mocks don't seem to be registered correctly

🐛 Bug Report

When setting up a mockResolvedValue, a mockImplementation, etc. for an async function (such as data fetching) inside beforeEach or a test the mock works as expected. However when the mock is set up in beforeAll the defined return value of the mock is not returned and an error is thrown. The same error is thrown when setting up the mock at the top of the module.

Since we’re setting up only one test the semantics of beforeEach and beforeAll should be the same.

Error message:

Error: Uncaught [TypeError: Cannot read property ‘then’ of undefined]

To Reproduce

See test in this repo

Expected behavior

When setting up the mock

• at the top of the module, the mock implementation / resolved value should still work
• in the beforeAll hook the mock should work the same way as the beforeEach (at least in our context, because we only have one test in this case)

Link to repl or repo (highly encouraged)

https://github.com/lehnerchristian/jest-test

envinfo

npx: installed 1 in 0.795s

  System:
    OS: Linux 5.8 Ubuntu 20.04.2 LTS (Focal Fossa)
    CPU: (16) x64 Intel(R) Xeon(R) W-10885M CPU @ 2.40GHz
  Binaries:
    Node: 16.0.0 - ~/.nvm/versions/node/v16.0.0/bin/node
    Yarn: 1.22.10 - ~/.nvm/versions/node/v16.0.0/bin/yarn
    npm: 6.14.13 - ~/.nvm/versions/node/v16.0.0/bin/npm

[idler8]

https://github.com/facebook/create-react-app/issues/10571#issuecomment-784923197 @lehnerchristian

[lehnerchristian]

This works indeed. Thanks for the link. Not sure how useful it is to have any mocks having their fake implementations removed (see the docs), because why write a fake implementation in the first place then.

So this means that if I try to set a mock in the beforeAll test lifecycle it gets overridden if this option is set before running the first test. This also applies for setting the mocks globally within the test file. Only beforeEach and setting the mocks in the test work, because the run after the resetMocks call?

Or in short:

1. beforeAll
2. resetMocks
3. beforeEach

Is this correct?