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How I Write Marble Tests For RxJS Observables In Angular

Michael Hoffmann on November 12, 2018

I am a really passionate Reactive Extensions user and mostly use them in RxJS which is integrated into the Angular framework. In Angular, I often ...
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Andrei Gatej •

You can avoid to explicitly specify the scheduler by running your tests inside TestScheduler.run(cb). TestScheduler.run will replace the AsyncScheduler with TestScheduler.

const testScheduler = new TestScheduler((actual, expected) => {})

testScheduler.run(({ cold, hot, expectObservable }) => {
 const src$ = interval(1000).pipe(take(3));
 const expected = '1000ms 0 999ms 1 999ms (2|)';

 expectObservable(src$).toBe(expected);
});
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green122 •

Hi, Michael. Thanks for the nice and informative article.
Did you find a way to visualize actual observable, maybe to convert it to a marble diagram? Cause in the more complex cases i've started not to understand what is really going on inside my observable and how to compare it with the expected one.

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Michael Hoffmann •

Unfortunately not inside the tests. But this website is in general quite nice: rxviz.com/