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.

What's worth a test (read FIRST)

Before writing ANY test, decide whether it earns its place. A test is worth committing ONLY if BOTH hold:

1. A future change could PLAUSIBLY and SILENTLY break it. (Not "could someone theoretically delete this" — a realistic code path that a normal edit could regress without noticing.)
2. The breakage MATTERS: user-facing behavior, data integrity, money, security, or an API/client contract.

If either fails, the test is pure cost with no protection — skip it. A committed assertion you have to maintain forever, that guards against a regression that can't realistically happen, is maintenance drag, not a safety net.

Bug fixes are still mandatory TDD (see the next section). The rubric here governs new coverage you choose to add, not the bug-fix discipline.