Test-Driven Development

Use the repository's existing test tooling and conventions.

One test, one behaviour, one reason to fail. A test name describes that one behaviour; never use joiners such as "and", "or", or "etc." to combine independent outcomes. Multiple assertions are acceptable only when together they establish that same behaviour.

Red

• Select one observable behaviour from the requirement.
• Write one test before changing implementation code.
• Run the test and confirm it fails because the behaviour is missing, not because the test is broken.

Green