Old Angular project with Claude Code

This is a common friction point with Angular projects: Claude Code will run Jest instead of Karma even if you have karma.conf.js. Why? Because most of the training data and community content from recent years skews heavily toward Jest (or Vitest) as the replacement.

So Claude Code's "prior" is that a modern JS/TS project uses Jest. Outside Angular <17, virtually nobody uses Karma anymore. Claude Code doesn't have deep framework-specific heuristics — it pattern-matches across all JS/TS projects, and Jest dominates that distribution overwhelmingly.

What we can do to steer it: in your project/CLAUDE.md file, write something like:

This project uses Karma + Jasmine for unit tests. Run tests with ng test or npx karma start. Do not use Jest.

Happy coding!