Drupal Testing (TDD)

Hard-won testing discipline for Drupal. Pairs with the test-writer and test-runner agents — this skill is the how, those agents are the who.

Bug-fix TDD — the RED step is non-negotiable

Every bug fix follows this exact sequence. Skipping step 2 is what makes "fixed" bugs come back.

1. Write a test that reproduces the bug — exercise the real code path the user hits, not a paraphrase of the suspected logic.
2. Run it and assert it FAILS, with the symptom matching the report. If it doesn't fail, you haven't reproduced the bug — keep digging until it fails for the right reason. The red-to-green transition is your only proof the test actually exercises the bug; without it, you can't tell whether the test catches the bug or just happens to pass on green.
3. Fix the production code.
4. Re-run the same test and assert it now passes.

Pick the lightest bootstrap that fits — it dominates cost

Drupal test base classes differ in bootstrap cost by orders of magnitude. Default to the cheapest one that can express the assertion.