test_eventemitter_abort_controller.js

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/* Any copyright is dedicated to the Public Domain.

   http://creativecommons.org/publicdomain/zero/1.0/ */

"use strict";

const EventEmitter = require("resource://devtools/shared/event-emitter.js");

add_task(function testAbortSingleListener() {

  // Test a simple case with AbortController

  info("Create an EventEmitter");

  const emitter = new EventEmitter();

  const abortController = new AbortController();

  const { signal } = abortController;

  info("Setup an event listener on test-event, controlled by an AbortSignal");

  let eventsReceived = 0;

  emitter.on("test-event", () => eventsReceived++, { signal });

  info("Emit test-event");

  emitter.emit("test-event");

  equal(eventsReceived, 1, "We received one event, as expected");

  info("Abort the AbortController…");

  abortController.abort();

  info("… and emit test-event again");

  emitter.emit("test-event");

  equal(eventsReceived, 1, "We didn't receive new event after aborting");

});

add_task(function testAbortSingleListenerOnce() {

  // Test a simple case with AbortController and once

  info("Create an EventEmitter");

  const emitter = new EventEmitter();

  const abortController = new AbortController();

  const { signal } = abortController;

  info("Setup an event listener on test-event, controlled by an AbortSignal");

  let eventReceived = false;

  emitter.once(

    "test-event",

    () => {

      eventReceived = true;

},

    { signal }

);

  info("Abort the AbortController…");

  abortController.abort();

  info("… and emit test-event");

  emitter.emit("test-event");

  equal(eventReceived, false, "We didn't receive the event after aborting");

});

add_task(function testAbortMultipleListener() {

  // Test aborting multiple event listeners with one call to abort

  info("Create an EventEmitter");

  const emitter = new EventEmitter();

  const abortController = new AbortController();

  const { signal } = abortController;

  info("Setup 3 event listeners controlled by an AbortSignal");

  let eventsReceived = 0;

  emitter.on("test-event", () => eventsReceived++, { signal });

  emitter.on("test-event", () => eventsReceived++, { signal });

  emitter.on("other-test-event", () => eventsReceived++, { signal });

  info("Emit test-event and other-test-event");

  emitter.emit("test-event");

  emitter.emit("other-test-event");

  equal(eventsReceived, 3, "We received 3 events, as expected");

  info("Abort the AbortController…");

  abortController.abort();

  info("… and emit events again");

  emitter.emit("test-event");

  emitter.emit("other-test-event");

  equal(eventsReceived, 3, "We didn't receive new event after aborting");

});

add_task(function testAbortMultipleEmitter() {

  // Test aborting multiple event listeners on different emitters with one call to abort

  info("Create 2 EventEmitter");

  const emitter1 = new EventEmitter();

  const emitter2 = new EventEmitter();

  const abortController = new AbortController();

  const { signal } = abortController;

  info("Setup 2 event listeners on test-event, controlled by an AbortSignal");

  let eventsReceived = 0;

  emitter1.on("test-event", () => eventsReceived++, { signal });

  emitter2.on("other-test-event", () => eventsReceived++, { signal });

  info("Emit test-event and other-test-event");

  emitter1.emit("test-event");

  emitter2.emit("other-test-event");

  equal(eventsReceived, 2, "We received 2 events, as expected");

  info("Abort the AbortController…");

  abortController.abort();

  info("… and emit events again");

  emitter1.emit("test-event");

  emitter2.emit("other-test-event");

  equal(eventsReceived, 2, "We didn't receive new event after aborting");

});

add_task(function testAbortBeforeEmitting() {

  // Check that aborting before emitting does unregister the event listener

  info("Create an EventEmitter");

  const emitter = new EventEmitter();

  const abortController = new AbortController();

  const { signal } = abortController;

  info("Setup an event listener on test-event, controlled by an AbortSignal");

  let eventsReceived = 0;

  emitter.on("test-event", () => eventsReceived++, { signal });

  info("Abort the AbortController…");

  abortController.abort();

  info("… and emit test-event");

  emitter.emit("test-event");

  equal(eventsReceived, 0, "We didn't receive any event");

});

add_task(function testAbortBeforeSettingListener() {

  // Check that aborting before creating the event listener won't register it

  info("Create an EventEmitter");

  const emitter = new EventEmitter();

  info("Create an AbortController and abort it immediately");

  const abortController = new AbortController();

  const { signal } = abortController;

  abortController.abort();

  info(

    "Setup an event listener on test-event, controlled by the aborted AbortSignal"

);

  let eventsReceived = 0;

  const off = emitter.on("test-event", () => eventsReceived++, { signal });

  info("Emit test-event");

  emitter.emit("test-event");

  equal(eventsReceived, 0, "We didn't receive any event");

  equal(typeof off, "function", "emitter.on still returned a function");

  // check that calling off does not throw

  off();

});

add_task(function testAbortAfterEventListenerIsRemoved() {

  // Check that aborting after there's no more event listener does not throw

  info("Create an EventEmitter");

  const emitter = new EventEmitter();

  const abortController = new AbortController();

  const { signal } = abortController;

  info(

    "Setup an event listener on test-event, controlled by the aborted AbortSignal"

);

  let eventsReceived = 0;

  const off = emitter.on("test-event", () => eventsReceived++, { signal });

  info("Emit test-event");

  emitter.emit("test-event");

  equal(eventsReceived, 1, "We received the expected event");

  info("Remove the event listener with the function returned by `on`");

  off();

  info("Emit test-event a second time");

  emitter.emit("test-event");

  equal(

    eventsReceived,

1,

    "We didn't receive new event after removing the event listener"

);

  info("Abort to check it doesn't throw");

  abortController.abort();

});