fix: unused identifiers should retain names when using css modules

[burhanuday]

Summary

🤖 Generated by Copilot at a9cbd06

This pull request adds and updates some test cases and files related to CSS modules, which are a feature of webpack that allows importing and exporting CSS selectors as JavaScript modules. The changes test the CSS module functionality, the generation of CSS class names, and the output of CSS files. The changes also fix some syntax and compatibility issues in the existing test files.

Details

🤖 Generated by Copilot at a9cbd06

• Add a condition to serialize method of CssLocalIdentifierDependency class to skip unused dependencies (link)
• Create a new CSS module file identifiers.module.css with two selectors: .UnusedClassName and .UsedClassName (link)
• Import and use the .UsedClassName selector in use-style.js entry point and export its CSS class name (link, link)

• Add a new property UsedClassName to the expected object with the correct CSS class name depending on the production mode (link)
• Read the CSS output file and check its content using __non_webpack_require__, cssOutputFilename, expect, and toMatchSnapshot (link)

• Add a custom configuration file test.config.js to specify the paths and names of the two bundle files for the test case (link)
• Disable mocking of __dirname and __filename in webpack.config.js to make __non_webpack_require__ work correctly (link, link)

[webpack-bot]

For maintainers only:

• This needs to be documented (issue in webpack/webpack.js.org will be filed when merged)
• This needs to be backported to webpack 4 (issue will be created when merged)

[TheLarkInn]

Fantastic work!