Fix expect().rejects.toThrow()

@silverwind

Shouldn't that be working?

Does this suit your needs?

import { describe, expect, test } from 'bun:test';

const askGPT = async (text: string, prompt: string, context: string): Promise<void> => {
	throw new Error('⛔ API error.');
};

describe('', () => {
	test('', async () => {
		await expect(async () => await askGPT('text', 'prompt', 'context')).toThrow(Error(`⛔ API error.`));
	});
});

This works only in bun, but not in vitest, so it's not compatible. It seems .rejects.toThrow is not implemented correctly or at all in bun, it throws Expected value must be a function on code like this that works in vitest:

await expect(asyncFn()).rejects.toThrow()

Originally posted by @silverwind in #1825 (comment)

32 |     await expect(async ()=>generator.next()).rejects.toThrow('Unsupported type passed')
              ^
error: expect(received).rejects.toThrow(expected)

Expected promise
Received: [Function: AsyncFunction]

This works when run with jest, but not when run with Bun. The above error output is from running bun test, but when run with jest this test passes.

This bug also happens for synchronous calls.

Version of Bun is running: 1.0.7+b0393fba6200d8573f3433fb0af258a0e33ac157
Platform: Linux 6.2.0-35-generic x86_64 x86_64

Still happening in bun 1.0.25

i do like this:

expect(
        BalanceWithdrawalService.addWithdrawalToQueue({
          toAddress: targetWallet.address!.toString(true, true, true),
          userId: targetUser.id,
        })
      ).rejects.toThrow("EMPTY_BALANCE");

it works.

the BalanceWithdrawalService.addWithdrawalToQueue is async

@Electroid

@Electroid I just upgraded to bun 1.1, and it looks like this has been fixed!

workaround

const expectedError = new Error()
try {
  await asyncFunctionThatThrows()
 } catch(error) {
   expect(error).toEqual(expectedError)
}

I believe I'm experiencing the same issue.
I have the following code that works with jest but fails with bun:

 it('rejects with a dom exception', () => {
    fetch.mockAbort()
    expect(fetch('/')).rejects.toThrow(expect.any(DOMException))
  })

It results in the following failure:

error: expect(received).toThrow(expected)

Expected constructor: ExpectAny
Received constructor: DOMException

The intended behavior that the .toThrow() function should be that toThrow should be checking what ExpectAny holds but it seems in this case toThrow is comparing against ExpectAny directly.

Update `expect().rejects` to call `async` functions

There seems to be no combination that I can use to get this to work (make a test pass where we expect the object being tested to throw an error), so I definitely believe this to be a bug.

docs: split UPSTREAM_ISSUES.md from ISSUES_WILL_CLOSE.md; drop phanto…

This works correctly now. Verified on Bun v1.4.0:

const asyncFn = async () => { throw new Error("fail"); };
await expect(asyncFn()).rejects.toThrow();           // ✓ pass
await expect(asyncFn()).rejects.toThrow("fail");     // ✓ pass
await expect(asyncFn()).rejects.toThrow(Error);      // ✓ pass

const p = Promise.reject(new DOMException("aborted", "AbortError"));
await expect(p).rejects.toThrow(DOMException);       // ✓ pass

No more Expected value must be a function error.

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Fix `expect().rejects.toThrow()` #5602

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Fix expect().rejects.toThrow() #5602

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mrbrianevans commented on Oct 9, 2023

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Fix `expect().rejects.toThrow()` #5602