How to combine a done callback with injection angular 2 unittest

Question

I like the ability to pass in a done-callback when making unittest to explicitly control when a unittest is considered done. Can anyone explain how this can be combined with dependency injection when using Angular 2?

A little more background:

A normal unittest with a callback function looks like this:

it('should work with done', (done: Function) => {
    setTimeout(() => {
      a.test();
    }, 1000);
    a.test = () => {
      console.log('zweiter test');
      expect(true).toBeFalsy();
      done();
    };

A unittest generated by the angular 2 framework uses injection and looks like this:

  it('should be defined', inject([TxparserService], (service: TxparserService) => {
    expect(service).toBeTruthy();
  }));

I want to use both a callback function and dependency injection. How does that look?

Answer 1

Not sure if you can. Personally though, I stopped using this style of injection for a couple reasons: 1. It's pretty verbose, and 2. You need to keep repeating it for each test case. A couple other options are to:

• Use a beforeEach

  let service: TxparserService;
  
  beforeEach(() => {  // configure });
  
  beforeEach(inject([TxperserverService], (svc: TxparserService) => {
    service = svc;
  }));
  

• For me, the beforeEach above, still breaks my first concern of being verbose, so I just do it this way now

  let service: TxparserService;
  
  beforeEach(() => {
      TestBed.configureTestingModule({
          providers: [ TxparserService ]
      });
  
      service = TestBed.get(TxparserService);
  });
  

Answer 2

If you need to combine done-style async test with injection you can simply do the following:

it('should work', (done) => inject([SomeService], (someService: SomeService) =>
{
  expect(true).toEqual(true);
  done();
})());

Make sure that you immediately call the function returned by inject.

PS: Sometimes neither async nor fakeAsync works and you still need it to be done in old-school fashion...

PPS: If someone is interested how to overcome problems with time-dependent operations of Observable with jasmine-marbles take a look at this short example: marble-scheduler-injector.ts

Answer 3

I was able to successfully combine fakeAsync with inject. So it would look like following:

it('should be defined', fakeAsync(inject([TxparserService], (service: TxparserService) => {
  expect(service).toBeTruthy();
})));

You can combine it then with the tick() function described in https://angular.io/guide/testing#the-fakeasync-function