Test-Driven Development

The Core Rule

IF YOU DIDN'T WATCH THE TEST FAIL, YOU DON'T KNOW IF IT TESTS THE RIGHT THING.

A green test you've never seen red is not a test — it's a decoration.

The Three Phases (Non-Negotiable)

Phase RED — Write a Failing Test

Write the test FIRST. Not after. Not "I'll add it later." First.