Adding upstream version 115.8.0esr.upstream/115.8.0esr

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

20 files changed, 9857 insertions, 0 deletions

diff --git a/services/fxaccounts/tests/xpcshell/head.js b/services/fxaccounts/tests/xpcshell/head.js
new file mode 100644
index 0000000000..6767553463
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/head.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* import-globals-from ../../../common/tests/unit/head_helpers.js */
+/* import-globals-from ../../../common/tests/unit/head_http.js */
+
+"use strict";
+
+const { XPCOMUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/XPCOMUtils.sys.mjs"
+);
+const { sinon } = ChromeUtils.importESModule(
+  "resource://testing-common/Sinon.sys.mjs"
+);
+const { SCOPE_OLD_SYNC, LEGACY_SCOPE_WEBEXT_SYNC } = ChromeUtils.import(
+  "resource://gre/modules/FxAccountsCommon.js"
+);
+
+// Some mock key data, in both scoped-key and legacy field formats.
+const MOCK_ACCOUNT_KEYS = {
+  scopedKeys: {
+    [SCOPE_OLD_SYNC]: {
+      kid: "1234567890123-u7u7u7u7u7u7u7u7u7u7uw",
+      k: "qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqg",
+      kty: "oct",
+    },
+    [LEGACY_SCOPE_WEBEXT_SYNC]: {
+      kid: "1234567890123-3d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3d0",
+      k: "zMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzA",
+      kty: "oct",
+    },
+  },
+  kSync:
+    "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+  kXCS: "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
+  kExtSync:
+    "cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
+  kExtKbHash:
+    "dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd ",
+};
+
+(function initFxAccountsTestingInfrastructure() {
+  do_get_profile();
+
+  let { initTestLogging } = ChromeUtils.importESModule(
+    "resource://testing-common/services/common/logging.sys.mjs"
+  );
+
+  initTestLogging("Trace");
+}).call(this);
diff --git a/services/fxaccounts/tests/xpcshell/test_accounts.js b/services/fxaccounts/tests/xpcshell/test_accounts.js
new file mode 100644
index 0000000000..11867f9672
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_accounts.js
@@ -0,0 +1,1666 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { CryptoUtils } = ChromeUtils.importESModule(
+  "resource://services-crypto/utils.sys.mjs"
+);
+const { FxAccounts } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+const { FxAccountsClient } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsClient.sys.mjs"
+);
+const {
+  ERRNO_INVALID_AUTH_TOKEN,
+  ERROR_NO_ACCOUNT,
+  FX_OAUTH_CLIENT_ID,
+  ONLOGIN_NOTIFICATION,
+  ONLOGOUT_NOTIFICATION,
+  ONVERIFIED_NOTIFICATION,
+  DEPRECATED_SCOPE_ECOSYSTEM_TELEMETRY,
+  PREF_LAST_FXA_USER,
+} = ChromeUtils.import("resource://gre/modules/FxAccountsCommon.js");
+const { PromiseUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/PromiseUtils.sys.mjs"
+);
+
+// We grab some additional stuff via backstage passes.
+var { AccountState } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+
+const MOCK_TOKEN_RESPONSE = {
+  access_token:
+    "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69",
+  token_type: "bearer",
+  scope: "https://identity.mozilla.com/apps/oldsync",
+  expires_in: 21600,
+  auth_at: 1589579900,
+};
+
+initTestLogging("Trace");
+
+var log = Log.repository.getLogger("Services.FxAccounts.test");
+log.level = Log.Level.Debug;
+
+// See verbose logging from FxAccounts.jsm and jwcrypto.jsm.
+Services.prefs.setCharPref("identity.fxaccounts.loglevel", "Trace");
+Log.repository.getLogger("FirefoxAccounts").level = Log.Level.Trace;
+Services.prefs.setCharPref("services.crypto.jwcrypto.log.level", "Debug");
+
+/*
+ * The FxAccountsClient communicates with the remote Firefox
+ * Accounts auth server.  Mock the server calls, with a little
+ * lag time to simulate some latency.
+ *
+ * We add the _verified attribute to mock the change in verification
+ * state on the FXA server.
+ */
+
+function MockStorageManager() {}
+
+MockStorageManager.prototype = {
+  promiseInitialized: Promise.resolve(),
+
+  initialize(accountData) {
+    this.accountData = accountData;
+  },
+
+  finalize() {
+    return Promise.resolve();
+  },
+
+  getAccountData(fields = null) {
+    let result;
+    if (!this.accountData) {
+      result = null;
+    } else if (fields == null) {
+      // can't use cloneInto as the keys get upset...
+      result = {};
+      for (let field of Object.keys(this.accountData)) {
+        result[field] = this.accountData[field];
+      }
+    } else {
+      if (!Array.isArray(fields)) {
+        fields = [fields];
+      }
+      result = {};
+      for (let field of fields) {
+        result[field] = this.accountData[field];
+      }
+    }
+    return Promise.resolve(result);
+  },
+
+  updateAccountData(updatedFields) {
+    if (!this.accountData) {
+      return Promise.resolve();
+    }
+    for (let [name, value] of Object.entries(updatedFields)) {
+      if (value == null) {
+        delete this.accountData[name];
+      } else {
+        this.accountData[name] = value;
+      }
+    }
+    return Promise.resolve();
+  },
+
+  deleteAccountData() {
+    this.accountData = null;
+    return Promise.resolve();
+  },
+};
+
+function MockFxAccountsClient() {
+  this._email = "nobody@example.com";
+  this._verified = false;
+  this._deletedOnServer = false; // for our accountStatus mock
+
+  // mock calls up to the auth server to determine whether the
+  // user account has been verified
+  this.recoveryEmailStatus = async function (sessionToken) {
+    // simulate a call to /recovery_email/status
+    return {
+      email: this._email,
+      verified: this._verified,
+    };
+  };
+
+  this.accountStatus = async function (uid) {
+    return !!uid && !this._deletedOnServer;
+  };
+
+  this.sessionStatus = async function () {
+    // If the sessionStatus check says an account is OK, we typically will not
+    // end up calling accountStatus - so this must return false if accountStatus
+    // would.
+    return !this._deletedOnServer;
+  };
+
+  this.accountKeys = function (keyFetchToken) {
+    return new Promise(resolve => {
+      do_timeout(50, () => {
+        resolve({
+          kA: expandBytes("11"),
+          wrapKB: expandBytes("22"),
+        });
+      });
+    });
+  };
+
+  this.getScopedKeyData = function (sessionToken, client_id, scopes) {
+    Assert.ok(sessionToken);
+    Assert.equal(client_id, FX_OAUTH_CLIENT_ID);
+    Assert.equal(scopes, SCOPE_OLD_SYNC);
+    return new Promise(resolve => {
+      do_timeout(50, () => {
+        resolve({
+          "https://identity.mozilla.com/apps/oldsync": {
+            identifier: "https://identity.mozilla.com/apps/oldsync",
+            keyRotationSecret:
+              "0000000000000000000000000000000000000000000000000000000000000000",
+            keyRotationTimestamp: 1234567890123,
+          },
+        });
+      });
+    });
+  };
+
+  this.resendVerificationEmail = function (sessionToken) {
+    // Return the session token to show that we received it in the first place
+    return Promise.resolve(sessionToken);
+  };
+
+  this.signOut = () => Promise.resolve();
+
+  FxAccountsClient.apply(this);
+}
+MockFxAccountsClient.prototype = {};
+Object.setPrototypeOf(
+  MockFxAccountsClient.prototype,
+  FxAccountsClient.prototype
+);
+/*
+ * We need to mock the FxAccounts module's interfaces to external
+ * services, such as storage and the FxAccounts client.  We also
+ * mock the now() method, so that we can simulate the passing of
+ * time and verify that signatures expire correctly.
+ */
+function MockFxAccounts(credentials = null) {
+  let result = new FxAccounts({
+    VERIFICATION_POLL_TIMEOUT_INITIAL: 100, // 100ms
+
+    _getCertificateSigned_calls: [],
+    _d_signCertificate: PromiseUtils.defer(),
+    _now_is: new Date(),
+    now() {
+      return this._now_is;
+    },
+    newAccountState(newCredentials) {
+      // we use a real accountState but mocked storage.
+      let storage = new MockStorageManager();
+      storage.initialize(newCredentials);
+      return new AccountState(storage);
+    },
+    fxAccountsClient: new MockFxAccountsClient(),
+    observerPreloads: [],
+    device: {
+      _registerOrUpdateDevice() {},
+      _checkRemoteCommandsUpdateNeeded: async () => false,
+    },
+    profile: {
+      getProfile() {
+        return null;
+      },
+    },
+  });
+  // and for convenience so we don't have to touch as many lines in this test
+  // when we refactored FxAccounts.jsm :)
+  result.setSignedInUser = function (creds) {
+    return result._internal.setSignedInUser(creds);
+  };
+  return result;
+}
+
+/*
+ * Some tests want a "real" fxa instance - however, we still mock the storage
+ * to keep the tests fast on b2g.
+ */
+async function MakeFxAccounts({ internal = {}, credentials } = {}) {
+  if (!internal.newAccountState) {
+    // we use a real accountState but mocked storage.
+    internal.newAccountState = function (newCredentials) {
+      let storage = new MockStorageManager();
+      storage.initialize(newCredentials);
+      return new AccountState(storage);
+    };
+  }
+  if (!internal._signOutServer) {
+    internal._signOutServer = () => Promise.resolve();
+  }
+  if (internal.device) {
+    if (!internal.device._registerOrUpdateDevice) {
+      internal.device._registerOrUpdateDevice = () => Promise.resolve();
+      internal.device._checkRemoteCommandsUpdateNeeded = async () => false;
+    }
+  } else {
+    internal.device = {
+      _registerOrUpdateDevice() {},
+      _checkRemoteCommandsUpdateNeeded: async () => false,
+    };
+  }
+  if (!internal.observerPreloads) {
+    internal.observerPreloads = [];
+  }
+  let result = new FxAccounts(internal);
+
+  if (credentials) {
+    await result._internal.setSignedInUser(credentials);
+  }
+  return result;
+}
+
+add_task(async function test_get_signed_in_user_initially_unset() {
+  _("Check getSignedInUser initially and after signout reports no user");
+  let account = await MakeFxAccounts();
+  let credentials = {
+    email: "foo@example.com",
+    uid: "1234567890abcdef1234567890abcdef",
+    sessionToken: "dead",
+    verified: true,
+    ...MOCK_ACCOUNT_KEYS,
+  };
+  let result = await account.getSignedInUser();
+  Assert.equal(result, null);
+
+  await account._internal.setSignedInUser(credentials);
+
+  // getSignedInUser only returns a subset.
+  result = await account.getSignedInUser();
+  Assert.deepEqual(result.email, credentials.email);
+  Assert.deepEqual(result.scopedKeys, undefined);
+  Assert.deepEqual(result.kSync, undefined);
+  Assert.deepEqual(result.kXCS, undefined);
+  Assert.deepEqual(result.kExtSync, undefined);
+  Assert.deepEqual(result.kExtKbHash, undefined);
+  // for the sake of testing, use the low-level function to check it's all there
+  result = await account._internal.currentAccountState.getUserAccountData();
+  Assert.deepEqual(result.email, credentials.email);
+  Assert.deepEqual(result.scopedKeys, credentials.scopedKeys);
+  Assert.ok(result.kSync);
+  Assert.ok(result.kXCS);
+  Assert.ok(result.kExtSync);
+  Assert.ok(result.kExtKbHash);
+
+  // sign out
+  let localOnly = true;
+  await account.signOut(localOnly);
+
+  // user should be undefined after sign out
+  result = await account.getSignedInUser();
+  Assert.equal(result, null);
+});
+
+add_task(async function test_set_signed_in_user_signs_out_previous_account() {
+  _("Check setSignedInUser signs out the previous account.");
+  let signOutServerCalled = false;
+  let credentials = {
+    email: "foo@example.com",
+    uid: "1234567890abcdef1234567890abcdef",
+    sessionToken: "dead",
+    verified: true,
+    ...MOCK_ACCOUNT_KEYS,
+  };
+  let account = await MakeFxAccounts({ credentials });
+
+  account._internal._signOutServer = () => {
+    signOutServerCalled = true;
+    return Promise.resolve(true);
+  };
+
+  await account._internal.setSignedInUser(credentials);
+  Assert.ok(signOutServerCalled);
+});
+
+add_task(async function test_update_account_data() {
+  _("Check updateUserAccountData does the right thing.");
+  let credentials = {
+    email: "foo@example.com",
+    uid: "1234567890abcdef1234567890abcdef",
+    sessionToken: "dead",
+    verified: true,
+    ...MOCK_ACCOUNT_KEYS,
+  };
+  let account = await MakeFxAccounts({ credentials });
+
+  let newCreds = {
+    email: credentials.email,
+    uid: credentials.uid,
+    sessionToken: "alive",
+  };
+  await account._internal.updateUserAccountData(newCreds);
+  Assert.equal(
+    (await account._internal.getUserAccountData()).sessionToken,
+    "alive",
+    "new field value was saved"
+  );
+
+  // but we should fail attempting to change the uid.
+  newCreds = {
+    email: credentials.email,
+    uid: "11111111111111111111222222222222",
+    sessionToken: "alive",
+  };
+  await Assert.rejects(
+    account._internal.updateUserAccountData(newCreds),
+    /The specified credentials aren't for the current user/
+  );
+
+  // should fail without the uid.
+  newCreds = {
+    sessionToken: "alive",
+  };
+  await Assert.rejects(
+    account._internal.updateUserAccountData(newCreds),
+    /The specified credentials have no uid/
+  );
+
+  // and should fail with a field name that's not known by storage.
+  newCreds = {
+    email: credentials.email,
+    uid: "11111111111111111111222222222222",
+    foo: "bar",
+  };
+  await Assert.rejects(
+    account._internal.updateUserAccountData(newCreds),
+    /The specified credentials aren't for the current user/
+  );
+});
+
+// Sanity-check that our mocked client is working correctly
+add_test(function test_client_mock() {
+  let fxa = new MockFxAccounts();
+  let client = fxa._internal.fxAccountsClient;
+  Assert.equal(client._verified, false);
+  Assert.equal(typeof client.signIn, "function");
+
+  // The recoveryEmailStatus function eventually fulfills its promise
+  client.recoveryEmailStatus().then(response => {
+    Assert.equal(response.verified, false);
+    run_next_test();
+  });
+});
+
+// Sign in a user, and after a little while, verify the user's email.
+// Right after signing in the user, we should get the 'onlogin' notification.
+// Polling should detect that the email is verified, and eventually
+// 'onverified' should be observed
+add_test(function test_verification_poll() {
+  let fxa = new MockFxAccounts();
+  let test_user = getTestUser("francine");
+  let login_notification_received = false;
+
+  makeObserver(ONVERIFIED_NOTIFICATION, function () {
+    log.debug("test_verification_poll observed onverified");
+    // Once email verification is complete, we will observe onverified
+    fxa._internal
+      .getUserAccountData()
+      .then(user => {
+        // And confirm that the user's state has changed
+        Assert.equal(user.verified, true);
+        Assert.equal(user.email, test_user.email);
+        Assert.equal(
+          Services.prefs.getStringPref(PREF_LAST_FXA_USER),
+          CryptoUtils.sha256Base64(test_user.email)
+        );
+        Assert.ok(login_notification_received);
+      })
+      .finally(run_next_test);
+  });
+
+  makeObserver(ONLOGIN_NOTIFICATION, function () {
+    log.debug("test_verification_poll observer onlogin");
+    login_notification_received = true;
+  });
+
+  fxa.setSignedInUser(test_user).then(() => {
+    fxa._internal.getUserAccountData().then(user => {
+      // The user is signing in, but email has not been verified yet
+      Assert.equal(user.verified, false);
+      do_timeout(200, function () {
+        log.debug("Mocking verification of francine's email");
+        fxa._internal.fxAccountsClient._email = test_user.email;
+        fxa._internal.fxAccountsClient._verified = true;
+      });
+    });
+  });
+});
+
+// Sign in the user, but never verify the email.  The check-email
+// poll should time out.  No verifiedlogin event should be observed, and the
+// internal whenVerified promise should be rejected
+add_test(function test_polling_timeout() {
+  // This test could be better - the onverified observer might fire on
+  // somebody else's stack, and we're not making sure that we're not receiving
+  // such a message. In other words, this tests either failure, or success, but
+  // not both.
+
+  let fxa = new MockFxAccounts();
+  let test_user = getTestUser("carol");
+
+  let removeObserver = makeObserver(ONVERIFIED_NOTIFICATION, function () {
+    do_throw("We should not be getting a login event!");
+  });
+
+  fxa._internal.POLL_SESSION = 1;
+
+  let p = fxa._internal.whenVerified({});
+
+  fxa.setSignedInUser(test_user).then(() => {
+    p.then(
+      success => {
+        do_throw("this should not succeed");
+      },
+      fail => {
+        removeObserver();
+        fxa.signOut().then(run_next_test);
+      }
+    );
+  });
+});
+
+// For bug 1585299 - ensure we only get a single ONVERIFIED notification.
+add_task(async function test_onverified_once() {
+  let fxa = new MockFxAccounts();
+  let user = getTestUser("francine");
+
+  let numNotifications = 0;
+
+  function observe(aSubject, aTopic, aData) {
+    numNotifications += 1;
+  }
+  Services.obs.addObserver(observe, ONVERIFIED_NOTIFICATION);
+
+  fxa._internal.POLL_SESSION = 1;
+
+  await fxa.setSignedInUser(user);
+
+  Assert.ok(!(await fxa.getSignedInUser()).verified, "starts unverified");
+
+  await fxa._internal.startPollEmailStatus(
+    fxa._internal.currentAccountState,
+    user.sessionToken,
+    "start"
+  );
+
+  Assert.ok(!(await fxa.getSignedInUser()).verified, "still unverified");
+
+  log.debug("Mocking verification of francine's email");
+  fxa._internal.fxAccountsClient._email = user.email;
+  fxa._internal.fxAccountsClient._verified = true;
+
+  await fxa._internal.startPollEmailStatus(
+    fxa._internal.currentAccountState,
+    user.sessionToken,
+    "again"
+  );
+
+  Assert.ok((await fxa.getSignedInUser()).verified, "now verified");
+
+  Assert.equal(numNotifications, 1, "expect exactly 1 ONVERIFIED");
+
+  Services.obs.removeObserver(observe, ONVERIFIED_NOTIFICATION);
+  await fxa.signOut();
+});
+
+add_test(function test_pollEmailStatus_start_verified() {
+  let fxa = new MockFxAccounts();
+  let test_user = getTestUser("carol");
+
+  fxa._internal.POLL_SESSION = 20 * 60000;
+  fxa._internal.VERIFICATION_POLL_TIMEOUT_INITIAL = 50000;
+
+  fxa.setSignedInUser(test_user).then(() => {
+    fxa._internal.getUserAccountData().then(user => {
+      fxa._internal.fxAccountsClient._email = test_user.email;
+      fxa._internal.fxAccountsClient._verified = true;
+      const mock = sinon.mock(fxa._internal);
+      mock.expects("_scheduleNextPollEmailStatus").never();
+      fxa._internal
+        .startPollEmailStatus(
+          fxa._internal.currentAccountState,
+          user.sessionToken,
+          "start"
+        )
+        .then(() => {
+          mock.verify();
+          mock.restore();
+          run_next_test();
+        });
+    });
+  });
+});
+
+add_test(function test_pollEmailStatus_start() {
+  let fxa = new MockFxAccounts();
+  let test_user = getTestUser("carol");
+
+  fxa._internal.POLL_SESSION = 20 * 60000;
+  fxa._internal.VERIFICATION_POLL_TIMEOUT_INITIAL = 123456;
+
+  fxa.setSignedInUser(test_user).then(() => {
+    fxa._internal.getUserAccountData().then(user => {
+      const mock = sinon.mock(fxa._internal);
+      mock
+        .expects("_scheduleNextPollEmailStatus")
+        .once()
+        .withArgs(
+          fxa._internal.currentAccountState,
+          user.sessionToken,
+          123456,
+          "start"
+        );
+      fxa._internal
+        .startPollEmailStatus(
+          fxa._internal.currentAccountState,
+          user.sessionToken,
+          "start"
+        )
+        .then(() => {
+          mock.verify();
+          mock.restore();
+          run_next_test();
+        });
+    });
+  });
+});
+
+add_test(function test_pollEmailStatus_start_subsequent() {
+  let fxa = new MockFxAccounts();
+  let test_user = getTestUser("carol");
+
+  fxa._internal.POLL_SESSION = 20 * 60000;
+  fxa._internal.VERIFICATION_POLL_TIMEOUT_INITIAL = 123456;
+  fxa._internal.VERIFICATION_POLL_TIMEOUT_SUBSEQUENT = 654321;
+  fxa._internal.VERIFICATION_POLL_START_SLOWDOWN_THRESHOLD = -1;
+
+  fxa.setSignedInUser(test_user).then(() => {
+    fxa._internal.getUserAccountData().then(user => {
+      const mock = sinon.mock(fxa._internal);
+      mock
+        .expects("_scheduleNextPollEmailStatus")
+        .once()
+        .withArgs(
+          fxa._internal.currentAccountState,
+          user.sessionToken,
+          654321,
+          "start"
+        );
+      fxa._internal
+        .startPollEmailStatus(
+          fxa._internal.currentAccountState,
+          user.sessionToken,
+          "start"
+        )
+        .then(() => {
+          mock.verify();
+          mock.restore();
+          run_next_test();
+        });
+    });
+  });
+});
+
+add_test(function test_pollEmailStatus_browser_startup() {
+  let fxa = new MockFxAccounts();
+  let test_user = getTestUser("carol");
+
+  fxa._internal.POLL_SESSION = 20 * 60000;
+  fxa._internal.VERIFICATION_POLL_TIMEOUT_SUBSEQUENT = 654321;
+
+  fxa.setSignedInUser(test_user).then(() => {
+    fxa._internal.getUserAccountData().then(user => {
+      const mock = sinon.mock(fxa._internal);
+      mock
+        .expects("_scheduleNextPollEmailStatus")
+        .once()
+        .withArgs(
+          fxa._internal.currentAccountState,
+          user.sessionToken,
+          654321,
+          "browser-startup"
+        );
+      fxa._internal
+        .startPollEmailStatus(
+          fxa._internal.currentAccountState,
+          user.sessionToken,
+          "browser-startup"
+        )
+        .then(() => {
+          mock.verify();
+          mock.restore();
+          run_next_test();
+        });
+    });
+  });
+});
+
+add_test(function test_pollEmailStatus_push() {
+  let fxa = new MockFxAccounts();
+  let test_user = getTestUser("carol");
+
+  fxa.setSignedInUser(test_user).then(() => {
+    fxa._internal.getUserAccountData().then(user => {
+      const mock = sinon.mock(fxa._internal);
+      mock.expects("_scheduleNextPollEmailStatus").never();
+      fxa._internal
+        .startPollEmailStatus(
+          fxa._internal.currentAccountState,
+          user.sessionToken,
+          "push"
+        )
+        .then(() => {
+          mock.verify();
+          mock.restore();
+          run_next_test();
+        });
+    });
+  });
+});
+
+add_test(function test_getKeyForScope() {
+  let fxa = new MockFxAccounts();
+  let user = getTestUser("eusebius");
+
+  // Once email has been verified, we will be able to get keys
+  user.verified = true;
+
+  fxa.setSignedInUser(user).then(() => {
+    fxa._internal.getUserAccountData().then(user2 => {
+      // Before getKeyForScope, we have no keys
+      Assert.equal(!!user2.scopedKeys, false);
+      Assert.equal(!!user2.kSync, false);
+      Assert.equal(!!user2.kXCS, false);
+      Assert.equal(!!user2.kExtSync, false);
+      Assert.equal(!!user2.kExtKbHash, false);
+      // And we still have a key-fetch token and unwrapBKey to use
+      Assert.equal(!!user2.keyFetchToken, true);
+      Assert.equal(!!user2.unwrapBKey, true);
+
+      fxa.keys.getKeyForScope(SCOPE_OLD_SYNC).then(() => {
+        fxa._internal.getUserAccountData().then(user3 => {
+          // Now we should have keys
+          Assert.equal(fxa._internal.isUserEmailVerified(user3), true);
+          Assert.equal(!!user3.verified, true);
+          Assert.notEqual(null, user3.scopedKeys);
+          Assert.notEqual(null, user3.kSync);
+          Assert.notEqual(null, user3.kXCS);
+          Assert.notEqual(null, user3.kExtSync);
+          Assert.notEqual(null, user3.kExtKbHash);
+          Assert.equal(user3.keyFetchToken, undefined);
+          Assert.equal(user3.unwrapBKey, undefined);
+          run_next_test();
+        });
+      });
+    });
+  });
+});
+
+add_task(async function test_getKeyForScope_kb_migration() {
+  let fxa = new MockFxAccounts();
+  let user = getTestUser("eusebius");
+
+  user.verified = true;
+  // Set-up the deprecated set of keys.
+  user.kA = "e0245ab7f10e483470388e0a28f0a03379a3b417174fb2b42feab158b4ac2dbd";
+  user.kB = "eaf9570b7219a4187d3d6bf3cec2770c2e0719b7cc0dfbb38243d6f1881675e9";
+
+  await fxa.setSignedInUser(user);
+  await fxa.keys.getKeyForScope(SCOPE_OLD_SYNC);
+  let newUser = await fxa._internal.getUserAccountData();
+  Assert.equal(newUser.kA, null);
+  Assert.equal(newUser.kB, null);
+  Assert.deepEqual(newUser.scopedKeys, {
+    "https://identity.mozilla.com/apps/oldsync": {
+      kid: "1234567890123-IqQv4onc7VcVE1kTQkyyOw",
+      k: "DW_ll5GwX6SJ5GPqJVAuMUP2t6kDqhUulc2cbt26xbTcaKGQl-9l29FHAQ7kUiJETma4s9fIpEHrt909zgFang",
+      kty: "oct",
+    },
+    "sync:addon_storage": {
+      kid: "1234567890123-pBOR6B6JulbJr3BxKVOqIU4Cq_WAjFp4ApLn5NRVARE",
+      k: "ut7VPrNYfXkA5gTopo2GCr-d4wtclV08TV26Y_Jv2IJlzYWSP26dzRau87gryIA5qJxZ7NnojeCadBjH2U-QyQ",
+      kty: "oct",
+    },
+  });
+  // These hex values were manually confirmed to be equivalent to the b64 values above.
+  Assert.equal(
+    newUser.kSync,
+    "0d6fe59791b05fa489e463ea25502e3143f6b7a903aa152e95cd9c6eddbac5b4" +
+      "dc68a19097ef65dbd147010ee45222444e66b8b3d7c8a441ebb7dd3dce015a9e"
+  );
+  Assert.equal(newUser.kXCS, "22a42fe289dced5715135913424cb23b");
+  Assert.equal(
+    newUser.kExtSync,
+    "baded53eb3587d7900e604e8a68d860abf9de30b5c955d3c4d5dba63f26fd882" +
+      "65cd85923f6e9dcd16aef3b82bc88039a89c59ecd9e88de09a7418c7d94f90c9"
+  );
+  Assert.equal(
+    newUser.kExtKbHash,
+    "a41391e81e89ba56c9af70712953aa214e02abf5808c5a780292e7e4d4550111"
+  );
+});
+
+add_task(async function test_getKeyForScope_scopedKeys_migration() {
+  let fxa = new MockFxAccounts();
+  let user = getTestUser("eusebius");
+
+  user.verified = true;
+  // Set-up the keys in deprecated fields.
+  user.kSync = MOCK_ACCOUNT_KEYS.kSync;
+  user.kXCS = MOCK_ACCOUNT_KEYS.kXCS;
+  user.kExtSync = MOCK_ACCOUNT_KEYS.kExtSync;
+  user.kExtKbHash = MOCK_ACCOUNT_KEYS.kExtKbHash;
+  Assert.equal(user.scopedKeys, null);
+
+  await fxa.setSignedInUser(user);
+  await fxa.keys.getKeyForScope(SCOPE_OLD_SYNC);
+  let newUser = await fxa._internal.getUserAccountData();
+  Assert.equal(newUser.kA, null);
+  Assert.equal(newUser.kB, null);
+  // It should have correctly formatted the corresponding scoped keys.
+  const expectedScopedKeys = { ...MOCK_ACCOUNT_KEYS.scopedKeys };
+  Assert.deepEqual(newUser.scopedKeys, expectedScopedKeys);
+  // And left the existing key fields unchanged.
+  Assert.equal(newUser.kSync, user.kSync);
+  Assert.equal(newUser.kXCS, user.kXCS);
+  Assert.equal(newUser.kExtSync, user.kExtSync);
+  Assert.equal(newUser.kExtKbHash, user.kExtKbHash);
+});
+
+add_task(
+  async function test_getKeyForScope_scopedKeys_migration_removes_deprecated_scoped_keys() {
+    let fxa = new MockFxAccounts();
+    let user = getTestUser("eusebius");
+
+    const EXTRA_SCOPE = "an unknown, but non-deprecated scope";
+    user.verified = true;
+    user.ecosystemUserId = "ecoUserId";
+    user.ecosystemAnonId = "ecoAnonId";
+    user.scopedKeys = {
+      ...MOCK_ACCOUNT_KEYS.scopedKeys,
+      [DEPRECATED_SCOPE_ECOSYSTEM_TELEMETRY]:
+        MOCK_ACCOUNT_KEYS.scopedKeys[SCOPE_OLD_SYNC],
+      [EXTRA_SCOPE]: MOCK_ACCOUNT_KEYS.scopedKeys[SCOPE_OLD_SYNC],
+    };
+
+    await fxa.setSignedInUser(user);
+    await fxa.keys.getKeyForScope(SCOPE_OLD_SYNC);
+    let newUser = await fxa._internal.getUserAccountData();
+    // It should have removed the deprecated ecosystem_telemetry key,
+    // but left the other keys intact.
+    const expectedScopedKeys = {
+      ...MOCK_ACCOUNT_KEYS.scopedKeys,
+      [EXTRA_SCOPE]: MOCK_ACCOUNT_KEYS.scopedKeys[SCOPE_OLD_SYNC],
+    };
+    Assert.deepEqual(newUser.scopedKeys, expectedScopedKeys);
+    Assert.equal(newUser.ecosystemUserId, null);
+    Assert.equal(newUser.ecosystemAnonId, null);
+  }
+);
+
+add_task(async function test_getKeyForScope_nonexistent_account() {
+  let fxa = new MockFxAccounts();
+  let bismarck = getTestUser("bismarck");
+
+  let client = fxa._internal.fxAccountsClient;
+  client.accountStatus = () => Promise.resolve(false);
+  client.sessionStatus = () => Promise.resolve(false);
+  client.accountKeys = () => {
+    return Promise.reject({
+      code: 401,
+      errno: ERRNO_INVALID_AUTH_TOKEN,
+    });
+  };
+
+  await fxa.setSignedInUser(bismarck);
+
+  let promiseLogout = new Promise(resolve => {
+    makeObserver(ONLOGOUT_NOTIFICATION, function () {
+      log.debug("test_getKeyForScope_nonexistent_account observed logout");
+      resolve();
+    });
+  });
+
+  // XXX - the exception message here isn't ideal, but doesn't really matter...
+  await Assert.rejects(
+    fxa.keys.getKeyForScope(SCOPE_OLD_SYNC),
+    /A different user signed in/
+  );
+
+  await promiseLogout;
+
+  let user = await fxa._internal.getUserAccountData();
+  Assert.equal(user, null);
+});
+
+// getKeyForScope with invalid keyFetchToken should delete keyFetchToken from storage
+add_task(async function test_getKeyForScope_invalid_token() {
+  let fxa = new MockFxAccounts();
+  let yusuf = getTestUser("yusuf");
+
+  let client = fxa._internal.fxAccountsClient;
+  client.accountStatus = () => Promise.resolve(true); // account exists.
+  client.sessionStatus = () => Promise.resolve(false); // session is invalid.
+  client.accountKeys = () => {
+    return Promise.reject({
+      code: 401,
+      errno: ERRNO_INVALID_AUTH_TOKEN,
+    });
+  };
+
+  await fxa.setSignedInUser(yusuf);
+  let user = await fxa._internal.getUserAccountData();
+  Assert.notEqual(user.encryptedSendTabKeys, null);
+
+  try {
+    await fxa.keys.getKeyForScope(SCOPE_OLD_SYNC);
+    Assert.ok(false);
+  } catch (err) {
+    Assert.equal(err.code, 401);
+    Assert.equal(err.errno, ERRNO_INVALID_AUTH_TOKEN);
+  }
+
+  user = await fxa._internal.getUserAccountData();
+  Assert.equal(user.email, yusuf.email);
+  Assert.equal(user.keyFetchToken, null);
+  // We verify that encryptedSendTabKeys are also wiped
+  // when a user's credentials are wiped
+  Assert.equal(user.encryptedSendTabKeys, null);
+  await fxa._internal.abortExistingFlow();
+});
+
+// This is the exact same test vectors as
+// https://github.com/mozilla/fxa-crypto-relier/blob/f94f441159029a645a474d4b6439c38308da0bb0/test/deriver/ScopedKeys.js#L58
+add_task(async function test_getKeyForScope_oldsync() {
+  let fxa = new MockFxAccounts();
+  let client = fxa._internal.fxAccountsClient;
+  client.getScopedKeyData = () =>
+    Promise.resolve({
+      "https://identity.mozilla.com/apps/oldsync": {
+        identifier: "https://identity.mozilla.com/apps/oldsync",
+        keyRotationSecret:
+          "0000000000000000000000000000000000000000000000000000000000000000",
+        keyRotationTimestamp: 1510726317123,
+      },
+    });
+  let user = {
+    ...getTestUser("eusebius"),
+    uid: "aeaa1725c7a24ff983c6295725d5fc9b",
+    kB: "eaf9570b7219a4187d3d6bf3cec2770c2e0719b7cc0dfbb38243d6f1881675e9",
+    verified: true,
+  };
+  await fxa.setSignedInUser(user);
+  const key = await fxa.keys.getKeyForScope(SCOPE_OLD_SYNC);
+  Assert.deepEqual(key, {
+    scope: SCOPE_OLD_SYNC,
+    kid: "1510726317123-IqQv4onc7VcVE1kTQkyyOw",
+    k: "DW_ll5GwX6SJ5GPqJVAuMUP2t6kDqhUulc2cbt26xbTcaKGQl-9l29FHAQ7kUiJETma4s9fIpEHrt909zgFang",
+    kty: "oct",
+  });
+});
+
+add_task(async function test_getScopedKeys_unavailable_scope() {
+  let fxa = new MockFxAccounts();
+  let user = {
+    ...getTestUser("eusebius"),
+    uid: "aeaa1725c7a24ff983c6295725d5fc9b",
+    verified: true,
+    ...MOCK_ACCOUNT_KEYS,
+  };
+  await fxa.setSignedInUser(user);
+  await Assert.rejects(
+    fxa.keys.getKeyForScope("otherkeybearingscope"),
+    /Key not available for scope/
+  );
+});
+
+add_task(async function test_getScopedKeys_misconfigured_fxa_server() {
+  let fxa = new MockFxAccounts();
+  let client = fxa._internal.fxAccountsClient;
+  client.getScopedKeyData = () =>
+    Promise.resolve({
+      wrongscope: {
+        identifier: "wrongscope",
+        keyRotationSecret:
+          "0000000000000000000000000000000000000000000000000000000000000000",
+        keyRotationTimestamp: 1510726331712,
+      },
+    });
+  let user = {
+    ...getTestUser("eusebius"),
+    uid: "aeaa1725c7a24ff983c6295725d5fc9b",
+    verified: true,
+    kSync:
+      "0d6fe59791b05fa489e463ea25502e3143f6b7a903aa152e95cd9c6eddbac5b4dc68a19097ef65dbd147010ee45222444e66b8b3d7c8a441ebb7dd3dce015a9e",
+    kXCS: "22a42fe289dced5715135913424cb23b",
+    kExtSync:
+      "baded53eb3587d7900e604e8a68d860abf9de30b5c955d3c4d5dba63f26fd88265cd85923f6e9dcd16aef3b82bc88039a89c59ecd9e88de09a7418c7d94f90c9",
+    kExtKbHash:
+      "b776a89db29f22daedd154b44ff88397d0b210223fb956f5a749521dd8de8ddf",
+  };
+  await fxa.setSignedInUser(user);
+  await Assert.rejects(
+    fxa.keys.getKeyForScope(SCOPE_OLD_SYNC),
+    /The FxA server did not grant Firefox the `oldsync` scope/
+  );
+});
+
+// _fetchAndUnwrapAndDeriveKeys with no keyFetchToken should trigger signOut
+// XXX - actually, it probably shouldn't - bug 1572313.
+add_test(function test_fetchAndUnwrapAndDeriveKeys_no_token() {
+  let fxa = new MockFxAccounts();
+  let user = getTestUser("lettuce.protheroe");
+  delete user.keyFetchToken;
+
+  makeObserver(ONLOGOUT_NOTIFICATION, function () {
+    log.debug("test_fetchAndUnwrapKeys_no_token observed logout");
+    fxa._internal.getUserAccountData().then(user2 => {
+      fxa._internal.abortExistingFlow().then(run_next_test);
+    });
+  });
+
+  fxa
+    .setSignedInUser(user)
+    .then(user2 => {
+      return fxa.keys._fetchAndUnwrapAndDeriveKeys();
+    })
+    .catch(error => {
+      log.info("setSignedInUser correctly rejected");
+    });
+});
+
+// Alice (User A) signs up but never verifies her email.  Then Bob (User B)
+// signs in with a verified email.  Ensure that no sign-in events are triggered
+// on Alice's behalf.  In the end, Bob should be the signed-in user.
+add_test(function test_overlapping_signins() {
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+  let bob = getTestUser("bob");
+
+  makeObserver(ONVERIFIED_NOTIFICATION, function () {
+    log.debug("test_overlapping_signins observed onverified");
+    // Once email verification is complete, we will observe onverified
+    fxa._internal.getUserAccountData().then(user => {
+      Assert.equal(user.email, bob.email);
+      Assert.equal(user.verified, true);
+      run_next_test();
+    });
+  });
+
+  // Alice is the user signing in; her email is unverified.
+  fxa.setSignedInUser(alice).then(() => {
+    log.debug("Alice signing in ...");
+    fxa._internal.getUserAccountData().then(user => {
+      Assert.equal(user.email, alice.email);
+      Assert.equal(user.verified, false);
+      log.debug("Alice has not verified her email ...");
+
+      // Now Bob signs in instead and actually verifies his email
+      log.debug("Bob signing in ...");
+      fxa.setSignedInUser(bob).then(() => {
+        do_timeout(200, function () {
+          // Mock email verification ...
+          log.debug("Bob verifying his email ...");
+          fxa._internal.fxAccountsClient._verified = true;
+        });
+      });
+    });
+  });
+});
+
+add_task(async function test_resend_email_not_signed_in() {
+  let fxa = new MockFxAccounts();
+
+  try {
+    await fxa.resendVerificationEmail();
+  } catch (err) {
+    Assert.equal(err.message, ERROR_NO_ACCOUNT);
+    return;
+  }
+  do_throw("Should not be able to resend email when nobody is signed in");
+});
+
+add_task(async function test_accountStatus() {
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+
+  // If we have no user, we have no account server-side
+  let result = await fxa.checkAccountStatus();
+  Assert.ok(!result);
+  // Set a user - the fxAccountsClient mock will say "ok".
+  await fxa.setSignedInUser(alice);
+  result = await fxa.checkAccountStatus();
+  Assert.ok(result);
+  // flag the item as deleted on the server.
+  fxa._internal.fxAccountsClient._deletedOnServer = true;
+  result = await fxa.checkAccountStatus();
+  Assert.ok(!result);
+  fxa._internal.fxAccountsClient._deletedOnServer = false;
+  await fxa.signOut();
+});
+
+add_task(async function test_resend_email_invalid_token() {
+  let fxa = new MockFxAccounts();
+  let sophia = getTestUser("sophia");
+  Assert.notEqual(sophia.sessionToken, null);
+
+  let client = fxa._internal.fxAccountsClient;
+  client.resendVerificationEmail = () => {
+    return Promise.reject({
+      code: 401,
+      errno: ERRNO_INVALID_AUTH_TOKEN,
+    });
+  };
+  // This test wants the account to exist but the local session invalid.
+  client.accountStatus = uid => {
+    Assert.ok(uid, "got a uid to check");
+    return Promise.resolve(true);
+  };
+  client.sessionStatus = token => {
+    Assert.ok(token, "got a token to check");
+    return Promise.resolve(false);
+  };
+
+  await fxa.setSignedInUser(sophia);
+  let user = await fxa._internal.getUserAccountData();
+  Assert.equal(user.email, sophia.email);
+  Assert.equal(user.verified, false);
+  log.debug("Sophia wants verification email resent");
+
+  try {
+    await fxa.resendVerificationEmail();
+    Assert.ok(
+      false,
+      "resendVerificationEmail should reject invalid session token"
+    );
+  } catch (err) {
+    Assert.equal(err.code, 401);
+    Assert.equal(err.errno, ERRNO_INVALID_AUTH_TOKEN);
+  }
+
+  user = await fxa._internal.getUserAccountData();
+  Assert.equal(user.email, sophia.email);
+  Assert.equal(user.sessionToken, null);
+  await fxa._internal.abortExistingFlow();
+});
+
+add_test(function test_resend_email() {
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+
+  let initialState = fxa._internal.currentAccountState;
+
+  // Alice is the user signing in; her email is unverified.
+  fxa.setSignedInUser(alice).then(() => {
+    log.debug("Alice signing in");
+
+    // We're polling for the first email
+    Assert.ok(fxa._internal.currentAccountState !== initialState);
+    let aliceState = fxa._internal.currentAccountState;
+
+    // The polling timer is ticking
+    Assert.ok(fxa._internal.currentTimer > 0);
+
+    fxa._internal.getUserAccountData().then(user => {
+      Assert.equal(user.email, alice.email);
+      Assert.equal(user.verified, false);
+      log.debug("Alice wants verification email resent");
+
+      fxa.resendVerificationEmail().then(result => {
+        // Mock server response; ensures that the session token actually was
+        // passed to the client to make the hawk call
+        Assert.equal(result, "alice's session token");
+
+        // Timer was not restarted
+        Assert.ok(fxa._internal.currentAccountState === aliceState);
+
+        // Timer is still ticking
+        Assert.ok(fxa._internal.currentTimer > 0);
+
+        // Ok abort polling before we go on to the next test
+        fxa._internal.abortExistingFlow();
+        run_next_test();
+      });
+    });
+  });
+});
+
+Services.prefs.setCharPref(
+  "identity.fxaccounts.remote.oauth.uri",
+  "https://example.com/v1"
+);
+
+add_test(async function test_getOAuthTokenWithSessionToken() {
+  Services.prefs.setBoolPref(
+    "identity.fxaccounts.useSessionTokensForOAuth",
+    true
+  );
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+  alice.verified = true;
+  let oauthTokenCalled = false;
+
+  let client = fxa._internal.fxAccountsClient;
+  client.accessTokenWithSessionToken = async (
+    sessionTokenHex,
+    clientId,
+    scope,
+    ttl
+  ) => {
+    oauthTokenCalled = true;
+    Assert.equal(sessionTokenHex, "alice's session token");
+    Assert.equal(clientId, "5882386c6d801776");
+    Assert.equal(scope, "profile");
+    Assert.equal(ttl, undefined);
+    return MOCK_TOKEN_RESPONSE;
+  };
+
+  await fxa.setSignedInUser(alice);
+  const result = await fxa.getOAuthToken({ scope: "profile" });
+  Assert.ok(oauthTokenCalled);
+  Assert.equal(result, MOCK_TOKEN_RESPONSE.access_token);
+  Services.prefs.setBoolPref(
+    "identity.fxaccounts.useSessionTokensForOAuth",
+    false
+  );
+  run_next_test();
+});
+
+add_task(async function test_getOAuthTokenCachedWithSessionToken() {
+  Services.prefs.setBoolPref(
+    "identity.fxaccounts.useSessionTokensForOAuth",
+    true
+  );
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+  alice.verified = true;
+  let numOauthTokenCalls = 0;
+
+  let client = fxa._internal.fxAccountsClient;
+  client.accessTokenWithSessionToken = async () => {
+    numOauthTokenCalls++;
+    return MOCK_TOKEN_RESPONSE;
+  };
+
+  await fxa.setSignedInUser(alice);
+  let result = await fxa.getOAuthToken({
+    scope: "profile",
+    service: "test-service",
+  });
+  Assert.equal(numOauthTokenCalls, 1);
+  Assert.equal(
+    result,
+    "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69"
+  );
+
+  // requesting it again should not re-fetch the token.
+  result = await fxa.getOAuthToken({
+    scope: "profile",
+    service: "test-service",
+  });
+  Assert.equal(numOauthTokenCalls, 1);
+  Assert.equal(
+    result,
+    "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69"
+  );
+  // But requesting the same service and a different scope *will* get a new one.
+  result = await fxa.getOAuthToken({
+    scope: "something-else",
+    service: "test-service",
+  });
+  Assert.equal(numOauthTokenCalls, 2);
+  Assert.equal(
+    result,
+    "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69"
+  );
+  Services.prefs.setBoolPref(
+    "identity.fxaccounts.useSessionTokensForOAuth",
+    false
+  );
+});
+
+add_test(function test_getOAuthTokenScopedWithSessionToken() {
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+  alice.verified = true;
+  let numOauthTokenCalls = 0;
+
+  let client = fxa._internal.fxAccountsClient;
+  client.accessTokenWithSessionToken = async (
+    _sessionTokenHex,
+    _clientId,
+    scopeString
+  ) => {
+    equal(scopeString, "bar foo"); // scopes are sorted locally before request.
+    numOauthTokenCalls++;
+    return MOCK_TOKEN_RESPONSE;
+  };
+
+  fxa.setSignedInUser(alice).then(() => {
+    fxa.getOAuthToken({ scope: ["foo", "bar"] }).then(result => {
+      Assert.equal(numOauthTokenCalls, 1);
+      Assert.equal(
+        result,
+        "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69"
+      );
+      run_next_test();
+    });
+  });
+});
+
+add_task(async function test_getOAuthTokenCachedScopeNormalization() {
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+  alice.verified = true;
+  let numOAuthTokenCalls = 0;
+
+  let client = fxa._internal.fxAccountsClient;
+  client.accessTokenWithSessionToken = async (
+    _sessionTokenHex,
+    _clientId,
+    scopeString
+  ) => {
+    numOAuthTokenCalls++;
+    return MOCK_TOKEN_RESPONSE;
+  };
+
+  await fxa.setSignedInUser(alice);
+  let result = await fxa.getOAuthToken({
+    scope: ["foo", "bar"],
+    service: "test-service",
+  });
+  Assert.equal(numOAuthTokenCalls, 1);
+  Assert.equal(
+    result,
+    "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69"
+  );
+
+  // requesting it again with the scope array in a different order should not re-fetch the token.
+  result = await fxa.getOAuthToken({
+    scope: ["bar", "foo"],
+    service: "test-service",
+  });
+  Assert.equal(numOAuthTokenCalls, 1);
+  Assert.equal(
+    result,
+    "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69"
+  );
+  // requesting it again with the scope array in different case should not re-fetch the token.
+  result = await fxa.getOAuthToken({
+    scope: ["Bar", "Foo"],
+    service: "test-service",
+  });
+  Assert.equal(numOAuthTokenCalls, 1);
+  Assert.equal(
+    result,
+    "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69"
+  );
+  // But requesting with a new entry in the array does fetch one.
+  result = await fxa.getOAuthToken({
+    scope: ["foo", "bar", "etc"],
+    service: "test-service",
+  });
+  Assert.equal(numOAuthTokenCalls, 2);
+  Assert.equal(
+    result,
+    "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69"
+  );
+});
+
+add_test(function test_getOAuthToken_invalid_param() {
+  let fxa = new MockFxAccounts();
+
+  fxa.getOAuthToken().catch(err => {
+    Assert.equal(err.message, "INVALID_PARAMETER");
+    fxa.signOut().then(run_next_test);
+  });
+});
+
+add_test(function test_getOAuthToken_invalid_scope_array() {
+  let fxa = new MockFxAccounts();
+
+  fxa.getOAuthToken({ scope: [] }).catch(err => {
+    Assert.equal(err.message, "INVALID_PARAMETER");
+    fxa.signOut().then(run_next_test);
+  });
+});
+
+add_test(function test_getOAuthToken_misconfigure_oauth_uri() {
+  let fxa = new MockFxAccounts();
+
+  const prevServerURL = Services.prefs.getCharPref(
+    "identity.fxaccounts.remote.oauth.uri"
+  );
+  Services.prefs.deleteBranch("identity.fxaccounts.remote.oauth.uri");
+
+  fxa.getOAuthToken().catch(err => {
+    Assert.equal(err.message, "INVALID_PARAMETER");
+    // revert the pref
+    Services.prefs.setCharPref(
+      "identity.fxaccounts.remote.oauth.uri",
+      prevServerURL
+    );
+    fxa.signOut().then(run_next_test);
+  });
+});
+
+add_test(function test_getOAuthToken_no_account() {
+  let fxa = new MockFxAccounts();
+
+  fxa._internal.currentAccountState.getUserAccountData = function () {
+    return Promise.resolve(null);
+  };
+
+  fxa.getOAuthToken({ scope: "profile" }).catch(err => {
+    Assert.equal(err.message, "NO_ACCOUNT");
+    fxa.signOut().then(run_next_test);
+  });
+});
+
+add_test(function test_getOAuthToken_unverified() {
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+
+  fxa.setSignedInUser(alice).then(() => {
+    fxa.getOAuthToken({ scope: "profile" }).catch(err => {
+      Assert.equal(err.message, "UNVERIFIED_ACCOUNT");
+      fxa.signOut().then(run_next_test);
+    });
+  });
+});
+
+add_test(function test_getOAuthToken_error() {
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+  alice.verified = true;
+
+  let client = fxa._internal.fxAccountsClient;
+  client.accessTokenWithSessionToken = () => {
+    return Promise.reject("boom");
+  };
+
+  fxa.setSignedInUser(alice).then(() => {
+    fxa.getOAuthToken({ scope: "profile" }).catch(err => {
+      equal(err.details, "boom");
+      run_next_test();
+    });
+  });
+});
+
+add_task(async function test_listAttachedOAuthClients() {
+  const ONE_HOUR = 60 * 60 * 1000;
+  const ONE_DAY = 24 * ONE_HOUR;
+
+  const timestamp = Date.now();
+
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+  alice.verified = true;
+
+  let client = fxa._internal.fxAccountsClient;
+  client.attachedClients = async () => {
+    return {
+      body: [
+        // This entry was previously filtered but no longer is!
+        {
+          clientId: "a2270f727f45f648",
+          deviceId: "deadbeef",
+          sessionTokenId: null,
+          name: "Firefox Preview (no session token)",
+          scope: ["profile", "https://identity.mozilla.com/apps/oldsync"],
+          lastAccessTime: Date.now(),
+        },
+        {
+          clientId: "802d56ef2a9af9fa",
+          deviceId: null,
+          sessionTokenId: null,
+          name: "Firefox Monitor",
+          scope: ["profile"],
+          lastAccessTime: Date.now() - ONE_DAY - ONE_HOUR,
+        },
+        {
+          clientId: "1f30e32975ae5112",
+          deviceId: null,
+          sessionTokenId: null,
+          name: "Firefox Send",
+          scope: ["profile", "https://identity.mozilla.com/apps/send"],
+          lastAccessTime: Date.now() - ONE_DAY * 2 - ONE_HOUR,
+        },
+        // One with a future date should be impossible, but having a negative
+        // result here would almost certainly confuse something!
+        {
+          clientId: "future-date",
+          deviceId: null,
+          sessionTokenId: null,
+          name: "Whatever",
+          lastAccessTime: Date.now() + ONE_DAY,
+        },
+        // A missing/null lastAccessTime should end up with a missing lastAccessedDaysAgo
+        {
+          clientId: "missing-date",
+          deviceId: null,
+          sessionTokenId: null,
+          name: "Whatever",
+        },
+      ],
+      headers: { "x-timestamp": timestamp.toString() },
+    };
+  };
+
+  await fxa.setSignedInUser(alice);
+  const clients = await fxa.listAttachedOAuthClients();
+  Assert.deepEqual(clients, [
+    {
+      id: "a2270f727f45f648",
+      lastAccessedDaysAgo: 0,
+    },
+    {
+      id: "802d56ef2a9af9fa",
+      lastAccessedDaysAgo: 1,
+    },
+    {
+      id: "1f30e32975ae5112",
+      lastAccessedDaysAgo: 2,
+    },
+    {
+      id: "future-date",
+      lastAccessedDaysAgo: 0,
+    },
+    {
+      id: "missing-date",
+      lastAccessedDaysAgo: null,
+    },
+  ]);
+});
+
+add_task(async function test_getSignedInUserProfile() {
+  let alice = getTestUser("alice");
+  alice.verified = true;
+
+  let mockProfile = {
+    getProfile() {
+      return Promise.resolve({ avatar: "image" });
+    },
+    tearDown() {},
+  };
+  let fxa = new FxAccounts({
+    _signOutServer() {
+      return Promise.resolve();
+    },
+    device: {
+      _registerOrUpdateDevice() {
+        return Promise.resolve();
+      },
+    },
+  });
+
+  await fxa._internal.setSignedInUser(alice);
+  fxa._internal._profile = mockProfile;
+  let result = await fxa.getSignedInUser();
+  Assert.ok(!!result);
+  Assert.equal(result.avatar, "image");
+});
+
+add_task(async function test_getSignedInUserProfile_error_uses_account_data() {
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+  alice.verified = true;
+
+  fxa._internal.getSignedInUser = function () {
+    return Promise.resolve({ email: "foo@bar.com" });
+  };
+  fxa._internal._profile = {
+    getProfile() {
+      return Promise.reject("boom");
+    },
+    tearDown() {
+      teardownCalled = true;
+    },
+  };
+
+  let teardownCalled = false;
+  await fxa.setSignedInUser(alice);
+  let result = await fxa.getSignedInUser();
+  Assert.deepEqual(result.avatar, null);
+  await fxa.signOut();
+  Assert.ok(teardownCalled);
+});
+
+add_task(async function test_checkVerificationStatusFailed() {
+  let fxa = new MockFxAccounts();
+  let alice = getTestUser("alice");
+  alice.verified = true;
+
+  let client = fxa._internal.fxAccountsClient;
+  client.recoveryEmailStatus = () => {
+    return Promise.reject({
+      code: 401,
+      errno: ERRNO_INVALID_AUTH_TOKEN,
+    });
+  };
+  client.accountStatus = () => Promise.resolve(true);
+  client.sessionStatus = () => Promise.resolve(false);
+
+  await fxa.setSignedInUser(alice);
+  let user = await fxa._internal.getUserAccountData();
+  Assert.notEqual(alice.sessionToken, null);
+  Assert.equal(user.email, alice.email);
+  Assert.equal(user.verified, true);
+
+  await fxa._internal.checkVerificationStatus();
+
+  user = await fxa._internal.getUserAccountData();
+  Assert.equal(user.email, alice.email);
+  Assert.equal(user.sessionToken, null);
+});
+
+add_task(async function test_deriveKeys() {
+  let account = await MakeFxAccounts();
+  let kBhex =
+    "fd5c747806c07ce0b9d69dcfea144663e630b65ec4963596a22f24910d7dd15d";
+  let kB = CommonUtils.hexToBytes(kBhex);
+  const uid = "1ad7f502-4cc7-4ec1-a209-071fd2fae348";
+
+  const { kSync, kXCS, kExtSync, kExtKbHash } = await account.keys._deriveKeys(
+    uid,
+    kB
+  );
+
+  Assert.equal(
+    kSync,
+    "ad501a50561be52b008878b2e0d8a73357778a712255f7722f497b5d4df14b05" +
+      "dc06afb836e1521e882f521eb34691d172337accdbf6e2a5b968b05a7bbb9885"
+  );
+  Assert.equal(kXCS, "6ae94683571c7a7c54dab4700aa3995f");
+  Assert.equal(
+    kExtSync,
+    "f5ccd9cfdefd9b1ac4d02c56964f59239d8dfa1ca326e63696982765c1352cdc" +
+      "5d78a5a9c633a6d25edfea0a6c221a3480332a49fd866f311c2e3508ddd07395"
+  );
+  Assert.equal(
+    kExtKbHash,
+    "6192f1cc7dce95334455ba135fa1d8fca8f70e8f594ae318528de06f24ed0273"
+  );
+});
+
+add_task(async function test_flushLogFile() {
+  _("Tests flushLogFile");
+  let account = await MakeFxAccounts();
+  let promiseObserved = new Promise(res => {
+    log.info("Adding flush-log-file observer.");
+    Services.obs.addObserver(function onFlushLogFile() {
+      Services.obs.removeObserver(
+        onFlushLogFile,
+        "service:log-manager:flush-log-file"
+      );
+      res();
+    }, "service:log-manager:flush-log-file");
+  });
+  account.flushLogFile();
+  await promiseObserved;
+});
+
+/*
+ * End of tests.
+ * Utility functions follow.
+ */
+
+function expandHex(two_hex) {
+  // Return a 64-character hex string, encoding 32 identical bytes.
+  let eight_hex = two_hex + two_hex + two_hex + two_hex;
+  let thirtytwo_hex = eight_hex + eight_hex + eight_hex + eight_hex;
+  return thirtytwo_hex + thirtytwo_hex;
+}
+
+function expandBytes(two_hex) {
+  return CommonUtils.hexToBytes(expandHex(two_hex));
+}
+
+function getTestUser(name) {
+  return {
+    email: name + "@example.com",
+    uid: "1ad7f5024cc74ec1a209071fd2fae348",
+    sessionToken: name + "'s session token",
+    keyFetchToken: name + "'s keyfetch token",
+    unwrapBKey: expandHex("44"),
+    verified: false,
+    encryptedSendTabKeys: name + "'s encrypted Send tab keys",
+  };
+}
+
+function makeObserver(aObserveTopic, aObserveFunc) {
+  let observer = {
+    // nsISupports provides type management in C++
+    // nsIObserver is to be an observer
+    QueryInterface: ChromeUtils.generateQI(["nsIObserver"]),
+
+    observe(aSubject, aTopic, aData) {
+      log.debug("observed " + aTopic + " " + aData);
+      if (aTopic == aObserveTopic) {
+        removeMe();
+        aObserveFunc(aSubject, aTopic, aData);
+      }
+    },
+  };
+
+  function removeMe() {
+    log.debug("removing observer for " + aObserveTopic);
+    Services.obs.removeObserver(observer, aObserveTopic);
+  }
+
+  Services.obs.addObserver(observer, aObserveTopic);
+  return removeMe;
+}
diff --git a/services/fxaccounts/tests/xpcshell/test_accounts_config.js b/services/fxaccounts/tests/xpcshell/test_accounts_config.js
new file mode 100644
index 0000000000..7849632224
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_accounts_config.js
@@ -0,0 +1,55 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { FxAccounts } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+
+add_task(
+  async function test_non_https_remote_server_uri_with_requireHttps_false() {
+    Services.prefs.setBoolPref("identity.fxaccounts.allowHttp", true);
+    Services.prefs.setCharPref(
+      "identity.fxaccounts.remote.root",
+      "http://example.com/"
+    );
+    Assert.equal(
+      await FxAccounts.config.promiseConnectAccountURI("test"),
+      "http://example.com/?context=fx_desktop_v3&entrypoint=test&action=email&service=sync"
+    );
+
+    Services.prefs.clearUserPref("identity.fxaccounts.remote.root");
+    Services.prefs.clearUserPref("identity.fxaccounts.allowHttp");
+  }
+);
+
+add_task(async function test_non_https_remote_server_uri() {
+  Services.prefs.setCharPref(
+    "identity.fxaccounts.remote.root",
+    "http://example.com/"
+  );
+  await Assert.rejects(
+    FxAccounts.config.promiseConnectAccountURI(),
+    /Firefox Accounts server must use HTTPS/
+  );
+  Services.prefs.clearUserPref("identity.fxaccounts.remote.root");
+});
+
+add_task(async function test_is_production_config() {
+  // should start with no auto-config URL.
+  Assert.ok(!FxAccounts.config.getAutoConfigURL());
+  // which means we are using prod.
+  Assert.ok(FxAccounts.config.isProductionConfig());
+
+  // Set an auto-config URL.
+  Services.prefs.setCharPref("identity.fxaccounts.autoconfig.uri", "http://x");
+  Assert.equal(FxAccounts.config.getAutoConfigURL(), "http://x");
+  Assert.ok(!FxAccounts.config.isProductionConfig());
+
+  // Clear the auto-config URL, but set one of the other config params.
+  Services.prefs.clearUserPref("identity.fxaccounts.autoconfig.uri");
+  Services.prefs.setCharPref("identity.sync.tokenserver.uri", "http://t");
+  Assert.ok(!FxAccounts.config.isProductionConfig());
+  Services.prefs.clearUserPref("identity.sync.tokenserver.uri");
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_accounts_device_registration.js b/services/fxaccounts/tests/xpcshell/test_accounts_device_registration.js
new file mode 100644
index 0000000000..ee2204f793
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_accounts_device_registration.js
@@ -0,0 +1,1202 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { FxAccounts } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+const { FxAccountsClient } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsClient.sys.mjs"
+);
+const { FxAccountsDevice } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsDevice.sys.mjs"
+);
+const {
+  ERRNO_DEVICE_SESSION_CONFLICT,
+  ERRNO_TOO_MANY_CLIENT_REQUESTS,
+  ERRNO_UNKNOWN_DEVICE,
+  ON_DEVICE_CONNECTED_NOTIFICATION,
+  ON_DEVICE_DISCONNECTED_NOTIFICATION,
+  ON_DEVICELIST_UPDATED,
+} = ChromeUtils.import("resource://gre/modules/FxAccountsCommon.js");
+var { AccountState } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+
+initTestLogging("Trace");
+
+var log = Log.repository.getLogger("Services.FxAccounts.test");
+log.level = Log.Level.Debug;
+
+const BOGUS_PUBLICKEY =
+  "BBXOKjUb84pzws1wionFpfCBjDuCh4-s_1b52WA46K5wYL2gCWEOmFKWn_NkS5nmJwTBuO8qxxdjAIDtNeklvQc";
+const BOGUS_AUTHKEY = "GSsIiaD2Mr83iPqwFNK4rw";
+
+Services.prefs.setCharPref("identity.fxaccounts.loglevel", "Trace");
+
+const DEVICE_REGISTRATION_VERSION = 42;
+
+function MockStorageManager() {}
+
+MockStorageManager.prototype = {
+  initialize(accountData) {
+    this.accountData = accountData;
+  },
+
+  finalize() {
+    return Promise.resolve();
+  },
+
+  getAccountData() {
+    return Promise.resolve(this.accountData);
+  },
+
+  updateAccountData(updatedFields) {
+    for (let [name, value] of Object.entries(updatedFields)) {
+      if (value == null) {
+        delete this.accountData[name];
+      } else {
+        this.accountData[name] = value;
+      }
+    }
+    return Promise.resolve();
+  },
+
+  deleteAccountData() {
+    this.accountData = null;
+    return Promise.resolve();
+  },
+};
+
+function MockFxAccountsClient(device) {
+  this._email = "nobody@example.com";
+  // Be careful relying on `this._verified` as it doesn't change if the user's
+  // state does via setting the `verified` flag in the user data.
+  this._verified = false;
+  this._deletedOnServer = false; // for testing accountStatus
+
+  // mock calls up to the auth server to determine whether the
+  // user account has been verified
+  this.recoveryEmailStatus = function (sessionToken) {
+    // simulate a call to /recovery_email/status
+    return Promise.resolve({
+      email: this._email,
+      verified: this._verified,
+    });
+  };
+
+  this.accountKeys = function (keyFetchToken) {
+    Assert.ok(keyFetchToken, "must be called with a key-fetch-token");
+    // ideally we'd check the verification status here to more closely simulate
+    // the server, but `this._verified` is a test-only construct and doesn't
+    // update when the user changes verification status.
+    Assert.ok(!this._deletedOnServer, "this test thinks the acct is deleted!");
+    return {
+      kA: "test-ka",
+      wrapKB: "X".repeat(32),
+    };
+  };
+
+  this.accountStatus = function (uid) {
+    return Promise.resolve(!!uid && !this._deletedOnServer);
+  };
+
+  this.registerDevice = (st, name, type) =>
+    Promise.resolve({ id: device.id, name });
+  this.updateDevice = (st, id, name) => Promise.resolve({ id, name });
+  this.signOut = () => Promise.resolve({});
+  this.getDeviceList = st =>
+    Promise.resolve([
+      {
+        id: device.id,
+        name: device.name,
+        type: device.type,
+        pushCallback: device.pushCallback,
+        pushEndpointExpired: device.pushEndpointExpired,
+        isCurrentDevice: st === device.sessionToken,
+      },
+    ]);
+
+  FxAccountsClient.apply(this);
+}
+MockFxAccountsClient.prototype = {};
+Object.setPrototypeOf(
+  MockFxAccountsClient.prototype,
+  FxAccountsClient.prototype
+);
+
+async function MockFxAccounts(credentials, device = {}) {
+  let fxa = new FxAccounts({
+    newAccountState(creds) {
+      // we use a real accountState but mocked storage.
+      let storage = new MockStorageManager();
+      storage.initialize(creds);
+      return new AccountState(storage);
+    },
+    fxAccountsClient: new MockFxAccountsClient(device, credentials),
+    fxaPushService: {
+      registerPushEndpoint() {
+        return new Promise(resolve => {
+          resolve({
+            endpoint: "http://mochi.test:8888",
+            getKey(type) {
+              return ChromeUtils.base64URLDecode(
+                type === "auth" ? BOGUS_AUTHKEY : BOGUS_PUBLICKEY,
+                { padding: "ignore" }
+              );
+            },
+          });
+        });
+      },
+      unsubscribe() {
+        return Promise.resolve();
+      },
+    },
+    commands: {
+      async availableCommands() {
+        return {};
+      },
+    },
+    device: {
+      DEVICE_REGISTRATION_VERSION,
+      _checkRemoteCommandsUpdateNeeded: async () => false,
+    },
+    VERIFICATION_POLL_TIMEOUT_INITIAL: 1,
+  });
+  fxa._internal.device._fxai = fxa._internal;
+  await fxa._internal.setSignedInUser(credentials);
+  Services.prefs.setStringPref(
+    "identity.fxaccounts.account.device.name",
+    device.name || "mock device name"
+  );
+  return fxa;
+}
+
+function updateUserAccountData(fxa, data) {
+  return fxa._internal.updateUserAccountData(data);
+}
+
+add_task(async function test_updateDeviceRegistration_with_new_device() {
+  const deviceName = "foo";
+  const deviceType = "bar";
+
+  const credentials = getTestUser("baz");
+  const fxa = await MockFxAccounts(credentials, { name: deviceName });
+  // Remove the current device registration (setSignedInUser does one!).
+  await updateUserAccountData(fxa, { uid: credentials.uid, device: null });
+
+  const spy = {
+    registerDevice: { count: 0, args: [] },
+    updateDevice: { count: 0, args: [] },
+    getDeviceList: { count: 0, args: [] },
+  };
+  const client = fxa._internal.fxAccountsClient;
+  client.registerDevice = function () {
+    spy.registerDevice.count += 1;
+    spy.registerDevice.args.push(arguments);
+    return Promise.resolve({
+      id: "newly-generated device id",
+      createdAt: Date.now(),
+      name: deviceName,
+      type: deviceType,
+    });
+  };
+  client.updateDevice = function () {
+    spy.updateDevice.count += 1;
+    spy.updateDevice.args.push(arguments);
+    return Promise.resolve({});
+  };
+  client.getDeviceList = function () {
+    spy.getDeviceList.count += 1;
+    spy.getDeviceList.args.push(arguments);
+    return Promise.resolve([]);
+  };
+
+  await fxa.updateDeviceRegistration();
+
+  Assert.equal(spy.updateDevice.count, 0);
+  Assert.equal(spy.getDeviceList.count, 0);
+  Assert.equal(spy.registerDevice.count, 1);
+  Assert.equal(spy.registerDevice.args[0].length, 4);
+  Assert.equal(spy.registerDevice.args[0][0], credentials.sessionToken);
+  Assert.equal(spy.registerDevice.args[0][1], deviceName);
+  Assert.equal(spy.registerDevice.args[0][2], "desktop");
+  Assert.equal(
+    spy.registerDevice.args[0][3].pushCallback,
+    "http://mochi.test:8888"
+  );
+  Assert.equal(spy.registerDevice.args[0][3].pushPublicKey, BOGUS_PUBLICKEY);
+  Assert.equal(spy.registerDevice.args[0][3].pushAuthKey, BOGUS_AUTHKEY);
+
+  const state = fxa._internal.currentAccountState;
+  const data = await state.getUserAccountData();
+
+  Assert.equal(data.device.id, "newly-generated device id");
+  Assert.equal(data.device.registrationVersion, DEVICE_REGISTRATION_VERSION);
+  await fxa.signOut(true);
+});
+
+add_task(async function test_updateDeviceRegistration_with_existing_device() {
+  const deviceId = "my device id";
+  const deviceName = "phil's device";
+
+  const credentials = getTestUser("pb");
+  const fxa = await MockFxAccounts(credentials, { name: deviceName });
+  await updateUserAccountData(fxa, {
+    uid: credentials.uid,
+    device: {
+      id: deviceId,
+      registeredCommandsKeys: [],
+      registrationVersion: 1, // < 42
+    },
+  });
+
+  const spy = {
+    registerDevice: { count: 0, args: [] },
+    updateDevice: { count: 0, args: [] },
+    getDeviceList: { count: 0, args: [] },
+  };
+  const client = fxa._internal.fxAccountsClient;
+  client.registerDevice = function () {
+    spy.registerDevice.count += 1;
+    spy.registerDevice.args.push(arguments);
+    return Promise.resolve({});
+  };
+  client.updateDevice = function () {
+    spy.updateDevice.count += 1;
+    spy.updateDevice.args.push(arguments);
+    return Promise.resolve({
+      id: deviceId,
+      name: deviceName,
+    });
+  };
+  client.getDeviceList = function () {
+    spy.getDeviceList.count += 1;
+    spy.getDeviceList.args.push(arguments);
+    return Promise.resolve([]);
+  };
+  await fxa.updateDeviceRegistration();
+
+  Assert.equal(spy.registerDevice.count, 0);
+  Assert.equal(spy.getDeviceList.count, 0);
+  Assert.equal(spy.updateDevice.count, 1);
+  Assert.equal(spy.updateDevice.args[0].length, 4);
+  Assert.equal(spy.updateDevice.args[0][0], credentials.sessionToken);
+  Assert.equal(spy.updateDevice.args[0][1], deviceId);
+  Assert.equal(spy.updateDevice.args[0][2], deviceName);
+  Assert.equal(
+    spy.updateDevice.args[0][3].pushCallback,
+    "http://mochi.test:8888"
+  );
+  Assert.equal(spy.updateDevice.args[0][3].pushPublicKey, BOGUS_PUBLICKEY);
+  Assert.equal(spy.updateDevice.args[0][3].pushAuthKey, BOGUS_AUTHKEY);
+
+  const state = fxa._internal.currentAccountState;
+  const data = await state.getUserAccountData();
+
+  Assert.equal(data.device.id, deviceId);
+  Assert.equal(data.device.registrationVersion, DEVICE_REGISTRATION_VERSION);
+  await fxa.signOut(true);
+});
+
+add_task(
+  async function test_updateDeviceRegistration_with_unknown_device_error() {
+    const deviceName = "foo";
+    const deviceType = "bar";
+    const currentDeviceId = "my device id";
+
+    const credentials = getTestUser("baz");
+    const fxa = await MockFxAccounts(credentials, { name: deviceName });
+    await updateUserAccountData(fxa, {
+      uid: credentials.uid,
+      device: {
+        id: currentDeviceId,
+        registeredCommandsKeys: [],
+        registrationVersion: 1, // < 42
+      },
+    });
+
+    const spy = {
+      registerDevice: { count: 0, args: [] },
+      updateDevice: { count: 0, args: [] },
+      getDeviceList: { count: 0, args: [] },
+    };
+    const client = fxa._internal.fxAccountsClient;
+    client.registerDevice = function () {
+      spy.registerDevice.count += 1;
+      spy.registerDevice.args.push(arguments);
+      return Promise.resolve({
+        id: "a different newly-generated device id",
+        createdAt: Date.now(),
+        name: deviceName,
+        type: deviceType,
+      });
+    };
+    client.updateDevice = function () {
+      spy.updateDevice.count += 1;
+      spy.updateDevice.args.push(arguments);
+      return Promise.reject({
+        code: 400,
+        errno: ERRNO_UNKNOWN_DEVICE,
+      });
+    };
+    client.getDeviceList = function () {
+      spy.getDeviceList.count += 1;
+      spy.getDeviceList.args.push(arguments);
+      return Promise.resolve([]);
+    };
+
+    await fxa.updateDeviceRegistration();
+
+    Assert.equal(spy.getDeviceList.count, 0);
+    Assert.equal(spy.registerDevice.count, 0);
+    Assert.equal(spy.updateDevice.count, 1);
+    Assert.equal(spy.updateDevice.args[0].length, 4);
+    Assert.equal(spy.updateDevice.args[0][0], credentials.sessionToken);
+    Assert.equal(spy.updateDevice.args[0][1], currentDeviceId);
+    Assert.equal(spy.updateDevice.args[0][2], deviceName);
+    Assert.equal(
+      spy.updateDevice.args[0][3].pushCallback,
+      "http://mochi.test:8888"
+    );
+    Assert.equal(spy.updateDevice.args[0][3].pushPublicKey, BOGUS_PUBLICKEY);
+    Assert.equal(spy.updateDevice.args[0][3].pushAuthKey, BOGUS_AUTHKEY);
+
+    const state = fxa._internal.currentAccountState;
+    const data = await state.getUserAccountData();
+
+    Assert.equal(null, data.device);
+    await fxa.signOut(true);
+  }
+);
+
+add_task(
+  async function test_updateDeviceRegistration_with_device_session_conflict_error() {
+    const deviceName = "foo";
+    const deviceType = "bar";
+    const currentDeviceId = "my device id";
+    const conflictingDeviceId = "conflicting device id";
+
+    const credentials = getTestUser("baz");
+    const fxa = await MockFxAccounts(credentials, { name: deviceName });
+    await updateUserAccountData(fxa, {
+      uid: credentials.uid,
+      device: {
+        id: currentDeviceId,
+        registeredCommandsKeys: [],
+        registrationVersion: 1, // < 42
+      },
+    });
+
+    const spy = {
+      registerDevice: { count: 0, args: [] },
+      updateDevice: { count: 0, args: [], times: [] },
+      getDeviceList: { count: 0, args: [] },
+    };
+    const client = fxa._internal.fxAccountsClient;
+    client.registerDevice = function () {
+      spy.registerDevice.count += 1;
+      spy.registerDevice.args.push(arguments);
+      return Promise.resolve({});
+    };
+    client.updateDevice = function () {
+      spy.updateDevice.count += 1;
+      spy.updateDevice.args.push(arguments);
+      spy.updateDevice.time = Date.now();
+      if (spy.updateDevice.count === 1) {
+        return Promise.reject({
+          code: 400,
+          errno: ERRNO_DEVICE_SESSION_CONFLICT,
+        });
+      }
+      return Promise.resolve({
+        id: conflictingDeviceId,
+        name: deviceName,
+      });
+    };
+    client.getDeviceList = function () {
+      spy.getDeviceList.count += 1;
+      spy.getDeviceList.args.push(arguments);
+      spy.getDeviceList.time = Date.now();
+      return Promise.resolve([
+        {
+          id: "ignore",
+          name: "ignore",
+          type: "ignore",
+          isCurrentDevice: false,
+        },
+        {
+          id: conflictingDeviceId,
+          name: deviceName,
+          type: deviceType,
+          isCurrentDevice: true,
+        },
+      ]);
+    };
+
+    await fxa.updateDeviceRegistration();
+
+    Assert.equal(spy.registerDevice.count, 0);
+    Assert.equal(spy.updateDevice.count, 1);
+    Assert.equal(spy.updateDevice.args[0].length, 4);
+    Assert.equal(spy.updateDevice.args[0][0], credentials.sessionToken);
+    Assert.equal(spy.updateDevice.args[0][1], currentDeviceId);
+    Assert.equal(spy.updateDevice.args[0][2], deviceName);
+    Assert.equal(
+      spy.updateDevice.args[0][3].pushCallback,
+      "http://mochi.test:8888"
+    );
+    Assert.equal(spy.updateDevice.args[0][3].pushPublicKey, BOGUS_PUBLICKEY);
+    Assert.equal(spy.updateDevice.args[0][3].pushAuthKey, BOGUS_AUTHKEY);
+    Assert.equal(spy.getDeviceList.count, 1);
+    Assert.equal(spy.getDeviceList.args[0].length, 1);
+    Assert.equal(spy.getDeviceList.args[0][0], credentials.sessionToken);
+    Assert.ok(spy.getDeviceList.time >= spy.updateDevice.time);
+
+    const state = fxa._internal.currentAccountState;
+    const data = await state.getUserAccountData();
+
+    Assert.equal(data.device.id, conflictingDeviceId);
+    Assert.equal(data.device.registrationVersion, null);
+    await fxa.signOut(true);
+  }
+);
+
+add_task(
+  async function test_updateDeviceRegistration_with_unrecoverable_error() {
+    const deviceName = "foo";
+
+    const credentials = getTestUser("baz");
+    const fxa = await MockFxAccounts(credentials, { name: deviceName });
+    await updateUserAccountData(fxa, { uid: credentials.uid, device: null });
+
+    const spy = {
+      registerDevice: { count: 0, args: [] },
+      updateDevice: { count: 0, args: [] },
+      getDeviceList: { count: 0, args: [] },
+    };
+    const client = fxa._internal.fxAccountsClient;
+    client.registerDevice = function () {
+      spy.registerDevice.count += 1;
+      spy.registerDevice.args.push(arguments);
+      return Promise.reject({
+        code: 400,
+        errno: ERRNO_TOO_MANY_CLIENT_REQUESTS,
+      });
+    };
+    client.updateDevice = function () {
+      spy.updateDevice.count += 1;
+      spy.updateDevice.args.push(arguments);
+      return Promise.resolve({});
+    };
+    client.getDeviceList = function () {
+      spy.getDeviceList.count += 1;
+      spy.getDeviceList.args.push(arguments);
+      return Promise.resolve([]);
+    };
+
+    await fxa.updateDeviceRegistration();
+
+    Assert.equal(spy.getDeviceList.count, 0);
+    Assert.equal(spy.updateDevice.count, 0);
+    Assert.equal(spy.registerDevice.count, 1);
+    Assert.equal(spy.registerDevice.args[0].length, 4);
+
+    const state = fxa._internal.currentAccountState;
+    const data = await state.getUserAccountData();
+
+    Assert.equal(null, data.device);
+    await fxa.signOut(true);
+  }
+);
+
+add_task(
+  async function test_getDeviceId_with_no_device_id_invokes_device_registration() {
+    const credentials = getTestUser("foo");
+    credentials.verified = true;
+    const fxa = await MockFxAccounts(credentials);
+    await updateUserAccountData(fxa, { uid: credentials.uid, device: null });
+
+    const spy = { count: 0, args: [] };
+    fxa._internal.currentAccountState.getUserAccountData = () =>
+      Promise.resolve({
+        email: credentials.email,
+        registrationVersion: DEVICE_REGISTRATION_VERSION,
+      });
+    fxa._internal.device._registerOrUpdateDevice = function () {
+      spy.count += 1;
+      spy.args.push(arguments);
+      return Promise.resolve("bar");
+    };
+
+    const result = await fxa.device.getLocalId();
+
+    Assert.equal(spy.count, 1);
+    Assert.equal(spy.args[0].length, 2);
+    Assert.equal(spy.args[0][1].email, credentials.email);
+    Assert.equal(null, spy.args[0][1].device);
+    Assert.equal(result, "bar");
+    await fxa.signOut(true);
+  }
+);
+
+add_task(
+  async function test_getDeviceId_with_registration_version_outdated_invokes_device_registration() {
+    const credentials = getTestUser("foo");
+    credentials.verified = true;
+    const fxa = await MockFxAccounts(credentials);
+
+    const spy = { count: 0, args: [] };
+    fxa._internal.currentAccountState.getUserAccountData = () =>
+      Promise.resolve({
+        device: {
+          id: "my id",
+          registrationVersion: 0,
+          registeredCommandsKeys: [],
+        },
+      });
+    fxa._internal.device._registerOrUpdateDevice = function () {
+      spy.count += 1;
+      spy.args.push(arguments);
+      return Promise.resolve("wibble");
+    };
+
+    const result = await fxa.device.getLocalId();
+
+    Assert.equal(spy.count, 1);
+    Assert.equal(spy.args[0].length, 2);
+    Assert.equal(spy.args[0][1].device.id, "my id");
+    Assert.equal(result, "wibble");
+    await fxa.signOut(true);
+  }
+);
+
+add_task(
+  async function test_getDeviceId_with_device_id_and_uptodate_registration_version_doesnt_invoke_device_registration() {
+    const credentials = getTestUser("foo");
+    credentials.verified = true;
+    const fxa = await MockFxAccounts(credentials);
+
+    const spy = { count: 0 };
+    fxa._internal.currentAccountState.getUserAccountData = async () => ({
+      device: {
+        id: "foo's device id",
+        registrationVersion: DEVICE_REGISTRATION_VERSION,
+        registeredCommandsKeys: [],
+      },
+    });
+    fxa._internal.device._registerOrUpdateDevice = function () {
+      spy.count += 1;
+      return Promise.resolve("bar");
+    };
+
+    const result = await fxa.device.getLocalId();
+
+    Assert.equal(spy.count, 0);
+    Assert.equal(result, "foo's device id");
+    await fxa.signOut(true);
+  }
+);
+
+add_task(
+  async function test_getDeviceId_with_device_id_and_with_no_registration_version_invokes_device_registration() {
+    const credentials = getTestUser("foo");
+    credentials.verified = true;
+    const fxa = await MockFxAccounts(credentials);
+
+    const spy = { count: 0, args: [] };
+    fxa._internal.currentAccountState.getUserAccountData = () =>
+      Promise.resolve({ device: { id: "wibble" } });
+    fxa._internal.device._registerOrUpdateDevice = function () {
+      spy.count += 1;
+      spy.args.push(arguments);
+      return Promise.resolve("wibble");
+    };
+
+    const result = await fxa.device.getLocalId();
+
+    Assert.equal(spy.count, 1);
+    Assert.equal(spy.args[0].length, 2);
+    Assert.equal(spy.args[0][1].device.id, "wibble");
+    Assert.equal(result, "wibble");
+    await fxa.signOut(true);
+  }
+);
+
+add_task(async function test_verification_updates_registration() {
+  const deviceName = "foo";
+
+  const credentials = getTestUser("baz");
+  const fxa = await MockFxAccounts(credentials, {
+    id: "device-id",
+    name: deviceName,
+  });
+
+  // We should already have a device registration, but without send-tab due to
+  // our inability to fetch keys for an unverified users.
+  const state = fxa._internal.currentAccountState;
+  const { device } = await state.getUserAccountData();
+  Assert.equal(device.registeredCommandsKeys.length, 0);
+
+  let updatePromise = new Promise(resolve => {
+    const old_registerOrUpdateDevice = fxa.device._registerOrUpdateDevice.bind(
+      fxa.device
+    );
+    fxa.device._registerOrUpdateDevice = async function (
+      currentState,
+      signedInUser
+    ) {
+      await old_registerOrUpdateDevice(currentState, signedInUser);
+      fxa.device._registerOrUpdateDevice = old_registerOrUpdateDevice;
+      resolve();
+    };
+  });
+
+  fxa._internal.checkEmailStatus = async function (sessionToken) {
+    credentials.verified = true;
+    return credentials;
+  };
+
+  await updatePromise;
+
+  const { device: newDevice, encryptedSendTabKeys } =
+    await state.getUserAccountData();
+  Assert.equal(newDevice.registeredCommandsKeys.length, 1);
+  Assert.notEqual(encryptedSendTabKeys, null);
+  await fxa.signOut(true);
+});
+
+add_task(async function test_devicelist_pushendpointexpired() {
+  const deviceId = "mydeviceid";
+  const credentials = getTestUser("baz");
+  credentials.verified = true;
+  const fxa = await MockFxAccounts(credentials);
+  await updateUserAccountData(fxa, {
+    uid: credentials.uid,
+    device: {
+      id: deviceId,
+      registeredCommandsKeys: [],
+      registrationVersion: 1, // < 42
+    },
+  });
+
+  const spy = {
+    updateDevice: { count: 0, args: [] },
+    getDeviceList: { count: 0, args: [] },
+  };
+  const client = fxa._internal.fxAccountsClient;
+  client.updateDevice = function () {
+    spy.updateDevice.count += 1;
+    spy.updateDevice.args.push(arguments);
+    return Promise.resolve({});
+  };
+  client.getDeviceList = function () {
+    spy.getDeviceList.count += 1;
+    spy.getDeviceList.args.push(arguments);
+    return Promise.resolve([
+      {
+        id: "mydeviceid",
+        name: "foo",
+        type: "desktop",
+        isCurrentDevice: true,
+        pushEndpointExpired: true,
+        pushCallback: "https://example.com",
+      },
+    ]);
+  };
+  let polledForMissedCommands = false;
+  fxa._internal.commands.pollDeviceCommands = () => {
+    polledForMissedCommands = true;
+  };
+
+  await fxa.device.refreshDeviceList();
+
+  Assert.equal(spy.getDeviceList.count, 1);
+  Assert.equal(spy.updateDevice.count, 1);
+  Assert.ok(polledForMissedCommands);
+  await fxa.signOut(true);
+});
+
+add_task(async function test_devicelist_nopushcallback() {
+  const deviceId = "mydeviceid";
+  const credentials = getTestUser("baz");
+  credentials.verified = true;
+  const fxa = await MockFxAccounts(credentials);
+  await updateUserAccountData(fxa, {
+    uid: credentials.uid,
+    device: {
+      id: deviceId,
+      registeredCommandsKeys: [],
+      registrationVersion: 1,
+    },
+  });
+
+  const spy = {
+    updateDevice: { count: 0, args: [] },
+    getDeviceList: { count: 0, args: [] },
+  };
+  const client = fxa._internal.fxAccountsClient;
+  client.updateDevice = function () {
+    spy.updateDevice.count += 1;
+    spy.updateDevice.args.push(arguments);
+    return Promise.resolve({});
+  };
+  client.getDeviceList = function () {
+    spy.getDeviceList.count += 1;
+    spy.getDeviceList.args.push(arguments);
+    return Promise.resolve([
+      {
+        id: "mydeviceid",
+        name: "foo",
+        type: "desktop",
+        isCurrentDevice: true,
+        pushEndpointExpired: false,
+        pushCallback: null,
+      },
+    ]);
+  };
+
+  let polledForMissedCommands = false;
+  fxa._internal.commands.pollDeviceCommands = () => {
+    polledForMissedCommands = true;
+  };
+
+  await fxa.device.refreshDeviceList();
+
+  Assert.equal(spy.getDeviceList.count, 1);
+  Assert.equal(spy.updateDevice.count, 1);
+  Assert.ok(polledForMissedCommands);
+  await fxa.signOut(true);
+});
+
+add_task(async function test_refreshDeviceList() {
+  let credentials = getTestUser("baz");
+
+  let storage = new MockStorageManager();
+  storage.initialize(credentials);
+  let state = new AccountState(storage);
+
+  let fxAccountsClient = new MockFxAccountsClient({
+    id: "deviceAAAAAA",
+    name: "iPhone",
+    type: "phone",
+    pushCallback: "http://mochi.test:8888",
+    pushEndpointExpired: false,
+    sessionToken: credentials.sessionToken,
+  });
+  let spy = {
+    getDeviceList: { count: 0 },
+  };
+  const deviceListUpdateObserver = {
+    count: 0,
+    observe(subject, topic, data) {
+      this.count++;
+    },
+  };
+  Services.obs.addObserver(deviceListUpdateObserver, ON_DEVICELIST_UPDATED);
+
+  fxAccountsClient.getDeviceList = (function (old) {
+    return function getDeviceList() {
+      spy.getDeviceList.count += 1;
+      return old.apply(this, arguments);
+    };
+  })(fxAccountsClient.getDeviceList);
+  let fxai = {
+    _now: Date.now(),
+    _generation: 0,
+    fxAccountsClient,
+    now() {
+      return this._now;
+    },
+    withVerifiedAccountState(func) {
+      // Ensure `func` is called asynchronously, and simulate the possibility
+      // of a different user signng in while the promise is in-flight.
+      const currentGeneration = this._generation;
+      return Promise.resolve()
+        .then(_ => func(state))
+        .then(result => {
+          if (currentGeneration < this._generation) {
+            throw new Error("Another user has signed in");
+          }
+          return result;
+        });
+    },
+    fxaPushService: {
+      registerPushEndpoint() {
+        return new Promise(resolve => {
+          resolve({
+            endpoint: "http://mochi.test:8888",
+            getKey(type) {
+              return ChromeUtils.base64URLDecode(
+                type === "auth" ? BOGUS_AUTHKEY : BOGUS_PUBLICKEY,
+                { padding: "ignore" }
+              );
+            },
+          });
+        });
+      },
+      unsubscribe() {
+        return Promise.resolve();
+      },
+      getSubscription() {
+        return Promise.resolve({
+          isExpired: () => {
+            return false;
+          },
+          endpoint: "http://mochi.test:8888",
+        });
+      },
+    },
+    async _handleTokenError(e) {
+      _(`Test failure: ${e} - ${e.stack}`);
+      throw e;
+    },
+  };
+  let device = new FxAccountsDevice(fxai);
+  device._checkRemoteCommandsUpdateNeeded = async () => false;
+
+  Assert.equal(
+    device.recentDeviceList,
+    null,
+    "Should not have device list initially"
+  );
+  Assert.ok(await device.refreshDeviceList(), "Should refresh list");
+  Assert.equal(
+    deviceListUpdateObserver.count,
+    1,
+    `${ON_DEVICELIST_UPDATED} was notified`
+  );
+  Assert.deepEqual(
+    device.recentDeviceList,
+    [
+      {
+        id: "deviceAAAAAA",
+        name: "iPhone",
+        type: "phone",
+        pushCallback: "http://mochi.test:8888",
+        pushEndpointExpired: false,
+        isCurrentDevice: true,
+      },
+    ],
+    "Should fetch device list"
+  );
+  Assert.equal(
+    spy.getDeviceList.count,
+    1,
+    "Should make request to refresh list"
+  );
+  Assert.ok(
+    !(await device.refreshDeviceList()),
+    "Should not refresh device list if fresh"
+  );
+  Assert.equal(
+    deviceListUpdateObserver.count,
+    1,
+    `${ON_DEVICELIST_UPDATED} was not notified`
+  );
+
+  fxai._now += device.TIME_BETWEEN_FXA_DEVICES_FETCH_MS;
+
+  let refreshPromise = device.refreshDeviceList();
+  let secondRefreshPromise = device.refreshDeviceList();
+  Assert.ok(
+    await Promise.all([refreshPromise, secondRefreshPromise]),
+    "Should refresh list if stale"
+  );
+  Assert.equal(
+    spy.getDeviceList.count,
+    2,
+    "Should only make one request if called with pending request"
+  );
+  Assert.equal(
+    deviceListUpdateObserver.count,
+    2,
+    `${ON_DEVICELIST_UPDATED} only notified once`
+  );
+
+  device.observe(null, ON_DEVICE_CONNECTED_NOTIFICATION);
+  await device.refreshDeviceList();
+  Assert.equal(
+    spy.getDeviceList.count,
+    3,
+    "Should refresh device list after connecting new device"
+  );
+  Assert.equal(
+    deviceListUpdateObserver.count,
+    3,
+    `${ON_DEVICELIST_UPDATED} notified when new device connects`
+  );
+  device.observe(
+    null,
+    ON_DEVICE_DISCONNECTED_NOTIFICATION,
+    JSON.stringify({ isLocalDevice: false })
+  );
+  await device.refreshDeviceList();
+  Assert.equal(
+    spy.getDeviceList.count,
+    4,
+    "Should refresh device list after disconnecting device"
+  );
+  Assert.equal(
+    deviceListUpdateObserver.count,
+    4,
+    `${ON_DEVICELIST_UPDATED} notified when device disconnects`
+  );
+  device.observe(
+    null,
+    ON_DEVICE_DISCONNECTED_NOTIFICATION,
+    JSON.stringify({ isLocalDevice: true })
+  );
+  await device.refreshDeviceList();
+  Assert.equal(
+    spy.getDeviceList.count,
+    4,
+    "Should not refresh device list after disconnecting this device"
+  );
+  Assert.equal(
+    deviceListUpdateObserver.count,
+    4,
+    `${ON_DEVICELIST_UPDATED} not notified again`
+  );
+
+  let refreshBeforeResetPromise = device.refreshDeviceList({
+    ignoreCached: true,
+  });
+  fxai._generation++;
+  Assert.equal(
+    deviceListUpdateObserver.count,
+    4,
+    `${ON_DEVICELIST_UPDATED} not notified`
+  );
+  await Assert.rejects(refreshBeforeResetPromise, /Another user has signed in/);
+
+  device.reset();
+  Assert.equal(
+    device.recentDeviceList,
+    null,
+    "Should clear device list after resetting"
+  );
+  Assert.ok(
+    await device.refreshDeviceList(),
+    "Should fetch new list after resetting"
+  );
+  Assert.equal(
+    deviceListUpdateObserver.count,
+    5,
+    `${ON_DEVICELIST_UPDATED} notified after reset`
+  );
+  Services.obs.removeObserver(deviceListUpdateObserver, ON_DEVICELIST_UPDATED);
+});
+
+add_task(async function test_push_resubscribe() {
+  let credentials = getTestUser("baz");
+
+  let storage = new MockStorageManager();
+  storage.initialize(credentials);
+  let state = new AccountState(storage);
+
+  let mockDevice = {
+    id: "deviceAAAAAA",
+    name: "iPhone",
+    type: "phone",
+    pushCallback: "http://mochi.test:8888",
+    pushEndpointExpired: false,
+    sessionToken: credentials.sessionToken,
+  };
+
+  var mockSubscription = {
+    isExpired: () => {
+      return false;
+    },
+    endpoint: "http://mochi.test:8888",
+  };
+
+  let fxAccountsClient = new MockFxAccountsClient(mockDevice);
+
+  const spy = {
+    _registerOrUpdateDevice: { count: 0 },
+  };
+
+  let fxai = {
+    _now: Date.now(),
+    _generation: 0,
+    fxAccountsClient,
+    now() {
+      return this._now;
+    },
+    withVerifiedAccountState(func) {
+      // Ensure `func` is called asynchronously, and simulate the possibility
+      // of a different user signng in while the promise is in-flight.
+      const currentGeneration = this._generation;
+      return Promise.resolve()
+        .then(_ => func(state))
+        .then(result => {
+          if (currentGeneration < this._generation) {
+            throw new Error("Another user has signed in");
+          }
+          return result;
+        });
+    },
+    fxaPushService: {
+      registerPushEndpoint() {
+        return new Promise(resolve => {
+          resolve({
+            endpoint: "http://mochi.test:8888",
+            getKey(type) {
+              return ChromeUtils.base64URLDecode(
+                type === "auth" ? BOGUS_AUTHKEY : BOGUS_PUBLICKEY,
+                { padding: "ignore" }
+              );
+            },
+          });
+        });
+      },
+      unsubscribe() {
+        return Promise.resolve();
+      },
+      getSubscription() {
+        return Promise.resolve(mockSubscription);
+      },
+    },
+    commands: {
+      async pollDeviceCommands() {},
+    },
+    async _handleTokenError(e) {
+      _(`Test failure: ${e} - ${e.stack}`);
+      throw e;
+    },
+  };
+  let device = new FxAccountsDevice(fxai);
+  device._checkRemoteCommandsUpdateNeeded = async () => false;
+  device._registerOrUpdateDevice = async () => {
+    spy._registerOrUpdateDevice.count += 1;
+  };
+
+  Assert.ok(await device.refreshDeviceList(), "Should refresh list");
+  Assert.equal(spy._registerOrUpdateDevice.count, 0, "not expecting a refresh");
+
+  mockDevice.pushEndpointExpired = true;
+  Assert.ok(
+    await device.refreshDeviceList({ ignoreCached: true }),
+    "Should refresh list"
+  );
+  Assert.equal(
+    spy._registerOrUpdateDevice.count,
+    1,
+    "end-point expired means should resubscribe"
+  );
+
+  mockDevice.pushEndpointExpired = false;
+  mockSubscription.isExpired = () => true;
+  Assert.ok(
+    await device.refreshDeviceList({ ignoreCached: true }),
+    "Should refresh list"
+  );
+  Assert.equal(
+    spy._registerOrUpdateDevice.count,
+    2,
+    "push service saying expired should resubscribe"
+  );
+
+  mockSubscription.isExpired = () => false;
+  mockSubscription.endpoint = "something-else";
+  Assert.ok(
+    await device.refreshDeviceList({ ignoreCached: true }),
+    "Should refresh list"
+  );
+  Assert.equal(
+    spy._registerOrUpdateDevice.count,
+    3,
+    "push service endpoint diff should resubscribe"
+  );
+
+  mockSubscription = null;
+  Assert.ok(
+    await device.refreshDeviceList({ ignoreCached: true }),
+    "Should refresh list"
+  );
+  Assert.equal(
+    spy._registerOrUpdateDevice.count,
+    4,
+    "push service saying no sub should resubscribe"
+  );
+
+  // reset everything to make sure we didn't leave something behind causing the above to
+  // not check what we thought it was.
+  mockSubscription = {
+    isExpired: () => {
+      return false;
+    },
+    endpoint: "http://mochi.test:8888",
+  };
+  Assert.ok(
+    await device.refreshDeviceList({ ignoreCached: true }),
+    "Should refresh list"
+  );
+  Assert.equal(
+    spy._registerOrUpdateDevice.count,
+    4,
+    "resetting to good data should not resubscribe"
+  );
+});
+
+add_task(async function test_checking_remote_availableCommands_mismatch() {
+  const credentials = getTestUser("baz");
+  credentials.verified = true;
+  const fxa = await MockFxAccounts(credentials);
+  fxa.device._checkRemoteCommandsUpdateNeeded =
+    FxAccountsDevice.prototype._checkRemoteCommandsUpdateNeeded;
+  fxa.commands.availableCommands = async () => {
+    return {
+      "https://identity.mozilla.com/cmd/open-uri": "local-keys",
+    };
+  };
+
+  const ourDevice = {
+    isCurrentDevice: true,
+    availableCommands: {
+      "https://identity.mozilla.com/cmd/open-uri": "remote-keys",
+    },
+  };
+  Assert.ok(
+    await fxa.device._checkRemoteCommandsUpdateNeeded(
+      ourDevice.availableCommands
+    )
+  );
+});
+
+add_task(async function test_checking_remote_availableCommands_match() {
+  const credentials = getTestUser("baz");
+  credentials.verified = true;
+  const fxa = await MockFxAccounts(credentials);
+  fxa.device._checkRemoteCommandsUpdateNeeded =
+    FxAccountsDevice.prototype._checkRemoteCommandsUpdateNeeded;
+  fxa.commands.availableCommands = async () => {
+    return {
+      "https://identity.mozilla.com/cmd/open-uri": "local-keys",
+    };
+  };
+
+  const ourDevice = {
+    isCurrentDevice: true,
+    availableCommands: {
+      "https://identity.mozilla.com/cmd/open-uri": "local-keys",
+    },
+  };
+  Assert.ok(
+    !(await fxa.device._checkRemoteCommandsUpdateNeeded(
+      ourDevice.availableCommands
+    ))
+  );
+});
+
+function getTestUser(name) {
+  return {
+    email: name + "@example.com",
+    uid: "1ad7f502-4cc7-4ec1-a209-071fd2fae348",
+    sessionToken: name + "'s session token",
+    verified: false,
+    ...MOCK_ACCOUNT_KEYS,
+  };
+}
diff --git a/services/fxaccounts/tests/xpcshell/test_client.js b/services/fxaccounts/tests/xpcshell/test_client.js
new file mode 100644
index 0000000000..f3cc48a70e
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_client.js
@@ -0,0 +1,966 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { FxAccountsClient } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsClient.sys.mjs"
+);
+
+const FAKE_SESSION_TOKEN =
+  "a0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebf";
+
+// https://wiki.mozilla.org/Identity/AttachedServices/KeyServerProtocol#.2Faccount.2Fkeys
+var ACCOUNT_KEYS = {
+  keyFetch: h(
+    // eslint-disable-next-line no-useless-concat
+    "8081828384858687 88898a8b8c8d8e8f" + "9091929394959697 98999a9b9c9d9e9f"
+  ),
+
+  response: h(
+    "ee5c58845c7c9412 b11bbd20920c2fdd" +
+      "d83c33c9cd2c2de2 d66b222613364636" +
+      "c2c0f8cfbb7c6304 72c0bd88451342c6" +
+      "c05b14ce342c5ad4 6ad89e84464c993c" +
+      "3927d30230157d08 17a077eef4b20d97" +
+      "6f7a97363faf3f06 4c003ada7d01aa70"
+  ),
+
+  kA: h(
+    // eslint-disable-next-line no-useless-concat
+    "2021222324252627 28292a2b2c2d2e2f" + "3031323334353637 38393a3b3c3d3e3f"
+  ),
+
+  wrapKB: h(
+    // eslint-disable-next-line no-useless-concat
+    "4041424344454647 48494a4b4c4d4e4f" + "5051525354555657 58595a5b5c5d5e5f"
+  ),
+};
+
+add_task(async function test_authenticated_get_request() {
+  let message = '{"msg": "Great Success!"}';
+  let credentials = {
+    id: "eyJleHBpcmVzIjogMTM2NTAxMDg5OC4x",
+    key: "qTZf4ZFpAMpMoeSsX3zVRjiqmNs=",
+    algorithm: "sha256",
+  };
+  let method = "GET";
+
+  let server = httpd_setup({
+    "/foo": function (request, response) {
+      Assert.ok(request.hasHeader("Authorization"));
+
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.bodyOutputStream.write(message, message.length);
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+
+  let result = await client._request("/foo", method, credentials);
+  Assert.equal("Great Success!", result.msg);
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_authenticated_post_request() {
+  let credentials = {
+    id: "eyJleHBpcmVzIjogMTM2NTAxMDg5OC4x",
+    key: "qTZf4ZFpAMpMoeSsX3zVRjiqmNs=",
+    algorithm: "sha256",
+  };
+  let method = "POST";
+
+  let server = httpd_setup({
+    "/foo": function (request, response) {
+      Assert.ok(request.hasHeader("Authorization"));
+
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.setHeader("Content-Type", "application/json");
+      response.bodyOutputStream.writeFrom(
+        request.bodyInputStream,
+        request.bodyInputStream.available()
+      );
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+
+  let result = await client._request("/foo", method, credentials, {
+    foo: "bar",
+  });
+  Assert.equal("bar", result.foo);
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_500_error() {
+  let message = "<h1>Ooops!</h1>";
+  let method = "GET";
+
+  let server = httpd_setup({
+    "/foo": function (request, response) {
+      response.setStatusLine(request.httpVersion, 500, "Internal Server Error");
+      response.bodyOutputStream.write(message, message.length);
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+
+  try {
+    await client._request("/foo", method);
+    do_throw("Expected to catch an exception");
+  } catch (e) {
+    Assert.equal(500, e.code);
+    Assert.equal("Internal Server Error", e.message);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_backoffError() {
+  let method = "GET";
+  let server = httpd_setup({
+    "/retryDelay": function (request, response) {
+      response.setHeader("Retry-After", "30");
+      response.setStatusLine(
+        request.httpVersion,
+        429,
+        "Client has sent too many requests"
+      );
+      let message = "<h1>Ooops!</h1>";
+      response.bodyOutputStream.write(message, message.length);
+    },
+    "/duringDelayIShouldNotBeCalled": function (request, response) {
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      let jsonMessage = '{"working": "yes"}';
+      response.bodyOutputStream.write(jsonMessage, jsonMessage.length);
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+
+  // Retry-After header sets client.backoffError
+  Assert.equal(client.backoffError, null);
+  try {
+    await client._request("/retryDelay", method);
+  } catch (e) {
+    Assert.equal(429, e.code);
+    Assert.equal(30, e.retryAfter);
+    Assert.notEqual(typeof client.fxaBackoffTimer, "undefined");
+    Assert.notEqual(client.backoffError, null);
+  }
+  // While delay is in effect, client short-circuits any requests
+  // and re-rejects with previous error.
+  try {
+    await client._request("/duringDelayIShouldNotBeCalled", method);
+    throw new Error("I should not be reached");
+  } catch (e) {
+    Assert.equal(e.retryAfter, 30);
+    Assert.equal(e.message, "Client has sent too many requests");
+    Assert.notEqual(client.backoffError, null);
+  }
+  // Once timer fires, client nulls error out and HTTP calls work again.
+  client._clearBackoff();
+  let result = await client._request("/duringDelayIShouldNotBeCalled", method);
+  Assert.equal(client.backoffError, null);
+  Assert.equal(result.working, "yes");
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_signUp() {
+  let creationMessage_noKey = JSON.stringify({
+    uid: "uid",
+    sessionToken: "sessionToken",
+  });
+  let creationMessage_withKey = JSON.stringify({
+    uid: "uid",
+    sessionToken: "sessionToken",
+    keyFetchToken: "keyFetchToken",
+  });
+  let errorMessage = JSON.stringify({
+    code: 400,
+    errno: 101,
+    error: "account exists",
+  });
+  let created = false;
+
+  // Note these strings must be unicode and not already utf-8 encoded.
+  let unicodeUsername = "andr\xe9@example.org"; // 'andré@example.org'
+  let unicodePassword = "p\xe4ssw\xf6rd"; // 'pässwörd'
+  let server = httpd_setup({
+    "/account/create": function (request, response) {
+      let body = CommonUtils.readBytesFromInputStream(request.bodyInputStream);
+      body = CommonUtils.decodeUTF8(body);
+      let jsonBody = JSON.parse(body);
+
+      // https://github.com/mozilla/fxa-auth-server/wiki/onepw-protocol#wiki-test-vectors
+
+      if (created) {
+        // Error trying to create same account a second time
+        response.setStatusLine(request.httpVersion, 400, "Bad request");
+        response.bodyOutputStream.write(errorMessage, errorMessage.length);
+        return;
+      }
+
+      if (jsonBody.email == unicodeUsername) {
+        Assert.equal("", request._queryString);
+        Assert.equal(
+          jsonBody.authPW,
+          "247b675ffb4c46310bc87e26d712153abe5e1c90ef00a4784594f97ef54f2375"
+        );
+
+        response.setStatusLine(request.httpVersion, 200, "OK");
+        response.bodyOutputStream.write(
+          creationMessage_noKey,
+          creationMessage_noKey.length
+        );
+        return;
+      }
+
+      if (jsonBody.email == "you@example.org") {
+        Assert.equal("keys=true", request._queryString);
+        Assert.equal(
+          jsonBody.authPW,
+          "e5c1cdfdaa5fcee06142db865b212cc8ba8abee2a27d639d42c139f006cdb930"
+        );
+        created = true;
+
+        response.setStatusLine(request.httpVersion, 200, "OK");
+        response.bodyOutputStream.write(
+          creationMessage_withKey,
+          creationMessage_withKey.length
+        );
+        return;
+      }
+      // just throwing here doesn't make any log noise, so have an assertion
+      // fail instead.
+      Assert.ok(false, "unexpected email: " + jsonBody.email);
+    },
+  });
+
+  // Try to create an account without retrieving optional keys.
+  let client = new FxAccountsClient(server.baseURI);
+  let result = await client.signUp(unicodeUsername, unicodePassword);
+  Assert.equal("uid", result.uid);
+  Assert.equal("sessionToken", result.sessionToken);
+  Assert.equal(undefined, result.keyFetchToken);
+  Assert.equal(
+    result.unwrapBKey,
+    "de6a2648b78284fcb9ffa81ba95803309cfba7af583c01a8a1a63e567234dd28"
+  );
+
+  // Try to create an account retrieving optional keys.
+  result = await client.signUp("you@example.org", "pässwörd", true);
+  Assert.equal("uid", result.uid);
+  Assert.equal("sessionToken", result.sessionToken);
+  Assert.equal("keyFetchToken", result.keyFetchToken);
+  Assert.equal(
+    result.unwrapBKey,
+    "f589225b609e56075d76eb74f771ff9ab18a4dc0e901e131ba8f984c7fb0ca8c"
+  );
+
+  // Try to create an existing account.  Triggers error path.
+  try {
+    result = await client.signUp(unicodeUsername, unicodePassword);
+    do_throw("Expected to catch an exception");
+  } catch (expectedError) {
+    Assert.equal(101, expectedError.errno);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_signIn() {
+  let sessionMessage_noKey = JSON.stringify({
+    sessionToken: FAKE_SESSION_TOKEN,
+  });
+  let sessionMessage_withKey = JSON.stringify({
+    sessionToken: FAKE_SESSION_TOKEN,
+    keyFetchToken: "keyFetchToken",
+  });
+  let errorMessage_notExistent = JSON.stringify({
+    code: 400,
+    errno: 102,
+    error: "doesn't exist",
+  });
+  let errorMessage_wrongCap = JSON.stringify({
+    code: 400,
+    errno: 120,
+    error: "Incorrect email case",
+    email: "you@example.com",
+  });
+
+  // Note this strings must be unicode and not already utf-8 encoded.
+  let unicodeUsername = "m\xe9@example.com"; // 'mé@example.com'
+  let server = httpd_setup({
+    "/account/login": function (request, response) {
+      let body = CommonUtils.readBytesFromInputStream(request.bodyInputStream);
+      body = CommonUtils.decodeUTF8(body);
+      let jsonBody = JSON.parse(body);
+
+      if (jsonBody.email == unicodeUsername) {
+        Assert.equal("", request._queryString);
+        Assert.equal(
+          jsonBody.authPW,
+          "08b9d111196b8408e8ed92439da49206c8ecfbf343df0ae1ecefcd1e0174a8b6"
+        );
+        response.setStatusLine(request.httpVersion, 200, "OK");
+        response.bodyOutputStream.write(
+          sessionMessage_noKey,
+          sessionMessage_noKey.length
+        );
+      } else if (jsonBody.email == "you@example.com") {
+        Assert.equal("keys=true", request._queryString);
+        Assert.equal(
+          jsonBody.authPW,
+          "93d20ec50304d496d0707ec20d7e8c89459b6396ec5dd5b9e92809c5e42856c7"
+        );
+        response.setStatusLine(request.httpVersion, 200, "OK");
+        response.bodyOutputStream.write(
+          sessionMessage_withKey,
+          sessionMessage_withKey.length
+        );
+      } else if (jsonBody.email == "You@example.com") {
+        // Error trying to sign in with a wrong capitalization
+        response.setStatusLine(request.httpVersion, 400, "Bad request");
+        response.bodyOutputStream.write(
+          errorMessage_wrongCap,
+          errorMessage_wrongCap.length
+        );
+      } else {
+        // Error trying to sign in to nonexistent account
+        response.setStatusLine(request.httpVersion, 400, "Bad request");
+        response.bodyOutputStream.write(
+          errorMessage_notExistent,
+          errorMessage_notExistent.length
+        );
+      }
+    },
+  });
+
+  // Login without retrieving optional keys
+  let client = new FxAccountsClient(server.baseURI);
+  let result = await client.signIn(unicodeUsername, "bigsecret");
+  Assert.equal(FAKE_SESSION_TOKEN, result.sessionToken);
+  Assert.equal(
+    result.unwrapBKey,
+    "c076ec3f4af123a615157154c6e1d0d6293e514fd7b0221e32d50517ecf002b8"
+  );
+  Assert.equal(undefined, result.keyFetchToken);
+
+  // Login with retrieving optional keys
+  result = await client.signIn("you@example.com", "bigsecret", true);
+  Assert.equal(FAKE_SESSION_TOKEN, result.sessionToken);
+  Assert.equal(
+    result.unwrapBKey,
+    "65970516211062112e955d6420bebe020269d6b6a91ebd288319fc8d0cb49624"
+  );
+  Assert.equal("keyFetchToken", result.keyFetchToken);
+
+  // Retry due to wrong email capitalization
+  result = await client.signIn("You@example.com", "bigsecret", true);
+  Assert.equal(FAKE_SESSION_TOKEN, result.sessionToken);
+  Assert.equal(
+    result.unwrapBKey,
+    "65970516211062112e955d6420bebe020269d6b6a91ebd288319fc8d0cb49624"
+  );
+  Assert.equal("keyFetchToken", result.keyFetchToken);
+
+  // Trigger error path
+  try {
+    result = await client.signIn("yøü@bad.example.org", "nofear");
+    do_throw("Expected to catch an exception");
+  } catch (expectedError) {
+    Assert.equal(102, expectedError.errno);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_signOut() {
+  let signoutMessage = JSON.stringify({});
+  let errorMessage = JSON.stringify({
+    code: 400,
+    errno: 102,
+    error: "doesn't exist",
+  });
+  let signedOut = false;
+
+  let server = httpd_setup({
+    "/session/destroy": function (request, response) {
+      if (!signedOut) {
+        signedOut = true;
+        Assert.ok(request.hasHeader("Authorization"));
+        response.setStatusLine(request.httpVersion, 200, "OK");
+        response.bodyOutputStream.write(signoutMessage, signoutMessage.length);
+        return;
+      }
+
+      // Error trying to sign out of nonexistent account
+      response.setStatusLine(request.httpVersion, 400, "Bad request");
+      response.bodyOutputStream.write(errorMessage, errorMessage.length);
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+  let result = await client.signOut("FakeSession");
+  Assert.equal(typeof result, "object");
+
+  // Trigger error path
+  try {
+    result = await client.signOut("FakeSession");
+    do_throw("Expected to catch an exception");
+  } catch (expectedError) {
+    Assert.equal(102, expectedError.errno);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_recoveryEmailStatus() {
+  let emailStatus = JSON.stringify({ verified: true });
+  let errorMessage = JSON.stringify({
+    code: 400,
+    errno: 102,
+    error: "doesn't exist",
+  });
+  let tries = 0;
+
+  let server = httpd_setup({
+    "/recovery_email/status": function (request, response) {
+      Assert.ok(request.hasHeader("Authorization"));
+      Assert.equal("", request._queryString);
+
+      if (tries === 0) {
+        tries += 1;
+        response.setStatusLine(request.httpVersion, 200, "OK");
+        response.bodyOutputStream.write(emailStatus, emailStatus.length);
+        return;
+      }
+
+      // Second call gets an error trying to query a nonexistent account
+      response.setStatusLine(request.httpVersion, 400, "Bad request");
+      response.bodyOutputStream.write(errorMessage, errorMessage.length);
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+  let result = await client.recoveryEmailStatus(FAKE_SESSION_TOKEN);
+  Assert.equal(result.verified, true);
+
+  // Trigger error path
+  try {
+    result = await client.recoveryEmailStatus("some bogus session");
+    do_throw("Expected to catch an exception");
+  } catch (expectedError) {
+    Assert.equal(102, expectedError.errno);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_recoveryEmailStatusWithReason() {
+  let emailStatus = JSON.stringify({ verified: true });
+  let server = httpd_setup({
+    "/recovery_email/status": function (request, response) {
+      Assert.ok(request.hasHeader("Authorization"));
+      // if there is a query string then it will have a reason
+      Assert.equal("reason=push", request._queryString);
+
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.bodyOutputStream.write(emailStatus, emailStatus.length);
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+  let result = await client.recoveryEmailStatus(FAKE_SESSION_TOKEN, {
+    reason: "push",
+  });
+  Assert.equal(result.verified, true);
+  await promiseStopServer(server);
+});
+
+add_task(async function test_resendVerificationEmail() {
+  let emptyMessage = "{}";
+  let errorMessage = JSON.stringify({
+    code: 400,
+    errno: 102,
+    error: "doesn't exist",
+  });
+  let tries = 0;
+
+  let server = httpd_setup({
+    "/recovery_email/resend_code": function (request, response) {
+      Assert.ok(request.hasHeader("Authorization"));
+      if (tries === 0) {
+        tries += 1;
+        response.setStatusLine(request.httpVersion, 200, "OK");
+        response.bodyOutputStream.write(emptyMessage, emptyMessage.length);
+        return;
+      }
+
+      // Second call gets an error trying to query a nonexistent account
+      response.setStatusLine(request.httpVersion, 400, "Bad request");
+      response.bodyOutputStream.write(errorMessage, errorMessage.length);
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+  let result = await client.resendVerificationEmail(FAKE_SESSION_TOKEN);
+  Assert.equal(JSON.stringify(result), emptyMessage);
+
+  // Trigger error path
+  try {
+    result = await client.resendVerificationEmail("some bogus session");
+    do_throw("Expected to catch an exception");
+  } catch (expectedError) {
+    Assert.equal(102, expectedError.errno);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_accountKeys() {
+  // Four calls to accountKeys().  The first one should work correctly, and we
+  // should get a valid bundle back, in exchange for our keyFetch token, from
+  // which we correctly derive kA and wrapKB.  The subsequent three calls
+  // should all trigger separate error paths.
+  let responseMessage = JSON.stringify({ bundle: ACCOUNT_KEYS.response });
+  let errorMessage = JSON.stringify({
+    code: 400,
+    errno: 102,
+    error: "doesn't exist",
+  });
+  let emptyMessage = "{}";
+  let attempt = 0;
+
+  let server = httpd_setup({
+    "/account/keys": function (request, response) {
+      Assert.ok(request.hasHeader("Authorization"));
+      attempt += 1;
+
+      switch (attempt) {
+        case 1:
+          // First time succeeds
+          response.setStatusLine(request.httpVersion, 200, "OK");
+          response.bodyOutputStream.write(
+            responseMessage,
+            responseMessage.length
+          );
+          break;
+
+        case 2:
+          // Second time, return no bundle to trigger client error
+          response.setStatusLine(request.httpVersion, 200, "OK");
+          response.bodyOutputStream.write(emptyMessage, emptyMessage.length);
+          break;
+
+        case 3:
+          // Return gibberish to trigger client MAC error
+          // Tweak a byte
+          let garbageResponse = JSON.stringify({
+            bundle: ACCOUNT_KEYS.response.slice(0, -1) + "1",
+          });
+          response.setStatusLine(request.httpVersion, 200, "OK");
+          response.bodyOutputStream.write(
+            garbageResponse,
+            garbageResponse.length
+          );
+          break;
+
+        case 4:
+          // Trigger error for nonexistent account
+          response.setStatusLine(request.httpVersion, 400, "Bad request");
+          response.bodyOutputStream.write(errorMessage, errorMessage.length);
+          break;
+      }
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+
+  // First try, all should be good
+  let result = await client.accountKeys(ACCOUNT_KEYS.keyFetch);
+  Assert.equal(CommonUtils.hexToBytes(ACCOUNT_KEYS.kA), result.kA);
+  Assert.equal(CommonUtils.hexToBytes(ACCOUNT_KEYS.wrapKB), result.wrapKB);
+
+  // Second try, empty bundle should trigger error
+  try {
+    result = await client.accountKeys(ACCOUNT_KEYS.keyFetch);
+    do_throw("Expected to catch an exception");
+  } catch (expectedError) {
+    Assert.equal(expectedError.message, "failed to retrieve keys");
+  }
+
+  // Third try, bad bundle results in MAC error
+  try {
+    result = await client.accountKeys(ACCOUNT_KEYS.keyFetch);
+    do_throw("Expected to catch an exception");
+  } catch (expectedError) {
+    Assert.equal(expectedError.message, "error unbundling encryption keys");
+  }
+
+  // Fourth try, pretend account doesn't exist
+  try {
+    result = await client.accountKeys(ACCOUNT_KEYS.keyFetch);
+    do_throw("Expected to catch an exception");
+  } catch (expectedError) {
+    Assert.equal(102, expectedError.errno);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_accessTokenWithSessionToken() {
+  let server = httpd_setup({
+    "/oauth/token": function (request, response) {
+      const responseMessage = JSON.stringify({
+        access_token:
+          "43793fdfffec22eb39fc3c44ed09193a6fde4c24e5d6a73f73178597b268af69",
+        token_type: "bearer",
+        scope: "https://identity.mozilla.com/apps/oldsync",
+        expires_in: 21600,
+        auth_at: 1589579900,
+      });
+
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.bodyOutputStream.write(responseMessage, responseMessage.length);
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+  let sessionTokenHex =
+    "0599c36ebb5cad6feb9285b9547b65342b5434d55c07b33bffd4307ab8f82dc4";
+  let clientId = "5882386c6d801776";
+  let scope = "https://identity.mozilla.com/apps/oldsync";
+  let ttl = 100;
+  let result = await client.accessTokenWithSessionToken(
+    sessionTokenHex,
+    clientId,
+    scope,
+    ttl
+  );
+  Assert.ok(result);
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_accountExists() {
+  let existsMessage = JSON.stringify({
+    error: "wrong password",
+    code: 400,
+    errno: 103,
+  });
+  let doesntExistMessage = JSON.stringify({
+    error: "no such account",
+    code: 400,
+    errno: 102,
+  });
+  let emptyMessage = "{}";
+
+  let server = httpd_setup({
+    "/account/login": function (request, response) {
+      let body = CommonUtils.readBytesFromInputStream(request.bodyInputStream);
+      let jsonBody = JSON.parse(body);
+
+      switch (jsonBody.email) {
+        // We'll test that these users' accounts exist
+        case "i.exist@example.com":
+        case "i.also.exist@example.com":
+          response.setStatusLine(request.httpVersion, 400, "Bad request");
+          response.bodyOutputStream.write(existsMessage, existsMessage.length);
+          break;
+
+        // This user's account doesn't exist
+        case "i.dont.exist@example.com":
+          response.setStatusLine(request.httpVersion, 400, "Bad request");
+          response.bodyOutputStream.write(
+            doesntExistMessage,
+            doesntExistMessage.length
+          );
+          break;
+
+        // This user throws an unexpected response
+        // This will reject the client signIn promise
+        case "i.break.things@example.com":
+          response.setStatusLine(request.httpVersion, 500, "Alas");
+          response.bodyOutputStream.write(emptyMessage, emptyMessage.length);
+          break;
+
+        default:
+          throw new Error("Unexpected login from " + jsonBody.email);
+      }
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+  let result;
+
+  result = await client.accountExists("i.exist@example.com");
+  Assert.ok(result);
+
+  result = await client.accountExists("i.also.exist@example.com");
+  Assert.ok(result);
+
+  result = await client.accountExists("i.dont.exist@example.com");
+  Assert.ok(!result);
+
+  try {
+    result = await client.accountExists("i.break.things@example.com");
+    do_throw("Expected to catch an exception");
+  } catch (unexpectedError) {
+    Assert.equal(unexpectedError.code, 500);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_registerDevice() {
+  const DEVICE_ID = "device id";
+  const DEVICE_NAME = "device name";
+  const DEVICE_TYPE = "device type";
+  const ERROR_NAME = "test that the client promise rejects";
+
+  const server = httpd_setup({
+    "/account/device": function (request, response) {
+      const body = JSON.parse(
+        CommonUtils.readBytesFromInputStream(request.bodyInputStream)
+      );
+
+      if (
+        body.id ||
+        !body.name ||
+        !body.type ||
+        Object.keys(body).length !== 2
+      ) {
+        response.setStatusLine(request.httpVersion, 400, "Invalid request");
+        response.bodyOutputStream.write("{}", 2);
+        return;
+      }
+
+      if (body.name === ERROR_NAME) {
+        response.setStatusLine(request.httpVersion, 500, "Alas");
+        response.bodyOutputStream.write("{}", 2);
+        return;
+      }
+
+      body.id = DEVICE_ID;
+      body.createdAt = Date.now();
+
+      const responseMessage = JSON.stringify(body);
+
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.bodyOutputStream.write(responseMessage, responseMessage.length);
+    },
+  });
+
+  const client = new FxAccountsClient(server.baseURI);
+  const result = await client.registerDevice(
+    FAKE_SESSION_TOKEN,
+    DEVICE_NAME,
+    DEVICE_TYPE
+  );
+
+  Assert.ok(result);
+  Assert.equal(Object.keys(result).length, 4);
+  Assert.equal(result.id, DEVICE_ID);
+  Assert.equal(typeof result.createdAt, "number");
+  Assert.ok(result.createdAt > 0);
+  Assert.equal(result.name, DEVICE_NAME);
+  Assert.equal(result.type, DEVICE_TYPE);
+
+  try {
+    await client.registerDevice(FAKE_SESSION_TOKEN, ERROR_NAME, DEVICE_TYPE);
+    do_throw("Expected to catch an exception");
+  } catch (unexpectedError) {
+    Assert.equal(unexpectedError.code, 500);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_updateDevice() {
+  const DEVICE_ID = "some other id";
+  const DEVICE_NAME = "some other name";
+  const ERROR_ID = "test that the client promise rejects";
+
+  const server = httpd_setup({
+    "/account/device": function (request, response) {
+      const body = JSON.parse(
+        CommonUtils.readBytesFromInputStream(request.bodyInputStream)
+      );
+
+      if (
+        !body.id ||
+        !body.name ||
+        body.type ||
+        Object.keys(body).length !== 2
+      ) {
+        response.setStatusLine(request.httpVersion, 400, "Invalid request");
+        response.bodyOutputStream.write("{}", 2);
+        return;
+      }
+
+      if (body.id === ERROR_ID) {
+        response.setStatusLine(request.httpVersion, 500, "Alas");
+        response.bodyOutputStream.write("{}", 2);
+        return;
+      }
+
+      const responseMessage = JSON.stringify(body);
+
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.bodyOutputStream.write(responseMessage, responseMessage.length);
+    },
+  });
+
+  const client = new FxAccountsClient(server.baseURI);
+  const result = await client.updateDevice(
+    FAKE_SESSION_TOKEN,
+    DEVICE_ID,
+    DEVICE_NAME
+  );
+
+  Assert.ok(result);
+  Assert.equal(Object.keys(result).length, 2);
+  Assert.equal(result.id, DEVICE_ID);
+  Assert.equal(result.name, DEVICE_NAME);
+
+  try {
+    await client.updateDevice(FAKE_SESSION_TOKEN, ERROR_ID, DEVICE_NAME);
+    do_throw("Expected to catch an exception");
+  } catch (unexpectedError) {
+    Assert.equal(unexpectedError.code, 500);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_getDeviceList() {
+  let canReturnDevices;
+
+  const server = httpd_setup({
+    "/account/devices": function (request, response) {
+      if (canReturnDevices) {
+        response.setStatusLine(request.httpVersion, 200, "OK");
+        response.bodyOutputStream.write("[]", 2);
+      } else {
+        response.setStatusLine(request.httpVersion, 500, "Alas");
+        response.bodyOutputStream.write("{}", 2);
+      }
+    },
+  });
+
+  const client = new FxAccountsClient(server.baseURI);
+
+  canReturnDevices = true;
+  const result = await client.getDeviceList(FAKE_SESSION_TOKEN);
+  Assert.ok(Array.isArray(result));
+  Assert.equal(result.length, 0);
+
+  try {
+    canReturnDevices = false;
+    await client.getDeviceList(FAKE_SESSION_TOKEN);
+    do_throw("Expected to catch an exception");
+  } catch (unexpectedError) {
+    Assert.equal(unexpectedError.code, 500);
+  }
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_client_metrics() {
+  function writeResp(response, msg) {
+    if (typeof msg === "object") {
+      msg = JSON.stringify(msg);
+    }
+    response.bodyOutputStream.write(msg, msg.length);
+  }
+
+  let server = httpd_setup({
+    "/session/destroy": function (request, response) {
+      response.setHeader("Content-Type", "application/json; charset=utf-8");
+      response.setStatusLine(request.httpVersion, 401, "Unauthorized");
+      writeResp(response, {
+        error: "invalid authentication timestamp",
+        code: 401,
+        errno: 111,
+      });
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+
+  await Assert.rejects(
+    client.signOut(FAKE_SESSION_TOKEN, {
+      service: "sync",
+    }),
+    function (err) {
+      return err.errno == 111;
+    }
+  );
+
+  await promiseStopServer(server);
+});
+
+add_task(async function test_email_case() {
+  let canonicalEmail = "greta.garbo@gmail.com";
+  let clientEmail = "Greta.Garbo@gmail.COM";
+  let attempts = 0;
+
+  function writeResp(response, msg) {
+    if (typeof msg === "object") {
+      msg = JSON.stringify(msg);
+    }
+    response.bodyOutputStream.write(msg, msg.length);
+  }
+
+  let server = httpd_setup({
+    "/account/login": function (request, response) {
+      response.setHeader("Content-Type", "application/json; charset=utf-8");
+      attempts += 1;
+      if (attempts > 2) {
+        response.setStatusLine(
+          request.httpVersion,
+          429,
+          "Sorry, you had your chance"
+        );
+        return writeResp(response, "");
+      }
+
+      let body = CommonUtils.readBytesFromInputStream(request.bodyInputStream);
+      let jsonBody = JSON.parse(body);
+      let email = jsonBody.email;
+
+      // If the client has the wrong case on the email, we return a 400, with
+      // the capitalization of the email as saved in the accounts database.
+      if (email == canonicalEmail) {
+        response.setStatusLine(request.httpVersion, 200, "Yay");
+        return writeResp(response, { areWeHappy: "yes" });
+      }
+
+      response.setStatusLine(request.httpVersion, 400, "Incorrect email case");
+      return writeResp(response, {
+        code: 400,
+        errno: 120,
+        error: "Incorrect email case",
+        email: canonicalEmail,
+      });
+    },
+  });
+
+  let client = new FxAccountsClient(server.baseURI);
+
+  let result = await client.signIn(clientEmail, "123456");
+  Assert.equal(result.areWeHappy, "yes");
+  Assert.equal(attempts, 2);
+
+  await promiseStopServer(server);
+});
+
+// turn formatted test vectors into normal hex strings
+function h(hexStr) {
+  return hexStr.replace(/\s+/g, "");
+}
diff --git a/services/fxaccounts/tests/xpcshell/test_commands.js b/services/fxaccounts/tests/xpcshell/test_commands.js
new file mode 100644
index 0000000000..c1e67ff105
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_commands.js
@@ -0,0 +1,708 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { FxAccountsCommands, SendTab } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsCommands.sys.mjs"
+);
+
+const { FxAccountsClient } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsClient.sys.mjs"
+);
+
+const { COMMAND_SENDTAB, COMMAND_SENDTAB_TAIL } = ChromeUtils.import(
+  "resource://gre/modules/FxAccountsCommon.js"
+);
+
+class TelemetryMock {
+  constructor() {
+    this._events = [];
+    this._uuid_counter = 0;
+  }
+
+  recordEvent(object, method, value, extra = undefined) {
+    this._events.push({ object, method, value, extra });
+  }
+
+  generateFlowID() {
+    this._uuid_counter += 1;
+    return this._uuid_counter.toString();
+  }
+
+  sanitizeDeviceId(id) {
+    return id + "-san";
+  }
+}
+
+function FxaInternalMock() {
+  return {
+    telemetry: new TelemetryMock(),
+  };
+}
+
+function MockFxAccountsClient() {
+  FxAccountsClient.apply(this);
+}
+
+MockFxAccountsClient.prototype = {};
+Object.setPrototypeOf(
+  MockFxAccountsClient.prototype,
+  FxAccountsClient.prototype
+);
+
+add_task(async function test_sendtab_isDeviceCompatible() {
+  const sendTab = new SendTab(null, null);
+  let device = { name: "My device" };
+  Assert.ok(!sendTab.isDeviceCompatible(device));
+  device = { name: "My device", availableCommands: {} };
+  Assert.ok(!sendTab.isDeviceCompatible(device));
+  device = {
+    name: "My device",
+    availableCommands: {
+      "https://identity.mozilla.com/cmd/open-uri": "payload",
+    },
+  };
+  Assert.ok(sendTab.isDeviceCompatible(device));
+});
+
+add_task(async function test_sendtab_send() {
+  const commands = {
+    invoke: sinon.spy((cmd, device, payload) => {
+      if (device.name == "Device 1") {
+        throw new Error("Invoke error!");
+      }
+      Assert.equal(payload.encrypted, "encryptedpayload");
+    }),
+  };
+  const fxai = FxaInternalMock();
+  const sendTab = new SendTab(commands, fxai);
+  sendTab._encrypt = (bytes, device) => {
+    if (device.name == "Device 2") {
+      throw new Error("Encrypt error!");
+    }
+    return "encryptedpayload";
+  };
+  const to = [
+    { name: "Device 1" },
+    { name: "Device 2" },
+    { id: "dev3", name: "Device 3" },
+  ];
+  // although we are sending to 3 devices, only 1 is successful - so there's
+  // only 1 streamID we care about. However, we've created IDs even for the
+  // failing items - so it's "4"
+  const expectedTelemetryStreamID = "4";
+  const tab = { title: "Foo", url: "https://foo.bar/" };
+  const report = await sendTab.send(to, tab);
+  Assert.equal(report.succeeded.length, 1);
+  Assert.equal(report.failed.length, 2);
+  Assert.equal(report.succeeded[0].name, "Device 3");
+  Assert.equal(report.failed[0].device.name, "Device 1");
+  Assert.equal(report.failed[0].error.message, "Invoke error!");
+  Assert.equal(report.failed[1].device.name, "Device 2");
+  Assert.equal(report.failed[1].error.message, "Encrypt error!");
+  Assert.ok(commands.invoke.calledTwice);
+  Assert.deepEqual(fxai.telemetry._events, [
+    {
+      object: "command-sent",
+      method: COMMAND_SENDTAB_TAIL,
+      value: "dev3-san",
+      extra: { flowID: "1", streamID: expectedTelemetryStreamID },
+    },
+  ]);
+});
+
+add_task(async function test_sendtab_send_rate_limit() {
+  const rateLimitReject = {
+    code: 429,
+    retryAfter: 5,
+    retryAfterLocalized: "retry after 5 seconds",
+  };
+  const fxAccounts = {
+    fxAccountsClient: new MockFxAccountsClient(),
+    getUserAccountData() {
+      return {};
+    },
+    telemetry: new TelemetryMock(),
+  };
+  let rejected = false;
+  let invoked = 0;
+  fxAccounts.fxAccountsClient.invokeCommand = async function invokeCommand() {
+    invoked++;
+    Assert.ok(invoked <= 2, "only called twice and not more");
+    if (rejected) {
+      return {};
+    }
+    rejected = true;
+    return Promise.reject(rateLimitReject);
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  const sendTab = new SendTab(commands, fxAccounts);
+  sendTab._encrypt = () => "encryptedpayload";
+
+  const tab = { title: "Foo", url: "https://foo.bar/" };
+  let report = await sendTab.send([{ name: "Device 1" }], tab);
+  Assert.equal(report.succeeded.length, 0);
+  Assert.equal(report.failed.length, 1);
+  Assert.equal(report.failed[0].error, rateLimitReject);
+
+  report = await sendTab.send([{ name: "Device 1" }], tab);
+  Assert.equal(report.succeeded.length, 0);
+  Assert.equal(report.failed.length, 1);
+  Assert.ok(
+    report.failed[0].error.message.includes(
+      "Invoke for " +
+        "https://identity.mozilla.com/cmd/open-uri is rate-limited"
+    )
+  );
+
+  commands._invokeRateLimitExpiry = Date.now() - 1000;
+  report = await sendTab.send([{ name: "Device 1" }], tab);
+  Assert.equal(report.succeeded.length, 1);
+  Assert.equal(report.failed.length, 0);
+});
+
+add_task(async function test_sendtab_receive() {
+  // We are testing 'receive' here, but might as well go through 'send'
+  // to package the data and for additional testing...
+  const commands = {
+    _invokes: [],
+    invoke(cmd, device, payload) {
+      this._invokes.push({ cmd, device, payload });
+    },
+  };
+
+  const fxai = FxaInternalMock();
+  const sendTab = new SendTab(commands, fxai);
+  sendTab._encrypt = (bytes, device) => {
+    return bytes;
+  };
+  sendTab._decrypt = bytes => {
+    return bytes;
+  };
+  const tab = { title: "tab title", url: "http://example.com" };
+  const to = [{ id: "devid", name: "The Device" }];
+  const reason = "push";
+
+  await sendTab.send(to, tab);
+  Assert.equal(commands._invokes.length, 1);
+
+  for (let { cmd, device, payload } of commands._invokes) {
+    Assert.equal(cmd, COMMAND_SENDTAB);
+    // Older Firefoxes would send a plaintext flowID in the top-level payload.
+    // Test that we sensibly ignore it.
+    Assert.ok(!payload.hasOwnProperty("flowID"));
+    // change it - ensure we still get what we expect in telemetry later.
+    payload.flowID = "ignore-me";
+    Assert.deepEqual(await sendTab.handle(device.id, payload, reason), {
+      title: "tab title",
+      uri: "http://example.com",
+    });
+  }
+
+  Assert.deepEqual(fxai.telemetry._events, [
+    {
+      object: "command-sent",
+      method: COMMAND_SENDTAB_TAIL,
+      value: "devid-san",
+      extra: { flowID: "1", streamID: "2" },
+    },
+    {
+      object: "command-received",
+      method: COMMAND_SENDTAB_TAIL,
+      value: "devid-san",
+      extra: { flowID: "1", streamID: "2", reason },
+    },
+  ]);
+});
+
+// Test that a client which only sends the flowID in the envelope and not in the
+// encrypted body gets recorded without the flowID.
+add_task(async function test_sendtab_receive_old_client() {
+  const fxai = FxaInternalMock();
+  const sendTab = new SendTab(null, fxai);
+  sendTab._decrypt = bytes => {
+    return bytes;
+  };
+  const data = { entries: [{ title: "title", url: "url" }] };
+  // No 'flowID' in the encrypted payload, no 'streamID' anywhere.
+  const payload = {
+    flowID: "flow-id",
+    encrypted: new TextEncoder().encode(JSON.stringify(data)),
+  };
+  const reason = "push";
+  await sendTab.handle("sender-id", payload, reason);
+  Assert.deepEqual(fxai.telemetry._events, [
+    {
+      object: "command-received",
+      method: COMMAND_SENDTAB_TAIL,
+      value: "sender-id-san",
+      // deepEqual doesn't ignore undefined, but our telemetry code and
+      // JSON.stringify() do...
+      extra: { flowID: undefined, streamID: undefined, reason },
+    },
+  ]);
+});
+
+add_task(function test_commands_getReason() {
+  const fxAccounts = {
+    async withCurrentAccountState(cb) {
+      await cb({});
+    },
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  const testCases = [
+    {
+      receivedIndex: 0,
+      currentIndex: 0,
+      expectedReason: "poll",
+      message: "should return reason 'poll'",
+    },
+    {
+      receivedIndex: 7,
+      currentIndex: 3,
+      expectedReason: "push-missed",
+      message: "should return reason 'push-missed'",
+    },
+    {
+      receivedIndex: 2,
+      currentIndex: 8,
+      expectedReason: "push",
+      message: "should return reason 'push'",
+    },
+  ];
+  for (const tc of testCases) {
+    const reason = commands._getReason(tc.receivedIndex, tc.currentIndex);
+    Assert.equal(reason, tc.expectedReason, tc.message);
+  }
+});
+
+add_task(async function test_commands_pollDeviceCommands_push() {
+  // Server state.
+  const remoteMessages = [
+    {
+      index: 11,
+      data: {},
+    },
+    {
+      index: 12,
+      data: {},
+    },
+  ];
+  const remoteIndex = 12;
+
+  // Local state.
+  const pushIndexReceived = 11;
+  const accountState = {
+    data: {
+      device: {
+        lastCommandIndex: 10,
+      },
+    },
+    getUserAccountData() {
+      return this.data;
+    },
+    updateUserAccountData(data) {
+      this.data = data;
+    },
+  };
+
+  const fxAccounts = {
+    async withCurrentAccountState(cb) {
+      await cb(accountState);
+    },
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  const mockCommands = sinon.mock(commands);
+  mockCommands.expects("_fetchDeviceCommands").once().withArgs(11).returns({
+    index: remoteIndex,
+    messages: remoteMessages,
+  });
+  mockCommands
+    .expects("_handleCommands")
+    .once()
+    .withArgs(remoteMessages, pushIndexReceived);
+  await commands.pollDeviceCommands(pushIndexReceived);
+
+  mockCommands.verify();
+  Assert.equal(accountState.data.device.lastCommandIndex, 12);
+});
+
+add_task(
+  async function test_commands_pollDeviceCommands_push_already_fetched() {
+    // Local state.
+    const pushIndexReceived = 12;
+    const accountState = {
+      data: {
+        device: {
+          lastCommandIndex: 12,
+        },
+      },
+      getUserAccountData() {
+        return this.data;
+      },
+      updateUserAccountData(data) {
+        this.data = data;
+      },
+    };
+
+    const fxAccounts = {
+      async withCurrentAccountState(cb) {
+        await cb(accountState);
+      },
+    };
+    const commands = new FxAccountsCommands(fxAccounts);
+    const mockCommands = sinon.mock(commands);
+    mockCommands.expects("_fetchDeviceCommands").never();
+    mockCommands.expects("_handleCommands").never();
+    await commands.pollDeviceCommands(pushIndexReceived);
+
+    mockCommands.verify();
+    Assert.equal(accountState.data.device.lastCommandIndex, 12);
+  }
+);
+
+add_task(async function test_commands_handleCommands() {
+  // This test ensures that `_getReason` is being called by
+  // `_handleCommands` with the expected parameters.
+  const pushIndexReceived = 12;
+  const senderID = "6d09f6c4-89b2-41b3-a0ac-e4c2502b5485";
+  const remoteMessageIndex = 8;
+  const remoteMessages = [
+    {
+      index: remoteMessageIndex,
+      data: {
+        command: COMMAND_SENDTAB,
+        payload: {
+          encrypted: {},
+        },
+        sender: senderID,
+      },
+    },
+  ];
+
+  const fxAccounts = {
+    async withCurrentAccountState(cb) {
+      await cb({});
+    },
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  commands.sendTab.handle = (sender, data, reason) => {
+    return {
+      title: "testTitle",
+      uri: "https://testURI",
+    };
+  };
+  commands._fxai.device = {
+    refreshDeviceList: () => {},
+    recentDeviceList: [
+      {
+        id: senderID,
+      },
+    ],
+  };
+  const mockCommands = sinon.mock(commands);
+  mockCommands
+    .expects("_getReason")
+    .once()
+    .withExactArgs(pushIndexReceived, remoteMessageIndex);
+  mockCommands.expects("_notifyFxATabsReceived").once();
+  await commands._handleCommands(remoteMessages, pushIndexReceived);
+  mockCommands.verify();
+});
+
+add_task(async function test_commands_handleCommands_invalid_tab() {
+  // This test ensures that `_getReason` is being called by
+  // `_handleCommands` with the expected parameters.
+  const pushIndexReceived = 12;
+  const senderID = "6d09f6c4-89b2-41b3-a0ac-e4c2502b5485";
+  const remoteMessageIndex = 8;
+  const remoteMessages = [
+    {
+      index: remoteMessageIndex,
+      data: {
+        command: COMMAND_SENDTAB,
+        payload: {
+          encrypted: {},
+        },
+        sender: senderID,
+      },
+    },
+  ];
+
+  const fxAccounts = {
+    async withCurrentAccountState(cb) {
+      await cb({});
+    },
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  commands.sendTab.handle = (sender, data, reason) => {
+    return {
+      title: "badUriTab",
+      uri: "file://path/to/pdf",
+    };
+  };
+  commands._fxai.device = {
+    refreshDeviceList: () => {},
+    recentDeviceList: [
+      {
+        id: senderID,
+      },
+    ],
+  };
+  const mockCommands = sinon.mock(commands);
+  mockCommands
+    .expects("_getReason")
+    .once()
+    .withExactArgs(pushIndexReceived, remoteMessageIndex);
+  // We shouldn't have tried to open a tab with an invalid uri
+  mockCommands.expects("_notifyFxATabsReceived").never();
+
+  await commands._handleCommands(remoteMessages, pushIndexReceived);
+  mockCommands.verify();
+});
+
+add_task(
+  async function test_commands_pollDeviceCommands_push_local_state_empty() {
+    // Server state.
+    const remoteMessages = [
+      {
+        index: 11,
+        data: {},
+      },
+      {
+        index: 12,
+        data: {},
+      },
+    ];
+    const remoteIndex = 12;
+
+    // Local state.
+    const pushIndexReceived = 11;
+    const accountState = {
+      data: {
+        device: {},
+      },
+      getUserAccountData() {
+        return this.data;
+      },
+      updateUserAccountData(data) {
+        this.data = data;
+      },
+    };
+
+    const fxAccounts = {
+      async withCurrentAccountState(cb) {
+        await cb(accountState);
+      },
+    };
+    const commands = new FxAccountsCommands(fxAccounts);
+    const mockCommands = sinon.mock(commands);
+    mockCommands.expects("_fetchDeviceCommands").once().withArgs(11).returns({
+      index: remoteIndex,
+      messages: remoteMessages,
+    });
+    mockCommands
+      .expects("_handleCommands")
+      .once()
+      .withArgs(remoteMessages, pushIndexReceived);
+    await commands.pollDeviceCommands(pushIndexReceived);
+
+    mockCommands.verify();
+    Assert.equal(accountState.data.device.lastCommandIndex, 12);
+  }
+);
+
+add_task(async function test_commands_pollDeviceCommands_scheduled_local() {
+  // Server state.
+  const remoteMessages = [
+    {
+      index: 11,
+      data: {},
+    },
+    {
+      index: 12,
+      data: {},
+    },
+  ];
+  const remoteIndex = 12;
+  const pushIndexReceived = 0;
+  // Local state.
+  const accountState = {
+    data: {
+      device: {
+        lastCommandIndex: 10,
+      },
+    },
+    getUserAccountData() {
+      return this.data;
+    },
+    updateUserAccountData(data) {
+      this.data = data;
+    },
+  };
+
+  const fxAccounts = {
+    async withCurrentAccountState(cb) {
+      await cb(accountState);
+    },
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  const mockCommands = sinon.mock(commands);
+  mockCommands.expects("_fetchDeviceCommands").once().withArgs(11).returns({
+    index: remoteIndex,
+    messages: remoteMessages,
+  });
+  mockCommands
+    .expects("_handleCommands")
+    .once()
+    .withArgs(remoteMessages, pushIndexReceived);
+  await commands.pollDeviceCommands();
+
+  mockCommands.verify();
+  Assert.equal(accountState.data.device.lastCommandIndex, 12);
+});
+
+add_task(
+  async function test_commands_pollDeviceCommands_scheduled_local_state_empty() {
+    // Server state.
+    const remoteMessages = [
+      {
+        index: 11,
+        data: {},
+      },
+      {
+        index: 12,
+        data: {},
+      },
+    ];
+    const remoteIndex = 12;
+    const pushIndexReceived = 0;
+    // Local state.
+    const accountState = {
+      data: {
+        device: {},
+      },
+      getUserAccountData() {
+        return this.data;
+      },
+      updateUserAccountData(data) {
+        this.data = data;
+      },
+    };
+
+    const fxAccounts = {
+      async withCurrentAccountState(cb) {
+        await cb(accountState);
+      },
+    };
+    const commands = new FxAccountsCommands(fxAccounts);
+    const mockCommands = sinon.mock(commands);
+    mockCommands.expects("_fetchDeviceCommands").once().withArgs(0).returns({
+      index: remoteIndex,
+      messages: remoteMessages,
+    });
+    mockCommands
+      .expects("_handleCommands")
+      .once()
+      .withArgs(remoteMessages, pushIndexReceived);
+    await commands.pollDeviceCommands();
+
+    mockCommands.verify();
+    Assert.equal(accountState.data.device.lastCommandIndex, 12);
+  }
+);
+
+add_task(async function test_send_tab_keys_regenerated_if_lost() {
+  const commands = {
+    _invokes: [],
+    invoke(cmd, device, payload) {
+      this._invokes.push({ cmd, device, payload });
+    },
+  };
+
+  // Local state.
+  const accountState = {
+    data: {
+      // Since the device object has no
+      // sendTabKeys, it will recover
+      // when we attempt to get the
+      // encryptedSendTabKeys
+      device: {
+        lastCommandIndex: 10,
+      },
+      encryptedSendTabKeys: "keys",
+    },
+    getUserAccountData() {
+      return this.data;
+    },
+    updateUserAccountData(data) {
+      this.data = data;
+    },
+  };
+
+  const fxAccounts = {
+    async withCurrentAccountState(cb) {
+      await cb(accountState);
+    },
+    async getUserAccountData(data) {
+      return accountState.getUserAccountData(data);
+    },
+    telemetry: new TelemetryMock(),
+  };
+  const sendTab = new SendTab(commands, fxAccounts);
+  let generateEncryptedKeysCalled = false;
+  sendTab._generateAndPersistEncryptedSendTabKey = async () => {
+    generateEncryptedKeysCalled = true;
+  };
+  await sendTab.getEncryptedSendTabKeys();
+  Assert.ok(generateEncryptedKeysCalled);
+});
+
+add_task(async function test_send_tab_keys_are_not_regenerated_if_not_lost() {
+  const commands = {
+    _invokes: [],
+    invoke(cmd, device, payload) {
+      this._invokes.push({ cmd, device, payload });
+    },
+  };
+
+  // Local state.
+  const accountState = {
+    data: {
+      // Since the device object has
+      // sendTabKeys, it will not try
+      // to regenerate them
+      // when we attempt to get the
+      // encryptedSendTabKeys
+      device: {
+        lastCommandIndex: 10,
+        sendTabKeys: "keys",
+      },
+      encryptedSendTabKeys: "encrypted-keys",
+    },
+    getUserAccountData() {
+      return this.data;
+    },
+    updateUserAccountData(data) {
+      this.data = data;
+    },
+  };
+
+  const fxAccounts = {
+    async withCurrentAccountState(cb) {
+      await cb(accountState);
+    },
+    async getUserAccountData(data) {
+      return accountState.getUserAccountData(data);
+    },
+    telemetry: new TelemetryMock(),
+  };
+  const sendTab = new SendTab(commands, fxAccounts);
+  let generateEncryptedKeysCalled = false;
+  sendTab._generateAndPersistEncryptedSendTabKey = async () => {
+    generateEncryptedKeysCalled = true;
+  };
+  await sendTab.getEncryptedSendTabKeys();
+  Assert.ok(!generateEncryptedKeysCalled);
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_credentials.js b/services/fxaccounts/tests/xpcshell/test_credentials.js
new file mode 100644
index 0000000000..c3656f219d
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_credentials.js
@@ -0,0 +1,130 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const { Credentials } = ChromeUtils.importESModule(
+  "resource://gre/modules/Credentials.sys.mjs"
+);
+const { CryptoUtils } = ChromeUtils.importESModule(
+  "resource://services-crypto/utils.sys.mjs"
+);
+
+var { hexToBytes: h2b, hexAsString: h2s, bytesAsHex: b2h } = CommonUtils;
+
+// Test vectors for the "onepw" protocol:
+// https://github.com/mozilla/fxa-auth-server/wiki/onepw-protocol#wiki-test-vectors
+var vectors = {
+  "client stretch-KDF": {
+    email: h("616e6472c3a94065 78616d706c652e6f 7267"),
+    password: h("70c3a4737377c3b6 7264"),
+    quickStretchedPW: h(
+      "e4e8889bd8bd61ad 6de6b95c059d56e7 b50dacdaf62bd846 44af7e2add84345d"
+    ),
+    authPW: h(
+      "247b675ffb4c4631 0bc87e26d712153a be5e1c90ef00a478 4594f97ef54f2375"
+    ),
+    authSalt: h(
+      "00f0000000000000 0000000000000000 0000000000000000 0000000000000000"
+    ),
+  },
+};
+
+// A simple test suite with no utf8 encoding madness.
+add_task(async function test_onepw_setup_credentials() {
+  let email = "francine@example.org";
+  let password = CommonUtils.encodeUTF8("i like pie");
+
+  let pbkdf2 = CryptoUtils.pbkdf2Generate;
+  let hkdf = CryptoUtils.hkdfLegacy;
+
+  // quickStretch the email
+  let saltyEmail = Credentials.keyWordExtended("quickStretch", email);
+
+  Assert.equal(
+    b2h(saltyEmail),
+    "6964656e746974792e6d6f7a696c6c612e636f6d2f7069636c2f76312f717569636b537472657463683a6672616e63696e65406578616d706c652e6f7267"
+  );
+
+  let pbkdf2Rounds = 1000;
+  let pbkdf2Len = 32;
+
+  let quickStretchedPW = await pbkdf2(
+    password,
+    saltyEmail,
+    pbkdf2Rounds,
+    pbkdf2Len
+  );
+  let quickStretchedActual =
+    "6b88094c1c73bbf133223f300d101ed70837af48d9d2c1b6e7d38804b20cdde4";
+  Assert.equal(b2h(quickStretchedPW), quickStretchedActual);
+
+  // obtain hkdf info
+  let authKeyInfo = Credentials.keyWord("authPW");
+  Assert.equal(
+    b2h(authKeyInfo),
+    "6964656e746974792e6d6f7a696c6c612e636f6d2f7069636c2f76312f617574685057"
+  );
+
+  // derive auth password
+  let hkdfSalt = h2b("00");
+  let hkdfLen = 32;
+  let authPW = await hkdf(quickStretchedPW, hkdfSalt, authKeyInfo, hkdfLen);
+
+  Assert.equal(
+    b2h(authPW),
+    "4b8dec7f48e7852658163601ff766124c312f9392af6c3d4e1a247eb439be342"
+  );
+
+  // derive unwrap key
+  let unwrapKeyInfo = Credentials.keyWord("unwrapBkey");
+  let unwrapKey = await hkdf(
+    quickStretchedPW,
+    hkdfSalt,
+    unwrapKeyInfo,
+    hkdfLen
+  );
+
+  Assert.equal(
+    b2h(unwrapKey),
+    "8ff58975be391338e4ec5d7138b5ed7b65c7d1bfd1f3a4f93e05aa47d5b72be9"
+  );
+});
+
+add_task(async function test_client_stretch_kdf() {
+  let expected = vectors["client stretch-KDF"];
+
+  let email = h2s(expected.email);
+  let password = h2s(expected.password);
+
+  // Intermediate value from sjcl implementation in fxa-js-client
+  // The key thing is the c3a9 sequence in "andré"
+  let salt = Credentials.keyWordExtended("quickStretch", email);
+  Assert.equal(
+    b2h(salt),
+    "6964656e746974792e6d6f7a696c6c612e636f6d2f7069636c2f76312f717569636b537472657463683a616e6472c3a9406578616d706c652e6f7267"
+  );
+
+  let options = {
+    stretchedPassLength: 32,
+    pbkdf2Rounds: 1000,
+    hkdfSalt: h2b("00"),
+    hkdfLength: 32,
+  };
+
+  let results = await Credentials.setup(email, password, options);
+
+  Assert.equal(
+    expected.quickStretchedPW,
+    b2h(results.quickStretchedPW),
+    "quickStretchedPW is wrong"
+  );
+
+  Assert.equal(expected.authPW, b2h(results.authPW), "authPW is wrong");
+});
+
+// End of tests
+// Utility functions follow
+
+// turn formatted test vectors into normal hex strings
+function h(hexStr) {
+  return hexStr.replace(/\s+/g, "");
+}
diff --git a/services/fxaccounts/tests/xpcshell/test_device.js b/services/fxaccounts/tests/xpcshell/test_device.js
new file mode 100644
index 0000000000..a7793fd856
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_device.js
@@ -0,0 +1,127 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { getFxAccountsSingleton } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+const fxAccounts = getFxAccountsSingleton();
+
+const { ON_NEW_DEVICE_ID, PREF_ACCOUNT_ROOT } = ChromeUtils.import(
+  "resource://gre/modules/FxAccountsCommon.js"
+);
+
+function promiseObserved(topic) {
+  return new Promise(res => {
+    Services.obs.addObserver(res, topic);
+  });
+}
+
+_("Misc tests for FxAccounts.device");
+
+fxAccounts.device._checkRemoteCommandsUpdateNeeded = async () => false;
+
+add_test(function test_default_device_name() {
+  // Note that head_helpers overrides getDefaultLocalName - this test is
+  // really just to ensure the actual implementation is sane - we can't
+  // really check the value it uses is correct.
+  // We are just hoping to avoid a repeat of bug 1369285.
+  let def = fxAccounts.device.getDefaultLocalName(); // make sure it doesn't throw.
+  _("default value is " + def);
+  ok(!!def.length);
+
+  // This is obviously tied to the implementation, but we want early warning
+  // if any of these things fail.
+  // We really want one of these 2 to provide a value.
+  let hostname = Services.sysinfo.get("device") || Services.dns.myHostName;
+  _("hostname is " + hostname);
+  ok(!!hostname.length);
+  // the hostname should be in the default.
+  ok(def.includes(hostname));
+  // We expect the following to work as a fallback to the above.
+  let fallback = Cc["@mozilla.org/network/protocol;1?name=http"].getService(
+    Ci.nsIHttpProtocolHandler
+  ).oscpu;
+  _("UA fallback is " + fallback);
+  ok(!!fallback.length);
+  // the fallback should not be in the default
+  ok(!def.includes(fallback));
+
+  run_next_test();
+});
+
+add_test(function test_migration() {
+  Services.prefs.clearUserPref("identity.fxaccounts.account.device.name");
+  Services.prefs.setStringPref("services.sync.client.name", "my client name");
+  // calling getLocalName() should move the name to the new pref and reset the old.
+  equal(fxAccounts.device.getLocalName(), "my client name");
+  equal(
+    Services.prefs.getStringPref("identity.fxaccounts.account.device.name"),
+    "my client name"
+  );
+  ok(!Services.prefs.prefHasUserValue("services.sync.client.name"));
+  run_next_test();
+});
+
+add_test(function test_migration_set_before_get() {
+  Services.prefs.setStringPref("services.sync.client.name", "old client name");
+  fxAccounts.device.setLocalName("new client name");
+  equal(fxAccounts.device.getLocalName(), "new client name");
+  run_next_test();
+});
+
+add_task(async function test_reset() {
+  // We don't test the client name specifically here because the client name
+  // is set as part of signing the user in via the attempt to register the
+  // device.
+  const testPref = PREF_ACCOUNT_ROOT + "test-pref";
+  Services.prefs.setStringPref(testPref, "whatever");
+  let credentials = {
+    email: "foo@example.com",
+    uid: "1234@lcip.org",
+    sessionToken: "dead",
+    verified: true,
+    ...MOCK_ACCOUNT_KEYS,
+  };
+  // FxA will try to register its device record in the background after signin.
+  const registerDevice = sinon
+    .stub(fxAccounts._internal.fxAccountsClient, "registerDevice")
+    .callsFake(async () => {
+      return { id: "foo" };
+    });
+  await fxAccounts._internal.setSignedInUser(credentials);
+  // wait for device registration to complete.
+  await promiseObserved(ON_NEW_DEVICE_ID);
+  ok(!Services.prefs.prefHasUserValue(testPref));
+  // signing the user out should reset the name pref.
+  const namePref = PREF_ACCOUNT_ROOT + "device.name";
+  ok(Services.prefs.prefHasUserValue(namePref));
+  await fxAccounts.signOut(/* localOnly = */ true);
+  ok(!Services.prefs.prefHasUserValue(namePref));
+  registerDevice.restore();
+});
+
+add_task(async function test_name_sanitization() {
+  fxAccounts.device.setLocalName("emoji is valid \u2665");
+  Assert.equal(fxAccounts.device.getLocalName(), "emoji is valid \u2665");
+
+  let invalid = "x\uFFFD\n\r\t" + "x".repeat(255);
+  let sanitized = "x\uFFFD\uFFFD\uFFFD\uFFFD" + "x".repeat(250); // 255 total.
+
+  // If the pref already has the invalid value we still get the valid one back.
+  Services.prefs.setStringPref(
+    "identity.fxaccounts.account.device.name",
+    invalid
+  );
+  Assert.equal(fxAccounts.device.getLocalName(), sanitized);
+
+  // But if we explicitly set it to an invalid name, the sanitized value ends
+  // up in the pref.
+  fxAccounts.device.setLocalName(invalid);
+  Assert.equal(fxAccounts.device.getLocalName(), sanitized);
+  Assert.equal(
+    Services.prefs.getStringPref("identity.fxaccounts.account.device.name"),
+    sanitized
+  );
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_keys.js b/services/fxaccounts/tests/xpcshell/test_keys.js
new file mode 100644
index 0000000000..6e650a1609
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_keys.js
@@ -0,0 +1,182 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { FxAccountsKeys } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsKeys.sys.mjs"
+);
+
+// Ref https://github.com/mozilla/fxa-crypto-relier/ for the details
+// of these test vectors.
+
+add_task(async function test_derive_scoped_key_test_vector() {
+  const keys = new FxAccountsKeys(null);
+  const uid = "aeaa1725c7a24ff983c6295725d5fc9b";
+  const kB = "8b2e1303e21eee06a945683b8d495b9bf079ca30baa37eb8392d9ffa4767be45";
+  const scopedKeyMetadata = {
+    identifier: "app_key:https%3A//example.com",
+    keyRotationTimestamp: 1510726317000,
+    keyRotationSecret:
+      "517d478cb4f994aa69930416648a416fdaa1762c5abf401a2acf11a0f185e98d",
+  };
+
+  const scopedKey = await keys._deriveScopedKey(
+    uid,
+    CommonUtils.hexToBytes(kB),
+    "app_key",
+    scopedKeyMetadata
+  );
+
+  Assert.deepEqual(scopedKey, {
+    kty: "oct",
+    kid: "1510726317-Voc-Eb9IpoTINuo9ll7bjA",
+    k: "Kkbk1_Q0oCcTmggeDH6880bQrxin2RLu5D00NcJazdQ",
+  });
+});
+
+add_task(async function test_derive_legacy_sync_key_test_vector() {
+  const keys = new FxAccountsKeys(null);
+  const uid = "aeaa1725c7a24ff983c6295725d5fc9b";
+  const kB = "eaf9570b7219a4187d3d6bf3cec2770c2e0719b7cc0dfbb38243d6f1881675e9";
+  const scopedKeyMetadata = {
+    identifier: "https://identity.mozilla.com/apps/oldsync",
+    keyRotationTimestamp: 1510726317123,
+    keyRotationSecret:
+      "0000000000000000000000000000000000000000000000000000000000000000",
+  };
+
+  const scopedKey = await keys._deriveLegacyScopedKey(
+    uid,
+    CommonUtils.hexToBytes(kB),
+    "https://identity.mozilla.com/apps/oldsync",
+    scopedKeyMetadata
+  );
+
+  Assert.deepEqual(scopedKey, {
+    kty: "oct",
+    kid: "1510726317123-IqQv4onc7VcVE1kTQkyyOw",
+    k: "DW_ll5GwX6SJ5GPqJVAuMUP2t6kDqhUulc2cbt26xbTcaKGQl-9l29FHAQ7kUiJETma4s9fIpEHrt909zgFang",
+  });
+});
+
+add_task(async function test_derive_multiple_keys_at_once() {
+  const keys = new FxAccountsKeys(null);
+  const uid = "aeaa1725c7a24ff983c6295725d5fc9b";
+  const kB = "eaf9570b7219a4187d3d6bf3cec2770c2e0719b7cc0dfbb38243d6f1881675e9";
+  const scopedKeysMetadata = {
+    app_key: {
+      identifier: "app_key:https%3A//example.com",
+      keyRotationTimestamp: 1510726317000,
+      keyRotationSecret:
+        "517d478cb4f994aa69930416648a416fdaa1762c5abf401a2acf11a0f185e98d",
+    },
+    "https://identity.mozilla.com/apps/oldsync": {
+      identifier: "https://identity.mozilla.com/apps/oldsync",
+      keyRotationTimestamp: 1510726318123,
+      keyRotationSecret:
+        "0000000000000000000000000000000000000000000000000000000000000000",
+    },
+  };
+
+  const scopedKeys = await keys._deriveScopedKeys(
+    uid,
+    CommonUtils.hexToBytes(kB),
+    scopedKeysMetadata
+  );
+
+  Assert.deepEqual(scopedKeys, {
+    app_key: {
+      kty: "oct",
+      kid: "1510726317-tUkxiR1lTlFrTgkF0tJidA",
+      k: "TYK6Hmj86PfKiqsk9DZmX61nxk9VsExGrwo94HP-0wU",
+    },
+    "https://identity.mozilla.com/apps/oldsync": {
+      kty: "oct",
+      kid: "1510726318123-IqQv4onc7VcVE1kTQkyyOw",
+      k: "DW_ll5GwX6SJ5GPqJVAuMUP2t6kDqhUulc2cbt26xbTcaKGQl-9l29FHAQ7kUiJETma4s9fIpEHrt909zgFang",
+    },
+  });
+});
+
+add_task(async function test_rejects_bad_scoped_key_data() {
+  const keys = new FxAccountsKeys(null);
+  const uid = "aeaa1725c7a24ff983c6295725d5fc9b";
+  const kB = "8b2e1303e21eee06a945683b8d495b9bf079ca30baa37eb8392d9ffa4767be45";
+  const scopedKeyMetadata = {
+    identifier: "app_key:https%3A//example.com",
+    keyRotationTimestamp: 1510726317000,
+    keyRotationSecret:
+      "517d478cb4f994aa69930416648a416fdaa1762c5abf401a2acf11a0f185e98d",
+  };
+
+  await Assert.rejects(
+    keys._deriveScopedKey(
+      uid.slice(0, -1),
+      CommonUtils.hexToBytes(kB),
+      "app_key",
+      scopedKeyMetadata
+    ),
+    /uid must be a 32-character hex string/
+  );
+  await Assert.rejects(
+    keys._deriveScopedKey(
+      uid.slice(0, -1) + "Q",
+      CommonUtils.hexToBytes(kB),
+      "app_key",
+      scopedKeyMetadata
+    ),
+    /uid must be a 32-character hex string/
+  );
+  await Assert.rejects(
+    keys._deriveScopedKey(
+      uid,
+      CommonUtils.hexToBytes(kB).slice(0, -1),
+      "app_key",
+      scopedKeyMetadata
+    ),
+    /kBbytes must be exactly 32 bytes/
+  );
+  await Assert.rejects(
+    keys._deriveScopedKey(uid, CommonUtils.hexToBytes(kB), "app_key", {
+      ...scopedKeyMetadata,
+      identifier: "foo",
+    }),
+    /identifier must be a string of length >= 10/
+  );
+  await Assert.rejects(
+    keys._deriveScopedKey(uid, CommonUtils.hexToBytes(kB), "app_key", {
+      ...scopedKeyMetadata,
+      identifier: {},
+    }),
+    /identifier must be a string of length >= 10/
+  );
+  await Assert.rejects(
+    keys._deriveScopedKey(uid, CommonUtils.hexToBytes(kB), "app_key", {
+      ...scopedKeyMetadata,
+      keyRotationTimestamp: "xyz",
+    }),
+    /keyRotationTimestamp must be a number/
+  );
+  await Assert.rejects(
+    keys._deriveScopedKey(uid, CommonUtils.hexToBytes(kB), "app_key", {
+      ...scopedKeyMetadata,
+      keyRotationTimestamp: 12345,
+    }),
+    /keyRotationTimestamp must round to a 10-digit number/
+  );
+  await Assert.rejects(
+    keys._deriveScopedKey(uid, CommonUtils.hexToBytes(kB), "app_key", {
+      ...scopedKeyMetadata,
+      keyRotationSecret: scopedKeyMetadata.keyRotationSecret.slice(0, -1),
+    }),
+    /keyRotationSecret must be a 64-character hex string/
+  );
+  await Assert.rejects(
+    keys._deriveScopedKey(uid, CommonUtils.hexToBytes(kB), "app_key", {
+      ...scopedKeyMetadata,
+      keyRotationSecret: scopedKeyMetadata.keyRotationSecret.slice(0, -1) + "z",
+    }),
+    /keyRotationSecret must be a 64-character hex string/
+  );
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_loginmgr_storage.js b/services/fxaccounts/tests/xpcshell/test_loginmgr_storage.js
new file mode 100644
index 0000000000..7abbd0e44a
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_loginmgr_storage.js
@@ -0,0 +1,314 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Tests for FxAccounts, storage and the master password.
+
+// See verbose logging from FxAccounts.jsm
+Services.prefs.setCharPref("identity.fxaccounts.loglevel", "Trace");
+
+const { FxAccounts } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+const { FXA_PWDMGR_HOST, FXA_PWDMGR_REALM } = ChromeUtils.import(
+  "resource://gre/modules/FxAccountsCommon.js"
+);
+
+// Use a backstage pass to get at our LoginManagerStorage object, so we can
+// mock the prototype.
+var { LoginManagerStorage } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsStorage.sys.mjs"
+);
+var isLoggedIn = true;
+LoginManagerStorage.prototype.__defineGetter__("_isLoggedIn", () => isLoggedIn);
+
+function setLoginMgrLoggedInState(loggedIn) {
+  isLoggedIn = loggedIn;
+}
+
+initTestLogging("Trace");
+
+function getLoginMgrData() {
+  let logins = Services.logins.findLogins(
+    FXA_PWDMGR_HOST,
+    null,
+    FXA_PWDMGR_REALM
+  );
+  if (!logins.length) {
+    return null;
+  }
+  Assert.equal(logins.length, 1, "only 1 login available");
+  return logins[0];
+}
+
+function createFxAccounts() {
+  return new FxAccounts({
+    _fxAccountsClient: {
+      async registerDevice() {
+        return { id: "deviceAAAAAA" };
+      },
+      async recoveryEmailStatus() {
+        return { verified: true };
+      },
+      async signOut() {},
+    },
+    updateDeviceRegistration() {},
+    _getDeviceName() {
+      return "mock device name";
+    },
+    observerPreloads: [],
+    fxaPushService: {
+      async registerPushEndpoint() {
+        return {
+          endpoint: "http://mochi.test:8888",
+          getKey() {
+            return null;
+          },
+        };
+      },
+      async unsubscribe() {
+        return true;
+      },
+    },
+  });
+}
+
+add_task(async function test_simple() {
+  let fxa = createFxAccounts();
+
+  let creds = {
+    uid: "abcd",
+    email: "test@example.com",
+    sessionToken: "sessionToken",
+    kSync: "the kSync value",
+    kXCS: "the kXCS value",
+    kExtSync: "the kExtSync value",
+    kExtKbHash: "the kExtKbHash value",
+    verified: true,
+  };
+  await fxa._internal.setSignedInUser(creds);
+
+  // This should have stored stuff in both the .json file in the profile
+  // dir, and the login dir.
+  let path = PathUtils.join(PathUtils.profileDir, "signedInUser.json");
+  let data = await IOUtils.readJSON(path);
+
+  Assert.strictEqual(
+    data.accountData.email,
+    creds.email,
+    "correct email in the clear text"
+  );
+  Assert.strictEqual(
+    data.accountData.sessionToken,
+    creds.sessionToken,
+    "correct sessionToken in the clear text"
+  );
+  Assert.strictEqual(
+    data.accountData.verified,
+    creds.verified,
+    "correct verified flag"
+  );
+
+  Assert.ok(!("kSync" in data.accountData), "kSync not stored in clear text");
+  Assert.ok(!("kXCS" in data.accountData), "kXCS not stored in clear text");
+  Assert.ok(
+    !("kExtSync" in data.accountData),
+    "kExtSync not stored in clear text"
+  );
+  Assert.ok(
+    !("kExtKbHash" in data.accountData),
+    "kExtKbHash not stored in clear text"
+  );
+
+  let login = getLoginMgrData();
+  Assert.strictEqual(login.username, creds.uid, "uid used for username");
+  let loginData = JSON.parse(login.password);
+  Assert.strictEqual(
+    loginData.version,
+    data.version,
+    "same version flag in both places"
+  );
+  Assert.strictEqual(
+    loginData.accountData.kSync,
+    creds.kSync,
+    "correct kSync in the login mgr"
+  );
+  Assert.strictEqual(
+    loginData.accountData.kXCS,
+    creds.kXCS,
+    "correct kXCS in the login mgr"
+  );
+  Assert.strictEqual(
+    loginData.accountData.kExtSync,
+    creds.kExtSync,
+    "correct kExtSync in the login mgr"
+  );
+  Assert.strictEqual(
+    loginData.accountData.kExtKbHash,
+    creds.kExtKbHash,
+    "correct kExtKbHash in the login mgr"
+  );
+
+  Assert.ok(!("email" in loginData), "email not stored in the login mgr json");
+  Assert.ok(
+    !("sessionToken" in loginData),
+    "sessionToken not stored in the login mgr json"
+  );
+  Assert.ok(
+    !("verified" in loginData),
+    "verified not stored in the login mgr json"
+  );
+
+  await fxa.signOut(/* localOnly = */ true);
+  Assert.strictEqual(
+    getLoginMgrData(),
+    null,
+    "login mgr data deleted on logout"
+  );
+});
+
+add_task(async function test_MPLocked() {
+  let fxa = createFxAccounts();
+
+  let creds = {
+    uid: "abcd",
+    email: "test@example.com",
+    sessionToken: "sessionToken",
+    kSync: "the kSync value",
+    kXCS: "the kXCS value",
+    kExtSync: "the kExtSync value",
+    kExtKbHash: "the kExtKbHash value",
+    verified: true,
+  };
+
+  Assert.strictEqual(getLoginMgrData(), null, "no login mgr at the start");
+  // tell the storage that the MP is locked.
+  setLoginMgrLoggedInState(false);
+  await fxa._internal.setSignedInUser(creds);
+
+  // This should have stored stuff in the .json, and the login manager stuff
+  // will not exist.
+  let path = PathUtils.join(PathUtils.profileDir, "signedInUser.json");
+  let data = await IOUtils.readJSON(path);
+
+  Assert.strictEqual(
+    data.accountData.email,
+    creds.email,
+    "correct email in the clear text"
+  );
+  Assert.strictEqual(
+    data.accountData.sessionToken,
+    creds.sessionToken,
+    "correct sessionToken in the clear text"
+  );
+  Assert.strictEqual(
+    data.accountData.verified,
+    creds.verified,
+    "correct verified flag"
+  );
+
+  Assert.ok(!("kSync" in data.accountData), "kSync not stored in clear text");
+  Assert.ok(!("kXCS" in data.accountData), "kXCS not stored in clear text");
+  Assert.ok(
+    !("kExtSync" in data.accountData),
+    "kExtSync not stored in clear text"
+  );
+  Assert.ok(
+    !("kExtKbHash" in data.accountData),
+    "kExtKbHash not stored in clear text"
+  );
+
+  Assert.strictEqual(getLoginMgrData(), null, "login mgr data doesn't exist");
+  await fxa.signOut(/* localOnly = */ true);
+});
+
+add_task(async function test_consistentWithMPEdgeCases() {
+  setLoginMgrLoggedInState(true);
+
+  let fxa = createFxAccounts();
+
+  let creds1 = {
+    uid: "uid1",
+    email: "test@example.com",
+    sessionToken: "sessionToken",
+    kSync: "the kSync value",
+    kXCS: "the kXCS value",
+    kExtSync: "the kExtSync value",
+    kExtKbHash: "the kExtKbHash value",
+    verified: true,
+  };
+
+  let creds2 = {
+    uid: "uid2",
+    email: "test2@example.com",
+    sessionToken: "sessionToken2",
+    kSync: "the kSync value2",
+    kXCS: "the kXCS value2",
+    kExtSync: "the kExtSync value2",
+    kExtKbHash: "the kExtKbHash value2",
+    verified: false,
+  };
+
+  // Log a user in while MP is unlocked.
+  await fxa._internal.setSignedInUser(creds1);
+
+  // tell the storage that the MP is locked - this will prevent logout from
+  // being able to clear the data.
+  setLoginMgrLoggedInState(false);
+
+  // now set the second credentials.
+  await fxa._internal.setSignedInUser(creds2);
+
+  // We should still have creds1 data in the login manager.
+  let login = getLoginMgrData();
+  Assert.strictEqual(login.username, creds1.uid);
+  // and that we do have the first kSync in the login manager.
+  Assert.strictEqual(
+    JSON.parse(login.password).accountData.kSync,
+    creds1.kSync,
+    "stale data still in login mgr"
+  );
+
+  // Make a new FxA instance (otherwise the values in memory will be used)
+  // and we want the login manager to be unlocked.
+  setLoginMgrLoggedInState(true);
+  fxa = createFxAccounts();
+
+  let accountData = await fxa.getSignedInUser();
+  Assert.strictEqual(accountData.email, creds2.email);
+  // we should have no kSync at all.
+  Assert.strictEqual(accountData.kSync, undefined, "stale kSync wasn't used");
+  await fxa.signOut(/* localOnly = */ true);
+});
+
+// A test for the fact we will accept either a UID or email when looking in
+// the login manager.
+add_task(async function test_uidMigration() {
+  setLoginMgrLoggedInState(true);
+  Assert.strictEqual(getLoginMgrData(), null, "expect no logins at the start");
+
+  // create the login entry using email as a key.
+  let contents = { kSync: "kSync" };
+
+  let loginInfo = new Components.Constructor(
+    "@mozilla.org/login-manager/loginInfo;1",
+    Ci.nsILoginInfo,
+    "init"
+  );
+  let login = new loginInfo(
+    FXA_PWDMGR_HOST,
+    null, // aFormActionOrigin,
+    FXA_PWDMGR_REALM, // aHttpRealm,
+    "foo@bar.com", // aUsername
+    JSON.stringify(contents), // aPassword
+    "", // aUsernameField
+    ""
+  ); // aPasswordField
+  await Services.logins.addLoginAsync(login);
+
+  // ensure we read it.
+  let storage = new LoginManagerStorage();
+  let got = await storage.get("uid", "foo@bar.com");
+  Assert.deepEqual(got, contents);
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_oauth_token_storage.js b/services/fxaccounts/tests/xpcshell/test_oauth_token_storage.js
new file mode 100644
index 0000000000..5a41cd4571
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_oauth_token_storage.js
@@ -0,0 +1,177 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { FxAccounts } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+const { FxAccountsClient } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsClient.sys.mjs"
+);
+
+// We grab some additional stuff via backstage passes.
+var { AccountState } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+
+function promiseNotification(topic) {
+  return new Promise(resolve => {
+    let observe = () => {
+      Services.obs.removeObserver(observe, topic);
+      resolve();
+    };
+    Services.obs.addObserver(observe, topic);
+  });
+}
+
+// A storage manager that doesn't actually write anywhere.
+function MockStorageManager() {}
+
+MockStorageManager.prototype = {
+  promiseInitialized: Promise.resolve(),
+
+  initialize(accountData) {
+    this.accountData = accountData;
+  },
+
+  finalize() {
+    return Promise.resolve();
+  },
+
+  getAccountData() {
+    return Promise.resolve(this.accountData);
+  },
+
+  updateAccountData(updatedFields) {
+    for (let [name, value] of Object.entries(updatedFields)) {
+      if (value == null) {
+        delete this.accountData[name];
+      } else {
+        this.accountData[name] = value;
+      }
+    }
+    return Promise.resolve();
+  },
+
+  deleteAccountData() {
+    this.accountData = null;
+    return Promise.resolve();
+  },
+};
+
+// Just enough mocks so we can avoid hawk etc.
+function MockFxAccountsClient() {
+  this._email = "nobody@example.com";
+  this._verified = false;
+
+  this.accountStatus = function (uid) {
+    return Promise.resolve(!!uid && !this._deletedOnServer);
+  };
+
+  this.signOut = function () {
+    return Promise.resolve();
+  };
+  this.registerDevice = function () {
+    return Promise.resolve();
+  };
+  this.updateDevice = function () {
+    return Promise.resolve();
+  };
+  this.signOutAndDestroyDevice = function () {
+    return Promise.resolve();
+  };
+  this.getDeviceList = function () {
+    return Promise.resolve();
+  };
+
+  FxAccountsClient.apply(this);
+}
+
+MockFxAccountsClient.prototype = {};
+Object.setPrototypeOf(
+  MockFxAccountsClient.prototype,
+  FxAccountsClient.prototype
+);
+
+function MockFxAccounts(device = {}) {
+  return new FxAccounts({
+    fxAccountsClient: new MockFxAccountsClient(),
+    newAccountState(credentials) {
+      // we use a real accountState but mocked storage.
+      let storage = new MockStorageManager();
+      storage.initialize(credentials);
+      return new AccountState(storage);
+    },
+    _getDeviceName() {
+      return "mock device name";
+    },
+    fxaPushService: {
+      registerPushEndpoint() {
+        return new Promise(resolve => {
+          resolve({
+            endpoint: "http://mochi.test:8888",
+          });
+        });
+      },
+    },
+  });
+}
+
+async function createMockFxA() {
+  let fxa = new MockFxAccounts();
+  let credentials = {
+    email: "foo@example.com",
+    uid: "1234@lcip.org",
+    sessionToken: "dead",
+    kSync: "beef",
+    kXCS: "cafe",
+    kExtSync: "bacon",
+    kExtKbHash: "cheese",
+    verified: true,
+  };
+  await fxa._internal.setSignedInUser(credentials);
+  return fxa;
+}
+
+// The tests.
+
+add_task(async function testCacheStorage() {
+  let fxa = await createMockFxA();
+
+  // Hook what the impl calls to save to disk.
+  let cas = fxa._internal.currentAccountState;
+  let origPersistCached = cas._persistCachedTokens.bind(cas);
+  cas._persistCachedTokens = function () {
+    return origPersistCached().then(() => {
+      Services.obs.notifyObservers(null, "testhelper-fxa-cache-persist-done");
+    });
+  };
+
+  let promiseWritten = promiseNotification("testhelper-fxa-cache-persist-done");
+  let tokenData = { token: "token1", somethingelse: "something else" };
+  let scopeArray = ["foo", "bar"];
+  cas.setCachedToken(scopeArray, tokenData);
+  deepEqual(cas.getCachedToken(scopeArray), tokenData);
+
+  deepEqual(cas.oauthTokens, { "bar|foo": tokenData });
+  // wait for background write to complete.
+  await promiseWritten;
+
+  // Check the token cache made it to our mocked storage.
+  deepEqual(cas.storageManager.accountData.oauthTokens, {
+    "bar|foo": tokenData,
+  });
+
+  // Drop the token from the cache and ensure it is removed from the json.
+  promiseWritten = promiseNotification("testhelper-fxa-cache-persist-done");
+  await cas.removeCachedToken("token1");
+  deepEqual(cas.oauthTokens, {});
+  await promiseWritten;
+  deepEqual(cas.storageManager.accountData.oauthTokens, {});
+
+  // sign out and the token storage should end up with null.
+  let storageManager = cas.storageManager; // .signOut() removes the attribute.
+  await fxa.signOut(/* localOnly = */ true);
+  deepEqual(storageManager.accountData, null);
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_oauth_tokens.js b/services/fxaccounts/tests/xpcshell/test_oauth_tokens.js
new file mode 100644
index 0000000000..43bdf614fc
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_oauth_tokens.js
@@ -0,0 +1,252 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { FxAccounts } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+const { FxAccountsClient } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsClient.sys.mjs"
+);
+var { AccountState } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+
+function promiseNotification(topic) {
+  return new Promise(resolve => {
+    let observe = () => {
+      Services.obs.removeObserver(observe, topic);
+      resolve();
+    };
+    Services.obs.addObserver(observe, topic);
+  });
+}
+
+// Just enough mocks so we can avoid hawk and storage.
+function MockStorageManager() {}
+
+MockStorageManager.prototype = {
+  promiseInitialized: Promise.resolve(),
+
+  initialize(accountData) {
+    this.accountData = accountData;
+  },
+
+  finalize() {
+    return Promise.resolve();
+  },
+
+  getAccountData() {
+    return Promise.resolve(this.accountData);
+  },
+
+  updateAccountData(updatedFields) {
+    for (let [name, value] of Object.entries(updatedFields)) {
+      if (value == null) {
+        delete this.accountData[name];
+      } else {
+        this.accountData[name] = value;
+      }
+    }
+    return Promise.resolve();
+  },
+
+  deleteAccountData() {
+    this.accountData = null;
+    return Promise.resolve();
+  },
+};
+
+function MockFxAccountsClient(activeTokens) {
+  this._email = "nobody@example.com";
+  this._verified = false;
+
+  this.accountStatus = function (uid) {
+    return Promise.resolve(!!uid && !this._deletedOnServer);
+  };
+
+  this.signOut = function () {
+    return Promise.resolve();
+  };
+  this.registerDevice = function () {
+    return Promise.resolve();
+  };
+  this.updateDevice = function () {
+    return Promise.resolve();
+  };
+  this.signOutAndDestroyDevice = function () {
+    return Promise.resolve();
+  };
+  this.getDeviceList = function () {
+    return Promise.resolve();
+  };
+  this.accessTokenWithSessionToken = function (
+    sessionTokenHex,
+    clientId,
+    scope,
+    ttl
+  ) {
+    let token = `token${this.numTokenFetches}`;
+    if (ttl) {
+      token += `-ttl-${ttl}`;
+    }
+    this.numTokenFetches += 1;
+    this.activeTokens.add(token);
+    print("accessTokenWithSessionToken returning token", token);
+    return Promise.resolve({ access_token: token, ttl });
+  };
+  this.oauthDestroy = sinon.stub().callsFake((_clientId, token) => {
+    this.activeTokens.delete(token);
+    return Promise.resolve();
+  });
+
+  // Test only stuff.
+  this.activeTokens = activeTokens;
+  this.numTokenFetches = 0;
+
+  FxAccountsClient.apply(this);
+}
+
+MockFxAccountsClient.prototype = {};
+Object.setPrototypeOf(
+  MockFxAccountsClient.prototype,
+  FxAccountsClient.prototype
+);
+
+function MockFxAccounts() {
+  // The FxA "auth" and "oauth" servers both share the same db of tokens,
+  // so we need to simulate the same here in the tests.
+  const activeTokens = new Set();
+  return new FxAccounts({
+    fxAccountsClient: new MockFxAccountsClient(activeTokens),
+    newAccountState(credentials) {
+      // we use a real accountState but mocked storage.
+      let storage = new MockStorageManager();
+      storage.initialize(credentials);
+      return new AccountState(storage);
+    },
+    _getDeviceName() {
+      return "mock device name";
+    },
+    fxaPushService: {
+      registerPushEndpoint() {
+        return new Promise(resolve => {
+          resolve({
+            endpoint: "http://mochi.test:8888",
+          });
+        });
+      },
+    },
+  });
+}
+
+async function createMockFxA() {
+  let fxa = new MockFxAccounts();
+  let credentials = {
+    email: "foo@example.com",
+    uid: "1234@lcip.org",
+    sessionToken: "dead",
+    kSync: "beef",
+    kXCS: "cafe",
+    kExtSync: "bacon",
+    kExtKbHash: "cheese",
+    verified: true,
+  };
+
+  await fxa._internal.setSignedInUser(credentials);
+  return fxa;
+}
+
+// The tests.
+
+add_task(async function testRevoke() {
+  let tokenOptions = { scope: "test-scope" };
+  let fxa = await createMockFxA();
+  let client = fxa._internal.fxAccountsClient;
+
+  // get our first token and check we hit the mock.
+  let token1 = await fxa.getOAuthToken(tokenOptions);
+  equal(client.numTokenFetches, 1);
+  equal(client.activeTokens.size, 1);
+  ok(token1, "got a token");
+  equal(token1, "token0");
+
+  // drop the new token from our cache.
+  await fxa.removeCachedOAuthToken({ token: token1 });
+  ok(client.oauthDestroy.calledOnce);
+
+  // the revoke should have been successful.
+  equal(client.activeTokens.size, 0);
+  // fetching it again hits the server.
+  let token2 = await fxa.getOAuthToken(tokenOptions);
+  equal(client.numTokenFetches, 2);
+  equal(client.activeTokens.size, 1);
+  ok(token2, "got a token");
+  notEqual(token1, token2, "got a different token");
+});
+
+add_task(async function testSignOutDestroysTokens() {
+  let fxa = await createMockFxA();
+  let client = fxa._internal.fxAccountsClient;
+
+  // get our first token and check we hit the mock.
+  let token1 = await fxa.getOAuthToken({ scope: "test-scope" });
+  equal(client.numTokenFetches, 1);
+  equal(client.activeTokens.size, 1);
+  ok(token1, "got a token");
+
+  // get another
+  let token2 = await fxa.getOAuthToken({ scope: "test-scope-2" });
+  equal(client.numTokenFetches, 2);
+  equal(client.activeTokens.size, 2);
+  ok(token2, "got a token");
+  notEqual(token1, token2, "got a different token");
+
+  // FxA fires an observer when the "background" signout is complete.
+  let signoutComplete = promiseNotification("testhelper-fxa-signout-complete");
+  // now sign out - they should be removed.
+  await fxa.signOut();
+  await signoutComplete;
+  ok(client.oauthDestroy.calledTwice);
+  // No active tokens left.
+  equal(client.activeTokens.size, 0);
+});
+
+add_task(async function testTokenRaces() {
+  // Here we do 2 concurrent fetches each for 2 different token scopes (ie,
+  // 4 token fetches in total).
+  // This should provoke a potential race in the token fetching but we use
+  // a map of in-flight token fetches, so we should still only perform 2
+  // fetches, but each of the 4 calls should resolve with the correct values.
+  let fxa = await createMockFxA();
+  let client = fxa._internal.fxAccountsClient;
+
+  let results = await Promise.all([
+    fxa.getOAuthToken({ scope: "test-scope" }),
+    fxa.getOAuthToken({ scope: "test-scope" }),
+    fxa.getOAuthToken({ scope: "test-scope-2" }),
+    fxa.getOAuthToken({ scope: "test-scope-2" }),
+  ]);
+
+  equal(client.numTokenFetches, 2, "should have fetched 2 tokens.");
+
+  // Should have 2 unique tokens
+  results.sort();
+  equal(results[0], results[1]);
+  equal(results[2], results[3]);
+  // should be 2 active.
+  equal(client.activeTokens.size, 2);
+  await fxa.removeCachedOAuthToken({ token: results[0] });
+  equal(client.activeTokens.size, 1);
+  await fxa.removeCachedOAuthToken({ token: results[2] });
+  equal(client.activeTokens.size, 0);
+  ok(client.oauthDestroy.calledTwice);
+});
+
+add_task(async function testTokenTTL() {
+  // This tests the TTL option passed into the method
+  let fxa = await createMockFxA();
+  let token = await fxa.getOAuthToken({ scope: "test-ttl", ttl: 1000 });
+  equal(token, "token0-ttl-1000");
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_pairing.js b/services/fxaccounts/tests/xpcshell/test_pairing.js
new file mode 100644
index 0000000000..abc094da54
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_pairing.js
@@ -0,0 +1,385 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { FxAccountsPairingFlow } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsPairing.sys.mjs"
+);
+const { EventEmitter } = ChromeUtils.importESModule(
+  "resource://gre/modules/EventEmitter.sys.mjs"
+);
+ChromeUtils.defineESModuleGetters(this, {
+  jwcrypto: "resource://services-crypto/jwcrypto.sys.mjs",
+});
+XPCOMUtils.defineLazyGlobalGetters(this, ["crypto"]);
+
+const CHANNEL_ID = "sW-UA97Q6Dljqen7XRlYPw";
+const CHANNEL_KEY = crypto.getRandomValues(new Uint8Array(32));
+
+const SENDER_SUPP = {
+  ua: "Firefox Supp",
+  city: "Nice",
+  region: "PACA",
+  country: "France",
+  remote: "127.0.0.1",
+};
+const UID = "abcd";
+const EMAIL = "foo@bar.com";
+const AVATAR = "https://foo.bar/avatar";
+const DISPLAY_NAME = "Foo bar";
+const DEVICE_NAME = "Foo's computer";
+
+const PAIR_URI = "https://foo.bar/pair";
+const OAUTH_URI = "https://foo.bar/oauth";
+const KSYNC = "myksync";
+const SESSION = "mysession";
+const fxaConfig = {
+  promisePairingURI() {
+    return PAIR_URI;
+  },
+  promiseOAuthURI() {
+    return OAUTH_URI;
+  },
+};
+const fxAccounts = {
+  getSignedInUser() {
+    return {
+      uid: UID,
+      email: EMAIL,
+      avatar: AVATAR,
+      displayName: DISPLAY_NAME,
+    };
+  },
+  async _withVerifiedAccountState(cb) {
+    return cb({
+      async getUserAccountData() {
+        return {
+          sessionToken: SESSION,
+        };
+      },
+    });
+  },
+  _internal: {
+    keys: {
+      getKeyForScope(scope) {
+        return {
+          kid: "123456",
+          k: KSYNC,
+          kty: "oct",
+        };
+      },
+    },
+    fxAccountsClient: {
+      async getScopedKeyData() {
+        return {
+          "https://identity.mozilla.com/apps/oldsync": {
+            identifier: "https://identity.mozilla.com/apps/oldsync",
+            keyRotationTimestamp: 12345678,
+          },
+        };
+      },
+      async oauthAuthorize() {
+        return { code: "mycode", state: "mystate" };
+      },
+    },
+  },
+};
+const weave = {
+  Service: { clientsEngine: { localName: DEVICE_NAME } },
+};
+
+class MockPairingChannel extends EventTarget {
+  get channelId() {
+    return CHANNEL_ID;
+  }
+
+  get channelKey() {
+    return CHANNEL_KEY;
+  }
+
+  send(data) {
+    this.dispatchEvent(
+      new CustomEvent("send", {
+        detail: { data },
+      })
+    );
+  }
+
+  simulateIncoming(data) {
+    this.dispatchEvent(
+      new CustomEvent("message", {
+        detail: { data, sender: SENDER_SUPP },
+      })
+    );
+  }
+
+  close() {
+    this.closed = true;
+  }
+}
+
+add_task(async function testFullFlow() {
+  const emitter = new EventEmitter();
+  const pairingChannel = new MockPairingChannel();
+  const pairingUri = await FxAccountsPairingFlow.start({
+    emitter,
+    pairingChannel,
+    fxAccounts,
+    fxaConfig,
+    weave,
+  });
+  Assert.equal(
+    pairingUri,
+    `${PAIR_URI}#channel_id=${CHANNEL_ID}&channel_key=${ChromeUtils.base64URLEncode(
+      CHANNEL_KEY,
+      { pad: false }
+    )}`
+  );
+
+  const flow = FxAccountsPairingFlow.get(CHANNEL_ID);
+
+  const promiseSwitchToWebContent = emitter.once("view:SwitchToWebContent");
+  const promiseMetadataSent = promiseOutgoingMessage(pairingChannel);
+  const epk = await generateEphemeralKeypair();
+
+  pairingChannel.simulateIncoming({
+    message: "pair:supp:request",
+    data: {
+      client_id: "client_id_1",
+      state: "mystate",
+      keys_jwk: ChromeUtils.base64URLEncode(
+        new TextEncoder().encode(JSON.stringify(epk.publicJWK)),
+        { pad: false }
+      ),
+      scope: "profile https://identity.mozilla.com/apps/oldsync",
+      code_challenge: "chal",
+      code_challenge_method: "S256",
+    },
+  });
+  const sentAuthMetadata = await promiseMetadataSent;
+  Assert.deepEqual(sentAuthMetadata, {
+    message: "pair:auth:metadata",
+    data: {
+      email: EMAIL,
+      avatar: AVATAR,
+      displayName: DISPLAY_NAME,
+      deviceName: DEVICE_NAME,
+    },
+  });
+  const oauthUrl = await promiseSwitchToWebContent;
+  Assert.equal(
+    oauthUrl,
+    `${OAUTH_URI}?client_id=client_id_1&scope=profile+https%3A%2F%2Fidentity.mozilla.com%2Fapps%2Foldsync&email=foo%40bar.com&uid=abcd&channel_id=${CHANNEL_ID}&redirect_uri=urn%3Aietf%3Awg%3Aoauth%3A2.0%3Aoob%3Apair-auth-webchannel`
+  );
+
+  let pairSuppMetadata = await simulateIncomingWebChannel(
+    flow,
+    "fxaccounts:pair_supplicant_metadata"
+  );
+  Assert.deepEqual(
+    {
+      ua: "Firefox Supp",
+      city: "Nice",
+      region: "PACA",
+      country: "France",
+      ipAddress: "127.0.0.1",
+    },
+    pairSuppMetadata
+  );
+
+  const generateJWE = sinon.spy(jwcrypto, "generateJWE");
+  const oauthAuthorize = sinon.spy(
+    fxAccounts._internal.fxAccountsClient,
+    "oauthAuthorize"
+  );
+  const promiseOAuthParamsMsg = promiseOutgoingMessage(pairingChannel);
+  await simulateIncomingWebChannel(flow, "fxaccounts:pair_authorize");
+  // We should have generated the expected JWE.
+  Assert.ok(generateJWE.calledOnce);
+  const generateArgs = generateJWE.firstCall.args;
+  Assert.deepEqual(generateArgs[0], epk.publicJWK);
+  Assert.deepEqual(JSON.parse(new TextDecoder().decode(generateArgs[1])), {
+    "https://identity.mozilla.com/apps/oldsync": {
+      kid: "123456",
+      k: KSYNC,
+      kty: "oct",
+    },
+  });
+  // We should have authorized an oauth code with expected parameters.
+  Assert.ok(oauthAuthorize.calledOnce);
+  const oauthCodeArgs = oauthAuthorize.firstCall.args[1];
+  console.log(oauthCodeArgs);
+  Assert.ok(!oauthCodeArgs.keys_jwk);
+  Assert.deepEqual(
+    oauthCodeArgs.keys_jwe,
+    await generateJWE.firstCall.returnValue
+  );
+  Assert.equal(oauthCodeArgs.client_id, "client_id_1");
+  Assert.equal(oauthCodeArgs.access_type, "offline");
+  Assert.equal(oauthCodeArgs.state, "mystate");
+  Assert.equal(
+    oauthCodeArgs.scope,
+    "profile https://identity.mozilla.com/apps/oldsync"
+  );
+  Assert.equal(oauthCodeArgs.code_challenge, "chal");
+  Assert.equal(oauthCodeArgs.code_challenge_method, "S256");
+
+  const oAuthParams = await promiseOAuthParamsMsg;
+  Assert.deepEqual(oAuthParams, {
+    message: "pair:auth:authorize",
+    data: { code: "mycode", state: "mystate" },
+  });
+
+  let heartbeat = await simulateIncomingWebChannel(
+    flow,
+    "fxaccounts:pair_heartbeat"
+  );
+  Assert.ok(!heartbeat.suppAuthorized);
+
+  await pairingChannel.simulateIncoming({
+    message: "pair:supp:authorize",
+  });
+
+  heartbeat = await simulateIncomingWebChannel(
+    flow,
+    "fxaccounts:pair_heartbeat"
+  );
+  Assert.ok(heartbeat.suppAuthorized);
+
+  await simulateIncomingWebChannel(flow, "fxaccounts:pair_complete");
+  // The flow should have been destroyed!
+  Assert.ok(!FxAccountsPairingFlow.get(CHANNEL_ID));
+  Assert.ok(pairingChannel.closed);
+  generateJWE.restore();
+  oauthAuthorize.restore();
+});
+
+add_task(async function testUnknownPairingMessage() {
+  const emitter = new EventEmitter();
+  const pairingChannel = new MockPairingChannel();
+  await FxAccountsPairingFlow.start({
+    emitter,
+    pairingChannel,
+    fxAccounts,
+    fxaConfig,
+    weave,
+  });
+  const flow = FxAccountsPairingFlow.get(CHANNEL_ID);
+  const viewErrorObserved = emitter.once("view:Error");
+  pairingChannel.simulateIncoming({
+    message: "pair:boom",
+  });
+  await viewErrorObserved;
+  let heartbeat = await simulateIncomingWebChannel(
+    flow,
+    "fxaccounts:pair_heartbeat"
+  );
+  Assert.ok(heartbeat.err);
+});
+
+add_task(async function testUnknownWebChannelCommand() {
+  const emitter = new EventEmitter();
+  const pairingChannel = new MockPairingChannel();
+  await FxAccountsPairingFlow.start({
+    emitter,
+    pairingChannel,
+    fxAccounts,
+    fxaConfig,
+    weave,
+  });
+  const flow = FxAccountsPairingFlow.get(CHANNEL_ID);
+  const viewErrorObserved = emitter.once("view:Error");
+  await simulateIncomingWebChannel(flow, "fxaccounts:boom");
+  await viewErrorObserved;
+  let heartbeat = await simulateIncomingWebChannel(
+    flow,
+    "fxaccounts:pair_heartbeat"
+  );
+  Assert.ok(heartbeat.err);
+});
+
+add_task(async function testPairingChannelFailure() {
+  const emitter = new EventEmitter();
+  const pairingChannel = new MockPairingChannel();
+  await FxAccountsPairingFlow.start({
+    emitter,
+    pairingChannel,
+    fxAccounts,
+    fxaConfig,
+    weave,
+  });
+  const flow = FxAccountsPairingFlow.get(CHANNEL_ID);
+  const viewErrorObserved = emitter.once("view:Error");
+  sinon.stub(pairingChannel, "send").callsFake(() => {
+    throw new Error("Boom!");
+  });
+  pairingChannel.simulateIncoming({
+    message: "pair:supp:request",
+    data: {
+      client_id: "client_id_1",
+      state: "mystate",
+      scope: "profile https://identity.mozilla.com/apps/oldsync",
+      code_challenge: "chal",
+      code_challenge_method: "S256",
+    },
+  });
+  await viewErrorObserved;
+
+  let heartbeat = await simulateIncomingWebChannel(
+    flow,
+    "fxaccounts:pair_heartbeat"
+  );
+  Assert.ok(heartbeat.err);
+});
+
+add_task(async function testFlowTimeout() {
+  const emitter = new EventEmitter();
+  const pairingChannel = new MockPairingChannel();
+  const viewErrorObserved = emitter.once("view:Error");
+  await FxAccountsPairingFlow.start({
+    emitter,
+    pairingChannel,
+    fxAccounts,
+    fxaConfig,
+    weave,
+    flowTimeout: 1,
+  });
+  const flow = FxAccountsPairingFlow.get(CHANNEL_ID);
+  await viewErrorObserved;
+
+  let heartbeat = await simulateIncomingWebChannel(
+    flow,
+    "fxaccounts:pair_heartbeat"
+  );
+  Assert.ok(heartbeat.err.match(/Timeout/));
+});
+
+async function simulateIncomingWebChannel(flow, command) {
+  return flow.onWebChannelMessage(command);
+}
+
+async function promiseOutgoingMessage(pairingChannel) {
+  return new Promise(res => {
+    const onMessage = event => {
+      pairingChannel.removeEventListener("send", onMessage);
+      res(event.detail.data);
+    };
+    pairingChannel.addEventListener("send", onMessage);
+  });
+}
+
+async function generateEphemeralKeypair() {
+  const keypair = await crypto.subtle.generateKey(
+    { name: "ECDH", namedCurve: "P-256" },
+    true,
+    ["deriveKey"]
+  );
+  const publicJWK = await crypto.subtle.exportKey("jwk", keypair.publicKey);
+  const privateJWK = await crypto.subtle.exportKey("jwk", keypair.privateKey);
+  delete publicJWK.key_ops;
+  return {
+    publicJWK,
+    privateJWK,
+  };
+}
diff --git a/services/fxaccounts/tests/xpcshell/test_profile.js b/services/fxaccounts/tests/xpcshell/test_profile.js
new file mode 100644
index 0000000000..7dca5c7512
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_profile.js
@@ -0,0 +1,680 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ON_PROFILE_CHANGE_NOTIFICATION, log } = ChromeUtils.import(
+  "resource://gre/modules/FxAccountsCommon.js"
+);
+const { FxAccountsProfileClient } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsProfileClient.sys.mjs"
+);
+const { FxAccountsProfile } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsProfile.sys.mjs"
+);
+const { PromiseUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/PromiseUtils.sys.mjs"
+);
+const { setTimeout } = ChromeUtils.importESModule(
+  "resource://gre/modules/Timer.sys.mjs"
+);
+
+let mockClient = function (fxa) {
+  let options = {
+    serverURL: "http://127.0.0.1:1111/v1",
+    fxa,
+  };
+  return new FxAccountsProfileClient(options);
+};
+
+const ACCOUNT_UID = "abc123";
+const ACCOUNT_EMAIL = "foo@bar.com";
+const ACCOUNT_DATA = {
+  uid: ACCOUNT_UID,
+  email: ACCOUNT_EMAIL,
+};
+
+let mockFxa = function () {
+  let fxa = {
+    // helpers to make the tests using this mock less verbose...
+    set _testProfileCache(profileCache) {
+      this._internal.currentAccountState._data.profileCache = profileCache;
+    },
+    get _testProfileCache() {
+      return this._internal.currentAccountState._data.profileCache;
+    },
+  };
+  fxa._internal = Object.assign(
+    {},
+    {
+      currentAccountState: Object.assign(
+        {},
+        {
+          _data: Object.assign({}, ACCOUNT_DATA),
+
+          get isCurrent() {
+            return true;
+          },
+
+          async getUserAccountData() {
+            return this._data;
+          },
+
+          async updateUserAccountData(data) {
+            this._data = Object.assign(this._data, data);
+          },
+        }
+      ),
+
+      withCurrentAccountState(cb) {
+        return cb(this.currentAccountState);
+      },
+
+      async _handleTokenError(err) {
+        // handleTokenError always rethrows.
+        throw err;
+      },
+    }
+  );
+  return fxa;
+};
+
+function CreateFxAccountsProfile(fxa = null, client = null) {
+  if (!fxa) {
+    fxa = mockFxa();
+  }
+  let options = {
+    fxai: fxa._internal,
+    profileServerUrl: "http://127.0.0.1:1111/v1",
+  };
+  if (client) {
+    options.profileClient = client;
+  }
+  return new FxAccountsProfile(options);
+}
+
+add_test(function cacheProfile_change() {
+  let setProfileCacheCalled = false;
+  let fxa = mockFxa();
+  fxa._internal.currentAccountState.updateUserAccountData = data => {
+    setProfileCacheCalled = true;
+    Assert.equal(data.profileCache.profile.avatar, "myurl");
+    Assert.equal(data.profileCache.etag, "bogusetag");
+    return Promise.resolve();
+  };
+  let profile = CreateFxAccountsProfile(fxa);
+
+  makeObserver(ON_PROFILE_CHANGE_NOTIFICATION, function (subject, topic, data) {
+    Assert.equal(data, ACCOUNT_DATA.uid);
+    Assert.ok(setProfileCacheCalled);
+    run_next_test();
+  });
+
+  return profile._cacheProfile({
+    body: { uid: ACCOUNT_UID, email: ACCOUNT_EMAIL, avatar: "myurl" },
+    etag: "bogusetag",
+  });
+});
+
+add_test(function fetchAndCacheProfile_ok() {
+  let client = mockClient(mockFxa());
+  client.fetchProfile = function () {
+    return Promise.resolve({ body: { uid: ACCOUNT_UID, avatar: "myimg" } });
+  };
+  let profile = CreateFxAccountsProfile(null, client);
+  profile._cachedAt = 12345;
+
+  profile._cacheProfile = function (toCache) {
+    Assert.equal(toCache.body.avatar, "myimg");
+    return Promise.resolve(toCache.body);
+  };
+
+  return profile._fetchAndCacheProfile().then(result => {
+    Assert.equal(result.avatar, "myimg");
+    Assert.notEqual(profile._cachedAt, 12345, "cachedAt has been bumped");
+    run_next_test();
+  });
+});
+
+add_test(function fetchAndCacheProfile_always_bumps_cachedAt() {
+  let client = mockClient(mockFxa());
+  client.fetchProfile = function () {
+    return Promise.reject(new Error("oops"));
+  };
+  let profile = CreateFxAccountsProfile(null, client);
+  profile._cachedAt = 12345;
+
+  return profile._fetchAndCacheProfile().then(
+    result => {
+      do_throw("Should not succeed");
+    },
+    err => {
+      Assert.notEqual(profile._cachedAt, 12345, "cachedAt has been bumped");
+      run_next_test();
+    }
+  );
+});
+
+add_test(function fetchAndCacheProfile_sendsETag() {
+  let fxa = mockFxa();
+  fxa._testProfileCache = { profile: {}, etag: "bogusETag" };
+  let client = mockClient(fxa);
+  client.fetchProfile = function (etag) {
+    Assert.equal(etag, "bogusETag");
+    return Promise.resolve({
+      body: { uid: ACCOUNT_UID, email: ACCOUNT_EMAIL, avatar: "myimg" },
+    });
+  };
+  let profile = CreateFxAccountsProfile(fxa, client);
+
+  return profile._fetchAndCacheProfile().then(result => {
+    run_next_test();
+  });
+});
+
+// Check that a second profile request when one is already in-flight reuses
+// the in-flight one.
+add_task(async function fetchAndCacheProfileOnce() {
+  // A promise that remains unresolved while we fire off 2 requests for
+  // a profile.
+  let resolveProfile;
+  let promiseProfile = new Promise(resolve => {
+    resolveProfile = resolve;
+  });
+  let numFetches = 0;
+  let client = mockClient(mockFxa());
+  client.fetchProfile = function () {
+    numFetches += 1;
+    return promiseProfile;
+  };
+  let fxa = mockFxa();
+  let profile = CreateFxAccountsProfile(fxa, client);
+
+  let request1 = profile._fetchAndCacheProfile();
+  profile._fetchAndCacheProfile();
+  await new Promise(res => setTimeout(res, 0)); // Yield so fetchProfile() is called (promise)
+
+  // should be one request made to fetch the profile (but the promise returned
+  // by it remains unresolved)
+  Assert.equal(numFetches, 1);
+
+  // resolve the promise.
+  resolveProfile({
+    body: { uid: ACCOUNT_UID, email: ACCOUNT_EMAIL, avatar: "myimg" },
+  });
+
+  // both requests should complete with the same data.
+  let got1 = await request1;
+  Assert.equal(got1.avatar, "myimg");
+  let got2 = await request1;
+  Assert.equal(got2.avatar, "myimg");
+
+  // and still only 1 request was made.
+  Assert.equal(numFetches, 1);
+});
+
+// Check that sharing a single fetch promise works correctly when the promise
+// is rejected.
+add_task(async function fetchAndCacheProfileOnce() {
+  // A promise that remains unresolved while we fire off 2 requests for
+  // a profile.
+  let rejectProfile;
+  let promiseProfile = new Promise((resolve, reject) => {
+    rejectProfile = reject;
+  });
+  let numFetches = 0;
+  let client = mockClient(mockFxa());
+  client.fetchProfile = function () {
+    numFetches += 1;
+    return promiseProfile;
+  };
+  let fxa = mockFxa();
+  let profile = CreateFxAccountsProfile(fxa, client);
+
+  let request1 = profile._fetchAndCacheProfile();
+  let request2 = profile._fetchAndCacheProfile();
+  await new Promise(res => setTimeout(res, 0)); // Yield so fetchProfile() is called (promise)
+
+  // should be one request made to fetch the profile (but the promise returned
+  // by it remains unresolved)
+  Assert.equal(numFetches, 1);
+
+  // reject the promise.
+  rejectProfile("oh noes");
+
+  // both requests should reject.
+  try {
+    await request1;
+    throw new Error("should have rejected");
+  } catch (ex) {
+    if (ex != "oh noes") {
+      throw ex;
+    }
+  }
+  try {
+    await request2;
+    throw new Error("should have rejected");
+  } catch (ex) {
+    if (ex != "oh noes") {
+      throw ex;
+    }
+  }
+
+  // but a new request should works.
+  client.fetchProfile = function () {
+    return Promise.resolve({
+      body: { uid: ACCOUNT_UID, email: ACCOUNT_EMAIL, avatar: "myimg" },
+    });
+  };
+
+  let got = await profile._fetchAndCacheProfile();
+  Assert.equal(got.avatar, "myimg");
+});
+
+add_test(function fetchAndCacheProfile_alreadyCached() {
+  let cachedUrl = "cachedurl";
+  let fxa = mockFxa();
+  fxa._testProfileCache = {
+    profile: { uid: ACCOUNT_UID, avatar: cachedUrl },
+    etag: "bogusETag",
+  };
+  let client = mockClient(fxa);
+  client.fetchProfile = function (etag) {
+    Assert.equal(etag, "bogusETag");
+    return Promise.resolve(null);
+  };
+
+  let profile = CreateFxAccountsProfile(fxa, client);
+  profile._cacheProfile = function (toCache) {
+    do_throw("This method should not be called.");
+  };
+
+  return profile._fetchAndCacheProfile().then(result => {
+    Assert.equal(result, null);
+    Assert.equal(fxa._testProfileCache.profile.avatar, cachedUrl);
+    run_next_test();
+  });
+});
+
+// Check that a new profile request within PROFILE_FRESHNESS_THRESHOLD of the
+// last one doesn't kick off a new request to check the cached copy is fresh.
+add_task(async function fetchAndCacheProfileAfterThreshold() {
+  /*
+   * This test was observed to cause a timeout for... any timer precision reduction.
+   * Even 1 us. Exact reason is still undiagnosed.
+   */
+  Services.prefs.setBoolPref("privacy.reduceTimerPrecision", false);
+
+  registerCleanupFunction(async () => {
+    Services.prefs.clearUserPref("privacy.reduceTimerPrecision");
+  });
+
+  let numFetches = 0;
+  let client = mockClient(mockFxa());
+  client.fetchProfile = async function () {
+    numFetches += 1;
+    return {
+      body: { uid: ACCOUNT_UID, email: ACCOUNT_EMAIL, avatar: "myimg" },
+    };
+  };
+  let profile = CreateFxAccountsProfile(null, client);
+  profile.PROFILE_FRESHNESS_THRESHOLD = 1000;
+
+  // first fetch should return null as we don't have data.
+  let p = await profile.getProfile();
+  Assert.equal(p, null);
+  // ensure we kicked off a fetch.
+  Assert.notEqual(profile._currentFetchPromise, null);
+  // wait for that fetch to finish
+  await profile._currentFetchPromise;
+  Assert.equal(numFetches, 1);
+  Assert.equal(profile._currentFetchPromise, null);
+
+  await profile.getProfile();
+  Assert.equal(numFetches, 1);
+  Assert.equal(profile._currentFetchPromise, null);
+
+  await new Promise(resolve => {
+    do_timeout(1000, resolve);
+  });
+
+  let origFetchAndCatch = profile._fetchAndCacheProfile;
+  let backgroundFetchDone = PromiseUtils.defer();
+  profile._fetchAndCacheProfile = async () => {
+    await origFetchAndCatch.call(profile);
+    backgroundFetchDone.resolve();
+  };
+  await profile.getProfile();
+  await backgroundFetchDone.promise;
+  Assert.equal(numFetches, 2);
+});
+
+add_task(async function test_ensureProfile() {
+  let client = new FxAccountsProfileClient({
+    serverURL: "http://127.0.0.1:1111/v1",
+    fxa: mockFxa(),
+  });
+  let profile = CreateFxAccountsProfile(null, client);
+
+  const testCases = [
+    // profile retrieval when there is no cached profile info
+    {
+      threshold: 1000,
+      expectsCachedProfileReturned: false,
+      cachedProfile: null,
+      fetchedProfile: {
+        uid: ACCOUNT_UID,
+        email: ACCOUNT_EMAIL,
+        avatar: "myimg",
+      },
+    },
+    // profile retrieval when the cached profile is recent
+    {
+      // Note: The threshold for this test case is being set to an arbitrary value that will
+      // be greater than Date.now() so the retrieved cached profile will be deemed recent.
+      threshold: Date.now() + 5000,
+      expectsCachedProfileReturned: true,
+      cachedProfile: {
+        uid: `${ACCOUNT_UID}2`,
+        email: `${ACCOUNT_EMAIL}2`,
+        avatar: "myimg2",
+      },
+    },
+    // profile retrieval when the cached profile is old and a new profile is fetched
+    {
+      threshold: 1000,
+      expectsCachedProfileReturned: false,
+      cachedProfile: {
+        uid: `${ACCOUNT_UID}3`,
+        email: `${ACCOUNT_EMAIL}3`,
+        avatar: "myimg3",
+      },
+      fetchAndCacheProfileResolves: true,
+      fetchedProfile: {
+        uid: `${ACCOUNT_UID}4`,
+        email: `${ACCOUNT_EMAIL}4`,
+        avatar: "myimg4",
+      },
+    },
+    // profile retrieval when the cached profile is old and a null profile is fetched
+    {
+      threshold: 1000,
+      expectsCachedProfileReturned: false,
+      cachedProfile: {
+        uid: `${ACCOUNT_UID}5`,
+        email: `${ACCOUNT_EMAIL}5`,
+        avatar: "myimg5",
+      },
+      fetchAndCacheProfileResolves: true,
+      fetchedProfile: null,
+    },
+    // profile retrieval when the cached profile is old and fetching a new profile errors
+    {
+      threshold: 1000,
+      expectsCachedProfileReturned: false,
+      cachedProfile: {
+        uid: `${ACCOUNT_UID}6`,
+        email: `${ACCOUNT_EMAIL}6`,
+        avatar: "myimg6",
+      },
+      fetchAndCacheProfileResolves: false,
+    },
+    // profile retrieval when we've cached a failure to fetch profile data
+    {
+      // Note: The threshold for this test case is being set to an arbitrary value that will
+      // be greater than Date.now() so the retrieved cached profile will be deemed recent.
+      threshold: Date.now() + 5000,
+      expectsCachedProfileReturned: false,
+      cachedProfile: null,
+      fetchedProfile: {
+        uid: `${ACCOUNT_UID}7`,
+        email: `${ACCOUNT_EMAIL}7`,
+        avatar: "myimg7",
+      },
+      fetchAndCacheProfileResolves: true,
+    },
+    // profile retrieval when the cached profile is old but staleOk is true.
+    {
+      threshold: 1000,
+      expectsCachedProfileReturned: true,
+      cachedProfile: {
+        uid: `${ACCOUNT_UID}8`,
+        email: `${ACCOUNT_EMAIL}8`,
+        avatar: "myimg8",
+      },
+      fetchAndCacheProfileResolves: false,
+      options: { staleOk: true },
+    },
+    // staleOk but no cached profile
+    {
+      threshold: 1000,
+      expectsCachedProfileReturned: false,
+      cachedProfile: null,
+      fetchedProfile: {
+        uid: `${ACCOUNT_UID}9`,
+        email: `${ACCOUNT_EMAIL}9`,
+        avatar: "myimg9",
+      },
+      options: { staleOk: true },
+    },
+    // fresh profile but forceFresh = true
+    {
+      // Note: The threshold for this test case is being set to an arbitrary value that will
+      // be greater than Date.now() so the retrieved cached profile will be deemed recent.
+      threshold: Date.now() + 5000,
+      expectsCachedProfileReturned: false,
+      fetchedProfile: {
+        uid: `${ACCOUNT_UID}10`,
+        email: `${ACCOUNT_EMAIL}10`,
+        avatar: "myimg10",
+      },
+      options: { forceFresh: true },
+    },
+  ];
+
+  for (const tc of testCases) {
+    print(`test case: ${JSON.stringify(tc)}`);
+    let mockProfile = sinon.mock(profile);
+    mockProfile
+      .expects("_getProfileCache")
+      .once()
+      .returns(
+        tc.cachedProfile
+          ? {
+              profile: tc.cachedProfile,
+            }
+          : null
+      );
+    profile.PROFILE_FRESHNESS_THRESHOLD = tc.threshold;
+
+    let options = tc.options || {};
+    if (tc.expectsCachedProfileReturned) {
+      mockProfile.expects("_fetchAndCacheProfile").never();
+      let actualProfile = await profile.ensureProfile(options);
+      mockProfile.verify();
+      Assert.equal(actualProfile, tc.cachedProfile);
+    } else if (tc.fetchAndCacheProfileResolves) {
+      mockProfile
+        .expects("_fetchAndCacheProfile")
+        .once()
+        .resolves(tc.fetchedProfile);
+
+      let actualProfile = await profile.ensureProfile(options);
+      let expectedProfile = tc.fetchedProfile
+        ? tc.fetchedProfile
+        : tc.cachedProfile;
+      mockProfile.verify();
+      Assert.equal(actualProfile, expectedProfile);
+    } else {
+      mockProfile.expects("_fetchAndCacheProfile").once().rejects();
+
+      let actualProfile = await profile.ensureProfile(options);
+      mockProfile.verify();
+      Assert.equal(actualProfile, tc.cachedProfile);
+    }
+  }
+});
+
+// Check that a new profile request within PROFILE_FRESHNESS_THRESHOLD of the
+// last one *does* kick off a new request if ON_PROFILE_CHANGE_NOTIFICATION
+// is sent.
+add_task(async function fetchAndCacheProfileBeforeThresholdOnNotification() {
+  let numFetches = 0;
+  let client = mockClient(mockFxa());
+  client.fetchProfile = async function () {
+    numFetches += 1;
+    return {
+      body: { uid: ACCOUNT_UID, email: ACCOUNT_EMAIL, avatar: "myimg" },
+    };
+  };
+  let profile = CreateFxAccountsProfile(null, client);
+  profile.PROFILE_FRESHNESS_THRESHOLD = 1000;
+
+  // first fetch should return null as we don't have data.
+  let p = await profile.getProfile();
+  Assert.equal(p, null);
+  // ensure we kicked off a fetch.
+  Assert.notEqual(profile._currentFetchPromise, null);
+  // wait for that fetch to finish
+  await profile._currentFetchPromise;
+  Assert.equal(numFetches, 1);
+  Assert.equal(profile._currentFetchPromise, null);
+
+  Services.obs.notifyObservers(null, ON_PROFILE_CHANGE_NOTIFICATION);
+
+  let origFetchAndCatch = profile._fetchAndCacheProfile;
+  let backgroundFetchDone = PromiseUtils.defer();
+  profile._fetchAndCacheProfile = async () => {
+    await origFetchAndCatch.call(profile);
+    backgroundFetchDone.resolve();
+  };
+  await profile.getProfile();
+  await backgroundFetchDone.promise;
+  Assert.equal(numFetches, 2);
+});
+
+add_test(function tearDown_ok() {
+  let profile = CreateFxAccountsProfile();
+
+  Assert.ok(!!profile.client);
+  Assert.ok(!!profile.fxai);
+
+  profile.tearDown();
+  Assert.equal(null, profile.fxai);
+  Assert.equal(null, profile.client);
+
+  run_next_test();
+});
+
+add_task(async function getProfile_ok() {
+  let cachedUrl = "myurl";
+  let didFetch = false;
+
+  let fxa = mockFxa();
+  fxa._testProfileCache = { profile: { uid: ACCOUNT_UID, avatar: cachedUrl } };
+  let profile = CreateFxAccountsProfile(fxa);
+
+  profile._fetchAndCacheProfile = function () {
+    didFetch = true;
+    return Promise.resolve();
+  };
+
+  let result = await profile.getProfile();
+
+  Assert.equal(result.avatar, cachedUrl);
+  Assert.ok(didFetch);
+});
+
+add_task(async function getProfile_no_cache() {
+  let fetchedUrl = "newUrl";
+  let fxa = mockFxa();
+  let profile = CreateFxAccountsProfile(fxa);
+
+  profile._fetchAndCacheProfileInternal = function () {
+    return Promise.resolve({ uid: ACCOUNT_UID, avatar: fetchedUrl });
+  };
+
+  await profile.getProfile(); // returns null.
+  let result = await profile._currentFetchPromise;
+  Assert.equal(result.avatar, fetchedUrl);
+});
+
+add_test(function getProfile_has_cached_fetch_deleted() {
+  let cachedUrl = "myurl";
+
+  let fxa = mockFxa();
+  let client = mockClient(fxa);
+  client.fetchProfile = function () {
+    return Promise.resolve({
+      body: { uid: ACCOUNT_UID, email: ACCOUNT_EMAIL, avatar: null },
+    });
+  };
+
+  let profile = CreateFxAccountsProfile(fxa, client);
+  fxa._testProfileCache = {
+    profile: { uid: ACCOUNT_UID, email: ACCOUNT_EMAIL, avatar: cachedUrl },
+  };
+
+  // instead of checking this in a mocked "save" function, just check after the
+  // observer
+  makeObserver(ON_PROFILE_CHANGE_NOTIFICATION, function (subject, topic, data) {
+    profile.getProfile().then(profileData => {
+      Assert.equal(null, profileData.avatar);
+      run_next_test();
+    });
+  });
+
+  return profile.getProfile().then(result => {
+    Assert.equal(result.avatar, "myurl");
+  });
+});
+
+add_test(function getProfile_fetchAndCacheProfile_throws() {
+  let fxa = mockFxa();
+  fxa._testProfileCache = {
+    profile: { uid: ACCOUNT_UID, email: ACCOUNT_EMAIL, avatar: "myimg" },
+  };
+  let profile = CreateFxAccountsProfile(fxa);
+
+  profile._fetchAndCacheProfile = () => Promise.reject(new Error());
+
+  return profile.getProfile().then(result => {
+    Assert.equal(result.avatar, "myimg");
+    run_next_test();
+  });
+});
+
+add_test(function getProfile_email_changed() {
+  let fxa = mockFxa();
+  let client = mockClient(fxa);
+  client.fetchProfile = function () {
+    return Promise.resolve({
+      body: { uid: ACCOUNT_UID, email: "newemail@bar.com" },
+    });
+  };
+  fxa._internal._handleEmailUpdated = email => {
+    Assert.equal(email, "newemail@bar.com");
+    run_next_test();
+  };
+
+  let profile = CreateFxAccountsProfile(fxa, client);
+  return profile._fetchAndCacheProfile();
+});
+
+function makeObserver(aObserveTopic, aObserveFunc) {
+  let callback = function (aSubject, aTopic, aData) {
+    log.debug("observed " + aTopic + " " + aData);
+    if (aTopic == aObserveTopic) {
+      removeMe();
+      aObserveFunc(aSubject, aTopic, aData);
+    }
+  };
+
+  function removeMe() {
+    log.debug("removing observer for " + aObserveTopic);
+    Services.obs.removeObserver(callback, aObserveTopic);
+  }
+
+  Services.obs.addObserver(callback, aObserveTopic);
+  return removeMe;
+}
diff --git a/services/fxaccounts/tests/xpcshell/test_profile_client.js b/services/fxaccounts/tests/xpcshell/test_profile_client.js
new file mode 100644
index 0000000000..e8bc47b63c
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_profile_client.js
@@ -0,0 +1,420 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  ERRNO_NETWORK,
+  ERRNO_PARSE,
+  ERRNO_UNKNOWN_ERROR,
+  ERROR_CODE_METHOD_NOT_ALLOWED,
+  ERROR_MSG_METHOD_NOT_ALLOWED,
+  ERROR_NETWORK,
+  ERROR_PARSE,
+  ERROR_UNKNOWN,
+} = ChromeUtils.import("resource://gre/modules/FxAccountsCommon.js");
+const { FxAccountsProfileClient, FxAccountsProfileClientError } =
+  ChromeUtils.importESModule(
+    "resource://gre/modules/FxAccountsProfileClient.sys.mjs"
+  );
+
+const STATUS_SUCCESS = 200;
+
+/**
+ * Mock request responder
+ * @param {String} response
+ *        Mocked raw response from the server
+ * @returns {Function}
+ */
+let mockResponse = function (response) {
+  let Request = function (requestUri) {
+    // Store the request uri so tests can inspect it
+    Request._requestUri = requestUri;
+    Request.ifNoneMatchSet = false;
+    return {
+      setHeader(header, value) {
+        if (header == "If-None-Match" && value == "bogusETag") {
+          Request.ifNoneMatchSet = true;
+        }
+      },
+      async dispatch(method, payload) {
+        this.response = response;
+        return this.response;
+      },
+    };
+  };
+
+  return Request;
+};
+
+// A simple mock FxA that hands out tokens without checking them and doesn't
+// expect tokens to be revoked. We have specific token tests further down that
+// has more checks here.
+let mockFxaInternal = {
+  getOAuthToken(options) {
+    Assert.equal(options.scope, "profile");
+    return "token";
+  },
+};
+
+const PROFILE_OPTIONS = {
+  serverURL: "http://127.0.0.1:1111/v1",
+  fxai: mockFxaInternal,
+};
+
+/**
+ * Mock request error responder
+ * @param {Error} error
+ *        Error object
+ * @returns {Function}
+ */
+let mockResponseError = function (error) {
+  return function () {
+    return {
+      setHeader() {},
+      async dispatch(method, payload) {
+        throw error;
+      },
+    };
+  };
+};
+
+add_test(function successfulResponse() {
+  let client = new FxAccountsProfileClient(PROFILE_OPTIONS);
+  let response = {
+    success: true,
+    status: STATUS_SUCCESS,
+    headers: { etag: "bogusETag" },
+    body: '{"email":"someone@restmail.net","uid":"0d5c1a89b8c54580b8e3e8adadae864a"}',
+  };
+
+  client._Request = new mockResponse(response);
+  client.fetchProfile().then(function (result) {
+    Assert.equal(
+      client._Request._requestUri,
+      "http://127.0.0.1:1111/v1/profile"
+    );
+    Assert.equal(result.body.email, "someone@restmail.net");
+    Assert.equal(result.body.uid, "0d5c1a89b8c54580b8e3e8adadae864a");
+    Assert.equal(result.etag, "bogusETag");
+    run_next_test();
+  });
+});
+
+add_test(function setsIfNoneMatchETagHeader() {
+  let client = new FxAccountsProfileClient(PROFILE_OPTIONS);
+  let response = {
+    success: true,
+    status: STATUS_SUCCESS,
+    headers: {},
+    body: '{"email":"someone@restmail.net","uid":"0d5c1a89b8c54580b8e3e8adadae864a"}',
+  };
+
+  let req = new mockResponse(response);
+  client._Request = req;
+  client.fetchProfile("bogusETag").then(function (result) {
+    Assert.equal(
+      client._Request._requestUri,
+      "http://127.0.0.1:1111/v1/profile"
+    );
+    Assert.equal(result.body.email, "someone@restmail.net");
+    Assert.equal(result.body.uid, "0d5c1a89b8c54580b8e3e8adadae864a");
+    Assert.ok(req.ifNoneMatchSet);
+    run_next_test();
+  });
+});
+
+add_test(function successful304Response() {
+  let client = new FxAccountsProfileClient(PROFILE_OPTIONS);
+  let response = {
+    success: true,
+    headers: { etag: "bogusETag" },
+    status: 304,
+  };
+
+  client._Request = new mockResponse(response);
+  client.fetchProfile().then(function (result) {
+    Assert.equal(result, null);
+    run_next_test();
+  });
+});
+
+add_test(function parseErrorResponse() {
+  let client = new FxAccountsProfileClient(PROFILE_OPTIONS);
+  let response = {
+    success: true,
+    status: STATUS_SUCCESS,
+    body: "unexpected",
+  };
+
+  client._Request = new mockResponse(response);
+  client.fetchProfile().catch(function (e) {
+    Assert.equal(e.name, "FxAccountsProfileClientError");
+    Assert.equal(e.code, STATUS_SUCCESS);
+    Assert.equal(e.errno, ERRNO_PARSE);
+    Assert.equal(e.error, ERROR_PARSE);
+    Assert.equal(e.message, "unexpected");
+    run_next_test();
+  });
+});
+
+add_test(function serverErrorResponse() {
+  let client = new FxAccountsProfileClient(PROFILE_OPTIONS);
+  let response = {
+    status: 500,
+    body: '{ "code": 500, "errno": 100, "error": "Bad Request", "message": "Something went wrong", "reason": "Because the internet" }',
+  };
+
+  client._Request = new mockResponse(response);
+  client.fetchProfile().catch(function (e) {
+    Assert.equal(e.name, "FxAccountsProfileClientError");
+    Assert.equal(e.code, 500);
+    Assert.equal(e.errno, 100);
+    Assert.equal(e.error, "Bad Request");
+    Assert.equal(e.message, "Something went wrong");
+    run_next_test();
+  });
+});
+
+// Test that we get a token, then if we get a 401 we revoke it, get a new one
+// and retry.
+add_test(function server401ResponseThenSuccess() {
+  // The last token we handed out.
+  let lastToken = -1;
+  // The number of times our removeCachedOAuthToken function was called.
+  let numTokensRemoved = 0;
+
+  let mockFxaWithRemove = {
+    getOAuthToken(options) {
+      Assert.equal(options.scope, "profile");
+      return "" + ++lastToken; // tokens are strings.
+    },
+    removeCachedOAuthToken(options) {
+      // This test never has more than 1 token alive at once, so the token
+      // being revoked must always be the last token we handed out.
+      Assert.equal(parseInt(options.token), lastToken);
+      ++numTokensRemoved;
+    },
+  };
+  let profileOptions = {
+    serverURL: "http://127.0.0.1:1111/v1",
+    fxai: mockFxaWithRemove,
+  };
+  let client = new FxAccountsProfileClient(profileOptions);
+
+  // 2 responses - first one implying the token has expired, second works.
+  let responses = [
+    {
+      status: 401,
+      body: '{ "code": 401, "errno": 100, "error": "Token expired", "message": "That token is too old", "reason": "Because security" }',
+    },
+    {
+      success: true,
+      status: STATUS_SUCCESS,
+      headers: {},
+      body: '{"avatar":"http://example.com/image.jpg","id":"0d5c1a89b8c54580b8e3e8adadae864a"}',
+    },
+  ];
+
+  let numRequests = 0;
+  let numAuthHeaders = 0;
+  // Like mockResponse but we want access to headers etc.
+  client._Request = function (requestUri) {
+    return {
+      setHeader(name, value) {
+        if (name == "Authorization") {
+          numAuthHeaders++;
+          Assert.equal(value, "Bearer " + lastToken);
+        }
+      },
+      async dispatch(method, payload) {
+        this.response = responses[numRequests];
+        ++numRequests;
+        return this.response;
+      },
+    };
+  };
+
+  client.fetchProfile().then(result => {
+    Assert.equal(result.body.avatar, "http://example.com/image.jpg");
+    Assert.equal(result.body.id, "0d5c1a89b8c54580b8e3e8adadae864a");
+    // should have been exactly 2 requests and exactly 2 auth headers.
+    Assert.equal(numRequests, 2);
+    Assert.equal(numAuthHeaders, 2);
+    // and we should have seen one token revoked.
+    Assert.equal(numTokensRemoved, 1);
+
+    run_next_test();
+  });
+});
+
+// Test that we get a token, then if we get a 401 we revoke it, get a new one
+// and retry - but we *still* get a 401 on the retry, so the caller sees that.
+add_test(function server401ResponsePersists() {
+  // The last token we handed out.
+  let lastToken = -1;
+  // The number of times our removeCachedOAuthToken function was called.
+  let numTokensRemoved = 0;
+
+  let mockFxaWithRemove = {
+    getOAuthToken(options) {
+      Assert.equal(options.scope, "profile");
+      return "" + ++lastToken; // tokens are strings.
+    },
+    removeCachedOAuthToken(options) {
+      // This test never has more than 1 token alive at once, so the token
+      // being revoked must always be the last token we handed out.
+      Assert.equal(parseInt(options.token), lastToken);
+      ++numTokensRemoved;
+    },
+  };
+  let profileOptions = {
+    serverURL: "http://127.0.0.1:1111/v1",
+    fxai: mockFxaWithRemove,
+  };
+  let client = new FxAccountsProfileClient(profileOptions);
+
+  let response = {
+    status: 401,
+    body: '{ "code": 401, "errno": 100, "error": "It\'s not your token, it\'s you!", "message": "I don\'t like you", "reason": "Because security" }',
+  };
+
+  let numRequests = 0;
+  let numAuthHeaders = 0;
+  client._Request = function (requestUri) {
+    return {
+      setHeader(name, value) {
+        if (name == "Authorization") {
+          numAuthHeaders++;
+          Assert.equal(value, "Bearer " + lastToken);
+        }
+      },
+      async dispatch(method, payload) {
+        this.response = response;
+        ++numRequests;
+        return this.response;
+      },
+    };
+  };
+
+  client.fetchProfile().catch(function (e) {
+    Assert.equal(e.name, "FxAccountsProfileClientError");
+    Assert.equal(e.code, 401);
+    Assert.equal(e.errno, 100);
+    Assert.equal(e.error, "It's not your token, it's you!");
+    // should have been exactly 2 requests and exactly 2 auth headers.
+    Assert.equal(numRequests, 2);
+    Assert.equal(numAuthHeaders, 2);
+    // and we should have seen both tokens revoked.
+    Assert.equal(numTokensRemoved, 2);
+    run_next_test();
+  });
+});
+
+add_test(function networkErrorResponse() {
+  let client = new FxAccountsProfileClient({
+    serverURL: "http://domain.dummy",
+    fxai: mockFxaInternal,
+  });
+  client.fetchProfile().catch(function (e) {
+    Assert.equal(e.name, "FxAccountsProfileClientError");
+    Assert.equal(e.code, null);
+    Assert.equal(e.errno, ERRNO_NETWORK);
+    Assert.equal(e.error, ERROR_NETWORK);
+    run_next_test();
+  });
+});
+
+add_test(function unsupportedMethod() {
+  let client = new FxAccountsProfileClient(PROFILE_OPTIONS);
+
+  return client._createRequest("/profile", "PUT").catch(function (e) {
+    Assert.equal(e.name, "FxAccountsProfileClientError");
+    Assert.equal(e.code, ERROR_CODE_METHOD_NOT_ALLOWED);
+    Assert.equal(e.errno, ERRNO_NETWORK);
+    Assert.equal(e.error, ERROR_NETWORK);
+    Assert.equal(e.message, ERROR_MSG_METHOD_NOT_ALLOWED);
+    run_next_test();
+  });
+});
+
+add_test(function onCompleteRequestError() {
+  let client = new FxAccountsProfileClient(PROFILE_OPTIONS);
+  client._Request = new mockResponseError(new Error("onComplete error"));
+  client.fetchProfile().catch(function (e) {
+    Assert.equal(e.name, "FxAccountsProfileClientError");
+    Assert.equal(e.code, null);
+    Assert.equal(e.errno, ERRNO_NETWORK);
+    Assert.equal(e.error, ERROR_NETWORK);
+    Assert.equal(e.message, "Error: onComplete error");
+    run_next_test();
+  });
+});
+
+add_test(function constructorTests() {
+  validationHelper(
+    undefined,
+    "Error: Missing 'serverURL' configuration option"
+  );
+
+  validationHelper({}, "Error: Missing 'serverURL' configuration option");
+
+  validationHelper({ serverURL: "badUrl" }, "Error: Invalid 'serverURL'");
+
+  run_next_test();
+});
+
+add_test(function errorTests() {
+  let error1 = new FxAccountsProfileClientError();
+  Assert.equal(error1.name, "FxAccountsProfileClientError");
+  Assert.equal(error1.code, null);
+  Assert.equal(error1.errno, ERRNO_UNKNOWN_ERROR);
+  Assert.equal(error1.error, ERROR_UNKNOWN);
+  Assert.equal(error1.message, null);
+
+  let error2 = new FxAccountsProfileClientError({
+    code: STATUS_SUCCESS,
+    errno: 1,
+    error: "Error",
+    message: "Something",
+  });
+  let fields2 = error2._toStringFields();
+  let statusCode = 1;
+
+  Assert.equal(error2.name, "FxAccountsProfileClientError");
+  Assert.equal(error2.code, STATUS_SUCCESS);
+  Assert.equal(error2.errno, statusCode);
+  Assert.equal(error2.error, "Error");
+  Assert.equal(error2.message, "Something");
+
+  Assert.equal(fields2.name, "FxAccountsProfileClientError");
+  Assert.equal(fields2.code, STATUS_SUCCESS);
+  Assert.equal(fields2.errno, statusCode);
+  Assert.equal(fields2.error, "Error");
+  Assert.equal(fields2.message, "Something");
+
+  Assert.ok(error2.toString().includes("Something"));
+  run_next_test();
+});
+
+/**
+ * Quick way to test the "FxAccountsProfileClient" constructor.
+ *
+ * @param {Object} options
+ *        FxAccountsProfileClient constructor options
+ * @param {String} expected
+ *        Expected error message
+ * @returns {*}
+ */
+function validationHelper(options, expected) {
+  // add fxai to options - that missing isn't what we are testing here.
+  if (options) {
+    options.fxai = mockFxaInternal;
+  }
+  try {
+    new FxAccountsProfileClient(options);
+  } catch (e) {
+    return Assert.equal(e.toString(), expected);
+  }
+  throw new Error("Validation helper error");
+}
diff --git a/services/fxaccounts/tests/xpcshell/test_push_service.js b/services/fxaccounts/tests/xpcshell/test_push_service.js
new file mode 100644
index 0000000000..cc01d256fe
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_push_service.js
@@ -0,0 +1,520 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Tests for the FxA push service.
+
+/* eslint-disable mozilla/use-chromeutils-generateqi */
+
+const {
+  FXA_PUSH_SCOPE_ACCOUNT_UPDATE,
+  ONLOGOUT_NOTIFICATION,
+  ON_ACCOUNT_DESTROYED_NOTIFICATION,
+  ON_DEVICE_CONNECTED_NOTIFICATION,
+  ON_DEVICE_DISCONNECTED_NOTIFICATION,
+  ON_PASSWORD_CHANGED_NOTIFICATION,
+  ON_PASSWORD_RESET_NOTIFICATION,
+  ON_PROFILE_CHANGE_NOTIFICATION,
+  ON_PROFILE_UPDATED_NOTIFICATION,
+  ON_VERIFY_LOGIN_NOTIFICATION,
+  log,
+} = ChromeUtils.import("resource://gre/modules/FxAccountsCommon.js");
+
+const { FxAccountsPushService } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsPush.sys.mjs"
+);
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "PushService",
+  "@mozilla.org/push/Service;1",
+  "nsIPushService"
+);
+
+initTestLogging("Trace");
+log.level = Log.Level.Trace;
+
+const MOCK_ENDPOINT = "http://mochi.test:8888";
+
+// tests do not allow external connections, mock the PushService
+let mockPushService = {
+  pushTopic: PushService.pushTopic,
+  subscriptionChangeTopic: PushService.subscriptionChangeTopic,
+  subscribe(scope, principal, cb) {
+    cb(Cr.NS_OK, {
+      endpoint: MOCK_ENDPOINT,
+    });
+  },
+  unsubscribe(scope, principal, cb) {
+    cb(Cr.NS_OK, true);
+  },
+};
+
+let mockFxAccounts = {
+  checkVerificationStatus() {},
+  updateDeviceRegistration() {},
+};
+
+let mockLog = {
+  trace() {},
+  debug() {},
+  warn() {},
+  error() {},
+};
+
+add_task(async function initialize() {
+  let pushService = new FxAccountsPushService();
+  equal(pushService.initialize(), false);
+});
+
+add_task(async function registerPushEndpointSuccess() {
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: mockFxAccounts,
+  });
+
+  let subscription = await pushService.registerPushEndpoint();
+  equal(subscription.endpoint, MOCK_ENDPOINT);
+});
+
+add_task(async function registerPushEndpointFailure() {
+  let failPushService = Object.assign(mockPushService, {
+    subscribe(scope, principal, cb) {
+      cb(Cr.NS_ERROR_ABORT);
+    },
+  });
+
+  let pushService = new FxAccountsPushService({
+    pushService: failPushService,
+    fxai: mockFxAccounts,
+  });
+
+  let subscription = await pushService.registerPushEndpoint();
+  equal(subscription, null);
+});
+
+add_task(async function unsubscribeSuccess() {
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: mockFxAccounts,
+  });
+
+  let result = await pushService.unsubscribe();
+  equal(result, true);
+});
+
+add_task(async function unsubscribeFailure() {
+  let failPushService = Object.assign(mockPushService, {
+    unsubscribe(scope, principal, cb) {
+      cb(Cr.NS_ERROR_ABORT);
+    },
+  });
+
+  let pushService = new FxAccountsPushService({
+    pushService: failPushService,
+    fxai: mockFxAccounts,
+  });
+
+  let result = await pushService.unsubscribe();
+  equal(result, null);
+});
+
+add_test(function observeLogout() {
+  let customLog = Object.assign(mockLog, {
+    trace(msg) {
+      if (msg === "FxAccountsPushService unsubscribe") {
+        // logout means we unsubscribe
+        run_next_test();
+      }
+    },
+  });
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    log: customLog,
+  });
+
+  pushService.observe(null, ONLOGOUT_NOTIFICATION);
+});
+
+add_test(function observePushTopicVerify() {
+  let emptyMsg = {
+    QueryInterface() {
+      return this;
+    },
+  };
+  let customAccounts = Object.assign(mockFxAccounts, {
+    checkVerificationStatus() {
+      // checking verification status on push messages without data
+      run_next_test();
+    },
+  });
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: customAccounts,
+  });
+
+  pushService.observe(
+    emptyMsg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+});
+
+add_test(function observePushTopicDeviceConnected() {
+  let msg = {
+    data: {
+      json: () => ({
+        command: ON_DEVICE_CONNECTED_NOTIFICATION,
+        data: {
+          deviceName: "My phone",
+        },
+      }),
+    },
+    QueryInterface() {
+      return this;
+    },
+  };
+  let obs = (subject, topic, data) => {
+    Services.obs.removeObserver(obs, topic);
+    run_next_test();
+  };
+  Services.obs.addObserver(obs, ON_DEVICE_CONNECTED_NOTIFICATION);
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: mockFxAccounts,
+  });
+
+  pushService.observe(
+    msg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+});
+
+add_task(async function observePushTopicDeviceDisconnected_current_device() {
+  const deviceId = "bogusid";
+  let msg = {
+    data: {
+      json: () => ({
+        command: ON_DEVICE_DISCONNECTED_NOTIFICATION,
+        data: {
+          id: deviceId,
+        },
+      }),
+    },
+    QueryInterface() {
+      return this;
+    },
+  };
+
+  let signoutCalled = false;
+  let { FxAccounts } = ChromeUtils.importESModule(
+    "resource://gre/modules/FxAccounts.sys.mjs"
+  );
+  const fxAccountsMock = new FxAccounts({
+    newAccountState() {
+      return {
+        async getUserAccountData() {
+          return { device: { id: deviceId } };
+        },
+      };
+    },
+    signOut() {
+      signoutCalled = true;
+    },
+  })._internal;
+
+  const deviceDisconnectedNotificationObserved = new Promise(resolve => {
+    Services.obs.addObserver(function obs(subject, topic, data) {
+      Services.obs.removeObserver(obs, topic);
+      equal(data, JSON.stringify({ isLocalDevice: true }));
+      resolve();
+    }, ON_DEVICE_DISCONNECTED_NOTIFICATION);
+  });
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: fxAccountsMock,
+  });
+
+  pushService.observe(
+    msg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+
+  await deviceDisconnectedNotificationObserved;
+  ok(signoutCalled);
+});
+
+add_task(async function observePushTopicDeviceDisconnected_another_device() {
+  const deviceId = "bogusid";
+  let msg = {
+    data: {
+      json: () => ({
+        command: ON_DEVICE_DISCONNECTED_NOTIFICATION,
+        data: {
+          id: deviceId,
+        },
+      }),
+    },
+    QueryInterface() {
+      return this;
+    },
+  };
+
+  let signoutCalled = false;
+  let { FxAccounts } = ChromeUtils.importESModule(
+    "resource://gre/modules/FxAccounts.sys.mjs"
+  );
+  const fxAccountsMock = new FxAccounts({
+    newAccountState() {
+      return {
+        async getUserAccountData() {
+          return { device: { id: "thelocaldevice" } };
+        },
+      };
+    },
+    signOut() {
+      signoutCalled = true;
+    },
+  })._internal;
+
+  const deviceDisconnectedNotificationObserved = new Promise(resolve => {
+    Services.obs.addObserver(function obs(subject, topic, data) {
+      Services.obs.removeObserver(obs, topic);
+      equal(data, JSON.stringify({ isLocalDevice: false }));
+      resolve();
+    }, ON_DEVICE_DISCONNECTED_NOTIFICATION);
+  });
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: fxAccountsMock,
+  });
+
+  pushService.observe(
+    msg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+
+  await deviceDisconnectedNotificationObserved;
+  ok(!signoutCalled);
+});
+
+add_test(function observePushTopicAccountDestroyed() {
+  const uid = "bogusuid";
+  let msg = {
+    data: {
+      json: () => ({
+        command: ON_ACCOUNT_DESTROYED_NOTIFICATION,
+        data: {
+          uid,
+        },
+      }),
+    },
+    QueryInterface() {
+      return this;
+    },
+  };
+  let customAccounts = Object.assign(mockFxAccounts, {
+    _handleAccountDestroyed() {
+      // checking verification status on push messages without data
+      run_next_test();
+    },
+  });
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: customAccounts,
+  });
+
+  pushService.observe(
+    msg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+});
+
+add_test(function observePushTopicVerifyLogin() {
+  let url = "http://localhost/newLogin";
+  let title = "bogustitle";
+  let body = "bogusbody";
+  let msg = {
+    data: {
+      json: () => ({
+        command: ON_VERIFY_LOGIN_NOTIFICATION,
+        data: {
+          body,
+          title,
+          url,
+        },
+      }),
+    },
+    QueryInterface() {
+      return this;
+    },
+  };
+  let obs = (subject, topic, data) => {
+    Services.obs.removeObserver(obs, topic);
+    Assert.equal(data, JSON.stringify(msg.data.json().data));
+    run_next_test();
+  };
+  Services.obs.addObserver(obs, ON_VERIFY_LOGIN_NOTIFICATION);
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: mockFxAccounts,
+  });
+
+  pushService.observe(
+    msg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+});
+
+add_test(function observePushTopicProfileUpdated() {
+  let msg = {
+    data: {
+      json: () => ({
+        command: ON_PROFILE_UPDATED_NOTIFICATION,
+      }),
+    },
+    QueryInterface() {
+      return this;
+    },
+  };
+  let obs = (subject, topic, data) => {
+    Services.obs.removeObserver(obs, topic);
+    run_next_test();
+  };
+  Services.obs.addObserver(obs, ON_PROFILE_CHANGE_NOTIFICATION);
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: mockFxAccounts,
+  });
+
+  pushService.observe(
+    msg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+});
+
+add_test(function observePushTopicPasswordChanged() {
+  let msg = {
+    data: {
+      json: () => ({
+        command: ON_PASSWORD_CHANGED_NOTIFICATION,
+      }),
+    },
+    QueryInterface() {
+      return this;
+    },
+  };
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+  });
+
+  pushService._onPasswordChanged = function () {
+    run_next_test();
+  };
+
+  pushService.observe(
+    msg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+});
+
+add_test(function observePushTopicPasswordReset() {
+  let msg = {
+    data: {
+      json: () => ({
+        command: ON_PASSWORD_RESET_NOTIFICATION,
+      }),
+    },
+    QueryInterface() {
+      return this;
+    },
+  };
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+  });
+
+  pushService._onPasswordChanged = function () {
+    run_next_test();
+  };
+
+  pushService.observe(
+    msg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+});
+
+add_task(async function commandReceived() {
+  let msg = {
+    data: {
+      json: () => ({
+        command: "fxaccounts:command_received",
+        data: {
+          url: "https://api.accounts.firefox.com/auth/v1/account/device/commands?index=42&limit=1",
+        },
+      }),
+    },
+    QueryInterface() {
+      return this;
+    },
+  };
+
+  let fxAccountsMock = {};
+  const promiseConsumeRemoteMessagesCalled = new Promise(res => {
+    fxAccountsMock.commands = {
+      pollDeviceCommands() {
+        res();
+      },
+    };
+  });
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: fxAccountsMock,
+  });
+
+  pushService.observe(
+    msg,
+    mockPushService.pushTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+  await promiseConsumeRemoteMessagesCalled;
+});
+
+add_test(function observeSubscriptionChangeTopic() {
+  let customAccounts = Object.assign(mockFxAccounts, {
+    updateDeviceRegistration() {
+      // subscription change means updating the device registration
+      run_next_test();
+    },
+  });
+
+  let pushService = new FxAccountsPushService({
+    pushService: mockPushService,
+    fxai: customAccounts,
+  });
+
+  pushService.observe(
+    null,
+    mockPushService.subscriptionChangeTopic,
+    FXA_PUSH_SCOPE_ACCOUNT_UPDATE
+  );
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_storage_manager.js b/services/fxaccounts/tests/xpcshell/test_storage_manager.js
new file mode 100644
index 0000000000..702cd34f3c
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_storage_manager.js
@@ -0,0 +1,587 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Tests for the FxA storage manager.
+
+const { FxAccountsStorageManager } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccountsStorage.sys.mjs"
+);
+const { DATA_FORMAT_VERSION, log } = ChromeUtils.import(
+  "resource://gre/modules/FxAccountsCommon.js"
+);
+
+initTestLogging("Trace");
+log.level = Log.Level.Trace;
+
+const DEVICE_REGISTRATION_VERSION = 42;
+
+// A couple of mocks we can use.
+function MockedPlainStorage(accountData) {
+  let data = null;
+  if (accountData) {
+    data = {
+      version: DATA_FORMAT_VERSION,
+      accountData,
+    };
+  }
+  this.data = data;
+  this.numReads = 0;
+}
+MockedPlainStorage.prototype = {
+  async get() {
+    this.numReads++;
+    Assert.equal(this.numReads, 1, "should only ever be 1 read of acct data");
+    return this.data;
+  },
+
+  async set(data) {
+    this.data = data;
+  },
+};
+
+function MockedSecureStorage(accountData) {
+  let data = null;
+  if (accountData) {
+    data = {
+      version: DATA_FORMAT_VERSION,
+      accountData,
+    };
+  }
+  this.data = data;
+  this.numReads = 0;
+}
+
+MockedSecureStorage.prototype = {
+  fetchCount: 0,
+  locked: false,
+  /* eslint-disable object-shorthand */
+  // This constructor must be declared without
+  // object shorthand or we get an exception of
+  // "TypeError: this.STORAGE_LOCKED is not a constructor"
+  STORAGE_LOCKED: function () {},
+  /* eslint-enable object-shorthand */
+  async get(uid, email) {
+    this.fetchCount++;
+    if (this.locked) {
+      throw new this.STORAGE_LOCKED();
+    }
+    this.numReads++;
+    Assert.equal(
+      this.numReads,
+      1,
+      "should only ever be 1 read of unlocked data"
+    );
+    return this.data;
+  },
+
+  async set(uid, contents) {
+    this.data = contents;
+  },
+};
+
+function add_storage_task(testFunction) {
+  add_task(async function () {
+    print("Starting test with secure storage manager");
+    await testFunction(new FxAccountsStorageManager());
+  });
+  add_task(async function () {
+    print("Starting test with simple storage manager");
+    await testFunction(new FxAccountsStorageManager({ useSecure: false }));
+  });
+}
+
+// initialized without account data and there's nothing to read. Not logged in.
+add_storage_task(async function checkInitializedEmpty(sm) {
+  if (sm.secureStorage) {
+    sm.secureStorage = new MockedSecureStorage(null);
+  }
+  await sm.initialize();
+  Assert.strictEqual(await sm.getAccountData(), null);
+  await Assert.rejects(
+    sm.updateAccountData({ kXCS: "kXCS" }),
+    /No user is logged in/
+  );
+});
+
+// Initialized with account data (ie, simulating a new user being logged in).
+// Should reflect the initial data and be written to storage.
+add_storage_task(async function checkNewUser(sm) {
+  let initialAccountData = {
+    uid: "uid",
+    email: "someone@somewhere.com",
+    kXCS: "kXCS",
+    device: {
+      id: "device id",
+    },
+  };
+  sm.plainStorage = new MockedPlainStorage();
+  if (sm.secureStorage) {
+    sm.secureStorage = new MockedSecureStorage(null);
+  }
+  await sm.initialize(initialAccountData);
+  let accountData = await sm.getAccountData();
+  Assert.equal(accountData.uid, initialAccountData.uid);
+  Assert.equal(accountData.email, initialAccountData.email);
+  Assert.equal(accountData.kXCS, initialAccountData.kXCS);
+  Assert.deepEqual(accountData.device, initialAccountData.device);
+
+  // and it should have been written to storage.
+  Assert.equal(sm.plainStorage.data.accountData.uid, initialAccountData.uid);
+  Assert.equal(
+    sm.plainStorage.data.accountData.email,
+    initialAccountData.email
+  );
+  Assert.deepEqual(
+    sm.plainStorage.data.accountData.device,
+    initialAccountData.device
+  );
+  // check secure
+  if (sm.secureStorage) {
+    Assert.equal(
+      sm.secureStorage.data.accountData.kXCS,
+      initialAccountData.kXCS
+    );
+  } else {
+    Assert.equal(
+      sm.plainStorage.data.accountData.kXCS,
+      initialAccountData.kXCS
+    );
+  }
+});
+
+// Initialized without account data but storage has it available.
+add_storage_task(async function checkEverythingRead(sm) {
+  sm.plainStorage = new MockedPlainStorage({
+    uid: "uid",
+    email: "someone@somewhere.com",
+    device: {
+      id: "wibble",
+      registrationVersion: null,
+    },
+  });
+  if (sm.secureStorage) {
+    sm.secureStorage = new MockedSecureStorage(null);
+  }
+  await sm.initialize();
+  let accountData = await sm.getAccountData();
+  Assert.ok(accountData, "read account data");
+  Assert.equal(accountData.uid, "uid");
+  Assert.equal(accountData.email, "someone@somewhere.com");
+  Assert.deepEqual(accountData.device, {
+    id: "wibble",
+    registrationVersion: null,
+  });
+  // Update the data - we should be able to fetch it back and it should appear
+  // in our storage.
+  await sm.updateAccountData({
+    verified: true,
+    kSync: "kSync",
+    kXCS: "kXCS",
+    kExtSync: "kExtSync",
+    kExtKbHash: "kExtKbHash",
+    device: {
+      id: "wibble",
+      registrationVersion: DEVICE_REGISTRATION_VERSION,
+    },
+  });
+  accountData = await sm.getAccountData();
+  Assert.equal(accountData.kSync, "kSync");
+  Assert.equal(accountData.kXCS, "kXCS");
+  Assert.equal(accountData.kExtSync, "kExtSync");
+  Assert.equal(accountData.kExtKbHash, "kExtKbHash");
+  Assert.deepEqual(accountData.device, {
+    id: "wibble",
+    registrationVersion: DEVICE_REGISTRATION_VERSION,
+  });
+  // Check the new value was written to storage.
+  await sm._promiseStorageComplete; // storage is written in the background.
+  Assert.equal(sm.plainStorage.data.accountData.verified, true);
+  Assert.deepEqual(sm.plainStorage.data.accountData.device, {
+    id: "wibble",
+    registrationVersion: DEVICE_REGISTRATION_VERSION,
+  });
+  // derive keys are secure
+  if (sm.secureStorage) {
+    Assert.equal(sm.secureStorage.data.accountData.kExtKbHash, "kExtKbHash");
+    Assert.equal(sm.secureStorage.data.accountData.kExtSync, "kExtSync");
+    Assert.equal(sm.secureStorage.data.accountData.kXCS, "kXCS");
+    Assert.equal(sm.secureStorage.data.accountData.kSync, "kSync");
+  } else {
+    Assert.equal(sm.plainStorage.data.accountData.kExtKbHash, "kExtKbHash");
+    Assert.equal(sm.plainStorage.data.accountData.kExtSync, "kExtSync");
+    Assert.equal(sm.plainStorage.data.accountData.kXCS, "kXCS");
+    Assert.equal(sm.plainStorage.data.accountData.kSync, "kSync");
+  }
+});
+
+add_storage_task(async function checkInvalidUpdates(sm) {
+  sm.plainStorage = new MockedPlainStorage({
+    uid: "uid",
+    email: "someone@somewhere.com",
+  });
+  if (sm.secureStorage) {
+    sm.secureStorage = new MockedSecureStorage(null);
+  }
+  await sm.initialize();
+
+  await Assert.rejects(
+    sm.updateAccountData({ uid: "another" }),
+    /Can't change uid/
+  );
+});
+
+add_storage_task(async function checkNullUpdatesRemovedUnlocked(sm) {
+  if (sm.secureStorage) {
+    sm.plainStorage = new MockedPlainStorage({
+      uid: "uid",
+      email: "someone@somewhere.com",
+    });
+    sm.secureStorage = new MockedSecureStorage({
+      kSync: "kSync",
+      kXCS: "kXCS",
+      kExtSync: "kExtSync",
+      kExtKbHash: "kExtKbHash",
+    });
+  } else {
+    sm.plainStorage = new MockedPlainStorage({
+      uid: "uid",
+      email: "someone@somewhere.com",
+      kSync: "kSync",
+      kXCS: "kXCS",
+      kExtSync: "kExtSync",
+      kExtKbHash: "kExtKbHash",
+    });
+  }
+  await sm.initialize();
+
+  await sm.updateAccountData({ kXCS: null });
+  let accountData = await sm.getAccountData();
+  Assert.ok(!accountData.kXCS);
+  Assert.equal(accountData.kSync, "kSync");
+});
+
+add_storage_task(async function checkNullRemovesUnlistedFields(sm) {
+  // kA and kB are not listed in FXA_PWDMGR_*_FIELDS, but we still want to
+  // be able to delete them (migration case).
+  if (sm.secureStorage) {
+    sm.plainStorage = new MockedPlainStorage({
+      uid: "uid",
+      email: "someone@somewhere.com",
+    });
+    sm.secureStorage = new MockedSecureStorage({ kA: "kA", kb: "kB" });
+  } else {
+    sm.plainStorage = new MockedPlainStorage({
+      uid: "uid",
+      email: "someone@somewhere.com",
+      kA: "kA",
+      kb: "kB",
+    });
+  }
+  await sm.initialize();
+
+  await sm.updateAccountData({ kA: null, kB: null });
+  let accountData = await sm.getAccountData();
+  Assert.ok(!accountData.kA);
+  Assert.ok(!accountData.kB);
+});
+
+add_storage_task(async function checkDelete(sm) {
+  if (sm.secureStorage) {
+    sm.plainStorage = new MockedPlainStorage({
+      uid: "uid",
+      email: "someone@somewhere.com",
+    });
+    sm.secureStorage = new MockedSecureStorage({
+      kSync: "kSync",
+      kXCS: "kXCS",
+      kExtSync: "kExtSync",
+      kExtKbHash: "kExtKbHash",
+    });
+  } else {
+    sm.plainStorage = new MockedPlainStorage({
+      uid: "uid",
+      email: "someone@somewhere.com",
+      kSync: "kSync",
+      kXCS: "kXCS",
+      kExtSync: "kExtSync",
+      kExtKbHash: "kExtKbHash",
+    });
+  }
+  await sm.initialize();
+
+  await sm.deleteAccountData();
+  // Storage should have been reset to null.
+  Assert.equal(sm.plainStorage.data, null);
+  if (sm.secureStorage) {
+    Assert.equal(sm.secureStorage.data, null);
+  }
+  // And everything should reflect no user.
+  Assert.equal(await sm.getAccountData(), null);
+});
+
+// Some tests only for the secure storage manager.
+add_task(async function checkNullUpdatesRemovedLocked() {
+  let sm = new FxAccountsStorageManager();
+  sm.plainStorage = new MockedPlainStorage({
+    uid: "uid",
+    email: "someone@somewhere.com",
+  });
+  sm.secureStorage = new MockedSecureStorage({
+    kSync: "kSync",
+    kXCS: "kXCS",
+    kExtSync: "kExtSync",
+    kExtKbHash: "kExtKbHash",
+  });
+  sm.secureStorage.locked = true;
+  await sm.initialize();
+
+  await sm.updateAccountData({ kSync: null });
+  let accountData = await sm.getAccountData();
+  Assert.ok(!accountData.kSync);
+  // still no kXCS as we are locked.
+  Assert.ok(!accountData.kXCS);
+
+  // now unlock - should still be no kSync but kXCS should appear.
+  sm.secureStorage.locked = false;
+  accountData = await sm.getAccountData();
+  Assert.ok(!accountData.kSync);
+  Assert.equal(accountData.kXCS, "kXCS");
+  // And secure storage should have been written with our previously-cached
+  // data.
+  Assert.strictEqual(sm.secureStorage.data.accountData.kSync, undefined);
+  Assert.strictEqual(sm.secureStorage.data.accountData.kXCS, "kXCS");
+});
+
+add_task(async function checkEverythingReadSecure() {
+  let sm = new FxAccountsStorageManager();
+  sm.plainStorage = new MockedPlainStorage({
+    uid: "uid",
+    email: "someone@somewhere.com",
+  });
+  sm.secureStorage = new MockedSecureStorage({ kXCS: "kXCS" });
+  await sm.initialize();
+
+  let accountData = await sm.getAccountData();
+  Assert.ok(accountData, "read account data");
+  Assert.equal(accountData.uid, "uid");
+  Assert.equal(accountData.email, "someone@somewhere.com");
+  Assert.equal(accountData.kXCS, "kXCS");
+});
+
+add_task(async function checkExplicitGet() {
+  let sm = new FxAccountsStorageManager();
+  sm.plainStorage = new MockedPlainStorage({
+    uid: "uid",
+    email: "someone@somewhere.com",
+  });
+  sm.secureStorage = new MockedSecureStorage({ kXCS: "kXCS" });
+  await sm.initialize();
+
+  let accountData = await sm.getAccountData(["uid", "kXCS"]);
+  Assert.ok(accountData, "read account data");
+  Assert.equal(accountData.uid, "uid");
+  Assert.equal(accountData.kXCS, "kXCS");
+  // We didn't ask for email so shouldn't have got it.
+  Assert.strictEqual(accountData.email, undefined);
+});
+
+add_task(async function checkExplicitGetNoSecureRead() {
+  let sm = new FxAccountsStorageManager();
+  sm.plainStorage = new MockedPlainStorage({
+    uid: "uid",
+    email: "someone@somewhere.com",
+  });
+  sm.secureStorage = new MockedSecureStorage({ kXCS: "kXCS" });
+  await sm.initialize();
+
+  Assert.equal(sm.secureStorage.fetchCount, 0);
+  // request 2 fields in secure storage - it should have caused a single fetch.
+  let accountData = await sm.getAccountData(["email", "uid"]);
+  Assert.ok(accountData, "read account data");
+  Assert.equal(accountData.uid, "uid");
+  Assert.equal(accountData.email, "someone@somewhere.com");
+  Assert.strictEqual(accountData.kXCS, undefined);
+  Assert.equal(sm.secureStorage.fetchCount, 1);
+});
+
+add_task(async function checkLockedUpdates() {
+  let sm = new FxAccountsStorageManager();
+  sm.plainStorage = new MockedPlainStorage({
+    uid: "uid",
+    email: "someone@somewhere.com",
+  });
+  sm.secureStorage = new MockedSecureStorage({
+    kSync: "old-kSync",
+    kXCS: "kXCS",
+  });
+  sm.secureStorage.locked = true;
+  await sm.initialize();
+
+  let accountData = await sm.getAccountData();
+  // requesting kSync and kXCS will fail as storage is locked.
+  Assert.ok(!accountData.kSync);
+  Assert.ok(!accountData.kXCS);
+  // While locked we can still update it and see the updated value.
+  sm.updateAccountData({ kSync: "new-kSync" });
+  accountData = await sm.getAccountData();
+  Assert.equal(accountData.kSync, "new-kSync");
+  // unlock.
+  sm.secureStorage.locked = false;
+  accountData = await sm.getAccountData();
+  // should reflect the value we updated and the one we didn't.
+  Assert.equal(accountData.kSync, "new-kSync");
+  Assert.equal(accountData.kXCS, "kXCS");
+  // And storage should also reflect it.
+  Assert.strictEqual(sm.secureStorage.data.accountData.kSync, "new-kSync");
+  Assert.strictEqual(sm.secureStorage.data.accountData.kXCS, "kXCS");
+});
+
+// Some tests for the "storage queue" functionality.
+
+// A helper for our queued tests. It creates a StorageManager and then queues
+// an unresolved promise. The tests then do additional setup and checks, then
+// resolves or rejects the blocked promise.
+async function setupStorageManagerForQueueTest() {
+  let sm = new FxAccountsStorageManager();
+  sm.plainStorage = new MockedPlainStorage({
+    uid: "uid",
+    email: "someone@somewhere.com",
+  });
+  sm.secureStorage = new MockedSecureStorage({ kXCS: "kXCS" });
+  sm.secureStorage.locked = true;
+  await sm.initialize();
+
+  let resolveBlocked, rejectBlocked;
+  let blockedPromise = new Promise((resolve, reject) => {
+    resolveBlocked = resolve;
+    rejectBlocked = reject;
+  });
+
+  sm._queueStorageOperation(() => blockedPromise);
+  return { sm, blockedPromise, resolveBlocked, rejectBlocked };
+}
+
+// First the general functionality.
+add_task(async function checkQueueSemantics() {
+  let { sm, resolveBlocked } = await setupStorageManagerForQueueTest();
+
+  // We've one unresolved promise in the queue - add another promise.
+  let resolveSubsequent;
+  let subsequentPromise = new Promise(resolve => {
+    resolveSubsequent = resolve;
+  });
+  let subsequentCalled = false;
+
+  sm._queueStorageOperation(() => {
+    subsequentCalled = true;
+    resolveSubsequent();
+    return subsequentPromise;
+  });
+
+  // Our "subsequent" function should not have been called yet.
+  Assert.ok(!subsequentCalled);
+
+  // Release our blocked promise.
+  resolveBlocked();
+
+  // Our subsequent promise should end up resolved.
+  await subsequentPromise;
+  Assert.ok(subsequentCalled);
+  await sm.finalize();
+});
+
+// Check that a queued promise being rejected works correctly.
+add_task(async function checkQueueSemanticsOnError() {
+  let { sm, blockedPromise, rejectBlocked } =
+    await setupStorageManagerForQueueTest();
+
+  let resolveSubsequent;
+  let subsequentPromise = new Promise(resolve => {
+    resolveSubsequent = resolve;
+  });
+  let subsequentCalled = false;
+
+  sm._queueStorageOperation(() => {
+    subsequentCalled = true;
+    resolveSubsequent();
+    return subsequentPromise;
+  });
+
+  // Our "subsequent" function should not have been called yet.
+  Assert.ok(!subsequentCalled);
+
+  // Reject our blocked promise - the subsequent operations should still work
+  // correctly.
+  rejectBlocked("oh no");
+
+  // Our subsequent promise should end up resolved.
+  await subsequentPromise;
+  Assert.ok(subsequentCalled);
+
+  // But the first promise should reflect the rejection.
+  try {
+    await blockedPromise;
+    Assert.ok(false, "expected this promise to reject");
+  } catch (ex) {
+    Assert.equal(ex, "oh no");
+  }
+  await sm.finalize();
+});
+
+// And some tests for the specific operations that are queued.
+add_task(async function checkQueuedReadAndUpdate() {
+  let { sm, resolveBlocked } = await setupStorageManagerForQueueTest();
+  // Mock the underlying operations
+  // _doReadAndUpdateSecure is queued by _maybeReadAndUpdateSecure
+  let _doReadCalled = false;
+  sm._doReadAndUpdateSecure = () => {
+    _doReadCalled = true;
+    return Promise.resolve();
+  };
+
+  let resultPromise = sm._maybeReadAndUpdateSecure();
+  Assert.ok(!_doReadCalled);
+
+  resolveBlocked();
+  await resultPromise;
+  Assert.ok(_doReadCalled);
+  await sm.finalize();
+});
+
+add_task(async function checkQueuedWrite() {
+  let { sm, resolveBlocked } = await setupStorageManagerForQueueTest();
+  // Mock the underlying operations
+  let __writeCalled = false;
+  sm.__write = () => {
+    __writeCalled = true;
+    return Promise.resolve();
+  };
+
+  let writePromise = sm._write();
+  Assert.ok(!__writeCalled);
+
+  resolveBlocked();
+  await writePromise;
+  Assert.ok(__writeCalled);
+  await sm.finalize();
+});
+
+add_task(async function checkQueuedDelete() {
+  let { sm, resolveBlocked } = await setupStorageManagerForQueueTest();
+  // Mock the underlying operations
+  let _deleteCalled = false;
+  sm._deleteAccountData = () => {
+    _deleteCalled = true;
+    return Promise.resolve();
+  };
+
+  let resultPromise = sm.deleteAccountData();
+  Assert.ok(!_deleteCalled);
+
+  resolveBlocked();
+  await resultPromise;
+  Assert.ok(_deleteCalled);
+  await sm.finalize();
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_telemetry.js b/services/fxaccounts/tests/xpcshell/test_telemetry.js
new file mode 100644
index 0000000000..3b9d318404
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_telemetry.js
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { getFxAccountsSingleton } = ChromeUtils.importESModule(
+  "resource://gre/modules/FxAccounts.sys.mjs"
+);
+const fxAccounts = getFxAccountsSingleton();
+
+_("Misc tests for FxAccounts.telemetry");
+
+const MOCK_HASHED_UID = "00112233445566778899aabbccddeeff";
+const MOCK_DEVICE_ID = "ffeeddccbbaa99887766554433221100";
+
+add_task(function test_sanitized_uid() {
+  Services.prefs.deleteBranch(
+    "identity.fxaccounts.account.telemetry.sanitized_uid"
+  );
+
+  // Returns `null` by default.
+  Assert.equal(fxAccounts.telemetry.getSanitizedUID(), null);
+
+  // Returns provided value if set.
+  fxAccounts.telemetry._setHashedUID(MOCK_HASHED_UID);
+  Assert.equal(fxAccounts.telemetry.getSanitizedUID(), MOCK_HASHED_UID);
+
+  // Reverts to unset for falsey values.
+  fxAccounts.telemetry._setHashedUID("");
+  Assert.equal(fxAccounts.telemetry.getSanitizedUID(), null);
+});
+
+add_task(function test_sanitize_device_id() {
+  Services.prefs.deleteBranch(
+    "identity.fxaccounts.account.telemetry.sanitized_uid"
+  );
+
+  // Returns `null` by default.
+  Assert.equal(fxAccounts.telemetry.sanitizeDeviceId(MOCK_DEVICE_ID), null);
+
+  // Hashes with the sanitized UID if set.
+  // (test value here is SHA256(MOCK_DEVICE_ID + MOCK_HASHED_UID))
+  fxAccounts.telemetry._setHashedUID(MOCK_HASHED_UID);
+  Assert.equal(
+    fxAccounts.telemetry.sanitizeDeviceId(MOCK_DEVICE_ID),
+    "dd7c845006df9baa1c6d756926519c8ce12f91230e11b6057bf8ec65f9b55c1a"
+  );
+
+  // Reverts to unset for falsey values.
+  fxAccounts.telemetry._setHashedUID("");
+  Assert.equal(fxAccounts.telemetry.sanitizeDeviceId(MOCK_DEVICE_ID), null);
+});
diff --git a/services/fxaccounts/tests/xpcshell/test_web_channel.js b/services/fxaccounts/tests/xpcshell/test_web_channel.js
new file mode 100644
index 0000000000..63742439ea
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/test_web_channel.js
@@ -0,0 +1,1358 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ON_PROFILE_CHANGE_NOTIFICATION, WEBCHANNEL_ID, log } =
+  ChromeUtils.import("resource://gre/modules/FxAccountsCommon.js");
+const { CryptoUtils } = ChromeUtils.importESModule(
+  "resource://services-crypto/utils.sys.mjs"
+);
+const { FxAccountsWebChannel, FxAccountsWebChannelHelpers } =
+  ChromeUtils.importESModule(
+    "resource://gre/modules/FxAccountsWebChannel.sys.mjs"
+  );
+
+const URL_STRING = "https://example.com";
+
+const mockSendingContext = {
+  browsingContext: { top: { embedderElement: {} } },
+  principal: {},
+  eventTarget: {},
+};
+
+add_test(function () {
+  validationHelper(undefined, "Error: Missing configuration options");
+
+  validationHelper(
+    {
+      channel_id: WEBCHANNEL_ID,
+    },
+    "Error: Missing 'content_uri' option"
+  );
+
+  validationHelper(
+    {
+      content_uri: "bad uri",
+      channel_id: WEBCHANNEL_ID,
+    },
+    /NS_ERROR_MALFORMED_URI/
+  );
+
+  validationHelper(
+    {
+      content_uri: URL_STRING,
+    },
+    "Error: Missing 'channel_id' option"
+  );
+
+  run_next_test();
+});
+
+add_task(async function test_rejection_reporting() {
+  Services.prefs.setBoolPref(
+    "browser.tabs.remote.separatePrivilegedMozillaWebContentProcess",
+    false
+  );
+
+  let mockMessage = {
+    command: "fxaccounts:login",
+    messageId: "1234",
+    data: { email: "testuser@testuser.com" },
+  };
+
+  let channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+    helpers: {
+      login(accountData) {
+        equal(
+          accountData.email,
+          "testuser@testuser.com",
+          "Should forward incoming message data to the helper"
+        );
+        return Promise.reject(new Error("oops"));
+      },
+    },
+  });
+
+  let promiseSend = new Promise(resolve => {
+    channel._channel.send = (message, context) => {
+      resolve({ message, context });
+    };
+  });
+
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+
+  let { message, context } = await promiseSend;
+
+  equal(context, mockSendingContext, "Should forward the original context");
+  equal(
+    message.command,
+    "fxaccounts:login",
+    "Should include the incoming command"
+  );
+  equal(message.messageId, "1234", "Should include the message ID");
+  equal(
+    message.data.error.message,
+    "Error: oops",
+    "Should convert the error message to a string"
+  );
+  notStrictEqual(
+    message.data.error.stack,
+    null,
+    "Should include the stack for JS error rejections"
+  );
+});
+
+add_test(function test_exception_reporting() {
+  let mockMessage = {
+    command: "fxaccounts:sync_preferences",
+    messageId: "5678",
+    data: { entryPoint: "fxa:verification_complete" },
+  };
+
+  let channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+    helpers: {
+      openSyncPreferences(browser, entryPoint) {
+        equal(
+          entryPoint,
+          "fxa:verification_complete",
+          "Should forward incoming message data to the helper"
+        );
+        throw new TypeError("splines not reticulated");
+      },
+    },
+  });
+
+  channel._channel.send = (message, context) => {
+    equal(context, mockSendingContext, "Should forward the original context");
+    equal(
+      message.command,
+      "fxaccounts:sync_preferences",
+      "Should include the incoming command"
+    );
+    equal(message.messageId, "5678", "Should include the message ID");
+    equal(
+      message.data.error.message,
+      "TypeError: splines not reticulated",
+      "Should convert the exception to a string"
+    );
+    notStrictEqual(
+      message.data.error.stack,
+      null,
+      "Should include the stack for JS exceptions"
+    );
+
+    run_next_test();
+  };
+
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+});
+
+add_test(function test_error_message_remove_profile_path() {
+  const errors = {
+    windows: {
+      err: new Error(
+        "Win error 183 during operation rename on file C:\\Users\\Some Computer\\AppData\\Roaming\\" +
+          "Mozilla\\Firefox\\Profiles\\dbzjmzxa.default\\signedInUser.json (Cannot create a file)"
+      ),
+      expected:
+        "Error: Win error 183 during operation rename on file C:[REDACTED]signedInUser.json (Cannot create a file)",
+    },
+    unix: {
+      err: new Error(
+        "Unix error 28 during operation write on file /Users/someuser/Library/Application Support/" +
+          "Firefox/Profiles/dbzjmzxa.default-release-7/signedInUser.json (No space left on device)"
+      ),
+      expected:
+        "Error: Unix error 28 during operation write on file [REDACTED]signedInUser.json (No space left on device)",
+    },
+    netpath: {
+      err: new Error(
+        "Win error 32 during operation rename on file \\\\SVC.LOC\\HOMEDIRS$\\USERNAME\\Mozilla\\" +
+          "Firefox\\Profiles\\dbzjmzxa.default-release-7\\signedInUser.json (No space left on device)"
+      ),
+      expected:
+        "Error: Win error 32 during operation rename on file [REDACTED]signedInUser.json (No space left on device)",
+    },
+    mount: {
+      err: new Error(
+        "Win error 649 during operation rename on file C:\\SnapVolumes\\MountPoints\\" +
+          "{9e399ec5-0000-0000-0000-100000000000}\\SVROOT\\Users\\username\\AppData\\Roaming\\Mozilla\\Firefox\\" +
+          "Profiles\\dbzjmzxa.default-release\\signedInUser.json (The create operation failed)"
+      ),
+      expected:
+        "Error: Win error 649 during operation rename on file C:[REDACTED]signedInUser.json " +
+        "(The create operation failed)",
+    },
+  };
+  const mockMessage = {
+    command: "fxaccounts:sync_preferences",
+    messageId: "1234",
+  };
+  const channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+  });
+
+  let testNum = 0;
+  const toTest = Object.keys(errors).length;
+  for (const key in errors) {
+    let error = errors[key];
+    channel._channel.send = (message, context) => {
+      equal(
+        message.data.error.message,
+        error.expected,
+        "Should remove the profile path from the error message"
+      );
+      testNum++;
+      if (testNum === toTest) {
+        run_next_test();
+      }
+    };
+    channel._sendError(error.err, mockMessage, mockSendingContext);
+  }
+});
+
+add_test(function test_profile_image_change_message() {
+  var mockMessage = {
+    command: "profile:change",
+    data: { uid: "foo" },
+  };
+
+  makeObserver(ON_PROFILE_CHANGE_NOTIFICATION, function (subject, topic, data) {
+    Assert.equal(data, "foo");
+    run_next_test();
+  });
+
+  var channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+  });
+
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+});
+
+add_test(function test_login_message() {
+  let mockMessage = {
+    command: "fxaccounts:login",
+    data: { email: "testuser@testuser.com" },
+  };
+
+  let channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+    helpers: {
+      login(accountData) {
+        Assert.equal(accountData.email, "testuser@testuser.com");
+        run_next_test();
+        return Promise.resolve();
+      },
+    },
+  });
+
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+});
+
+add_test(function test_logout_message() {
+  let mockMessage = {
+    command: "fxaccounts:logout",
+    data: { uid: "foo" },
+  };
+
+  let channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+    helpers: {
+      logout(uid) {
+        Assert.equal(uid, "foo");
+        run_next_test();
+        return Promise.resolve();
+      },
+    },
+  });
+
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+});
+
+add_test(function test_delete_message() {
+  let mockMessage = {
+    command: "fxaccounts:delete",
+    data: { uid: "foo" },
+  };
+
+  let channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+    helpers: {
+      logout(uid) {
+        Assert.equal(uid, "foo");
+        run_next_test();
+        return Promise.resolve();
+      },
+    },
+  });
+
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+});
+
+add_test(function test_can_link_account_message() {
+  let mockMessage = {
+    command: "fxaccounts:can_link_account",
+    data: { email: "testuser@testuser.com" },
+  };
+
+  let channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+    helpers: {
+      shouldAllowRelink(email) {
+        Assert.equal(email, "testuser@testuser.com");
+        run_next_test();
+      },
+    },
+  });
+
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+});
+
+add_test(function test_sync_preferences_message() {
+  let mockMessage = {
+    command: "fxaccounts:sync_preferences",
+    data: { entryPoint: "fxa:verification_complete" },
+  };
+
+  let channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+    helpers: {
+      openSyncPreferences(browser, entryPoint) {
+        Assert.equal(entryPoint, "fxa:verification_complete");
+        Assert.equal(
+          browser,
+          mockSendingContext.browsingContext.top.embedderElement
+        );
+        run_next_test();
+      },
+    },
+  });
+
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+});
+
+add_test(function test_fxa_status_message() {
+  let mockMessage = {
+    command: "fxaccounts:fxa_status",
+    messageId: 123,
+    data: {
+      service: "sync",
+      context: "fx_desktop_v3",
+    },
+  };
+
+  let channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+    helpers: {
+      async getFxaStatus(service, sendingContext, isPairing, context) {
+        Assert.equal(service, "sync");
+        Assert.equal(sendingContext, mockSendingContext);
+        Assert.ok(!isPairing);
+        Assert.equal(context, "fx_desktop_v3");
+        return {
+          signedInUser: {
+            email: "testuser@testuser.com",
+            sessionToken: "session-token",
+            uid: "uid",
+            verified: true,
+          },
+          capabilities: {
+            engines: ["creditcards", "addresses"],
+          },
+        };
+      },
+    },
+  });
+
+  channel._channel = {
+    send(response, sendingContext) {
+      Assert.equal(response.command, "fxaccounts:fxa_status");
+      Assert.equal(response.messageId, 123);
+
+      let signedInUser = response.data.signedInUser;
+      Assert.ok(!!signedInUser);
+      Assert.equal(signedInUser.email, "testuser@testuser.com");
+      Assert.equal(signedInUser.sessionToken, "session-token");
+      Assert.equal(signedInUser.uid, "uid");
+      Assert.equal(signedInUser.verified, true);
+
+      deepEqual(response.data.capabilities.engines, [
+        "creditcards",
+        "addresses",
+      ]);
+
+      run_next_test();
+    },
+  };
+
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+});
+
+add_test(function test_unrecognized_message() {
+  let mockMessage = {
+    command: "fxaccounts:unrecognized",
+    data: {},
+  };
+
+  let channel = new FxAccountsWebChannel({
+    channel_id: WEBCHANNEL_ID,
+    content_uri: URL_STRING,
+  });
+
+  // no error is expected.
+  channel._channelCallback(WEBCHANNEL_ID, mockMessage, mockSendingContext);
+  run_next_test();
+});
+
+add_test(function test_helpers_should_allow_relink_same_email() {
+  let helpers = new FxAccountsWebChannelHelpers();
+
+  helpers.setPreviousAccountNameHashPref("testuser@testuser.com");
+  Assert.ok(helpers.shouldAllowRelink("testuser@testuser.com"));
+
+  run_next_test();
+});
+
+add_test(function test_helpers_should_allow_relink_different_email() {
+  let helpers = new FxAccountsWebChannelHelpers();
+
+  helpers.setPreviousAccountNameHashPref("testuser@testuser.com");
+
+  helpers._promptForRelink = acctName => {
+    return acctName === "allowed_to_relink@testuser.com";
+  };
+
+  Assert.ok(helpers.shouldAllowRelink("allowed_to_relink@testuser.com"));
+  Assert.ok(!helpers.shouldAllowRelink("not_allowed_to_relink@testuser.com"));
+
+  run_next_test();
+});
+
+add_task(async function test_helpers_login_without_customize_sync() {
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {
+      _internal: {
+        setSignedInUser(accountData) {
+          return new Promise(resolve => {
+            // ensure fxAccounts is informed of the new user being signed in.
+            Assert.equal(accountData.email, "testuser@testuser.com");
+
+            // verifiedCanLinkAccount should be stripped in the data.
+            Assert.equal(false, "verifiedCanLinkAccount" in accountData);
+
+            resolve();
+          });
+        },
+      },
+      telemetry: {
+        recordConnection: sinon.spy(),
+      },
+    },
+    weaveXPCOM: {
+      whenLoaded() {},
+      Weave: {
+        Service: {
+          configure() {},
+        },
+      },
+    },
+  });
+
+  // ensure the previous account pref is overwritten.
+  helpers.setPreviousAccountNameHashPref("lastuser@testuser.com");
+
+  await helpers.login({
+    email: "testuser@testuser.com",
+    verifiedCanLinkAccount: true,
+    customizeSync: false,
+  });
+  Assert.ok(
+    helpers._fxAccounts.telemetry.recordConnection.calledWith([], "webchannel")
+  );
+});
+
+add_task(async function test_helpers_login_set_previous_account_name_hash() {
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {
+      _internal: {
+        setSignedInUser(accountData) {
+          return new Promise(resolve => {
+            // previously signed in user preference is updated.
+            Assert.equal(
+              helpers.getPreviousAccountNameHashPref(),
+              CryptoUtils.sha256Base64("newuser@testuser.com")
+            );
+            resolve();
+          });
+        },
+      },
+      telemetry: {
+        recordConnection() {},
+      },
+    },
+    weaveXPCOM: {
+      whenLoaded() {},
+      Weave: {
+        Service: {
+          configure() {},
+        },
+      },
+    },
+  });
+
+  // ensure the previous account pref is overwritten.
+  helpers.setPreviousAccountNameHashPref("lastuser@testuser.com");
+
+  await helpers.login({
+    email: "newuser@testuser.com",
+    verifiedCanLinkAccount: true,
+    customizeSync: false,
+    verified: true,
+  });
+});
+
+add_task(
+  async function test_helpers_login_dont_set_previous_account_name_hash_for_unverified_emails() {
+    let helpers = new FxAccountsWebChannelHelpers({
+      fxAccounts: {
+        _internal: {
+          setSignedInUser(accountData) {
+            return new Promise(resolve => {
+              // previously signed in user preference should not be updated.
+              Assert.equal(
+                helpers.getPreviousAccountNameHashPref(),
+                CryptoUtils.sha256Base64("lastuser@testuser.com")
+              );
+              resolve();
+            });
+          },
+        },
+        telemetry: {
+          recordConnection() {},
+        },
+      },
+      weaveXPCOM: {
+        whenLoaded() {},
+        Weave: {
+          Service: {
+            configure() {},
+          },
+        },
+      },
+    });
+
+    // ensure the previous account pref is overwritten.
+    helpers.setPreviousAccountNameHashPref("lastuser@testuser.com");
+
+    await helpers.login({
+      email: "newuser@testuser.com",
+      verifiedCanLinkAccount: true,
+      customizeSync: false,
+    });
+  }
+);
+
+add_task(async function test_helpers_login_with_customize_sync() {
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {
+      _internal: {
+        setSignedInUser(accountData) {
+          return new Promise(resolve => {
+            // ensure fxAccounts is informed of the new user being signed in.
+            Assert.equal(accountData.email, "testuser@testuser.com");
+
+            // customizeSync should be stripped in the data.
+            Assert.equal(false, "customizeSync" in accountData);
+
+            resolve();
+          });
+        },
+      },
+      telemetry: {
+        recordConnection: sinon.spy(),
+      },
+    },
+    weaveXPCOM: {
+      whenLoaded() {},
+      Weave: {
+        Service: {
+          configure() {},
+        },
+      },
+    },
+  });
+
+  await helpers.login({
+    email: "testuser@testuser.com",
+    verifiedCanLinkAccount: true,
+    customizeSync: true,
+  });
+  Assert.ok(
+    helpers._fxAccounts.telemetry.recordConnection.calledWith([], "webchannel")
+  );
+});
+
+add_task(
+  async function test_helpers_login_with_customize_sync_and_declined_engines() {
+    let configured = false;
+    let helpers = new FxAccountsWebChannelHelpers({
+      fxAccounts: {
+        _internal: {
+          setSignedInUser(accountData) {
+            return new Promise(resolve => {
+              // ensure fxAccounts is informed of the new user being signed in.
+              Assert.equal(accountData.email, "testuser@testuser.com");
+
+              // customizeSync should be stripped in the data.
+              Assert.equal(false, "customizeSync" in accountData);
+              Assert.equal(false, "services" in accountData);
+              resolve();
+            });
+          },
+        },
+        telemetry: {
+          recordConnection: sinon.spy(),
+        },
+      },
+      weaveXPCOM: {
+        whenLoaded() {},
+        Weave: {
+          Service: {
+            configure() {
+              configured = true;
+            },
+          },
+        },
+      },
+    });
+
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.addons"),
+      true
+    );
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.bookmarks"),
+      true
+    );
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.history"),
+      true
+    );
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.passwords"),
+      true
+    );
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.prefs"),
+      true
+    );
+    Assert.equal(Services.prefs.getBoolPref("services.sync.engine.tabs"), true);
+    await helpers.login({
+      email: "testuser@testuser.com",
+      verifiedCanLinkAccount: true,
+      customizeSync: true,
+      services: {
+        sync: {
+          offeredEngines: [
+            "addons",
+            "bookmarks",
+            "history",
+            "passwords",
+            "prefs",
+          ],
+          declinedEngines: ["addons", "prefs"],
+        },
+      },
+    });
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.addons"),
+      false
+    );
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.bookmarks"),
+      true
+    );
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.history"),
+      true
+    );
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.passwords"),
+      true
+    );
+    Assert.equal(
+      Services.prefs.getBoolPref("services.sync.engine.prefs"),
+      false
+    );
+    Assert.equal(Services.prefs.getBoolPref("services.sync.engine.tabs"), true);
+    Assert.ok(configured, "sync was configured");
+    Assert.ok(
+      helpers._fxAccounts.telemetry.recordConnection.calledWith(
+        ["sync"],
+        "webchannel"
+      )
+    );
+  }
+);
+
+add_task(async function test_helpers_login_with_offered_sync_engines() {
+  let helpers;
+  let configured = false;
+  const setSignedInUserCalled = new Promise(resolve => {
+    helpers = new FxAccountsWebChannelHelpers({
+      fxAccounts: {
+        _internal: {
+          async setSignedInUser(accountData) {
+            resolve(accountData);
+          },
+        },
+        telemetry: {
+          recordConnection() {},
+        },
+      },
+      weaveXPCOM: {
+        whenLoaded() {},
+        Weave: {
+          Service: {
+            configure() {
+              configured = true;
+            },
+          },
+        },
+      },
+    });
+  });
+
+  Services.prefs.setBoolPref("services.sync.engine.creditcards", false);
+  Services.prefs.setBoolPref("services.sync.engine.addresses", false);
+
+  await helpers.login({
+    email: "testuser@testuser.com",
+    verifiedCanLinkAccount: true,
+    customizeSync: true,
+    services: {
+      sync: {
+        declinedEngines: ["addresses"],
+        offeredEngines: ["creditcards", "addresses"],
+      },
+    },
+  });
+
+  const accountData = await setSignedInUserCalled;
+
+  // ensure fxAccounts is informed of the new user being signed in.
+  equal(accountData.email, "testuser@testuser.com");
+
+  // services should be stripped in the data.
+  ok(!("services" in accountData));
+  // credit cards was offered but not declined.
+  equal(Services.prefs.getBoolPref("services.sync.engine.creditcards"), true);
+  // addresses was offered and explicitely declined.
+  equal(Services.prefs.getBoolPref("services.sync.engine.addresses"), false);
+  ok(configured);
+});
+
+add_task(async function test_helpers_login_nothing_offered() {
+  let helpers;
+  let configured = false;
+  const setSignedInUserCalled = new Promise(resolve => {
+    helpers = new FxAccountsWebChannelHelpers({
+      fxAccounts: {
+        _internal: {
+          async setSignedInUser(accountData) {
+            resolve(accountData);
+          },
+        },
+        telemetry: {
+          recordConnection() {},
+        },
+      },
+      weaveXPCOM: {
+        whenLoaded() {},
+        Weave: {
+          Service: {
+            configure() {
+              configured = true;
+            },
+          },
+        },
+      },
+    });
+  });
+
+  // doesn't really matter if it's *all* engines...
+  const allEngines = [
+    "addons",
+    "addresses",
+    "bookmarks",
+    "creditcards",
+    "history",
+    "passwords",
+    "prefs",
+  ];
+  for (let name of allEngines) {
+    Services.prefs.clearUserPref("services.sync.engine." + name);
+  }
+
+  await helpers.login({
+    email: "testuser@testuser.com",
+    verifiedCanLinkAccount: true,
+    services: {
+      sync: {},
+    },
+  });
+
+  const accountData = await setSignedInUserCalled;
+  // ensure fxAccounts is informed of the new user being signed in.
+  equal(accountData.email, "testuser@testuser.com");
+
+  for (let name of allEngines) {
+    Assert.ok(!Services.prefs.prefHasUserValue("services.sync.engine." + name));
+  }
+  Assert.ok(configured);
+});
+
+add_test(function test_helpers_open_sync_preferences() {
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {},
+  });
+
+  let mockBrowser = {
+    loadURI(uri) {
+      Assert.equal(
+        uri.spec,
+        "about:preferences?entrypoint=fxa%3Averification_complete#sync"
+      );
+      run_next_test();
+    },
+  };
+
+  helpers.openSyncPreferences(mockBrowser, "fxa:verification_complete");
+});
+
+add_task(async function test_helpers_getFxAStatus_extra_engines() {
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {
+      _internal: {
+        getUserAccountData() {
+          return Promise.resolve({
+            email: "testuser@testuser.com",
+            sessionToken: "sessionToken",
+            uid: "uid",
+            verified: true,
+          });
+        },
+      },
+    },
+    privateBrowsingUtils: {
+      isBrowserPrivate: () => true,
+    },
+  });
+
+  Services.prefs.setBoolPref(
+    "services.sync.engine.creditcards.available",
+    true
+  );
+  // Not defining "services.sync.engine.addresses.available" on purpose.
+
+  let fxaStatus = await helpers.getFxaStatus("sync", mockSendingContext);
+  ok(!!fxaStatus);
+  ok(!!fxaStatus.signedInUser);
+  deepEqual(fxaStatus.capabilities.engines, ["creditcards"]);
+});
+
+add_task(async function test_helpers_getFxaStatus_allowed_signedInUser() {
+  let wasCalled = {
+    getUserAccountData: false,
+    shouldAllowFxaStatus: false,
+  };
+
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {
+      _internal: {
+        getUserAccountData() {
+          wasCalled.getUserAccountData = true;
+          return Promise.resolve({
+            email: "testuser@testuser.com",
+            sessionToken: "sessionToken",
+            uid: "uid",
+            verified: true,
+          });
+        },
+      },
+    },
+  });
+
+  helpers.shouldAllowFxaStatus = (service, sendingContext) => {
+    wasCalled.shouldAllowFxaStatus = true;
+    Assert.equal(service, "sync");
+    Assert.equal(sendingContext, mockSendingContext);
+
+    return true;
+  };
+
+  return helpers.getFxaStatus("sync", mockSendingContext).then(fxaStatus => {
+    Assert.ok(!!fxaStatus);
+    Assert.ok(wasCalled.getUserAccountData);
+    Assert.ok(wasCalled.shouldAllowFxaStatus);
+
+    Assert.ok(!!fxaStatus.signedInUser);
+    let { signedInUser } = fxaStatus;
+
+    Assert.equal(signedInUser.email, "testuser@testuser.com");
+    Assert.equal(signedInUser.sessionToken, "sessionToken");
+    Assert.equal(signedInUser.uid, "uid");
+    Assert.ok(signedInUser.verified);
+
+    // These properties are filtered and should not
+    // be returned to the requester.
+    Assert.equal(false, "kSync" in signedInUser);
+    Assert.equal(false, "kXCS" in signedInUser);
+    Assert.equal(false, "kExtSync" in signedInUser);
+    Assert.equal(false, "kExtKbHash" in signedInUser);
+  });
+});
+
+add_task(async function test_helpers_getFxaStatus_allowed_no_signedInUser() {
+  let wasCalled = {
+    getUserAccountData: false,
+    shouldAllowFxaStatus: false,
+  };
+
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {
+      _internal: {
+        getUserAccountData() {
+          wasCalled.getUserAccountData = true;
+          return Promise.resolve(null);
+        },
+      },
+    },
+  });
+
+  helpers.shouldAllowFxaStatus = (service, sendingContext) => {
+    wasCalled.shouldAllowFxaStatus = true;
+    Assert.equal(service, "sync");
+    Assert.equal(sendingContext, mockSendingContext);
+
+    return true;
+  };
+
+  return helpers.getFxaStatus("sync", mockSendingContext).then(fxaStatus => {
+    Assert.ok(!!fxaStatus);
+    Assert.ok(wasCalled.getUserAccountData);
+    Assert.ok(wasCalled.shouldAllowFxaStatus);
+
+    Assert.equal(null, fxaStatus.signedInUser);
+  });
+});
+
+add_task(async function test_helpers_getFxaStatus_not_allowed() {
+  let wasCalled = {
+    getUserAccountData: false,
+    shouldAllowFxaStatus: false,
+  };
+
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {
+      _internal: {
+        getUserAccountData() {
+          wasCalled.getUserAccountData = true;
+          return Promise.resolve(null);
+        },
+      },
+    },
+  });
+
+  helpers.shouldAllowFxaStatus = (
+    service,
+    sendingContext,
+    isPairing,
+    context
+  ) => {
+    wasCalled.shouldAllowFxaStatus = true;
+    Assert.equal(service, "sync");
+    Assert.equal(sendingContext, mockSendingContext);
+    Assert.ok(!isPairing);
+    Assert.equal(context, "fx_desktop_v3");
+
+    return false;
+  };
+
+  return helpers
+    .getFxaStatus("sync", mockSendingContext, false, "fx_desktop_v3")
+    .then(fxaStatus => {
+      Assert.ok(!!fxaStatus);
+      Assert.ok(!wasCalled.getUserAccountData);
+      Assert.ok(wasCalled.shouldAllowFxaStatus);
+
+      Assert.equal(null, fxaStatus.signedInUser);
+    });
+});
+
+add_task(
+  async function test_helpers_shouldAllowFxaStatus_sync_service_not_private_browsing() {
+    let wasCalled = {
+      isPrivateBrowsingMode: false,
+    };
+    let helpers = new FxAccountsWebChannelHelpers({});
+
+    helpers.isPrivateBrowsingMode = sendingContext => {
+      wasCalled.isPrivateBrowsingMode = true;
+      Assert.equal(sendingContext, mockSendingContext);
+      return false;
+    };
+
+    let shouldAllowFxaStatus = helpers.shouldAllowFxaStatus(
+      "sync",
+      mockSendingContext,
+      false
+    );
+    Assert.ok(shouldAllowFxaStatus);
+    Assert.ok(wasCalled.isPrivateBrowsingMode);
+  }
+);
+
+add_task(
+  async function test_helpers_shouldAllowFxaStatus_desktop_context_not_private_browsing() {
+    let wasCalled = {
+      isPrivateBrowsingMode: false,
+    };
+    let helpers = new FxAccountsWebChannelHelpers({});
+
+    helpers.isPrivateBrowsingMode = sendingContext => {
+      wasCalled.isPrivateBrowsingMode = true;
+      Assert.equal(sendingContext, mockSendingContext);
+      return false;
+    };
+
+    let shouldAllowFxaStatus = helpers.shouldAllowFxaStatus(
+      "",
+      mockSendingContext,
+      false,
+      "fx_desktop_v3"
+    );
+    Assert.ok(shouldAllowFxaStatus);
+    Assert.ok(wasCalled.isPrivateBrowsingMode);
+  }
+);
+
+add_task(
+  async function test_helpers_shouldAllowFxaStatus_oauth_service_not_private_browsing() {
+    let wasCalled = {
+      isPrivateBrowsingMode: false,
+    };
+    let helpers = new FxAccountsWebChannelHelpers({});
+
+    helpers.isPrivateBrowsingMode = sendingContext => {
+      wasCalled.isPrivateBrowsingMode = true;
+      Assert.equal(sendingContext, mockSendingContext);
+      return false;
+    };
+
+    let shouldAllowFxaStatus = helpers.shouldAllowFxaStatus(
+      "dcdb5ae7add825d2",
+      mockSendingContext,
+      false
+    );
+    Assert.ok(shouldAllowFxaStatus);
+    Assert.ok(wasCalled.isPrivateBrowsingMode);
+  }
+);
+
+add_task(
+  async function test_helpers_shouldAllowFxaStatus_no_service_not_private_browsing() {
+    let wasCalled = {
+      isPrivateBrowsingMode: false,
+    };
+    let helpers = new FxAccountsWebChannelHelpers({});
+
+    helpers.isPrivateBrowsingMode = sendingContext => {
+      wasCalled.isPrivateBrowsingMode = true;
+      Assert.equal(sendingContext, mockSendingContext);
+      return false;
+    };
+
+    let shouldAllowFxaStatus = helpers.shouldAllowFxaStatus(
+      "",
+      mockSendingContext,
+      false
+    );
+    Assert.ok(shouldAllowFxaStatus);
+    Assert.ok(wasCalled.isPrivateBrowsingMode);
+  }
+);
+
+add_task(
+  async function test_helpers_shouldAllowFxaStatus_sync_service_private_browsing() {
+    let wasCalled = {
+      isPrivateBrowsingMode: false,
+    };
+    let helpers = new FxAccountsWebChannelHelpers({});
+
+    helpers.isPrivateBrowsingMode = sendingContext => {
+      wasCalled.isPrivateBrowsingMode = true;
+      Assert.equal(sendingContext, mockSendingContext);
+      return true;
+    };
+
+    let shouldAllowFxaStatus = helpers.shouldAllowFxaStatus(
+      "sync",
+      mockSendingContext,
+      false
+    );
+    Assert.ok(shouldAllowFxaStatus);
+    Assert.ok(wasCalled.isPrivateBrowsingMode);
+  }
+);
+
+add_task(
+  async function test_helpers_shouldAllowFxaStatus_desktop_context_private_browsing() {
+    let wasCalled = {
+      isPrivateBrowsingMode: false,
+    };
+    let helpers = new FxAccountsWebChannelHelpers({});
+
+    helpers.isPrivateBrowsingMode = sendingContext => {
+      wasCalled.isPrivateBrowsingMode = true;
+      Assert.equal(sendingContext, mockSendingContext);
+      return true;
+    };
+
+    let shouldAllowFxaStatus = helpers.shouldAllowFxaStatus(
+      "",
+      mockSendingContext,
+      false,
+      "fx_desktop_v3"
+    );
+    Assert.ok(shouldAllowFxaStatus);
+    Assert.ok(wasCalled.isPrivateBrowsingMode);
+  }
+);
+
+add_task(
+  async function test_helpers_shouldAllowFxaStatus_oauth_service_private_browsing() {
+    let wasCalled = {
+      isPrivateBrowsingMode: false,
+    };
+    let helpers = new FxAccountsWebChannelHelpers({});
+
+    helpers.isPrivateBrowsingMode = sendingContext => {
+      wasCalled.isPrivateBrowsingMode = true;
+      Assert.equal(sendingContext, mockSendingContext);
+      return true;
+    };
+
+    let shouldAllowFxaStatus = helpers.shouldAllowFxaStatus(
+      "dcdb5ae7add825d2",
+      mockSendingContext,
+      false
+    );
+    Assert.ok(!shouldAllowFxaStatus);
+    Assert.ok(wasCalled.isPrivateBrowsingMode);
+  }
+);
+
+add_task(
+  async function test_helpers_shouldAllowFxaStatus_oauth_service_pairing_private_browsing() {
+    let wasCalled = {
+      isPrivateBrowsingMode: false,
+    };
+    let helpers = new FxAccountsWebChannelHelpers({});
+
+    helpers.isPrivateBrowsingMode = sendingContext => {
+      wasCalled.isPrivateBrowsingMode = true;
+      Assert.equal(sendingContext, mockSendingContext);
+      return true;
+    };
+
+    let shouldAllowFxaStatus = helpers.shouldAllowFxaStatus(
+      "dcdb5ae7add825d2",
+      mockSendingContext,
+      true
+    );
+    Assert.ok(shouldAllowFxaStatus);
+    Assert.ok(wasCalled.isPrivateBrowsingMode);
+  }
+);
+
+add_task(
+  async function test_helpers_shouldAllowFxaStatus_no_service_private_browsing() {
+    let wasCalled = {
+      isPrivateBrowsingMode: false,
+    };
+    let helpers = new FxAccountsWebChannelHelpers({});
+
+    helpers.isPrivateBrowsingMode = sendingContext => {
+      wasCalled.isPrivateBrowsingMode = true;
+      Assert.equal(sendingContext, mockSendingContext);
+      return true;
+    };
+
+    let shouldAllowFxaStatus = helpers.shouldAllowFxaStatus(
+      "",
+      mockSendingContext,
+      false
+    );
+    Assert.ok(!shouldAllowFxaStatus);
+    Assert.ok(wasCalled.isPrivateBrowsingMode);
+  }
+);
+
+add_task(async function test_helpers_isPrivateBrowsingMode_private_browsing() {
+  let wasCalled = {
+    isBrowserPrivate: false,
+  };
+  let helpers = new FxAccountsWebChannelHelpers({
+    privateBrowsingUtils: {
+      isBrowserPrivate(browser) {
+        wasCalled.isBrowserPrivate = true;
+        Assert.equal(
+          browser,
+          mockSendingContext.browsingContext.top.embedderElement
+        );
+        return true;
+      },
+    },
+  });
+
+  let isPrivateBrowsingMode = helpers.isPrivateBrowsingMode(mockSendingContext);
+  Assert.ok(isPrivateBrowsingMode);
+  Assert.ok(wasCalled.isBrowserPrivate);
+});
+
+add_task(async function test_helpers_isPrivateBrowsingMode_private_browsing() {
+  let wasCalled = {
+    isBrowserPrivate: false,
+  };
+  let helpers = new FxAccountsWebChannelHelpers({
+    privateBrowsingUtils: {
+      isBrowserPrivate(browser) {
+        wasCalled.isBrowserPrivate = true;
+        Assert.equal(
+          browser,
+          mockSendingContext.browsingContext.top.embedderElement
+        );
+        return false;
+      },
+    },
+  });
+
+  let isPrivateBrowsingMode = helpers.isPrivateBrowsingMode(mockSendingContext);
+  Assert.ok(!isPrivateBrowsingMode);
+  Assert.ok(wasCalled.isBrowserPrivate);
+});
+
+add_task(async function test_helpers_change_password() {
+  let wasCalled = {
+    updateUserAccountData: false,
+    updateDeviceRegistration: false,
+  };
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {
+      _internal: {
+        updateUserAccountData(credentials) {
+          return new Promise(resolve => {
+            Assert.ok(credentials.hasOwnProperty("email"));
+            Assert.ok(credentials.hasOwnProperty("uid"));
+            Assert.ok(credentials.hasOwnProperty("unwrapBKey"));
+            Assert.ok(credentials.hasOwnProperty("device"));
+            Assert.equal(null, credentials.device);
+            Assert.equal(null, credentials.encryptedSendTabKeys);
+            // "foo" isn't a field known by storage, so should be dropped.
+            Assert.ok(!credentials.hasOwnProperty("foo"));
+            wasCalled.updateUserAccountData = true;
+
+            resolve();
+          });
+        },
+
+        updateDeviceRegistration() {
+          Assert.equal(arguments.length, 0);
+          wasCalled.updateDeviceRegistration = true;
+          return Promise.resolve();
+        },
+      },
+    },
+  });
+  await helpers.changePassword({
+    email: "email",
+    uid: "uid",
+    unwrapBKey: "unwrapBKey",
+    foo: "foo",
+  });
+  Assert.ok(wasCalled.updateUserAccountData);
+  Assert.ok(wasCalled.updateDeviceRegistration);
+});
+
+add_task(async function test_helpers_change_password_with_error() {
+  let wasCalled = {
+    updateUserAccountData: false,
+    updateDeviceRegistration: false,
+  };
+  let helpers = new FxAccountsWebChannelHelpers({
+    fxAccounts: {
+      _internal: {
+        updateUserAccountData() {
+          wasCalled.updateUserAccountData = true;
+          return Promise.reject();
+        },
+
+        updateDeviceRegistration() {
+          wasCalled.updateDeviceRegistration = true;
+          return Promise.resolve();
+        },
+      },
+    },
+  });
+  try {
+    await helpers.changePassword({});
+    Assert.equal(false, "changePassword should have rejected");
+  } catch (_) {
+    Assert.ok(wasCalled.updateUserAccountData);
+    Assert.ok(!wasCalled.updateDeviceRegistration);
+  }
+});
+
+function makeObserver(aObserveTopic, aObserveFunc) {
+  let callback = function (aSubject, aTopic, aData) {
+    log.debug("observed " + aTopic + " " + aData);
+    if (aTopic == aObserveTopic) {
+      removeMe();
+      aObserveFunc(aSubject, aTopic, aData);
+    }
+  };
+
+  function removeMe() {
+    log.debug("removing observer for " + aObserveTopic);
+    Services.obs.removeObserver(callback, aObserveTopic);
+  }
+
+  Services.obs.addObserver(callback, aObserveTopic);
+  return removeMe;
+}
+
+function validationHelper(params, expected) {
+  try {
+    new FxAccountsWebChannel(params);
+  } catch (e) {
+    if (typeof expected === "string") {
+      return Assert.equal(e.toString(), expected);
+    }
+    return Assert.ok(e.toString().match(expected));
+  }
+  throw new Error("Validation helper error");
+}
diff --git a/services/fxaccounts/tests/xpcshell/xpcshell.ini b/services/fxaccounts/tests/xpcshell/xpcshell.ini
new file mode 100644
index 0000000000..2086db8349
--- /dev/null
+++ b/services/fxaccounts/tests/xpcshell/xpcshell.ini
@@ -0,0 +1,26 @@
+[DEFAULT]
+head = head.js ../../../common/tests/unit/head_helpers.js ../../../common/tests/unit/head_http.js
+firefox-appdir = browser
+skip-if = (toolkit == 'android' || appname == 'thunderbird')
+support-files =
+  !/services/common/tests/unit/head_helpers.js
+  !/services/common/tests/unit/head_http.js
+
+[test_accounts.js]
+[test_accounts_config.js]
+[test_accounts_device_registration.js]
+[test_client.js]
+[test_commands.js]
+[test_credentials.js]
+[test_device.js]
+[test_keys.js]
+[test_loginmgr_storage.js]
+[test_oauth_tokens.js]
+[test_oauth_token_storage.js]
+[test_pairing.js]
+[test_profile_client.js]
+[test_push_service.js]
+[test_telemetry.js]
+[test_web_channel.js]
+[test_profile.js]
+[test_storage_manager.js]