Angular2 test async Http.MockBackend.connections promise not yielding

Question

I'm having trouble using injectAsync with the http.MockBackend . The auth.ngOnInit() method calls Http.get() , but in this test the MockBackend.connections.toPromise().then() method is never called:

it('should check if the user is authenticated',
   injectAsync([Auth, MockBackend], (auth, backend) => {
     let promise = backend.connections.toPromise().then(
       (connection) => {
         let link = document.createElement('a');
         link.href = connection.request.url;
         expect(link.pathname).toBe('/api/auth/user/');
       });
     auth.ngOnInit();
     return promise;
}));

I've confirmed in the debugger that the MockBackend.connections.next() method is being called. When I run the test, however, it fails with Error: Timeout - Async callback was not invoked within timeout specified by jasmine.DEFAULT_TIMEOUT_INTERVAL. What am I missing here?

Answer 1

Thanks to @alxhub and @ericmartinezr in gitter , the issue is that I need to narrow the observable to a single result before I can call toPromise() . So this works:

it('should check if the user is authenticated',
   injectAsync([Auth, MockBackend], (auth, backend) => {
     let promise = backend.connections.first().toPromise().then(
       (connection) => {
         let link = document.createElement('a');
         link.href = connection.request.url;
         expect(link.pathname).toBe('/api/auth/user/');
       });
     auth.ngOnInit();
     return promise;
}));