Jest: 5 builtins missing from `jest-resolve`

[wmhilton]

Expected result: tests pass
Actual result:

  ● Test suite failed to run

    Cannot find module '_stream_transform' from 'index.js'

      at Resolver.resolveModule (node_modules/jest-resolve/build/index.js:191:17)
      at Object.<anonymous> (node_modules/thru/index.js:1:106)

These are builtin modules that are part of the undocumented "private" core API but are unfortunately shimmed in browserify, and some module authors continue to prefer them over the public builtins because using them shaves a few kb off of their bundle size:

_stream_duplex
_stream_passthrough
_stream_readable
_stream_transform
_stream_writable

My root problem is that the test-runner, jest, does not recognize _stream_transform as a core module and breaks as a result. You can see I originally tried to submit a fix to thru (the module that requires _stream_transform) but as switching from _stream_transform to stream would have increased the bundle size, I am now looking for other solutions. builtin-modules is philosophically opposed to adding them to it's list. is-builtin-module is by the same author. So I've worked my way up the dependency chain to jest-resolve. Hopefully you will see that practicality of adding these to the list of builtin modules, since browserify makes this assumption already.

[cpojer]

Feel free to send a PR to check for these in Jest.

[wmhilton]

I'll give it a shot!

[SimenB]

We should whitelist all with an underscore here: https://github.com/nodejs/node/tree/master/lib

Fix should be here: https://github.com/facebook/jest/blob/0748e6f76394b58ce24aee42e08c96fb509e8744/packages/jest-resolve/src/index.js#L199

[wmhilton]

We should whitelist all with an underscore

Awesome! @SimenB that was the solution I was trying, but I got stuck on something. Happy to see somebody figured it out. 😄

[SimenB]

BTW, requiring _stream_transform et.al. will 100% break in future versions of node (deprecation warning likely in node 9), so relying on it is not a good idea. I'm happy that the solution in #4740 will automatically support whatever is in the running version of node, so nothing needs to happen from Jest's side. This is more a warning for consumers

https://github.com/nodejs/node/pull/11957

[wmhilton]

I'm happy that the solution in #4750 [sic] will automatically support whatever is in the running version of node

I'm going to double check that with - dang Twitter is fast, James already replied https://twitter.com/jasnell/status/923895172705824768