RFC: Run from nearest package.json

[cdaringe]

Problem

In monorepos, some modules are only available in the sub-package under test, thus aren't available if cwd the monorepo root.

For example:

<root>
  packages/
     foo/
       package.json
       __tests__/
         foo.spec.ts
     bar/
       package.json
       __tests__/
         bar.spec.ts

If cwd is <root>, and foo.spec.ts calls jest.mock on a package that is only present packages/foo/node_modules, jest crashes!

Discussion

• it is common for monorepo users to open their project from the <root>
• it is common for monorepo users to try and exec a test from a child package from the VSCode root workspace ctx
• the aforementioned CWD mismatch can lead to this ext crashing (no fault of the extension)

Support for a feature like cwdNearestPackageJson: true could easily:

• discern the spec filename under test
• find the nearest package.json filename
• set the cwd to the dirname of the prior found package.json filename

With such a feature, monorepo users could run a test from any sub-package, and reliably run in the same pwd and node_modules context as if they had just cd <path-to-package> && jest .!

[domsleee]

I'll reopen this one for discussion 👍

I think this case is already supported, but I could be wrong.

If you try it with jestrunner.changeDirectoryToWorkspaceRoot, it will run cd <path> before running the jest command.

You can see here it is falling back to currentPackagePath, which upsearches for package.json:

https://github.com/firsttris/vscode-jest-runner/blob/43cc89b213698c2971b8b3437345ad6d04b1eb6d/src/jestRunnerConfig.ts#L51-L77

Based on the code, perhaps the current docs could be improved:

jestrunner.changeDirectoryToWorkspaceRoot | Changes directory to workspace root before executing the test -- | --

I think this setting should really be:

Changes directory to the resolved project path. The fallback order is jestrunner.projectPath, falling back to the nearest package.json, falling back to the workspace root.

Does this cover your use case? Thanks