[0.18.1] TypeError: Symbol.hasInstance is read-only

[wKovacs64]

Describe the bug

My tests that use vi.mock (in this case, mocking out the ora module) started failing as of vitest v0.18.1 with the following error:

TypeError: Cannot assign to read only property 'Symbol(Symbol.hasInstance)' of function 'function(...o) {
    if (e.called = !0, e.callCount++, e.calls.push(o), e.next) {
      let [s, l] = e.next;
  ...<omitted>... }'

In the reproduction (below), it presents itself as simply: TypeError: Symbol.hasInstance is read-only

I'm assuming this is related to PR #1648 but I'm not sure if I need to update my usage to comply with the intent of the PR or what.

Reproduction

https://stackblitz.com/edit/vitest-dev-vitest-ht4a9x?file=test/mock.test.ts&view=editor

System Info

System:
    OS: Windows 10 10.0.19044
    CPU: (16) x64 Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz
    Memory: 17.74 GB / 31.92 GB
  Binaries:
    Node: 16.16.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.18 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 8.12.2 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Chrome: 103.0.5060.114
    Edge: Spartan (44.19041.1266.0), Chromium (103.0.1264.62)
    Internet Explorer: 11.0.19041.1566
  npmPackages:
    vitest: 0.18.1 => 0.18.1

Used Package Manager

npm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[spacedawwwg]

I've just come across this issue with my mocks, too. Locked in my project to 0.18.0 for now

[sheremet-va]

@simon-abbott do you have any ideas on how to fix this?

[spacedawwwg]

Still an issue in 0.19.0

[dojineko]

Reproduced it with 0.19.1.
I used a workaround like this. :)

vi.mock('something', async () => ({
  // @ts-ignore for mocking
  ...(await vi.importActual('something')),
}))

Edit:
@sheremet-va
I felt like sharing a means to fix it in case you really need to fix it in a hurry. Sorry if I made you feel disappointed by describing a reproduction by version.

[sheremet-va]

Please, don't post comments like "still not working". When someone will work on a fix, it will be displayed here.

[nieyuyao]

When the newContainer[property] is a function, is there no need to continue recursion?

vitest/packages/vitest/src/runtime/mocker.ts

Lines 213 to 217 in 57c2367

	if (isFunction) {
	spyModule.spyOn(newContainer, property).mockImplementation(() => undefined)
	// tinyspy retains length, but jest doesn't.
	Object.defineProperty(newContainer[property], 'length', { value: 0 })
	}

[simon-abbott]

@simon-abbott do you have any ideas on how to fix this?

Hmm. I know roughly what is causing this, but I'll need a little bit of time to be able to fix it. I'll try to take a look this evening.

[simon-abbott]

When the newContainer[property] is a function, is there no need to continue recursion?

@nieyuyao Not recursing into functions was the cause of #1523, since Classes in javascript are just functions with special properties.

[simon-abbott]

Figured out a fix! #1786.