test/src/lib/helpers/async.spec.js

import expect from '../../../expect';
import { delay, promisified } from '../../../../src/lib/helpers/async';

/** @test {delay} */
describe('delay', function () {
  it('should resolve after duration', function () {
    return expect(() => delay(100), 'to be fulfilled');
  });
});

/** @test {promisified} */
describe('promisified', function () {
  it('should be fulfilled when async function calls callback', function () {
    return expect(
      promisified((cb) => process.nextTick(cb)),
      'to be fulfilled'
    );
  });

  it('should be rejected when async function fails', function () {
    function failingAsync(callback) {
      process.nextTick(() => {
        callback(new Error('Oops'));
      });
    }

    return expect(
      promisified((cb) => failingAsync(cb)),
      'to be rejected with',
      'Oops'
    );
  });
});