Modules missing from node_modules but listed in lock file

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

Bug report.

What is the current behavior?

My build scripts started failing after a recent yarn install and I noticed that certain packages were completely missing from the node_modules folder, yet are listed in yarn.lock, as seen here:

@beemo/driver-babel and @beemo/driver-jest are entirely missing.

screen shot 2018-04-27 at 19 05 16

Running yarn cache clean and rm -rf node_modules did not resolve this issue.

If the current behavior is a bug, please provide the steps to reproduce.

  • Clone the repo
  • yarn install
  • yarn test

What is the expected behavior?

Node modules are installed.

Please mention your node.js, yarn and operating system version.

Node v10.0.0
Yarn v1.6.0
OSX v10.13.4

Author: Fantashit

1 thought on “Modules missing from node_modules but listed in lock file

  1. That doesn’t matter. If you depend on something, you must specify it into your dependencies. The reason it was working before is that Yarn was optimizing your tree to make the node_modules smaller, and that the Node resolution isn’t able to prevent you from using packages optimized this way even if it should.

    Then you upgraded @rails/webpacker, the optimization wasn’t possible anymore without doing many other changes to your lockfile, so Yarn put babel-loader into @rails/webpack/node_modules/babel-loader, where you couldn’t access it. And finally when you deleted the lockfile, Yarn reoptimized everything without regard for the dependencies already installed, and node_modules/babel-loader was made available again.

    Relying on this is entirely undefined behavior, do not do it. Always list your dependencies explicitely. Note that this isn’t unique to Yarn, the same is true for npm. And pnpm will break your application entirely.

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