I'm encounter the same issue with angular in version 4.4.6.

Is there a workaround?

Any update on this issue? I have the same problem. My application run Angular 5.2.1.

I found a workaround. But i'm not sure if it is the best solution.

Here what I did until they fix it.

testService.isEnabled().subscribe((result: boolean) => {
  expect(result).toEqual(Observable.of(true));
});

const req = httpMock.expectOne('some-url');
req.flush(Obserbvable.of(true));

Your workaround gave me this:

error TS2345: Argument of type 'Observable<boolean>' is not assignable to parameter of type 'Expected<boolean>'.
  Type 'Observable<boolean>' is not assignable to type 'ObjectContaining<boolean>'.

Can you add a snippet of your code?

Sure... It is like this:

export const FLUSH_OK = {status: 200, statusText: 'Ok'};
// ... 
it('should work', async(() => {     
        service.myFunction().subscribe((data) => {
            expect(data).toEqual(Observable.of(true));
        });
       
    
     httpMock.expectOne((req) => {
            return req.url === MY_URL
        }).flush(Observable.of(true), FLUSH_OK);

}));

submitted a PR, but i doubt i did it right... one of the travis builds doesnt like me

this is super annoying. please get fix in soon

work-a-round:

const req = httpMock.expectOne('some-url');
req.event(new HttpResponse<boolean>({body: true}));

instead of req.flush(true)

The above workaround simply masks the issue, since no response is actually resolved without calling 'flush' or 'error'. The reason it will appear to succeed is simply due to the specific nature of the testing scenario, for example:

it ("should verify that user is authenticated", () => {
    // calls underlying http post at 'api/account/isAuth'
    service.isAuth().then(response => {
      // does not execute, and so test defaults to success
      console.log("success!");
      expect(response).toBe(true);
    });

    const req = backend.expectOne("api/account/isAuth");
    req.event(new HttpResponse<boolean>({ body: true }));
  });

As stated in the docs, 'event' is used for sending HttpEvent responses for things like progress updates, and as such doesn't appear to have much use unless 'flush' or 'error' is used to call 'complete' or 'error' on the underlying observable.

The solution I used was simply to use a 'truthy' value in place of the boolean. Any underlying checks against a boolean value can usually be resolved within conditional statements this way, and so any logic checks in the underlying method code should be covered in this scenario:

it ("should verify that user is authenticated", () => {
    service.isAuth().then(response => {
      console.log("success!"); // underlying check successfully calls
      expect(response).toBe(true); // response is 'true', since underlying check against 1 is 'true'
    });

    const req = backend.expectOne("api/account/isAuth");
    // underlying post response body should be 'true', but 1 is truthy, and so will work in most scenarios
    req.flush(1); 
  });

Changing the one to zero in the above test causes the test to fail, and as such achieves the exact same behaviour as I would have expected from using a boolean value in the body of the response.

Any updates on if this is getting fixed?

I did not manage to find a solution with above comments.
2 years and no solution ?!

• Angular 7.2.3

Maybe this will help anybody:
http.get<Object>(url, { responseType: 'blob' as 'json' })

I'm still seeing this issue. Any update?

Angular 8... same issue :-(

Should just be able to write: req.flush({ body: true })

yes, this still is a problem. I could not get @adamlarner's solution to work (above) but was able to tweak with flushing a 0 or 1 and then having the test verify as:
expect(result).toBeTruthy();
for 0 and:
expect(result).toBeFalsy();
for the 1 test.

I am not sure this will pass muster, but would like to see the httpTestingController handle this more cleanly as well.

I also couldn't get @adamlarner's solution to work, but a simple modification of his workaround is to use double-not !! to convert the flushed number to a boolean:

service.isAuth().then(response => {
  expect(!!response).toBe(true);
});

Another alternative is to flush a string of 'true' (or 'false') req.flush('true'); and then compare strings:

service.isAuth().then(response => {
  expect(`${response}`).toBe('true');
});

Confirmed as reported, and this should be an easy fix. Definitely an opportunity for a community PR (I see there is one, but it's a few years old - hopefully @jdell64 is still around!)

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