CODEWITHSUNDEEP
javascriptjestjssettimeout
wsu49
wsu49

Reputation: 21

Jest how to test error thrown in setTimeout

My code looks like this:

const myFunc =() =>{
    setTimeout(()=>throw new Error('err within setTimeout'),500);
}

How do I test in the Jest framework that the error is thrown?

Upvotes: 2

Views: 758

Answers (1)

skyboyer
skyboyer

Reputation: 23753

The only way I see is to mock setTimeout itself to make it run synchronously. jest.useFakeTimers() + jest.runAllTimers() can do that for you:

jest.useFakeTimers();

it("throws", () => {
  expect.assertions(1); // don't miss that to ensure exception has been thrown!
  myFunc();
  try {
    jest.runAllTimers();
  } catch(e) {
    expect(e.message).toEqual('err within setTimeout');
  }
});

Upvotes: 1

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