Getting "function did not throw" While Testing Async Function to Throw Error with Jest

Question

I'm trying to test an async function with Jest and I can't get my test to pass.

My Code

export class UnexpectedRequestError {
  constructor(public message: string = 'Unauthorized') {
    this.message = message;
  }
}

export const foo = async (arg: boolean) => {
  if (arg) {
    return true;
  } else {
    const message = 'message';
    await sendSlackMessage(message);
    throw new UnexpectedRequestError(message);
  }
};

Test Code

test('throws UnexpectedRequestError', async () => {
  await expect(foo(false)).rejects.toThrow(UnexpectedRequestError);
});

My test returns:

expect(received).rejects.toThrow(expected)

Expected constructor: UnexpectedRequestError

Received function did not throw

I've searched for other similar questions here on StackOverFlow but I couldn't find anything wrong with my codes. Any ideas what I'm doing wrong?

Thanks for your comment. await expect(() => foo(false)).rejects.toThrow(UnexpectedRequestError) gave me the same result, which is Received function did not throw. — ta539tg70
– ta539tg70, Commented Sep 16, 2022 at 1:04
Make sure that your function will be call with actual logic in your test. — hoangdv
– hoangdv, Commented Sep 16, 2022 at 1:10
@hoangdv I've tried putting console.log('abc') right before throw new UnexpectedRequestError(message) and abc gets displayed when I run the test. Is this what you mean? — ta539tg70
– ta539tg70, Commented Sep 16, 2022 at 1:16
Yes, it seem something went wrong. Let's try to call await foo(); before the assertion line. — hoangdv
– hoangdv, Commented Sep 16, 2022 at 1:29

Willian Arana · Accepted Answer · 2022-09-16 04:01:19Z

4

Your error class needs the "Error" inheritance.

export class UnexpectedRequestError extends Error {
  constructor(public message: string = 'Unauthorized') {
    super(message);
  }
}

edited Sep 16, 2022 at 4:01

answered Sep 16, 2022 at 3:49

Willian Arana

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2 Comments

Thejas Over a year ago

This worked for me. But is there any other method to solve this? In here throw new Error(err); I am getting this error as I am using ts. No overload matches this call.

Willian Arana Over a year ago

You can use your error class, exemple throw new UnexpectedRequestError(err);, maybe worked without this another error.

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