Jest expect exception not working with async

Question

I am writing a test that supposedly should catch an exception

describe('unauthorized', () => {
  const client = jayson.Client.http({
    host: 'localhost',
    port: PORT,
    path: '/bots/uuid',
  })

  it('should return unauthorized response', async () => {
    const t = async () => {
      await client.request('listUsers', {})
    }

    expect(t()).toThrow(Error)
  })
})

I am pretty sure that client.request is throwing an exception but Jest says:

Received function did not throw

const test = async () => {
 ...
}

Is the correct way to check?

UPDATE

If I change to

expect(t()).toThrow(Error)

I got

expect(received).toThrow(expected)

Matcher error: received value must be a function

Received has type:  object
Received has value: {}

You may need to await the `test` function as it's just an unresolved async function at that point, hence why it hasn't thrown. — Mark Atkinson, Feb 01 '21 at 21:10
Async functions *return promises*, which may reject, they don't throw errors. Read https://jestjs.io/docs/en/asynchronous. — jonrsharpe, Feb 01 '21 at 22:04

lissettdm · Accepted Answer · 2021-02-01T22:16:48.850

22

You can use rejects

 it('should return unauthorized response', async () => {
    await expect(client.request('listUsers', {})).rejects.toThrow(/* error you are expecting*/);
 })

Or

You can use try/catch

 it('should return unauthorized response', async () => {
    const err= null;
    try {
      await client.request('listUsers', {});
    } catch(error) {
      err= error; //--> if async fn fails the line will be executed
    }

    expect(err).toBe(/* data you are expecting */)
  })

You can check the error type of and the error message

edited Feb 01 '21 at 22:16

answered Feb 01 '21 at 22:11

lissettdm

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You can also use toStrictEqual in place of toBe and add the exception being thrown as argument. ```expect(err).toStrictEqual(Exception); ``` – Anurag Phadnis Apr 20 '21 at 07:59

Jest expect exception not working with async

UPDATE

1 Answers1