Jest tests cause require-dir to break in dependencies

[nickserv]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
When a Jest test requires a module in node_modules that uses require-dir with a relative path, the path is resolved relatively to the package that has the executed Jest test instead of the package that uses require-dir (what's supposed to happen). This issue does not occur if exactly the same code is executed directly through Node instead of Jest.

If the current behavior is a bug, please provide the steps to reproduce and either a repl.it demo through https://repl.it/languages/jest or a minimal repository on GitHub that we can yarn install and yarn test.

1. Clone https://github.com/nickmccurdy/jest-require-dir-bug
2. npm install-test

~/Repos/jest-require-dir-bug → node index.test.js 
~/Repos/jest-require-dir-bug → npm test

> @ test /Users/nick/Repos/ncu-example
> jest

 FAIL  ./index.test.js
  ● Test suite failed to run

    ENOENT: no such file or directory, scandir '/Users/nick/Repos/ncu-example/dir'
      
      at Object.fs.readdirSync (fs.js:911:18)
      at requireDir (node_modules/require-dir/index.js:25:20)
      at Object.<anonymous> (node_modules/example/index.js:1:112)
      at Object.<anonymous> (index.test.js:1:90)

Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        0.88s
Ran all test suites.
npm ERR! Test failed.  See above for more details.

This issue can also be observed by requiring code that uses npm-check-updates (which also uses require-dir) via JavaScript in a Jest test.

What is the expected behavior?
Jest's execution environment should allow require-dir to function normally, requiring a relative directory with the requireDir('./example') syntax even in a dependency. Jest should also behave the same as Node itself, or work around this difference in execution environments.

Please provide your exact Jest configuration and mention your Jest, node, yarn/npm version and operating system.

• Empty configuration
• index.test.js or __tests__/index.js naming conventions
• Jest 15-21.2.1
• require-dir 0.3.2
• Node 8.6.0
• npm 5.4.2
• macOS 10.13

[jvivs]

Looks like it's a wontfix: #1657 @cpojer can you confirm?

Currently looking into how and the right place to mock the problematic part of my dependency graph.

[nickserv]

Thanks for the helpful issue link, I am interesting in knowing if module.parent is a wontfix. I also noticed that when I did use __dirname, I got errors suggesting that Jest was marking the directory as empty (as reported in that issue).

While I personally dislike directory require utilities (in favor of index.js files using static dependencies), it's unfortunate that this causes some third party library (including npm-check-updates to fail in Jest tests when the tested project itself doesn't use them. Is there any way around this besides reimplementing module.parent or patching dependencies to not use module.parent? I was also thinking about a mocking solution, I wonder if we could somehow automatically mock module.parent in a way that could allow these utilities to continue working automatically (or at least with some sort of additional opt in mocking API).

[cpojer]

At this point I'm ok if somebody adds support for module.parent, granted the PR includes tests.

We do not support require.cache, so it would only work if you also call jest.resetModules(), which I guess is fine for your use-case, right?

[nickserv]

Cool, do you know roughly how involved it would be to add support? Is it a matter of hooking into module loading in the VMs and adding metadata or is it a more invasive refactor?

[cpojer]

Shouldn't be too much, check out jest-runtime's main module, which is Jest's require implementation.

[SimenB]

@nickmccurdy I've opened a PR for it

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