unity-tdd
Unity Test-Driven Development
TDD is the red → green loop. This skill is the reference that makes that loop produce tests worth keeping: what a good test is, where tests go, the anti-patterns, and the rules of the loop. Every section applies on every cycle — consult them before and during the loop, not after.
When exploring the codebase, read CONTEXT.md (if it exists) so test names and interface vocabulary match the project's domain language, and respect ADRs in the area you're touching.
What a good test is
Tests verify behavior through public interfaces, not implementation details. Code can change entirely; tests shouldn't. A good test reads like a specification — "player cannot spend more mana than is available" tells you exactly what capability exists — and survives refactors because it doesn't care about internal structure.
See tests.md for EditMode and PlayMode examples. Read mocking.md before the code under test depends on an engine static (Time, Input, PlayerPrefs, SceneManager), a backend client, or file IO — it covers where the seam goes and how to fake it.
Seams — where tests go
A seam is the public boundary you test at: the interface where you observe behavior without reaching inside. Tests live at seams, never against internals.