# Testing

- Prefer dependency injection over module mocking; define contracts in `common/src/types/contracts/`.
- Use `spyOn()` only for globals / legacy seams.
- Avoid `mock.module()` for functions; use `@codebuff/common/testing/mock-modules.ts` helpers for constants only.

CLI hook testing note: React 19 + Bun + RTL `renderHook()` is unreliable; prefer integration tests via components for hook behavior.

## CLI tmux Testing

For testing CLI behavior via tmux, use the helper scripts in `scripts/tmux/`. These handle bracketed paste mode and session logging automatically. Session data is saved to `debug/tmux-sessions/` in YAML format and can be viewed with `bun scripts/tmux/tmux-viewer/index.tsx`. See `scripts/tmux/README.md` for details.