Failing expect() inside subscribe() does not mark test as invalid

Question

We recently upgraded to Angular 6.0.3, RxJs 6.2.0 and jest 23.1.0 (upgrading from RxJS 5 & Angular 4).

There seems to be a problem with Jest & RxJs as failing expect-statements inside a subscribe-Block do not mark the test as failed. Here's a minimal example:

    it("should fail", () => {

        const obs = Observable.create((observer) => {
            observer.next(false);
        });

        obs.subscribe((value) => {
            console.log(value); // => false
            expect(value).toBeTruthy();
        });

    });

The expect-Statement gets executed, but the test still passes. We didn't observe this behaviour with the previous RxJs version and Jest.

Answer 1

Try to use done.

it("should fail", (done) => {

    const obs = Observable.create((observer) => {
        observer.next(false);
    });

    obs.subscribe((value) => {
        console.log(value); // => false
        expect(value).toBeTruthy();
        done();
    });

});

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