waitForProperty never yielded when used when @tracked property changes

I’m not entirely sure if this is an e-c bug or an issue with Octane Edition, but combining waitForProperty with a @tracked property doesn’t work.

export default class SomeService extends Service {
  @tracked someProperty = false;

  @task(function *() {
    yield waitForProperty(this, 'someProperty');

    // this code is unreached even if `someProperty`
    // becomes true.
  }) aTaskThatWaits  
}

This appears to be caused by the various waitFor{*}s being based on addObserver.

Although I’d assume backwards interop at the EmberObject level to not break SemVer in Ember.js itself.

[andrewfan]

@trek @rwjblue @maxfierke I got the same error and found that it happens because https://github.com/machty/ember-concurrency/blob/d6b30e8b55c18b1e3da97d880c7ef612a5168aab/addon/-wait-for.js#L96 here we are trying to call missing addObserver / removeObserver methods If I add those 2 missing methods everything works fine with @tracked @trek

import { addObserver, removeObserver } from '@ember/object/observers';

export default class SomeService extends Service {
  @tracked someProperty = false;

  addObserver() {
    addObserver(this, ...arguments);
  }

  removeObserver() {
    removeObserver(this, ...arguments);
  }

  @task(function *() {
    yield waitForProperty(this, 'someProperty');

    // this code is unreached even if `someProperty`
    // becomes true.
  }) aTaskThatWaits  
}

So I believe everything can be fixed with exported add/removeObserver methods

[Herriau]

Similarly I have found waitForProperty() to be unreliable for observing state derived from @tracked properties. It seems however that this isn’t an issue with EC itself but rather with Ember’s addObserver(). We are refactoring away from using EC as much as possible as a result, which is quite a shame as we had some good patterns going.