in document
it('should raise selected event when clicked', () => {
let selectedHero: Hero;
comp.selected.subscribe((hero: Hero) => selectedHero = hero);
heroEl.triggerEventHandler('click', null);
expect(selectedHero).toBe(expectedHero);
});
Shouldn't it be like
comp.selected.subscribe((hero: Hero) => {
selectedHero = hero;
expect(selectedHero).toBe(expectedHero);
});
It can't be like this because of jasmine.
If you do:
it('should raise selected event when clicked', () => {
let selectedHero: Hero;
comp.selected.subscribe((hero: Hero) => {
selectedHero = hero;
expect(selectedHero).toBe(expectedHero);
});
heroEl.triggerEventHandler('click', null);
});
And, because of a bug, the event click is not caught, then your expectation will never be tested, and you don't have a failure.
By testing selectedHero after the click, the tests ensures that if the click event is not handled, the test will fail because selectedHero will be undefined.
selectedHero = hero; ?
= null; at selectedHero declaration. The expectation is after the event trigger because the subscribe does not actually trigger the event, it's here to receive data when this event gets triggered. Which is what is done using heroEl.triggerEventHandler('click', null); once the sobscription is created.strictNullChecks. But the part I don't get it is when we run the code, if we run expect first, how can we get selectedHero = hero. Shouldn't it be async ? Let's say there is a debounceTime in event handler in component for 500. It will always run expect first then run ` selectedHero = hero;`subscribe call is equivalent to "When selected will emit something, set it in my selectedHero variable", it's not an actual assignment.