14-TEST-unit-test

To write unit tests for pure functions using Vitest, target high-ROI code with real logic. Focus on complex transforms and state machines, and avoid testing thin wrappers to ensure your test suite remains efficient and valuable.

The best way to scope unit tests for code changed on the current branch is to restrict test generation to modified files. This prevents unnecessary work by ensuring you only write tests for the specific code segments altered in your current development cycle.

You need to use mocking patterns in test automation when testing hooks and pure functions with external dependencies. Effective mocking isolates the code under test, ensuring your unit tests remain atomic and follow DRY principles for reusable fixtures.

Vitest works well for regression testing of new data transformation functions by allowing you to quickly identify and write targeted unit tests. This ensures the accuracy of complex logic and prevents future regressions in your codebase.

You should avoid writing unit tests for thin wrapper functions because they offer low ROI and do not contain real logic. Prioritizing tests based on risk ensures your unit tests focus on complex transforms and state machines where failures are more likely.