How do you assert a run loop was used in Ember.js?

Question

I have this code inside an Ember service:

return new Promise((resolve, reject) => {
  semaphore.take(() => {
    this.get('limiter').removeTokens(1, () => {
      semaphore.leave();

      this.get('requestSender').sendRequest(url).then(data => {
        run(null, resolve, cache.put(url, data, cacheTime));
      }).catch(function() {
        run(null, reject, arguments);
      });
    });
  });
});

I'm going through the limiter callback, so I need a run loop (to my understanding). I would like to assert in a unit test that a run loop was used. I can assert the promise resolves the correct value from the cache, but I don't know how to verify a run loop was used. In other words, I could remove the run call and all my tests would still pass, which is not desirable.

Things I've thought of that I don't want to resort to:

• I could use Ember.run instead of run and use stubbing and restoring, but I like to deconstruct globals at the top of the file ( const { run } = Ember; ), so I would not like to sacrifice that just for a test.
• I could wrap the run loop call in another Ember service so I can stub it, but that seems like overkill.

Basically I'm wondering if there are any events that fire when a run loop is entered that I can listen to in a test. It's OK if involves Ember privates.

Answer 1

You could add argument to your method which would make your method of service more "testable". Analyse this fragment of code:

const Ember = {
  run() {
    console.log('ORIGINAL METHOD');
  }
};
const { run } = Ember;

const service = {
  method(runMethod) {
    let runToCall = runMethod ? runMethod : run;
    runToCall();
  }
};

// in application
service.method();

// in tests
function mockedRun() {
  console.log('REPLACED METHOD');  
};

service.method(mockedRun);

Which outputs:

ORIGINAL METHOD

REPLACED METHOD

Here's demo .

Eventually you could use:

I could wrap the run loop call in another Ember service so I can stub it, but that seems like overkill.

But seems like passing function as argument is simpler.

Answer 2

Test will fail if run loop is not started because you'll get an assertion. Is this not enough?

Why do you need to assert that run loop was used?