exp-test-gap-analysis

# Test Gap Analysis via Pseudo-Mutation Analyze .NET production code by reasoning about hypothetical mutations and checking whether existing tests would catch them. This reveals blind spots where tests pass but would continue to pass even if the code were broken. ## Why Pseudo-Mutation Matters Code coverage tells you what code ran during tests. It does **not** tell you whether tests would fail if that code were wrong. A method can have 100% line coverage but zero tests that would catch a sign flip, an off-by-one error, or a removed null check. Pseudo-mutation analysis asks: _"If I changed this line, would any test fail?"_ When the answer is "no," you've found a test gap. | Coverage Metric | What It Measures | What It Misses | |----------------|-----------------|----------------| | Line coverage | Which lines executed | Whether assertions verify those lines' behavior | | Branch coverage | Which branches taken | Whether both branches produce different asserted outcomes | | **Mutation score** | Whether tests detect code changes | Nothing — this is the gold standard | This skill performs **static pseudo-mutation** — reasoning about mutations without actually running them — to approximate mutation testing at the speed of code review. ## When to Use - User asks "would my tests catch a bug in this code?" - User wants to find weak or shallow tests - User wants to evaluate test effectiveness beyond coverage - User asks for mutation testing or mutation analysis - User asks "whe...