How to mock ViewController.willEnter.subscribe?

When testing components that utilizes the viewController, you must mock the viewController using a viewControllerMock. By the standards of this seeder project, we are placing that class in mock.ts, and importing it in test.ts.

However, I’m having trouble mocking the willEnter() method, as even when I return an Observable, as per the docks, it’s giving me a TypeError: viewCtrl.willEnter.subscribe is not a function.

Has anyone successfully mock these Observables in their app?

Here’s my attempt at writing a function that returns an Observable, which returns true when subscribed to it.

public willEnter(): Observable<boolean> {
    let observable = Observable.create(function (observer) {
    observer.onNext(true);
    observer.onCompleted();
    });

    return observable
  };

[kamok]

@masimplo That did the trick. Thank you. Posted on stack and nobody knew what to do.

[masimplo]

@kamok willEnter is not a function but an Observable to which you can subscribe. In your mock you can declare it either as a property and set it to and Observable or even better as a getter.

you can just write

import { Observable } from 'rxjs/Rx';

public get willEnter(): Observable<boolean>{
   return Observable.of(true);
}

This will emit a single “marble” with the value true and then complete. If you want more fine control you can return a Subject instead and feed it with values on demand.