Jest: useFakeTimers() with async/await caused Timeout error

[leader22]

Do you want to request a _feature_ or report a _bug_?

bug(or my misunderstanding?)

What is the current behavior?

This code ends up with Timeout - Async callback was not invoked within timeout specified by jasmine.DEFAULT_TIMEOUT_INTERVAL.

jest.useFakeTimers();

test('why timeout?', async () => {
  // If you comment out this line, test passes
  await new Promise(r => setTimeout(r, 1000));
  expect(1).toBe(1);

  jest.runTimersToTime(3000);
});

Do I misunderstand something?
Thanks in advance.

What is the expected behavior?

Expect test to be passed with 1000ms delay.

Please provide your exact Jest configuration and mention your Jest, node,
yarn/npm version and operating system.

• Jest v21.2.1
• node v8.1.4
• npm v5.5.1
• macOS Siera 10.12.6

[fringd]

I'm not 100% sure but i think you Either want to write something like

done => {
 setTimeout(() => done(), 1000);
}

or

async () => {
  result =  await someOtherPromise;
  expect(await).toBe(...);
}

or without the es6 sugar the last one could be rewritten as

() => {
  return someOtherPromise.then((result) => {
    expect(result).toBe(...);
  });
}

so EITHER promises OR done... not both.

That said I'm having a bad time with async tests right now and that's why I'm here, so please someone with more knowledge feel free to correct me.

[leader22]

Thanks for the comment.
But I need to use BOTH done for callback and await for promises.

Because some libraries only provide callback style API, then this situation happens.

[fringd]

Use promise and new Promise(resolve => callbackneedingfunction(resolve))

On Tue, Nov 28, 2017, 8:55 PM Yuji Sugiura [e-mail] wrote:

Thanks for the comment.
But I need to use BOTH done for callback and await for promises.

Because some libraries only provide callback style API, then this
situation happens.

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[leader22]

Of course I know that.

But in this issue, the point I want to know, is why the code above does not work.
Is this limitation of Jest or some mistakes there.

(I updated repro codes more clearly

[lukeapage]

Because it never gets to runTimersToTime
Because it’s awaiting the promise that only gets resolved when time goes forward, which doesn’t happen till you call runTimersToTime.

[cpojer]

Yeah these two don't work together as @lukeapage identified in the latest comment. I'm closing this as wontfix but you can try doing something like:

const promise = startPromiseTask();
jest.runAllTimers();
const result = await promise;