mutation-testinglisted

# Mutation Testing Verify that tests **actually catch bugs** — not just execute code. ## Core Rule A test that kills no mutant is noise. DELETE IT. ## When to Load - Entering phase 4 (COMMIT & VERIFY) of the TDD cycle. - Investigating a surviving mutant. - Confirming a kill after writing a boundary test. **Never run on a red baseline** — fix tests first. ## S7 — Deterministic Execution (Non-Negotiable) Mutation testing MUST be executed via terminal tool calls. Do NOT assert results from prose. The flow is: ``` 1. runInTerminal → dotnet stryker (with correct args) 2. Parse JSON output → extract survivors 3. Decide: kill (write test) or document (equivalent mutant) 4. Re-run scoped stryker → confirm kill ``` ## Step 1: Run Stryker (via terminal) ### Detect project paths first Before running, identify: - `--project` : the production `.csproj` being mutated (Domain or Application) - `-tp` : the test `.csproj` that exercises it ### During development (fast — changed code only) ```bash dotnet stryker \ --project <Production.csproj> \ -tp <Tests.csproj> \ --since:main \ --break-at 100 \ --reporter json --reporter cleartext ``` ### Before merge (full business logic) ```bash dotnet stryker \ --project <Production.csproj> \ -tp <Tests.csproj> \ --mutate "**/*.cs" \ --mutate "!**/*Marker.cs" \ --mutate "!**/DependencyInjection.cs" \ --mutate "!**/obj/**" \ --break-at 100 \ --threshold-high 90 --threshold-low 80 \ --reporter json --reporter cle