Cannot find module, because of infinite loop in jest-resolver

[eaviles]

After experiencing a lot of intermittent errors like this one:

Cannot find module 'X' from 'Y'
      
      at Resolver.resolveModule (node_modules/jest-resolve/build/index.js:191:17)

I looked at the resolver code and realized there was an infinite loop that would eventually cause this error to appear. We have a couple of NPM modules that in their package.json file have the main entry point defined as:

    "main": "."

Because of this, the following line of code would make a path resolve into the same path.

https://github.com/facebook/jest/blob/78477eb526f2ebd901f3daa0abef0e8cc591bfb8/packages/jest-resolve/src/default_resolver.js#L133

This will call the tryResolve function with the same path, that will go on and on until the maximum call stack is reached. I tried changing pkgmain to "index.js" whenever it was defined as "." and the issue went away.

Wondering if there could be other differences in how Node resolution of modules works vs. how the Jest resolver works. Let me know if my team can contribute to fix this. Looking forward to help.

[SimenB]

Would love a PR fixing main: "." 🙂

Wondering if there could be other differences in how Node resolution of modules works vs. how the Jest resolver works.

Hopefully not. You can take a look at node's resolution to see if there are any holes? https://github.com/nodejs/node/blob/604578f47ea360980110e2cd7d4a636f9942b1f0/lib/module.js#L151-L153

[eaviles]

Thanks @SimenB, we will send a PR soon!

[kenzable]

@SimenB Opened PR

[mtlewis]

Looks like modules with a main entry of "./" (like co-request) are also susceptible to this issue. I'll open a separate issue for this.

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