Commits on Jan 27, 2024

1. Babel-ignore node_modules on Windows consistently with others (face… …

   …book#42681)
   
   Summary:
   
   CI failures in Windows JS tests recently (facebook#41463) were caused by the triggering of Babel registration during tests, due to an import of `packages/dev-middleware` (index), breaking subsequent transformation of other tests.
   
   ## Root cause
   Example of a problematic import:
   https://github.com/facebook/react-native/blob/a5d8ea4579c630af1e4e0fe1d99ad9dc0915df86/packages/dev-middleware/src/__tests__/ServerUtils.js#L15
   
   ..which triggers a Babel registration:
   https://github.com/facebook/react-native/blob/a5d8ea4579c630af1e4e0fe1d99ad9dc0915df86/packages/dev-middleware/src/index.js#L16-L18
   
   That registration behaves differently on Windows due to the `ignore: [/\/node_modules\/\]`, which doesn't match against Windows path separators - Babel matches against system separators.
   
   In particular, this changed whether `node_modules/flow-parser` was transformed when loading the RN Babel transformer. Transforming this file causes a `console.warn` from Babel due to its size:
   > [BABEL] Note: The code generator has deoptimised the styling of /Users/robhogan/workspace/react-native/node_modules/flow-parser/flow_parser.js as it exceeds the max of 500KB.
   
   This throws due to our setup:
   https://github.com/facebook/react-native/blob/a5d8ea4579c630af1e4e0fe1d99ad9dc0915df86/packages/react-native/jest/local-setup.js#L27
   
   This all manifests as the first test following a Babel registration (within the same Jest worker) that requires the RN Babel transformer throwing during script transformation.
   
   ## This change
   This is the minimally disruptive change that makes Babel registration behaviour consistent between Windows and other platforms. The more durable solution here would be *not* to rely on any Babel registration for Jest, which has its own `ScriptTransformer` mechanism for running code from source. Given the fragile way our internal+OSS Babel set up hangs together that's a higher-risk change, so I'll follow up separately.
   
   Changelog: [Internal]
   
   Reviewed By: huntie
   
   Differential Revision: D53124578

   

   robhogan authored and facebook-github-bot committed Jan 27, 2024
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