fix: Fix incorrect rootPath resolution in jest plugin

[tryggvigy]

This PR

Stops joining contructing a jest config rootDir via join(configFileDir, localConfig.rootDir)
when a localConfig rootDir is defined. Instead, we always prefer the local config rootDir and fall back to configFileDir.

I also include a new unit test that tests that this bug is fixed.

Context

I noticed that jest setup files that used the '<rootDir>/...' alias in places like setupFilesAfterEnv were resolving incorrectly. For example,

when I specify

config: ['tests/framework/e2e/jest-configs/jest.config.base.ts']

in the jest plugin,

Where jest.config.base.ts contains:

// abs path to repo root (/Users/me/work/repo/)
rootDir: REPO_ROOT_PATH,
setupFilesAfterEnv: [
    '<rootDir>/tests/framework/e2e/setup-files/setup.base.ts',
  ],

I get the following incorrect resolve:

'deferResolve:/Users/me/work/repo/tests/framework/e2e/jest-configs/Users/me/work/repo/tests/framework/e2e/setup-files/setup.base.ts (tests/framework/e2e/jest-configs/jest.config.base.ts)'

Where it was joining

• the directory of the config file path (/Users/me/work/repo/tests/framework/e2e/jest-configs/)
• with the specified rootDir in the config file (/Users/me/work/repo/)
• and then adding the rest of the path (tests/framework/e2e/setup-files/setup.base.ts)

This is happening

• here https://github.com/tryggvigy/knip/blob/main/packages/knip/src/plugins/jest/index.ts#L115
• and here https://github.com/tryggvigy/knip/blob/main/packages/knip/src/plugins/jest/index.ts#L123

I might be wrong, I don't have all the context, but this feels like wrong behaviour.

[webpro]

Thanks for the PR, @tryggvigy!

Would be great if you could add fixtures for this case. There's one for Jest in packages/knip/fixtures/plugins/jest, you could add a folder next to it like jest2. And then use it from a new test next to packages/knip/test/plugins/jest.test.ts.

And there's DEVELOPMENT.md which might be helpful here.

[tryggvigy]

Thanks for the pointers @webpro, I'll try to get some test coverage on this asap

[pkg-pr-new]

Open in Stackblitz

bun add https://pkg.pr.new/knip@833

commit: 041ee1f

[tryggvigy]

@webpro I've pushed a new commit which includes a unit test that verifies the code changes fix the issue.
I can see the test failing on main and passing on this PR.

[tryggvigy]

I think I found two more missig features the jest plugin could handle.

1. Reporters like this are not caught

  reporters: [
    'default',
    [
      'jest-junit',
      {
        outputDirectory: '<rootDir>',
        outputName: 'junit-e2e.xml',
        testSuitePropertiesFile: 'junitProperties.e2e.cjs',
      },
    ],
   ...
]

2. testEnvironment like this is not caught

  testEnvironment:
    '<rootDir>/tests/framework/e2e/jest-environments/E2EEnvironment.ts',

I can make separate PRs to try and fix those.

[webpro]

@webpro I've pushed a new commit which includes a unit test that verifies the code changes fix the issue. I can see the test failing on main and passing on this PR.

Perfect, thank you!

I can make separate PRs to try and fix those.

That would be great. Guess we could use the new fixture/test for this as well. Thanks in advance!

[webpro]

🚀 This pull request is included in v5.37.0. See Release 5.37.0 for release notes.

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