debounceTime does not emit with jasmine.clock.tick in v7

[dpurp]

Bug Report

\cc @leggechr

Current Behavior
In v7, debounceTime does not emit any values when installing the jasmine clock and using tick. (This works in v6)

Expected behavior
rxjs is compatible with jasmine.clock, or there is a documented workaround.

Reproduction
Note the reproductions below contain examples using the jasmine clock (which fails in v7) and the native clock (which succeeds).

v7: https://stackblitz.com/edit/rxjs-v7-debouncetime?file=test.ts
v6: https://stackblitz.com/edit/rxjs-v6-debouncetime?file=test.ts

describe('failing time tests with jasmine clock', () => {
  beforeEach(() => {
    jasmine.clock().install();
  });

  afterEach(() => {
    jasmine.clock().uninstall();
  });

  it('debounces time', async () => {
    const duration = 10;
    const source = new Subject<string>();
    const debouncedSource$ = source.pipe(
      debounceTime(duration),
      shareReplay(1)
    );
    debouncedSource$.subscribe();

    source.next('should not be emitted');
    source.next('expected value');
    jasmine.clock().tick(duration + 1); // Wait for debounce to happen.

    expect(await firstValueFrom(debouncedSource$)).toEqual('expected value');
  });
});

[cartant]

Thanks. This is a bug. setInterval is captured in the interval provider:

rxjs/src/internal/scheduler/intervalProvider.ts

Lines 18 to 25 in 53ef494

	setInterval(...args) {
	const { delegate } = intervalProvider;
	return (delegate?.setInterval || setInterval)(...args);
	},
	clearInterval(handle) {
	const { delegate } = intervalProvider;
	return (delegate?.clearInterval || clearInterval)(handle);
	},

Instead, the provider should obtain the setInterval and clearInterval functions via globalThis.

[cartant]

Nope. That's not the problem. The debounceTime implementation now uses the scheduler's now function:

rxjs/src/internal/operators/debounceTime.ts

Lines 84 to 86 in 53ef494

	const targetTime = lastTime! + dueTime;
	const now = scheduler.now();
	if (now < targetTime) {

and

rxjs/src/internal/operators/debounceTime.ts

Lines 99 to 100 in 53ef494

	lastValue = value;
	lastTime = scheduler.now();

So the issue is that Jasmine purports to mock the clock, but it does not patch Date.now.

@benlesh

[cartant]

Apparently, Jasmine now has a mockDate method:

beforeEach(() => {
  jasmine.clock().install()
  jasmine.clock().mockDate();
});

Calling that resolves the issue.

[benlesh]

Ugh. Jasmine. There's a reason we stopped using it on this project. Haha.

[dpurp]

Thanks for figuring this out for me. I confirmed it worked on a subset of tests and am rolling out the fix to the rest of the codebase.

[matheo]

@benlesh the operator is broken in jest too.
something can be done over here to fix the failing tests please?

[ortegamarcel]

@matheo @avast-ye found a work around for it: change debounceTime(x) to debounce(() => interval(x)).

You can also mock it inside your tests:

import { interval } from 'rxjs';
import { debounce } from 'rxjs/operators';
import * as rxjsOperators from 'rxjs/operators';

// inside beforeEach
jest.spyOn(rxjsOperators, 'debounceTime').mockImplementation((timeout) => debounce(() => interval(timeout)));

Found here.

[AntonioEduardo1998]

I know the issue is closed, but has anyone found a definitive solution? I just upgraded to v7 and am facing the same problem using Jest.
Using debounce(() => timer(time)) seems to work, but I'm not sure if the behavior stays the same.

[villanuevadani]

Hey @AntonioEduardo1998 @ortegamarcel , thank you a lot for these ideas! Do you know if there is any recent approach that is able as well to use fakeAsync with debounceTime or something?