test.sendMessage("capturePrimedEvent", eventName);
+          await eventPageExtensionReadyPromise;
+          let eventPageExtensionFinishedPromise = window.waitForMessage();
+          callback();
+          return eventPageExtensionFinishedPromise;
+        }
+
+        async function checkMessagesInFolder(expectedKeys, folder) {
+          let expectedSubjects = expectedKeys.map(k => messages[k].subject);
+
+          let { messages: actualMessages } = await browser.messages.list(
+            folder
+          );
+          browser.test.log("expect: " + expectedSubjects.sort());
+          browser.test.log(
+            "actual: " + actualMessages.map(m => m.subject).sort()
+          );
+
+          browser.test.assertEq(
+            expectedSubjects.sort().toString(),
+            actualMessages
+              .map(m => m.subject)
+              .sort()
+              .toString(),
+            "Messages on server should be correct"
+          );
+          for (let m of actualMessages) {
+            browser.test.assertTrue(
+              expectedSubjects.includes(m.subject),
+              `${m.subject} at ${m.id}`
+            );
+            messages[m.subject.split(" ")[0]].id = m.id;
+          }
+
+          // Return the messages for convenience.
+          return actualMessages;
+        }
+
+        function newMovePromise(numberOfEventsToCollapse = 1) {
+          return new Promise(resolve => {
+            let seenEvents = 0;
+            let seenSrcMsgs = [];
+            let seenDstMsgs = [];
+            const listener = (srcMsgs, dstMsgs) => {
+              seenEvents++;
+              seenSrcMsgs.push(...srcMsgs.messages);
+              seenDstMsgs.push(...dstMsgs.messages);
+              if (seenEvents == numberOfEventsToCollapse) {
+                browser.messages.onMoved.removeListener(listener);
+                resolve({ srcMsgs: seenSrcMsgs, dstMsgs: seenDstMsgs });
+              }
+            };
+            browser.messages.onMoved.addListener(listener);
+          });
+        }
+
+        function newCopyPromise(numberOfEventsToCollapse = 1) {
+          return new Promise(resolve => {
+            let seenEvents = 0;
+            let seenSrcMsgs = [];
+            let seenDstMsgs = [];
+            const listener = (srcMsgs, dstMsgs) => {
+              seenEvents++;
+              seenSrcMsgs.push(...srcMsgs.messages);
+              seenDstMsgs.push(...dstMsgs.messages);
+              if (seenEvents == numberOfEventsToCollapse) {
+                browser.messages.onCopied.removeListener(listener);
+                resolve({ srcMsgs: seenSrcMsgs, dstMsgs: seenDstMsgs });
+              }
+            };
+            browser.messages.onCopied.addListener(listener);
+          });
+        }
+
+        function newDeletePromise(numberOfEventsToCollapse = 1) {
+          return new Promise(resolve => {
+            let seenEvents = 0;
+            let seenMsgs = [];
+            const listener = msgs => {
+              seenEvents++;
+              seenMsgs.push(...msgs.messages);
+              if (seenEvents == numberOfEventsToCollapse) {
+                browser.messages.onDeleted.removeListener(listener);
+                resolve(seenMsgs);
+              }
+            };
+            browser.messages.onDeleted.addListener(listener);
+          });
+        }
+
+        async function checkEventInformation(
+          infoPromise,
+          expected,
+          messages,
+          dstFolder
+        ) {
+          let eventInfo = await infoPromise;
+          browser.test.assertEq(eventInfo.srcMsgs.length, expected.length);
+          browser.test.assertEq(eventInfo.dstMsgs.length, expected.length);
+          for (let msg of expected) {
+            let idx = eventInfo.srcMsgs.findIndex(
+              e => e.id == messages[msg].id
+            );
+            browser.test.assertEq(
+              eventInfo.srcMsgs[idx].subject,
+              messages[msg].subject
+            );
+            browser.test.assertEq(
+              eventInfo.dstMsgs[idx].subject,
+              messages[msg].subject
+            );
+            browser.test.assertEq(
+              eventInfo.dstMsgs[idx].folder.path,
+              dstFolder.path
+            );
+          }
+        }
+
+        let [accountId] = await window.sendMessage("getAccount");
+        let { folders } = await browser.accounts.get(accountId);
+        let testFolder1 = folders.find(f => f.name == "test1");
+        let testFolder2 = folders.find(f => f.name == "test2");
+        let testFolder3 = folders.find(f => f.name == "test3");
+        let trashFolder = folders.find(f => f.name == "Trash");
+
+        let { messages: folder1Messages } = await browser.messages.list(
+          testFolder1
+        );
+
+        // Since the ID of a message changes when it is moved, track by subject.
+        let messages = {};
+        for (let m of folder1Messages) {
+          messages[m.subject.split(" ")[0]] = { id: m.id, subject: m.subject };
+        }
+
+        // To help with debugging, output the IDs of our five messages.
+        browser.test.log(JSON.stringify(messages)); // Red:1, Green:2, Blue:3, My:4, Happy:5
+
+        browser.test.log("");
+        browser.test.log(" --> Move one message to another folder.");
+        let movePromise = newMovePromise();
+        let primedMoveInfo = await capturePrimedEvent("onMoved", () =>
+          browser.messages.move([messages.Red.id], testFolder2)
+        );
+        window.assertDeepEqual(
+          await movePromise,
+          {
+            srcMsgs: primedMoveInfo[0].messages,
+            dstMsgs: primedMoveInfo[1].messages,
+          },
+          "The primed and non-primed onMoved events should return the same values",
+          { strict: true }
+        );
+        await checkEventInformation(
+          movePromise,
+          ["Red"],
+          messages,
+          testFolder2
+        );
+
+        await window.sendMessage("forceServerUpdate", testFolder1.name);
+        await window.sendMessage("forceServerUpdate", testFolder2.name);
+
+        await checkMessagesInFolder(
+          ["Green", "Blue", "My", "Happy"],
+          testFolder1
+        );
+        await checkMessagesInFolder(["Red"], testFolder2);
+        browser.test.log(JSON.stringify(messages)); // Red:6, Green:2, Blue:3, My:4, Happy:5
+
+        browser.test.log("");
+        browser.test.log(" --> And back again.");
+        movePromise = newMovePromise();
+        primedMoveInfo = await capturePrimedEvent("onMoved", () =>
+          browser.messages.move([messages.Red.id], testFolder1)
+        );
+        window.assertDeepEqual(
+          await movePromise,
+          {
+            srcMsgs: primedMoveInfo[0].messages,
+            dstMsgs: primedMoveInfo[1].messages,
+          },
+          "The primed and non-primed onMoved events should return the same values",
+          { strict: true }
+        );
+        await checkEventInformation(
+          movePromise,
+          ["Red"],
+          messages,
+          testFolder1
+        );
+
+        await window.sendMessage("forceServerUpdate", testFolder2.name);
+        await window.sendMessage("forceServerUpdate", testFolder1.name);
+
+        await checkMessagesInFolder(
+          ["Red", "Green", "Blue", "My", "Happy"],
+          testFolder1
+        );
+        await checkMessagesInFolder([], testFolder2);
+        browser.test.log(JSON.stringify(messages)); // Red:7, Green:2, Blue:3, My:4, Happy:5
+
+        browser.test.log("");
+        browser.test.log(" --> Move two messages to another folder.");
+        movePromise = newMovePromise();
+        primedMoveInfo = await capturePrimedEvent("onMoved", () =>
+          browser.messages.move(
+            [messages.Green.id, messages.My.id],
+            testFolder2
+          )
+        );
+        window.assertDeepEqual(
+          await movePromise,
+          {
+            srcMsgs: primedMoveInfo[0].messages,
+            dstMsgs: primedMoveInfo[1].messages,
+          },
+          "The primed and non-primed onMoved events should return the same values",
+          { strict: true }
+        );
+        await checkEventInformation(
+          movePromise,
+          ["Green", "My"],
+          messages,
+          testFolder2
+        );
+
+        await window.sendMessage("forceServerUpdate", testFolder1.name);
+        await window.sendMessage("forceServerUpdate", testFolder2.name);
+
+        await checkMessagesInFolder(["Red", "Blue", "Happy"], testFolder1);
+        await checkMessagesInFolder(["Green", "My"], testFolder2);
+        browser.test.log(JSON.stringify(messages)); // Red:7, Green:8, Blue:3, My:9, Happy:5
+
+        browser.test.log("");
+        browser.test.log(" --> Move one back again: " + messages.My.id);
+        movePromise = newMovePromise();
+        primedMoveInfo = await capturePrimedEvent("onMoved", () =>
+          browser.messages.move([messages.My.id], testFolder1)
+        );
+        window.assertDeepEqual(
+          await movePromise,
+          {
+            srcMsgs: primedMoveInfo[0].messages,
+            dstMsgs: primedMoveInfo[1].messages,
+          },
+          "The primed and non-primed onMoved events should return the same values",
+          { strict: true }
+        );
+        await checkEventInformation(movePromise, ["My"], messages, testFolder1);
+
+        await window.sendMessage("forceServerUpdate", testFolder2.name);
+        await window.sendMessage("forceServerUpdate", testFolder1.name);
+
+        await checkMessagesInFolder(
+          ["Red", "Blue", "My", "Happy"],
+          testFolder1
+        );
+        await checkMessagesInFolder(["Green"], testFolder2);
+        browser.test.log(JSON.stringify(messages)); // Red:7, Green:8, Blue:3, My:10, Happy:5
+
+        browser.test.log("");
+        browser.test.log(
+          " --> Move messages from different folders to a third folder."
+        );
+        // We collapse the two events (one for each source folder).
+        movePromise = newMovePromise(2);
+        await browser.messages.move(
+          [messages.Green.id, messages.My.id],
+          testFolder3
+        );
+        await checkEventInformation(
+          movePromise,
+          ["Green", "My"],
+          messages,
+          testFolder3
+        );
+
+        await window.sendMessage("forceServerUpdate", testFolder1.name);
+        await window.sendMessage("forceServerUpdate", testFolder2.name);
+        await window.sendMessage("forceServerUpdate", testFolder3.name);
+
+        await checkMessagesInFolder(["Red", "Blue", "Happy"], testFolder1);
+        await checkMessagesInFolder([], testFolder2);
+        await checkMessagesInFolder(["Green", "My"], testFolder3);
+        browser.test.log(JSON.stringify(messages)); // Red:7, Green:11, Blue:3, My:12, Happy:5
+
+        browser.test.log("");
+        browser.test.log(
+          " --> The following tests should not trigger move events."
+        );
+        let listenerCalls = 0;
+        const listenerFunc = () => {
+          listenerCalls++;
+        };
+        browser.messages.onMoved.addListener(listenerFunc);
+
+        // Move a message to the folder it's already in.
+        await browser.messages.move([messages.Green.id], testFolder3);
+        await checkMessagesInFolder(["Green", "My"], testFolder3);
+        browser.test.log(JSON.stringify(messages)); // Red:7, Green:11, Blue:3, My:12, Happy:5
+
+        // Move no messages.
+        await browser.messages.move([], testFolder3);
+        await checkMessagesInFolder(["Red", "Blue", "Happy"], testFolder1);
+        await checkMessagesInFolder([], testFolder2);
+        await checkMessagesInFolder(["Green", "My"], testFolder3);
+        browser.test.log(JSON.stringify(messages)); // Red:7, Green:11, Blue:3, My:12, Happy:5
+
+        // Move a non-existent message.
+        await browser.test.assertRejects(
+          browser.messages.move([9999], testFolder1),
+          /Error moving message/,
+          "something should happen"
+        );
+
+        // Move to a non-existent folder.
+        await browser.test.assertRejects(
+          browser.messages.move([messages.Red.id], {
+            accountId,
+            path: "/missing",
+          }),
+          /Error moving message/,
+          "something should happen"
+        );
+
+        // Check that no move event was triggered.
+        browser.messages.onMoved.removeListener(listenerFunc);
+        browser.test.assertEq(0, listenerCalls);
+
+        browser.test.log("");
+        browser.test.log(
+          " --> Put everything back where it was at the start of the test."
+        );
+        movePromise = newMovePromise();
+        await browser.messages.move(
+          [messages.My.id, messages.Green.id],
+          testFolder1
+        );
+        await checkEventInformation(
+          movePromise,
+          ["Green", "My"],
+          messages,
+          testFolder1
+        );
+
+        await window.sendMessage("forceServerUpdate", testFolder3.name);
+        await window.sendMessage("forceServerUpdate", testFolder1.name);
+
+        await checkMessagesInFolder(
+          ["Red", "Green", "Blue", "My", "Happy"],
+          testFolder1
+        );
+        await checkMessagesInFolder([], testFolder2);
+        await checkMessagesInFolder([], testFolder3);
+        browser.test.log(JSON.stringify(messages)); // Red:7, Green:13, Blue:3, My:14, Happy:5
+
+        browser.test.log("");
+        browser.test.log(" --> Copy one message to another folder.");
+        let copyPromise = newCopyPromise();
+        let primedCopyInfo = await capturePrimedEvent("onCopied", () =>
+          browser.messages.copy([messages.Happy.id], testFolder2)
+        );
+        window.assertDeepEqual(
+          await copyPromise,
+          {
+            srcMsgs: primedCopyInfo[0].messages,
+            dstMsgs: primedCopyInfo[1].messages,
+          },
+          "The primed and non-primed onCopied events should return the same values",
+          { strict: true }
+        );
+        await checkEventInformation(
+          copyPromise,
+          ["Happy"],
+          messages,
+          testFolder2
+        );
+
+        await window.sendMessage("forceServerUpdate", testFolder1.name);
+        await window.sendMessage("forceServerUpdate", testFolder2.name);
+        await window.sendMessage("forceServerUpdate", testFolder3.name);
+
+        await checkMessagesInFolder(
+          ["Red", "Green", "Blue", "My", "Happy"],
+          testFolder1
+        );
+        let { messages: folder2Messages } = await browser.messages.list(
+          testFolder2
+        );
+        browser.test.assertEq(1, folder2Messages.length);
+        browser.test.assertEq(
+          messages.Happy.subject,
+          folder2Messages[0].subject
+        );
+        browser.test.assertTrue(folder2Messages[0].id != messages.Happy.id);
+        browser.test.log(JSON.stringify(messages)); // Red:7, Green:13, Blue:3, My:14, Happy:5
+
+        browser.test.log("");
+        browser.test.log(" --> Delete the copied message.");
+        let deletePromise = newDeletePromise();
+        let primedDeleteLog = await capturePrimedEvent("onDeleted", () =>
+          browser.messages.delete([folder2Messages[0].id], true)
+        );
+        // Check if the delete information is correct.
+        let deleteLog = await deletePromise;
+        window.assertDeepEqual(
+          [
+            {
+              id: null,
+              messages: deleteLog,
+            },
+          ],
+          primedDeleteLog,
+          "The primed and non-primed onDeleted events should return the same values",
+          { strict: true }
+        );
+        browser.test.assertEq(1, deleteLog.length);
+        browser.test.assertEq(folder2Messages[0].id, deleteLog[0].id);
+
+        await window.sendMessage("forceServerUpdate", testFolder1.name);
+        await window.sendMessage("forceServerUpdate", testFolder2.name);
+        await window.sendMessage("forceServerUpdate", testFolder3.name);
+
+        // Check if the message was deleted.
+        await checkMessagesInFolder(
+          ["Red", "Green", "Blue", "My", "Happy"],
+          testFolder1
+        );
+        await checkMessagesInFolder([], testFolder2);
+        await checkMessagesInFolder([], testFolder3);
+        browser.test.log(JSON.stringify(messages)); // Red:7, Green:13, Blue:3, My:14, Happy:5
+
+        browser.test.log("");
+        browser.test.log(" --> Move a message to the trash.");
+        movePromise = newMovePromise();
+        primedMoveInfo = await capturePrimedEvent("onMoved", () =>
+          browser.messages.move([messages.Green.id], trashFolder)
+        );
+        window.assertDeepEqual(
+          await movePromise,
+          {
+            srcMsgs: primedMoveInfo[0].messages,
+            dstMsgs: primedMoveInfo[1].messages,
+          },
+          "The primed and non-primed onMoved events should return the same values",
+          { strict: true }
+        );
+        await checkEventInformation(
+          movePromise,
+          ["Green"],
+          messages,
+          trashFolder
+        );
+
+        await window.sendMessage("forceServerUpdate", testFolder1.name);
+        await window.sendMessage("forceServerUpdate", testFolder2.name);
+        await window.sendMessage("forceServerUpdate", testFolder3.name);
+
+        await checkMessagesInFolder(
+          ["Red", "Blue", "My", "Happy"],
+          testFolder1
+        );
+        await checkMessagesInFolder([], testFolder2);
+        await checkMessagesInFolder([], testFolder3);
+
+        let { messages: trashFolderMessages } = await browser.messages.list(
+          trashFolder
+        );
+        browser.test.assertTrue(
+          trashFolderMessages.find(m => m.subject == messages.Green.subject)
+        );
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: [
+          "accountsRead",
+          "messagesMove",
+          "messagesRead",
+          "messagesDelete",
+        ],
+        browser_specific_settings: {
+          gecko: { id: "messages.move@mochi.test" },
+        },
+      },
+    });
+
+    extension.onMessage("forceServerUpdate", async foldername => {
+      if (IS_IMAP) {
+        let folder = rootFolder
+          .getChildNamed(foldername)
+          .QueryInterface(Ci.nsIMsgImapMailFolder);
+
+        let listener = new PromiseTestUtils.PromiseUrlListener();
+        folder.updateFolderWithListener(null, listener);
+        await listener.promise;
+
+        // ...and download for offline use.
+        let promiseUrlListener = new PromiseTestUtils.PromiseUrlListener();
+        folder.downloadAllForOffline(promiseUrlListener, null);
+        await promiseUrlListener.promise;
+      }
+      extension.sendMessage();
+    });
+
+    extension.onMessage("capturePrimedEvent", async eventName => {
+      let primedEventData = await event_page_extension(eventName, () => {
+        // Resume execution in the main test, after the event page extension is
+        // ready to capture the event with deactivated background.
+        extension.sendMessage();
+      });
+      extension.sendMessage(...primedEventData);
+    });
+
+    extension.onMessage("getAccount", () => {
+      extension.sendMessage(account.key);
+    });
+
+    // The sync between the IMAP Service and the fake IMAP Server is partially
+    // broken: It is not possible to re-move messages cleanly. The move commands
+    // are send to the server about 500ms after the local operation and the server
+    // will update the local state wrongly.
+    // In this test we enforce a server update after each operation. If this is
+    // still causing intermittent fails, enable the offline mode for this test.
+    // See https://bugzilla.mozilla.org/show_bug.cgi?id=1797764#c24
+    await extension.startup();
+    await extension.awaitFinish("finished");
+    await extension.unload();
+
+    cleanUpAccount(account);
+    await AddonTestUtils.promiseShutdownManager();
+  }
+);
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_messages_onNewMailReceived.js b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_onNewMailReceived.js
new file mode 100644
index 0000000000..5c8e62872d
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_onNewMailReceived.js
@@ -0,0 +1,153 @@
+/* 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/. */
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+
+ExtensionTestUtils.mockAppInfo();
+AddonTestUtils.maybeInit(this);
+
+registerCleanupFunction(async () => {
+  // Remove the temporary MozillaMailnews folder, which is not deleted in time when
+  // the cleanupFunction registered by AddonTestUtils.maybeInit() checks for left over
+  // files in the temp folder.
+  // Note: PathUtils.tempDir points to the system temp folder, which is different.
+  let path = PathUtils.join(
+    Services.dirsvc.get("TmpD", Ci.nsIFile).path,
+    "MozillaMailnews"
+  );
+  await IOUtils.remove(path, { recursive: true });
+});
+
+// Function to start an event page extension (MV3), which can be called whenever
+// the main test is about to trigger an event. The extension terminates its
+// background and listens for that single event, verifying it is waking up correctly.
+async function event_page_extension(eventName, actionCallback) {
+  let ext = ExtensionTestUtils.loadExtension({
+    files: {
+      "background.js": async () => {
+        // Whenever the extension starts or wakes up, hasFired is set to false. In
+        // case of a wake-up, the first fired event is the one that woke up the background.
+        let hasFired = false;
+        let _eventName = browser.runtime.getManifest().description;
+
+        browser.messages[_eventName].addListener(async (...args) => {
+          // Only send the first event after background wake-up, this should
+          // be the only one expected.
+          if (!hasFired) {
+            hasFired = true;
+            browser.test.sendMessage(`${_eventName} received`, args);
+          }
+        });
+        browser.test.sendMessage("background started");
+      },
+    },
+    manifest: {
+      manifest_version: 3,
+      description: eventName,
+      background: { scripts: ["background.js"] },
+      browser_specific_settings: {
+        gecko: { id: "event_page_extension@mochi.test" },
+      },
+      permissions: ["accountsRead", "messagesRead", "messagesMove"],
+    },
+  });
+  await ext.startup();
+  await ext.awaitMessage("background started");
+  // The listener should be persistent, but not primed.
+  assertPersistentListeners(ext, "messages", eventName, { primed: false });
+
+  await ext.terminateBackground({ disableResetIdleForTest: true });
+  // Verify the primed persistent listener.
+  assertPersistentListeners(ext, "messages", eventName, { primed: true });
+
+  await actionCallback();
+  let rv = await ext.awaitMessage(`${eventName} received`);
+  await ext.awaitMessage("background started");
+  // The listener should be persistent, but not primed.
+  assertPersistentListeners(ext, "messages", eventName, { primed: false });
+
+  await ext.unload();
+  return rv;
+}
+
+add_task(async function () {
+  await AddonTestUtils.promiseStartupManager();
+
+  let account = createAccount();
+  let inbox = await createSubfolder(account.incomingServer.rootFolder, "test1");
+
+  let files = {
+    "background.js": async () => {
+      browser.messages.onNewMailReceived.addListener((folder, messageList) => {
+        window.assertDeepEqual(
+          { accountId: "account1", name: "test1", path: "/test1" },
+          folder
+        );
+        browser.test.sendMessage("onNewMailReceived event received", [
+          folder,
+          messageList,
+        ]);
+      });
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "messagesRead"],
+    },
+  });
+
+  await extension.startup();
+
+  // Create a new message.
+
+  await createMessages(inbox, 1);
+  inbox.hasNewMessages = true;
+  inbox.setNumNewMessages(1);
+  inbox.biffState = Ci.nsIMsgFolder.nsMsgBiffState_NewMail;
+
+  let inboxMessages = [...inbox.messages];
+  let newMessages = await extension.awaitMessage(
+    "onNewMailReceived event received"
+  );
+  equal(newMessages[1].messages.length, 1);
+  equal(newMessages[1].messages[0].subject, inboxMessages[0].subject);
+
+  // Create 2 more new messages.
+
+  let primedOnNewMailReceivedEventData = await event_page_extension(
+    "onNewMailReceived",
+    async () => {
+      await createMessages(inbox, 2);
+      inbox.hasNewMessages = true;
+      inbox.setNumNewMessages(2);
+      inbox.biffState = Ci.nsIMsgFolder.nsMsgBiffState_NewMail;
+    }
+  );
+
+  inboxMessages = [...inbox.messages];
+  newMessages = await extension.awaitMessage(
+    "onNewMailReceived event received"
+  );
+  Assert.deepEqual(
+    primedOnNewMailReceivedEventData,
+    newMessages,
+    "The primed and non-primed onNewMailReceived events should return the same values"
+  );
+  equal(newMessages[1].messages.length, 2);
+  equal(newMessages[1].messages[0].subject, inboxMessages[1].subject);
+  equal(newMessages[1].messages[1].subject, inboxMessages[2].subject);
+
+  await extension.unload();
+
+  cleanUpAccount(account);
+  await AddonTestUtils.promiseShutdownManager();
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_messages_query.js b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_query.js
new file mode 100644
index 0000000000..9d9e5d8595
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_query.js
@@ -0,0 +1,333 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+
+add_task(async function test_query() {
+  let account = createAccount();
+
+  let textAttachment = {
+    body: "textAttachment",
+    filename: "test.txt",
+    contentType: "text/plain",
+  };
+
+  let subFolders = {
+    test1: await createSubfolder(account.incomingServer.rootFolder, "test1"),
+    test2: await createSubfolder(account.incomingServer.rootFolder, "test2"),
+  };
+  await createMessages(subFolders.test1, { count: 9, age_incr: { days: 2 } });
+
+  let messages = [...subFolders.test1.messages];
+  // NB: Here, the messages are zero-indexed. In the test they're one-indexed.
+  subFolders.test1.markMessagesRead([messages[0]], true);
+  subFolders.test1.markMessagesFlagged([messages[1]], true);
+  subFolders.test1.markMessagesFlagged([messages[6]], true);
+
+  subFolders.test1.addKeywordsToMessages(messages.slice(0, 1), "notATag");
+  subFolders.test1.addKeywordsToMessages(messages.slice(2, 4), "$label2");
+  subFolders.test1.addKeywordsToMessages(messages.slice(3, 6), "$label3");
+
+  addIdentity(account, messages[5].author.replace(/.*<(.*)>/, "$1"));
+  // No recipient support for NNTP.
+  if (account.incomingServer.type != "nntp") {
+    addIdentity(account, messages[2].recipients.replace(/.*<(.*)>/, "$1"));
+  }
+
+  await createMessages(subFolders.test2, { count: 7, age_incr: { days: 2 } });
+  // Email with multipart/alternative.
+  await createMessageFromFile(
+    subFolders.test2,
+    do_get_file("messages/alternative.eml").path
+  );
+
+  await createMessages(subFolders.test2, {
+    count: 1,
+    subject: "1 text attachment",
+    attachments: [textAttachment],
+  });
+
+  let files = {
+    "background.js": async () => {
+      let [accountId] = await window.waitForMessage();
+      let _account = await browser.accounts.get(accountId);
+      let accountType = _account.type;
+
+      let messages1 = await browser.messages.list({
+        accountId,
+        path: "/test1",
+      });
+      browser.test.assertEq(9, messages1.messages.length);
+      let messages2 = await browser.messages.list({
+        accountId,
+        path: "/test2",
+      });
+      browser.test.assertEq(9, messages2.messages.length);
+
+      // Check all messages are returned.
+      let { messages: allMessages } = await browser.messages.query({});
+      browser.test.assertEq(18, allMessages.length);
+
+      let folder1 = { accountId, path: "/test1" };
+      let folder2 = { accountId, path: "/test2" };
+      let rootFolder = { accountId, path: "/" };
+
+      // Query messages from test1. No messages from test2 should be returned.
+      // We'll use these messages as a reference for further tests.
+      let { messages: referenceMessages } = await browser.messages.query({
+        folder: folder1,
+      });
+      browser.test.assertEq(9, referenceMessages.length);
+      browser.test.assertTrue(
+        referenceMessages.every(m => m.folder.path == "/test1")
+      );
+
+      // Test includeSubFolders: Default (False).
+      let { messages: searchRecursiveDefault } = await browser.messages.query({
+        folder: rootFolder,
+      });
+      browser.test.assertEq(
+        0,
+        searchRecursiveDefault.length,
+        "includeSubFolders: Default"
+      );
+
+      // Test includeSubFolders: True.
+      let { messages: searchRecursiveTrue } = await browser.messages.query({
+        folder: rootFolder,
+        includeSubFolders: true,
+      });
+      browser.test.assertEq(
+        18,
+        searchRecursiveTrue.length,
+        "includeSubFolders: True"
+      );
+
+      // Test includeSubFolders: False.
+      let { messages: searchRecursiveFalse } = await browser.messages.query({
+        folder: rootFolder,
+        includeSubFolders: false,
+      });
+      browser.test.assertEq(
+        0,
+        searchRecursiveFalse.length,
+        "includeSubFolders: False"
+      );
+
+      // Test attachment query: False.
+      let { messages: searchAttachmentFalse } = await browser.messages.query({
+        attachment: false,
+        includeSubFolders: true,
+      });
+      browser.test.assertEq(
+        17,
+        searchAttachmentFalse.length,
+        "attachment: False"
+      );
+
+      // Test attachment query: True.
+      let { messages: searchAttachmentTrue } = await browser.messages.query({
+        attachment: true,
+        includeSubFolders: true,
+      });
+      browser.test.assertEq(1, searchAttachmentTrue.length, "attachment: True");
+
+      // Dump the reference messages to the console for easier debugging.
+      browser.test.log("Reference messages:");
+      for (let m of referenceMessages) {
+        let date = m.date.toISOString().substring(0, 10);
+        let author = m.author.replace(/"(.*)".*/, "$1").padEnd(16, " ");
+        // No recipient support for NNTP.
+        let recipients =
+          accountType == "nntp"
+            ? ""
+            : m.recipients[0].replace(/(.*) <.*>/, "$1").padEnd(16, " ");
+        browser.test.log(
+          `[${m.id}] ${date} From: ${author} To: ${recipients} Subject: ${m.subject}`
+        );
+      }
+
+      let subtest = async function (queryInfo, ...expectedMessageIndices) {
+        if (!queryInfo.folder) {
+          queryInfo.folder = folder1;
+        }
+        browser.test.log("Testing " + JSON.stringify(queryInfo));
+        let { messages: actualMessages } = await browser.messages.query(
+          queryInfo
+        );
+
+        browser.test.assertEq(
+          expectedMessageIndices.length,
+          actualMessages.length,
+          "Correct number of messages"
+        );
+        for (let index of expectedMessageIndices) {
+          // browser.test.log(`Looking for message ${index}`);
+          if (!actualMessages.some(am => am.id == index)) {
+            browser.test.fail(`Message ${index} was not returned`);
+            browser.test.log(
+              "These messages were returned: " + actualMessages.map(am => am.id)
+            );
+          }
+        }
+      };
+
+      // Date range query. The messages are 0 days old, 2 days old, 4 days old, etc..
+      let today = new Date();
+      let date1 = new Date(
+        today.getFullYear(),
+        today.getMonth(),
+        today.getDate() - 5
+      );
+      let date2 = new Date(
+        today.getFullYear(),
+        today.getMonth(),
+        today.getDate() - 11
+      );
+      await subtest({ fromDate: today });
+      await subtest({ fromDate: date1 }, 1, 2, 3);
+      await subtest({ fromDate: date2 }, 1, 2, 3, 4, 5, 6);
+      await subtest({ toDate: date1 }, 4, 5, 6, 7, 8, 9);
+      await subtest({ toDate: date2 }, 7, 8, 9);
+      await subtest({ fromDate: date1, toDate: date2 });
+      await subtest({ fromDate: date2, toDate: date1 }, 4, 5, 6);
+
+      // Unread query. Only message 1 has been read.
+      await subtest({ unread: false }, 1);
+      await subtest({ unread: true }, 2, 3, 4, 5, 6, 7, 8, 9);
+
+      // Flagged query. Messages 2 and 7 are flagged.
+      await subtest({ flagged: true }, 2, 7);
+      await subtest({ flagged: false }, 1, 3, 4, 5, 6, 8, 9);
+
+      // Subject query.
+      let keyword = referenceMessages[1].subject.split(" ")[1];
+      await subtest({ subject: keyword }, 2);
+      await subtest({ fullText: keyword }, 2);
+
+      // Author query.
+      keyword = referenceMessages[2].author.replace('"', "").split(" ")[0];
+      await subtest({ author: keyword }, 3);
+      await subtest({ fullText: keyword }, 3);
+
+      // Recipients query.
+      // No recipient support for NNTP.
+      if (accountType != "nntp") {
+        keyword = referenceMessages[7].recipients[0].split(" ")[0];
+        await subtest({ recipients: keyword }, 8);
+        await subtest({ fullText: keyword }, 8);
+        await subtest({ body: keyword }, 8);
+      }
+
+      // From Me and To Me. These use the identities added to account.
+      await subtest({ fromMe: true }, 6);
+      // No recipient support for NNTP.
+      if (accountType != "nntp") {
+        await subtest({ toMe: true }, 3);
+      }
+
+      // Tags query.
+      await subtest({ tags: { mode: "any", tags: { notATag: true } } });
+      await subtest({ tags: { mode: "any", tags: { $label2: true } } }, 3, 4);
+      await subtest(
+        { tags: { mode: "any", tags: { $label3: true } } },
+        4,
+        5,
+        6
+      );
+      await subtest(
+        { tags: { mode: "any", tags: { $label2: true, $label3: true } } },
+        3,
+        4,
+        5,
+        6
+      );
+      await subtest({
+        tags: { mode: "all", tags: { $label1: true, $label2: true } },
+      });
+      await subtest(
+        { tags: { mode: "all", tags: { $label2: true, $label3: true } } },
+        4
+      );
+      await subtest(
+        { tags: { mode: "any", tags: { $label2: false, $label3: false } } },
+        1,
+        2,
+        7,
+        8,
+        9
+      );
+      await subtest(
+        { tags: { mode: "all", tags: { $label2: false, $label3: false } } },
+        1,
+        2,
+        3,
+        5,
+        6,
+        7,
+        8,
+        9
+      );
+
+      // headerMessageId query
+      await subtest({ headerMessageId: "0@made.up.invalid" }, 1);
+      await subtest({ headerMessageId: "7@made.up.invalid" }, 8);
+      await subtest({ headerMessageId: "8@made.up.invalid" }, 9);
+      await subtest({ headerMessageId: "unknown@made.up.invalid" });
+
+      // attachment query
+      await subtest({ folder: folder2, attachment: true }, 18);
+
+      // text in nested html part of multipart/alternative
+      await subtest({ folder: folder2, body: "I am HTML!" }, 17);
+
+      // No recipient support for NNTP.
+      if (accountType != "nntp") {
+        // advanced search on recipients
+        await subtest({ folder: folder2, recipients: "karl; heinz" }, 17);
+        await subtest(
+          { folder: folder2, recipients: "<friedrich@example.COM>; HEINZ" },
+          17
+        );
+        await subtest(
+          {
+            folder: folder2,
+            recipients: "karl <friedrich@example.COM>; HEINZ",
+          },
+          17
+        );
+        await subtest({
+          folder: folder2,
+          recipients: "Heinz <friedrich@example.COM>; Karl",
+        });
+      }
+
+      browser.test.notifyPass("finished");
+    },
+    "utils.js": await getUtilsJS(),
+  };
+  let extension = ExtensionTestUtils.loadExtension({
+    files,
+    manifest: {
+      background: { scripts: ["utils.js", "background.js"] },
+      permissions: ["accountsRead", "messagesRead"],
+    },
+  });
+
+  await extension.startup();
+  extension.sendMessage(account.key);
+  await extension.awaitFinish("finished");
+  await extension.unload();
+});
+
+registerCleanupFunction(() => {
+  // Make sure any open address book database is given a chance to close.
+  Services.startup.advanceShutdownPhase(
+    Services.startup.SHUTDOWN_PHASE_APPSHUTDOWNCONFIRMED
+  );
+});
diff --git a/comm/mail/components/extensions/test/xpcshell/test_ext_messages_update.js b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_update.js
new file mode 100644
index 0000000000..4771f3ee17
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/test_ext_messages_update.js
@@ -0,0 +1,415 @@
+/* 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";
+
+var { ExtensionTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/ExtensionXPCShellUtils.sys.mjs"
+);
+var { TestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TestUtils.sys.mjs"
+);
+var { ExtensionsUI } = ChromeUtils.import(
+  "resource:///modules/ExtensionsUI.jsm"
+);
+var { AddonTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/AddonTestUtils.sys.mjs"
+);
+
+ExtensionTestUtils.mockAppInfo();
+AddonTestUtils.maybeInit(this);
+
+registerCleanupFunction(async () => {
+  // Remove the temporary MozillaMailnews folder, which is not deleted in time when
+  // the cleanupFunction registered by AddonTestUtils.maybeInit() checks for left over
+  // files in the temp folder.
+  // Note: PathUtils.tempDir points to the system temp folder, which is different.
+  let path = PathUtils.join(
+    Services.dirsvc.get("TmpD", Ci.nsIFile).path,
+    "MozillaMailnews"
+  );
+  await IOUtils.remove(path, { recursive: true });
+});
+
+// Function to start an event page extension (MV3), which can be called whenever
+// the main test is about to trigger an event. The extension terminates its
+// background and listens for that single event, verifying it is waking up correctly.
+async function event_page_extension(eventName, actionCallback) {
+  let ext = ExtensionTestUtils.loadExtension({
+    files: {
+      "background.js": async () => {
+        // Whenever the extension starts or wakes up, hasFired is set to false. In
+        // case of a wake-up, the first fired event is the one that woke up the background.
+        let hasFired = false;
+        let _eventName = browser.runtime.getManifest().description;
+
+        browser.messages[_eventName].addListener(async (...args) => {
+          // Only send the first event after background wake-up, this should
+          // be the only one expected.
+          if (!hasFired) {
+            hasFired = true;
+            browser.test.sendMessage(`${_eventName} received`, args);
+          }
+        });
+        browser.test.sendMessage("background started");
+      },
+    },
+    manifest: {
+      manifest_version: 3,
+      description: eventName,
+      background: { scripts: ["background.js"] },
+      browser_specific_settings: {
+        gecko: { id: "event_page_extension@mochi.test" },
+      },
+      permissions: ["accountsRead", "messagesRead", "messagesMove"],
+    },
+  });
+  await ext.startup();
+  await ext.awaitMessage("background started");
+  // The listener should be persistent, but not primed.
+  assertPersistentListeners(ext, "messages", eventName, { primed: false });
+
+  await ext.terminateBackground({ disableResetIdleForTest: true });
+  // Verify the primed persistent listener.
+  assertPersistentListeners(ext, "messages", eventName, { primed: true });
+
+  await actionCallback();
+  let rv = await ext.awaitMessage(`${eventName} received`);
+  await ext.awaitMessage("background started");
+  // The listener should be persistent, but not primed.
+  assertPersistentListeners(ext, "messages", eventName, { primed: false });
+
+  await ext.unload();
+  return rv;
+}
+
+add_task(
+  {
+    skip_if: () => IS_NNTP,
+  },
+  async function test_update() {
+    await AddonTestUtils.promiseStartupManager();
+
+    let account = createAccount();
+    let rootFolder = account.incomingServer.rootFolder;
+    let testFolder0 = await createSubfolder(rootFolder, "test0");
+    await createMessages(testFolder0, 1);
+    testFolder0.addKeywordsToMessages(
+      [[...testFolder0.messages][0]],
+      "testkeyword"
+    );
+
+    let files = {
+      "background.js": async () => {
+        async function capturePrimedEvent(eventName, callback) {
+          let eventPageExtensionReadyPromise = window.waitForMessage();
+          browser.test.sendMessage("capturePrimedEvent", eventName);
+          await eventPageExtensionReadyPromise;
+          let eventPageExtensionFinishedPromise = window.waitForMessage();
+          callback();
+          return eventPageExtensionFinishedPromise;
+        }
+
+        function newUpdatePromise(numberOfEventsToCollapse = 1) {
+          return new Promise(resolve => {
+            let seenEvents = {};
+            const listener = (msg, props) => {
+              if (!seenEvents.hasOwnProperty(msg.id)) {
+                seenEvents[msg.id] = {
+                  counts: 0,
+                  props: {},
+                };
+              }
+
+              seenEvents[msg.id].counts++;
+              for (let prop of Object.keys(props)) {
+                seenEvents[msg.id].props[prop] = props[prop];
+              }
+
+              if (seenEvents[msg.id].counts == numberOfEventsToCollapse) {
+                browser.messages.onUpdated.removeListener(listener);
+                resolve({ msg, props: seenEvents[msg.id].props });
+              }
+            };
+            browser.messages.onUpdated.addListener(listener);
+          });
+        }
+        let tags = await browser.messages.listTags();
+        let [data] = await window.sendMessage("getFolder");
+        let messageList = await browser.messages.list(data.folder);
+        browser.test.assertEq(1, messageList.messages.length);
+        let message = messageList.messages[0];
+        browser.test.assertFalse(message.flagged);
+        browser.test.assertFalse(message.read);
+        browser.test.assertFalse(message.junk);
+        browser.test.assertEq(0, message.junkScore);
+        browser.test.assertEq(0, message.tags.length);
+        browser.test.assertEq(data.size, message.size);
+        browser.test.assertEq("0@made.up.invalid", message.headerMessageId);
+
+        // Test that setting flagged works.
+        let updatePromise = newUpdatePromise();
+        let primedUpdatedInfo = await capturePrimedEvent("onUpdated", () =>
+          browser.messages.update(message.id, { flagged: true })
+        );
+        let updateInfo = await updatePromise;
+        window.assertDeepEqual(
+          [updateInfo.msg, updateInfo.props],
+          primedUpdatedInfo,
+          "The primed and non-primed onUpdated events should return the same values",
+          { strict: true }
+        );
+        browser.test.assertEq(message.id, updateInfo.msg.id);
+        window.assertDeepEqual({ flagged: true }, updateInfo.props);
+        await window.sendMessage("flagged");
+
+        // Test that setting read works.
+        updatePromise = newUpdatePromise();
+        primedUpdatedInfo = await capturePrimedEvent("onUpdated", () =>
+          browser.messages.update(message.id, { read: true })
+        );
+        updateInfo = await updatePromise;
+        window.assertDeepEqual(
+          [updateInfo.msg, updateInfo.props],
+          primedUpdatedInfo,
+          "The primed and non-primed onUpdated events should return the same values",
+          { strict: true }
+        );
+        browser.test.assertEq(message.id, updateInfo.msg.id);
+        window.assertDeepEqual({ read: true }, updateInfo.props);
+        await window.sendMessage("read");
+
+        // Test that setting junk works.
+        updatePromise = newUpdatePromise();
+        primedUpdatedInfo = await capturePrimedEvent("onUpdated", () =>
+          browser.messages.update(message.id, { junk: true })
+        );
+        updateInfo = await updatePromise;
+        window.assertDeepEqual(
+          [updateInfo.msg, updateInfo.props],
+          primedUpdatedInfo,
+          "The primed and non-primed onUpdated events should return the same values",
+          { strict: true }
+        );
+        browser.test.assertEq(message.id, updateInfo.msg.id);
+        window.assertDeepEqual({ junk: true }, updateInfo.props);
+        await window.sendMessage("junk");
+
+        // Test that setting one tag works.
+        updatePromise = newUpdatePromise();
+        primedUpdatedInfo = await capturePrimedEvent("onUpdated", () =>
+          browser.messages.update(message.id, { tags: [tags[0].key] })
+        );
+        updateInfo = await updatePromise;
+        window.assertDeepEqual(
+          [updateInfo.msg, updateInfo.props],
+          primedUpdatedInfo,
+          "The primed and non-primed onUpdated events should return the same values",
+          { strict: true }
+        );
+        browser.test.assertEq(message.id, updateInfo.msg.id);
+        window.assertDeepEqual({ tags: [tags[0].key] }, updateInfo.props);
+        await window.sendMessage("tags1");
+
+        // Test that setting two tags works. We get 3 events: one removing tags0,
+        // one adding tags1 and one adding tags2. updatePromise is waiting for
+        // the third one before resolving.
+        updatePromise = newUpdatePromise(3);
+        await browser.messages.update(message.id, {
+          tags: [tags[1].key, tags[2].key],
+        });
+        updateInfo = await updatePromise;
+        browser.test.assertEq(message.id, updateInfo.msg.id);
+        window.assertDeepEqual(
+          { tags: [tags[1].key, tags[2].key] },
+          updateInfo.props
+        );
+        await window.sendMessage("tags2");
+
+        // Test that unspecified properties aren't changed.
+        let listenerCalls = 0;
+        const listenerFunc = (msg, props) => {
+          listenerCalls++;
+        };
+        browser.messages.onUpdated.addListener(listenerFunc);
+        await browser.messages.update(message.id, {});
+        await window.sendMessage("empty");
+        // Check if the no-op update call triggered a listener.
+        await new Promise(resolve => setTimeout(resolve));
+        browser.messages.onUpdated.removeListener(listenerFunc);
+        browser.test.assertEq(
+          0,
+          listenerCalls,
+          "Not expecting listener callbacks on no-op updates."
+        );
+
+        message = await browser.messages.get(message.id);
+        browser.test.assertTrue(message.flagged);
+        browser.test.assertTrue(message.read);
+        browser.test.assertTrue(message.junk);
+        browser.test.assertEq(100, message.junkScore);
+        browser.test.assertEq(2, message.tags.length);
+        browser.test.assertEq(tags[1].key, message.tags[0]);
+        browser.test.assertEq(tags[2].key, message.tags[1]);
+        browser.test.assertEq("0@made.up.invalid", message.headerMessageId);
+
+        // Test that clearing properties works.
+        updatePromise = newUpdatePromise(5);
+        await browser.messages.update(message.id, {
+          flagged: false,
+          read: false,
+          junk: false,
+          tags: [],
+        });
+        updateInfo = await updatePromise;
+        window.assertDeepEqual(
+          {
+            flagged: false,
+            read: false,
+            junk: false,
+            tags: [],
+          },
+          updateInfo.props
+        );
+        await window.sendMessage("clear");
+
+        message = await browser.messages.get(message.id);
+        browser.test.assertFalse(message.flagged);
+        browser.test.assertFalse(message.read);
+        browser.test.assertFalse(message.external);
+        browser.test.assertFalse(message.junk);
+        browser.test.assertEq(0, message.junkScore);
+        browser.test.assertEq(0, message.tags.length);
+        browser.test.assertEq("0@made.up.invalid", message.headerMessageId);
+
+        browser.test.notifyPass("finished");
+      },
+      "utils.js": await getUtilsJS(),
+    };
+    let extension = ExtensionTestUtils.loadExtension({
+      files,
+      manifest: {
+        background: { scripts: ["utils.js", "background.js"] },
+        permissions: ["accountsRead", "messagesRead"],
+        browser_specific_settings: {
+          gecko: { id: "messages.update@mochi.test" },
+        },
+      },
+    });
+
+    let message = [...testFolder0.messages][0];
+    ok(!message.isFlagged);
+    ok(!message.isRead);
+    equal(message.getStringProperty("keywords"), "testkeyword");
+
+    extension.onMessage("capturePrimedEvent", async eventName => {
+      let primedEventData = await event_page_extension(eventName, () => {
+        // Resume execution in the main test, after the event page extension is
+        // ready to capture the event with deactivated background.
+        extension.sendMessage();
+      });
+      extension.sendMessage(...primedEventData);
+    });
+
+    extension.onMessage("flagged", async () => {
+      await TestUtils.waitForCondition(() => message.isFlagged);
+      extension.sendMessage();
+    });
+
+    extension.onMessage("read", async () => {
+      await TestUtils.waitForCondition(() => message.isRead);
+      extension.sendMessage();
+    });
+
+    extension.onMessage("junk", async () => {
+      await TestUtils.waitForCondition(
+        () => message.getStringProperty("junkscore") == 100
+      );
+      extension.sendMessage();
+    });
+
+    extension.onMessage("tags1", async () => {
+      if (IS_IMAP) {
+        // Only IMAP sets the junk/nonjunk keyword.
+        await TestUtils.waitForCondition(
+          () =>
+            message.getStringProperty("keywords") == "testkeyword junk $label1"
+        );
+      } else {
+        await TestUtils.waitForCondition(
+          () => message.getStringProperty("keywords") == "testkeyword $label1"
+        );
+      }
+      extension.sendMessage();
+    });
+
+    extension.onMessage("tags2", async () => {
+      if (IS_IMAP) {
+        await TestUtils.waitForCondition(
+          () =>
+            message.getStringProperty("keywords") ==
+            "testkeyword junk $label2 $label3"
+        );
+      } else {
+        await TestUtils.waitForCondition(
+          () =>
+            message.getStringProperty("keywords") ==
+            "testkeyword $label2 $label3"
+        );
+      }
+      extension.sendMessage();
+    });
+
+    extension.onMessage("empty", async () => {
+      await TestUtils.waitForCondition(() => message.isFlagged);
+      await TestUtils.waitForCondition(() => message.isRead);
+      if (IS_IMAP) {
+        await TestUtils.waitForCondition(
+          () =>
+            message.getStringProperty("keywords") ==
+            "testkeyword junk $label2 $label3"
+        );
+      } else {
+        await TestUtils.waitForCondition(
+          () =>
+            message.getStringProperty("keywords") ==
+            "testkeyword $label2 $label3"
+        );
+      }
+      extension.sendMessage();
+    });
+
+    extension.onMessage("clear", async () => {
+      await TestUtils.waitForCondition(() => !message.isFlagged);
+      await TestUtils.waitForCondition(() => !message.isRead);
+      await TestUtils.waitForCondition(
+        () => message.getStringProperty("junkscore") == 0
+      );
+      if (IS_IMAP) {
+        await TestUtils.waitForCondition(
+          () => message.getStringProperty("keywords") == "testkeyword nonjunk"
+        );
+      } else {
+        await TestUtils.waitForCondition(
+          () => message.getStringProperty("keywords") == "testkeyword"
+        );
+      }
+      extension.sendMessage();
+    });
+
+    extension.onMessage("getFolder", async () => {
+      extension.sendMessage({
+        folder: { accountId: account.key, path: "/test0" },
+        size: message.messageSize,
+      });
+    });
+
+    await extension.startup();
+    await extension.awaitFinish("finished");
+    await extension.unload();
+
+    cleanUpAccount(account);
+    await AddonTestUtils.promiseShutdownManager();
+  }
+);
diff --git a/comm/mail/components/extensions/test/xpcshell/xpcshell-imap.ini b/comm/mail/components/extensions/test/xpcshell/xpcshell-imap.ini
new file mode 100644
index 0000000000..88659a20ad
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/xpcshell-imap.ini
@@ -0,0 +1,7 @@
+[default]
+dupe-manifest = true
+head = head.js head-imap.js
+support-files = data/utils.js
+tags = imap webextensions
+
+[include:xpcshell.ini]
diff --git a/comm/mail/components/extensions/test/xpcshell/xpcshell-local.ini b/comm/mail/components/extensions/test/xpcshell/xpcshell-local.ini
new file mode 100644
index 0000000000..19d50044cd
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/xpcshell-local.ini
@@ -0,0 +1,23 @@
+[default]
+dupe-manifest = true
+head = head.js
+support-files = data/utils.js
+tags = local webextensions
+
+[include:xpcshell.ini]
+[test_ext_accounts.js]
+[test_ext_accounts_mv3_event_pages.js]
+[test_ext_identities_mv3_event_pages.js]
+[test_ext_addressBook.js]
+support-files = images/**
+tags = addrbook
+[test_ext_addressBook_readonly.js]
+tags = addrbook
+[test_ext_addressBook_remote.js]
+tags = addrbook
+[test_ext_addressBook_provider.js]
+tags = addrbook
+[test_ext_addressBook_quickSearch.js]
+tags = addrbook
+[test_ext_alias.js]
+[test_ext_browserAction_unifiedtoolbar_restart.js]
diff --git a/comm/mail/components/extensions/test/xpcshell/xpcshell-nntp.ini b/comm/mail/components/extensions/test/xpcshell/xpcshell-nntp.ini
new file mode 100644
index 0000000000..66e23e03bd
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/xpcshell-nntp.ini
@@ -0,0 +1,7 @@
+[default]
+dupe-manifest = true
+head = head.js head-nntp.js
+support-files = data/utils.js
+tags = nntp webextensions
+
+[include:xpcshell.ini]
diff --git a/comm/mail/components/extensions/test/xpcshell/xpcshell.ini b/comm/mail/components/extensions/test/xpcshell/xpcshell.ini
new file mode 100644
index 0000000000..666a67d5da
--- /dev/null
+++ b/comm/mail/components/extensions/test/xpcshell/xpcshell.ini
@@ -0,0 +1,17 @@
+[test_ext_experiments.js]
+tags = addrbook
+[test_ext_folders.js] # NNTP disabled (no support for folder operations).
+[test_ext_folders_mv3_event_pages.js] # NNTP disabled (no support for folder operations).
+[test_ext_messages.js] # NNTP disabled (no support for Trash folder).
+[test_ext_messages_attachments.js] # IMAP disabled (doesn't work with test server).
+support-files = messages/**
+[test_ext_messages_get.js] # NNTP disabled for PGP tests.
+support-files = messages/**
+[test_ext_messages_id.js] # NNTP disabled (message move not supported).
+[test_ext_messages_import.js]
+support-files = messages/**
+[test_ext_messages_move_copy_delete.js] # NNTP disabled (no support for Trash folder).
+[test_ext_messages_onNewMailReceived.js]
+[test_ext_messages_query.js]
+support-files = messages/alternative.eml
+[test_ext_messages_update.js] # NNTP disabled (no support for Trash folder).