Fail to run Vitest test with an error: "Vitest caught 1 unhandled error during the test run"

[tal-rofe]

I have a function which I try to test using Vitest.

This is my function (I test the exported one):

import os from 'node:os';

import { AI_COMMIT_IGNORED_FILES } from '../constants/ai-commit';
import { asyncExec } from './os';

/**
 * The function returns array of files paths that are in staged mode
 * @returns array of files paths in staged mode
 */
const getStagedFiles = async () => {
	const gitCommand = 'git diff --name-only --cached --relative .';
	const { stdout: filesOutput, stderr } = await asyncExec(gitCommand);

	if (stderr) {
		throw new Error(stderr);
	}

	const filesList = filesOutput.split(os.EOL).filter(Boolean);

	return filesList;
};


/**
 * The function returns the "git diff" command output for relevant staged files in the commit
 * @returns "git diff" output as a string
 */
export const getStagedFilesDiff = async () => {
	const stagedFiles = await getStagedFiles();
	const filteredFiles = stagedFiles.filter((file) => !AI_COMMIT_IGNORED_FILES.includes(file));

	const gitCommand = `git diff --staged -- ${filteredFiles.join(' ')}`;
	const { stdout: diffOutput, stderr } = await asyncExec(gitCommand);

	if (stderr) {
		throw new Error(stderr);
	}

	return diffOutput;
};

And this is the asyncExec function:

import { exec } from 'node:child_process';
import util from 'node:util';

export const asyncExec = util.promisify(exec);

I wrote the following test:

import { describe, it, expect, vi } from 'vitest';

import { asyncExec } from '@/utils/os';
import { getStagedFilesDiff } from '@/utils/git-info';

vi.mock('@/utils/os');

describe('[utils/git-info]', () => {
	describe('getStagedFilesDiff()', () => {
		it('should throw an error when "asyncExec" throws', () => {
			vi.mocked(asyncExec).mockRejectedValueOnce(undefined);

			expect(() => getStagedFilesDiff()).toThrowError();
		});
	});
});

But then I got the error:

Vitest caught 1 unhandled error during the test run.
This might cause false positive tests. Resolve unhandled errors to make sure your tests are not affected.


This error originated in "tests/utils/git-info.spec.ts" test file. It doesn't mean the error was thrown inside the file itself, but while it was running.
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
 ELIFECYCLE  Test failed. See above for more details.

I have followed this: https://vitest.dev/api/expect.html#tothrowerror

So I don't understand why doesn't it work..?

I tried the following also:

		it('should throw an error when "asyncExec" throws', async () => {
			vi.mocked(asyncExec).mockRejectedValueOnce(undefined);

			await expect(() => getStagedFilesDiff()).rejects.toThrowError(undefined);
		});

But got the error: AssertionError: expected [Function] to throw an error.

Then I wrapped the getStagedFilesDiff function with try {} catch {} as follows:

export const getStagedFilesDiff = async () => {
	try {
		const stagedFiles = await getStagedFiles();
		const filteredFiles = stagedFiles.filter((file) => !AI_COMMIT_IGNORED_FILES.includes(file));

		if (filteredFiles.length === 0) {
			return null;
		}

		const gitCommand = `git diff --staged -- ${filteredFiles.join(' ')}`;
		const { stdout: diffOutput, stderr } = await asyncExec(gitCommand);

		if (stderr) {
			throw new Error(`Failed to get "git diff" output of staged files with error:\n${stderr}`);
		}

		return diffOutput;
	} catch {
		throw new Error();
	}
};

Then the test completed successfully (when using the previous test code, not the original one - first one).

[sheremet-va]

I have followed this: vitest.dev/api/expect.html#tothrowerror

You did not follow this.

Your function is async. It needs rejects.

[tal-rofe]

@sheremet-va
My lord, I tried it as well:

		it('should throw an error when "asyncExec" throws', async () => {
			vi.mocked(asyncExec).mockRejectedValueOnce(undefined);

			await expect(() => getStagedFilesDiff()).rejects.toThrowError(undefined);
		});

the error is:

AssertionError: expected [Function] to throw an error

[tal-rofe]

@sheremet-va
Should I convert this one to an issue?

[sheremet-va]

You cannot convert this to an issue because there is no reproduction.

[tal-rofe]

@sheremet-va
Ok, my lord. I will try to create a reproduction repository, and then, I will create an issue. :)

[shadowCruz]

i feel your pain tal. I am having similar problem :)

[camboYY]

Vitest caught 14 unhandled errors during the test run.
this happens when i run test coverage

[p0wl90]

Same here with Quasar, always different Errors in always different files. So it is impossible to find the actual problem (we run around 1k tests).

[roccomilicic]

Ever fix it?

[piecyk]

Is there any way to catch what throws this error? Pretty hard to pinpoint it in large codebase.

[sheremet-va]

Is there any way to catch what throws this error?

The error is called "unhandled". It means that nothing could catch it

[piecyk]

Vitest caught 1 unhandled error during the test run.

Something did ;) but jokes aside... Can't really pin it, mostly getting it randomly in netlify preview build, after manually triggering it again then it's ok, no errors when running it locally.

[p0wl90]

Here are some more infos on resolving this:

• Tests pass but vitest fails non-deterministically and sometimes causes Unhandled Rejection #1692 (comment)
• Test passes, but fails with .then()  #1720 (comment)

I did not find time to investigate it in our large codebase myself but maybe it helps you. I'd be thankful if you cold keep us updated!

[unional]

I'm getting this randomly (but very frequently) when I use maxWorkers and Vitest Browser Mode together. Without maxWorkers, the tests passes all the time.

[SimpleCookie]

I realise it's an old post, but if someone else finds this place and has the same error you could have the same issue as I did.
Meaning: Wrong node version.

My tests ran fine in terminal where I explicitly set the correct node version. But my system default was different, so when I ran tests through the vscode extension vitest I got the same error "Vitest caught 1 unhandled error during the test run".

Hopefully this might help someone in the future :)

Background:
In my case I tracked it down to a package in jsdom -> whatwg-url
So it's probably something there that's uncompatible with earlier versions of node

[roccomilicic]

What version of node and vitest were you using to remove the unhandeld error?

[kelvinwop]

For me it was some kind of strange memory leak over time. Found it via

logHeapUsage: true,

Ended up fixing via switching 'vmForks' to straight up 'forks'. tests take 3x as long now but at least they're totally isolated from each other and work now lol