Coverage Gaps

Coverage % is a vanity metric. Hunt the gaps that bite:

• Error paths — the 500, the timeout, the empty/null input, the malformed payload. Almost always untested.
• Boundaries — 0, 1, max, off-by-one, empty collection.
• Branches — every if/else and catch exercised, not just the happy line.
• Concurrency / order — anything stateful tested in isolation AND in sequence.

Skip tests that assert a constructor sets a property — worthless. Test behavior, not implementation. Output: the 3-5 highest-risk untested paths, ranked by blast radius, with the test to add.