Problem with useFakeTimers: Promise are freeze when resolve it from setTimeout

[qoter]

• Sinon version : 2.2.0
• Environment : Node.js v6.10.2
• Other libraries: mocha 3.3.0

Code example

it('promise freeze', () => {
    let clock = sinon.useFakeTimers();
    let p = Promise.resolve()
        .then(() => new Promise(resolve => setTimeout(resolve, 5)));
    clock.tick(1000);
    return p;
});

I expect that test will pass.
But test fail with timeout and promise are frozen.
Without sinon.useFakeTimers() this test will pass.

[lucasfcosta]

Hi @qoter, thanks for your issue 😄

I believe this happens because you either gotta use a timer from the clock variable you assigned useFakeTimers to or you need to call the install method.

This is one of the possible fixes for your test:

let clock = fakeTimers.useFakeTimers();
let p = Promise.resolve()
  .then(() => new Promise(resolve => fakeTimers.timers.setTimeout(resolve, 5)));
clock.tick(1000);
return p;

The other one, using install to replace the global setTimeout function can be used by installing the lolex module, as you can see in this section at Lolex docs.

[qoter]

Hello @lucasfcosta)))
Your test works!)
But when i use lolex.install() to replace global setTimeout promise still frozen.

Examples:

1. It works (use lolex.timers.setTimeout)

let clock = lolex.install();
let p = Promise.resolve()
    .then(() => new Promise(resolve => lolex.timers.setTimeout(resolve, 5)));
clock.tick(1000);
return p;

2. It fails with timeout (replace global setTimeout)

let clock = lolex.install();
let p = Promise.resolve()
    .then(() => new Promise(resolve => setTimeout(resolve, 5)));
clock.tick(1000);
return p;

3. btw it also works (not return promise from then)

let clock = lolex.install();
let p = new Promise(resolve => setTimeout(resolve, 5));
clock.tick(1000);
return p;

I really do not understand why this happens.
Thank you!

[mroderick]

Has this stalled?

[qoter]

@mroderick
Sorry, i didn't understand you(
What do you mean?

[fatso83]

Are you using any Promise libraries? They often use timers to create polyfills, which might be affected by faking time.

[qoter]

@fatso83 No, I use default Promise from node.js

[macdonaldr93]

+1 I'm having this issue too. Just using native Promise

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[robertstettner]

+1 I'm having this issue too.

[fatso83]

We should probably move this to lolex, to get it fixed.

[fatso83]

This issue was moved to sinonjs/fake-timers#194