ui/file_manager/image_loader/scheduler_unittest.m.js

// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import {assertEquals} from 'chrome://test/chai_assert.js';
import {ImageRequestTask} from './image_request_task.js';
import {Scheduler} from './scheduler.js';


/**
 * Fake global clock used to record the "time" at which a task was run.
 */
let globalTime = 0;

export function setUp() {
  globalTime = 0;
}

/**
 * @typedef{{
 *   cancelCallCount: number,
 *   runTime: number,
 * }}
 */
let FakeImageRequestTask;

/**
 * @param {string} taskId
 * @return {!FakeImageRequestTask}
 */
function newTask(taskId, priority) {
  return /** @type !FakeImageRequestTask */ ({
    // Counts how many times cancel method was called.
    // Used to test multiple cancellation of the same task.
    cancelCallCount: 0,

    // Records value of globalTime variable at the time the main method,
    // loadFromCacheAndProcess is called. Used to test if the task was
    // executed and in what orders tasks were executed.
    runTime: 0,

    getId() {
      return taskId;
    },
    getPriority() {
      return priority;
    },
    cancel() {
      ++this.cancelCallCount;
    },
    loadFromCacheAndProcess(resolve, reject) {
      this.runTime = ++globalTime;
      setTimeout(resolve);
    },
  });
}

/**
 * Checks that adding and removing tasks before the scheduler is started works.
 */
export function testIdleSchedulerAddRemove() {
  const scheduler = new Scheduler();
  const fakeTask = newTask('task-1', 0);
  scheduler.add(/** @type {!ImageRequestTask} */ (fakeTask));
  assertEquals(0, fakeTask.cancelCallCount);
  scheduler.remove('task-1');
  assertEquals(1, fakeTask.cancelCallCount);
  scheduler.remove('task-1');
  assertEquals(1, fakeTask.cancelCallCount);
}

/**
 * Checks that tasks that were in newTasks are correctly copied to pending
 * tasks when scheduler is started. They also should be executed in the
 * order of their priorities.
 */
export function testNewTasksMovedAndRunInPriorityOrder() {
  const fakeTask1 = newTask('task-1', 1);
  const fakeTask2 = newTask('task-2', 0);

  const scheduler = new Scheduler();
  scheduler.add(/** @type {!ImageRequestTask} */ (fakeTask1));
  scheduler.add(/** @type {!ImageRequestTask} */ (fakeTask2));

  scheduler.start();
  assertEquals(2, fakeTask1.runTime);
  assertEquals(1, fakeTask2.runTime);
}

/**
 * Checks that the scheduler only launches MAXIMUM_IN_PARALLEL tasks.
 */
export function testParallelTasks() {
  const scheduler = new Scheduler();
  const taskList = [];
  for (let i = 0; i <= Scheduler.MAXIMUM_IN_PARALLEL; ++i) {
    taskList.push(newTask(`task-${i}`, 0));
    scheduler.add(/** @type {!ImageRequestTask} */ (taskList[i]));
  }
  scheduler.start();
  for (let i = 0; i < Scheduler.MAXIMUM_IN_PARALLEL; ++i) {
    assertEquals(i + 1, taskList[i].runTime, `task ${i} did not run`);
  }
  assertEquals(0, taskList[Scheduler.MAXIMUM_IN_PARALLEL].runTime);
}