browser_shutdown_doc_acc_reference.js

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/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

add_task(async function () {

  // Create a11y service.

  const [a11yInitObserver, a11yInit] = initAccService();

  await a11yInitObserver;

  let accService = Cc["@mozilla.org/accessibilityService;1"].getService(

    Ci.nsIAccessibilityService

);

  await a11yInit;

  ok(accService, "Service initialized");

  // Accessible document reference will live longer than the scope of this

  // function.

  let docAcc = accService.getAccessibleFor(document);

  ok(docAcc, "Accessible document is created");

  let canShutdown = false;

  // This promise will resolve only if canShutdown flag is set to true. If

  // 'a11y-init-or-shutdown' event with '0' flag comes before it can be shut

  // down, the promise will reject.

  const [a11yShutdownObserver, a11yShutdownPromise] = shutdownAccService();

  await a11yShutdownObserver;

  const a11yShutdown = new Promise((resolve, reject) =>

    a11yShutdownPromise.then(() =>

      canShutdown

        ? resolve()

        : reject("Accessible service was shut down incorrectly")

);

  accService = null;

  ok(!accService, "Service is removed");

  // Force garbage collection that should not trigger shutdown because there is

  // a reference to an accessible document.

  forceGC();

  // Have some breathing room when removing a11y service references.

  await TestUtils.waitForTick();

  // Now allow a11y service to shutdown.

  canShutdown = true;

  // Remove a reference to an accessible document.

  docAcc = null;

  ok(!docAcc, "Accessible document is removed");

  // Force garbage collection that should now trigger shutdown.

  forceGC();

  await a11yShutdown;

});