fix(webpack-batteries-included-preprocessor): Disable loading babel config files

[chrisbreiding]

• Closes Webpack Compilation Error: Cannot find module - Babel dependency when .babelrc defines plugins #8364

User facing changelog

• Spec files now properly compile when there is a .babelrc or babel.config.json present in the project

Additional details

This disables loading .babelrc and babel.config.json in the default preprocessor. Since the default preprocessor can't anticipate per-user config, it's best for it to use its own config alone. Users that need custom configuration can utilize the preprocessor plugin API.

How has the user experience changed?

Preprocessing no longer fails when a project has a .babelrc or babel.config.json present. Users no longer need to add an empty .babelrc to the cypress directory as a workaround.

PR Tasks

• Have tests been added/updated? No tests were directly added or updated, but by adding .babelrc and babel.config.json files to the project, most of the tests will fail without the fix.
• Has the original issue or this PR been tagged with a release in ZenHub?
• N/A Has a PR for user-facing changes been opened in cypress-documentation?
• N/A Have API changes been updated in the type definitions?
• N/A Have new configuration options been added to the cypress.schema.json?

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[cypress]

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Test summary

8158 • 0 • 103 • 3 • 0

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Run details

Project	cypress
Status	Passed
Commit	6aedc5b
Started	Jun 17, 2021 2:07 PM
Ended	Jun 17, 2021 2:18 PM
Duration	10:42 💡
OS	Linux Debian - 10.8
Browser	Multiple

View run in Cypress Dashboard ➡️

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[flotwig]

So this is blocking an unintended way that users were accidentally modifying the babel config, correct? Do users not want their babel config to apply to the webpack preprocessor?

From what I can see, the cause of #8364 is that webpack-batteries-included-preprocessor is resolving modules defined in .babelrc from the server's working directory, instead of from the user's project root. Would it also fix #8364 to somehow correct the module resolution for things configured in .babelrc?

I'm probably not totally understanding this, since I've not worked in webpack-batteries-included-preprocessor, so lmk if I'm missing something.

[chrisbreiding]

The intention of this package is to provide the webpack configuration (the included batteries) and not need the user to configure it. While it's possible to customize the configuration when using this package directly, that isn't be needed in most circumstances and isn't particularly advocated. If a user needs custom configuration, we recommend they use the base webpack-preprocessor.

This package is what Cypress uses as the default preprocessor, and based on the reproductions in the issue, that's how users are running into this issue. They aren't using this package directly or trying to configure it. It's an unintentional side effect of babel loading these config files. The solution that seems to be accepted by a lot of users is to put an empty .babelrc in their cypress directory, which is essentially the same as not loading it at all.

While we could fix the issue with module resolution, I still think we would want to turn off loading babel config files in this package by default. Especially in its use as the default preprocessor, it could cause problems to load babel plugins on top of the ones we already have configured. Also, it's likely not the intention or expectation of the user to have their source code babel config loaded for their Cypress tests.

[flotwig]

Alright, that makes sense, thank you for clarifying