feature request: method to wait for task queue

[Manuel Guilbault]

Many operations are asynchronous in the framework. For example, updating the target of a two-way binding is done asynchronously. When depending on such operations in a test, you need to enqueue the rest of the test on the task queue, which requires code that is repetitive and that adds noise to the tests.

For example:

import {StageComponent} from 'aurelia-testing';
import {bootstrap} from 'aurelia-bootstrapper';
import {TaskQueue} from 'aurelia-framework';

describe('the my-component custom element', () => {
  let viewModel, component, taskQueue;

  beforeEach(() => {
    viewModel = { result = null };
    component = StageComponent
      .withResource('my-component')
      .inView('<my-component value.two-way="result"></my-component>')
      .boundTo(viewModel);
    component.bootstrap(aurelia => {
      aurelia.use.standardConfiguration();
      taskQueue = aurelia.container.get(TaskQueue);
    });
  });

  afterEach(() => {
    component.dispose();
  });

  it('should assign value when whatever', done => {
    //trigger something that should update the value property on the component
    taskQueue.queueMicroTask(() => {
      //assert something about viewModel.result
      done();
    });
  });
});

At the moment, we have to:

• import the TaskQueue
• define a custom bootstrap function to get the TaskQueue instance
• manually queue a task

This last point is mostly annoying because it is not Promise-friendly. Since I use mostly jasmine-promises instead of the done callback, I am forced to wrap the call to queueMicroTask inside a Promise constructor.

All of this contribute to make tests bloated with details related to the Aurelia implementation. A new Promise-friendly method on ComponentTester that would wrap all of this could be nice. I could even quickly come up with a PR for this.

[Jeremy Danyow]

use .then(done) instead. Here's an example (needs to be split up, but you'll see what I mean): https://github.com/aurelia/validation/blob/master/test/basic.ts

[Manuel Guilbault]

Oh so the recommended solution is to use setTimeout instead of the task queue?

[Jeremy Danyow]

Using the task queue works, and would make your tests execute faster. You may want to wait two cycles though. Maybe the change and blur methods in the example should be exported from the testing repo?

[Manuel Guilbault]

Could be useful indeed.
And thanks for the example :)

[Romke van der Meulen]

So which is better? new Promise(setTimeout) or taskQueue.queueMicroTask()?

[Vildan Softic]

@RomkeVdMeulen https://github.com/aurelia/testing/pull/79/files see the use of flushMicroTaskQueue. I just couldn't merge it so far as it seems there is some bogus in getting it to work with our test-environment :(