[Bug]: createMockFromModule not mocking class correctly

[dominiktopp]

Version

29.5.0

Steps to reproduce

1. Clone my repo at https://github.com/dominiktopp/jestCreateMockFromModuleIssue
2. npm install
3. npm test
4. tests will fail

Expected behavior

I expect the test cases to succeed.

Actual behavior

Tests are failing because jest.createMockFromModule only mocks constructor and functions for classes but no other properties (also no getters).
The example for jest.createMockFromModule does not mock an exported class but an instance of a class:
class: new (class Bar {...})()

Additional context

No response

Environment

System:
  OS: Windows 10 10.0.19045
  CPU: (12) x64 Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz
  Memory: 10.67 GB / 31.76 GB
Binaries:
  Node: 16.15.0 - C:\Program Files\nodejs\node.EXE
  npm: 8.5.5 - C:\Program Files\nodejs\npm.CMD

[mattvot]

Just to add I've been seeing a similar issue. Using the package.json resolves and yarn I determined that our tests work fine when I set:

{
  ...
  "resolutions": {
    "jest-mock": "29.4.2"
  }
}

However with:

{
  ...
  "resolutions": {
    "jest-mock": "29.4.3"
  }
}

Our failing tests call a function of an instance that has been mocked with jest.mock(). They fail because the function returns undefined instead of the expected value.

While I'm not 100% familiar with how jest-mock works yet, I've been looking though the history and spotted a few things that may have caused this:

• refactor(jest-mock): remove unused specificReturnValues property #13889
  • Is specificReturnValues definitely not used? Sounds like a potential cause for this.
• There is also a couple of PRs that change how reseting mocks work.
  • fix(jest-mock): do not restore mocks when jest.resetAllMocks() is called #13866
  • fix(jest-mock): clear mock when jest.restoreAllMocks() is called #13867

Other than that I can't see how the other commits would make a difference here: https://github.com/facebook/jest/commits/main/packages/jest-mock

[mrazauskas]

That seems different and not related with this issue. See #13925 for details and possible solutions.

[mattvot]

Thanks @mrazauskas. I can confirm that when I made a new codebase to reproduce the issue, the fix suggested by @CreativeTechGuy in #13925 (comment) worked. Unfortunately for our main codebase this did not work, so something else is afoot. We will be looking further at this in time. For now we've pinned jest at 29.4.2.

[mrazauskas]

In your place I would try looking for jest.restoreAllMocks() in test files. If these are, try replacing them with jest.clearAllMocks() or recreating mocks within beforeEach.

Unfortunately jest.restoreAllMocks() did not call .mockRestore() on each mock before #13867. Now it does, but that isn’t always what was intended.

[github-actions]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 30 days.

[dominiktopp]

Since the previous comments seem to be related to another problem, can anyone help me with my problem mocking classes with createMockFromModule please?

[github-actions]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 30 days.

[dominiktopp]

still active, not stale

[github-actions]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 30 days.

[dominiktopp]

not stale!

[mrazauskas]

Duplicate of #14178

[github-actions]

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