Tests pass but vitest fails non-deterministically and sometimes causes Unhandled Rejection

Describe the bug

While test cases results themselves are deterministic but the runs are not. Some of the runs produce unhandled rejection. This seems to be similar to https://github.com/vitest-dev/vitest/issues/1191 but not same. My test specs are fairly minimal at this time, like just checking for component rendering and not much.

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ Unhandled Errors ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

Vitest caught 2 unhandled errors during the test run. This might cause false positive tests.
Please, resolve all the errors to make sure your tests are not affected.

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ Unhandled Rejection ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Error: 
 ❯ post node_modules/vitest/dist/worker.mjs:70:14
 ❯ node_modules/vitest/dist/chunk-vite-node-utils.8077cd3c.mjs:1376:11
 ❯ sendCall node_modules/vitest/dist/chunk-vite-node-utils.8077cd3c.mjs:1373:16
 ❯ node_modules/vitest/dist/chunk-runtime-rpc.9d1f4c48.mjs:7:55
      5|   return new Proxy(rpc2, {
      6|     get(target, p, handler) {
      7|       const sendCall = Reflect.get(target, p, handler);
       |                                                       ^
      8|       const safeSendCall = (...args) => withSafeTimers(() => sendCall(...args));
      9|       safeSendCall.asEvent = sendCall.asEvent;
 ❯ withSafeTimers node_modules/vitest/dist/chunk-utils-global.0a7416cf.mjs:472:20
 ❯ Proxy.safeSendCall node_modules/vitest/dist/chunk-runtime-rpc.9d1f4c48.mjs:7:41
 ❯ process.<anonymous> node_modules/vitest/dist/worker.mjs:34:11
 ❯ process.emit node:events:527:28
 ❯ emit node:internal/process/promises:140:20

Reproduction

You should be able to reproduce it using this repo.

https://github.com/zinclabs/zinc/tree/38303f59af5f329c62068a320eecd4f53c17b107

steps.

git clone https://github.com/zinclabs/zinc
cd zinc
git checkout 38303f59af5f329c62068a320eecd4f53c17b107
cd web
npm i 
npm run test-once

run the test a couple of times. You will notice that sometimes tests are successful however sometimes there is unhandled rejection.

System Info

System:
    OS: macOS 12.4
    CPU: (8) arm64 Apple M2
    Memory: 372.69 MB / 24.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 16.16.0 - /usr/local/bin/node
    npm: 8.11.0 - /usr/local/bin/npm
  Browsers:
    Brave Browser: 103.1.41.96
    Chrome: 103.0.5060.134
    Safari: 15.5
  npmPackages:
    @vitejs/plugin-vue: ^2.3.3 => 2.3.3 
    vite: ^2.9.14 => 2.9.14 
    vitest: ^0.18.1 => 0.18.1

Used Package Manager

npm

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• Read the Contributing Guidelines.
• Read the docs.
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• The provided reproduction is a minimal reproducible example of the bug.

[sheremet-va]

@calvinf thank you for pointing it out, Vitest didn’t serialise errors thrown in unhandledRejection, so some errors might’ve slipped as Unknown Error: undefined. #2253 should fix it.

[sheremet-va]

@sheremet-va could you confirm if the issue was fixed? Facing the same problem right now and I’m using version 0.24.5.

I am randomly getting unhandled rejection errors.

Like 30% of the time the tests pass but get this unhanded rejection that doesn’t show exactly which test caused it.

Yes, mentioned in this PR error is fixed.

You probably have an asynchronous process that’s executed after all tests have passed. Vitest cannot track it, it’s unhandled.