New to rxjs and angular, attempting to write some basic unit tests for a simple rxjs observable with a success / error scenario:
Service method:
export class MyService {
constructor(private http: HttpClient) {}
public getId(id) {
return this.http.get('www.myurl.com/' + id, {
withCredential: true,
responseType: 'json' as 'json'
})
.pipe(
map(response => {
return response;
}),
catchError(() => {
return 'Service returned error';
})
};
}
}
Test:
it('should throw an error',() => {
spyOn(httpClientMock, 'get').and.returnValue(Observable.throw('error));
myService.getId('test1')
.subscribe(
() => {},
error => {
expect(error).toEqual('Service returned error');
}
};
});
The above passes, however, if i change the expect statement to:
expect(error).toEqual('Service returned erro');
The unit test still passes.
If i log out error, i see:
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Seems the issue is that catchError
expects an Observable to be returned from the callback fn, not just a value. Try
import { of } from 'rxjs';
// ...
catchError(() => {
return of('Service returned error');
})
see example of it here https://observable-playground.github.io/gist/aa4e24897f4fce150dd92a6fdb0f5929
UPDATE
I just realized that your main concern might be particularly passing test. Then the issue probably is in async nature of observables. You need to have a callback in your test to indicate that the test is async and call the callback to mark completion of execution.
E.g. :
it('should throw an error',(done) => {
spyOn(httpClientMock, 'get').and.returnValue(Observable.throw('error));
myService.getId('test1')
.subscribe(
() => {},
error => {
expect(error).toEqual('Service returned error');
},
// We will call done when Observable completes
() => done()
};
});
Heres an article on Jasmine and async calls:
https://medium.com/dailyjs/unit-testing-async-calls-and-promises-with-jasmine-a20a5d7f051e