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skills/python-test-strategy/reference/coverage.md

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+# Code Coverage Configuration
+
+## Goals
+
+- **Target**: 95%+ coverage for all implementation files
+- Prevents untested code paths
+- Detects breaking changes early
+
+## Configuration File
+
+`.coveragerc` at project root controls coverage:
+
+```ini
+[report]
+exclude_lines =
+    pragma: no cover
+    if __name__ == .__main__.:
+    raise NotImplementedError
+
+omit =
+    */tests/*
+    */venv/*
+```
+
+## Running Coverage
+
+```bash
+# Individual module with coverage report
+.venv/bin/python tests/subpackage/test_module.py
+
+# Entire package
+.venv/bin/python tests/subpackage/all.py
+
+# All tests
+.venv/bin/python tests/all.py
+```
+
+Output: HTML report in `htmlcov/` showing covered/uncovered lines.
+
+## Marking Code as Non-Testable
+
+Use `# pragma: no cover` for untestable code:
+
+```python
+if sys.platform == "win32":  # pragma: no cover
+    return "windows"
+```
+
+Use for:
+- Platform-specific code
+- Emergency fallbacks
+- Code that shouldn't occur in normal operation
+
+Don't use for regular logic or error handling.