Frame differs in running all test from running only one test, why?

Question

If I run all tests for one epic at once only the first test passes. The other tests fail because the frame differs. But every test singly run passes.

I could not find any related problem to this nether found something in the RxJS not the redux observable docs. I thought there could be some kind of a reset function on the TestScheduler but there isn't.

One of my test (they all look pretty simular):

test('should fail if e-mail is missing', () => {
    testScheduler.run(({ hot, expectObservable }) => {
        const action$ = new ActionsObservable(
            hot('-a', {
                a: login('', 'secret')
            })
        );

        const output$ = epic(action$, null, null);

        expectObservable(output$).toBe('-a', {
            a: failure(
                formErrors.credentialsEmpty(['email', 'password'])
            )
        });
    });
});

I expect the frame of output marble to be 1 but it is 2. The output of a failing test:

Array [
        Object {
    -     "frame": 1,
    +     "frame": 2,
          "notification": Notification {
            "error": undefined,
            "hasValue": true,
            "kind": "N",
            "value": Object {

---

edit

I could get around that behaviour by creating one TestScheduler instance per test but I am not sure if I am supposed to do it this way.

Answer 1

Stumbled across this today. I think creating one new TestScheduler per test is probably a good idea. It doesn't seem to have a noticeable impact between tests - and that way you're sure that the state is reset between tests.

One other workaround is to do testScheduler.frame = 0 in a beforeEach - but I opted to just create it from scratch each time.