Test Coverage

Analyze test coverage and generate missing tests using gcov/lcov:

1. Build with coverage instrumentation:

   cmake -B build-cov -DCMAKE_BUILD_TYPE=Debug \
     -DCMAKE_CXX_FLAGS="--coverage -fprofile-arcs -ftest-coverage"
   cmake --build build-cov
   

2. Run all tests:

   ctest --test-dir build-cov --output-on-failure
   

3. Generate coverage report:

   lcov --capture --directory build-cov --output-file coverage.info
   lcov --remove coverage.info '/usr/*' '*/test/*' '*/build/*' --output-file coverage.info
   genhtml coverage.info --output-directory coverage_report
   lcov --summary coverage.info
   

4. Identify files below 80% coverage threshold

5. For each under-covered file:

   • Analyze untested code paths (uncovered lines in lcov report)
   • Generate unit tests for uncovered functions
   • Generate integration tests for uncovered error paths
   • Add edge case tests (empty input, overflow, boundary values)

6. Verify new tests pass:

   cmake --build build-cov && ctest --test-dir build-cov --output-on-failure
   

7. Re-run coverage and show before/after metrics

8. Ensure project reaches 80%+ overall coverage

Focus on:

• Untested branches (if/else paths)
• Error handling paths (catch blocks, error returns)
• Edge cases (empty containers, zero values, max values)
• Boundary conditions (off-by-one, overflow)
• Template instantiations with different types