ohif-viewer/platform/core/src/utils/Queue.test.js

import makeDeferred from './makeDeferred';
import Queue from './Queue';

/**
 * Utils
 */

function timeout(delay) {
  const { resolve, promise } = makeDeferred();
  setTimeout(() => void resolve(Date.now()), delay);
  return promise;
}

/**
 * Tests
 */

describe('Queue', () => {
  it('should bind functions to the queue', async () => {
    const queue = new Queue(2);
    const mockedTimeout = jest.fn(timeout);
    const timer = queue.bind(mockedTimeout);
    const start = Date.now();
    timer(1200).then(now => {
      const elapsed = now - start;
      expect(elapsed >= 1200 && elapsed < 2400).toBe(true);
    });
    const end = await timer(1200);
    expect(end - start > 2400).toBe(true);
    expect(mockedTimeout).toBeCalledTimes(2);
  });
  it('should prevent task execution when queue limit is reached', async () => {
    const queue = new Queue(1);
    const mockedTimeout = jest.fn(timeout);
    const timer = queue.bind(mockedTimeout);
    const start = Date.now();
    const promise = timer(1200).then(time => time - start);
    try {
      await timer(1200);
    } catch (e) {
      expect(Date.now() - start < 1200).toBe(true);
      expect(e.message).toBe('Queue limit reached');
    }
    const elapsed = await promise;
    expect(elapsed >= 1200 && elapsed < 2400).toBe(true);
    expect(mockedTimeout).toBeCalledTimes(1);
  });
  it('should safely bind tasks to the queue', async () => {
    const queue = new Queue(1);
    const mockedErrorHandler = jest.fn();
    const mockedTimeout = jest.fn(timeout);
    const timer = queue.bindSafe(mockedTimeout, mockedErrorHandler);
    const start = Date.now();
    const promise = timer(1200).then(time => time - start);
    await timer(1200);
    expect(Date.now() - start < 1200).toBe(true);
    expect(mockedErrorHandler).toBeCalledTimes(1);
    expect(mockedErrorHandler).nthCalledWith(
      1,
      expect.objectContaining({ message: 'Queue limit reached' })
    );
    const elapsed = await promise;
    expect(elapsed >= 1200 && elapsed < 2400).toBe(true);
    expect(mockedTimeout).toBeCalledTimes(1);
  });
});