Add code coverage reporting

Assisted-by: Cursor

Author: twaugh

.github/workflows/ci.yml

@@ -25,22 +25,48 @@ jobs:
           diffutils \
           xmlto \
           libpcre2-dev \
-          gnulib
+          gnulib \
+          lcov
 
     - name: Bootstrap
       run: ./bootstrap
 
     - name: Configure
       run: |
         ./configure \
-          --with-pcre2
+          --with-pcre2 \
+          CFLAGS="--coverage -g -O0" \
+          LDFLAGS="--coverage"
 
     - name: Build
       run: make -j$(nproc)
 
     - name: Run tests
       run: make check
 
+    - name: Generate coverage report
+      run: |
+        # Create coverage directory
+        mkdir -p coverage
+
+        # Capture coverage data with geninfo options to handle warnings
+        lcov --capture --directory . --output-file coverage/coverage.info --rc geninfo_unexecuted_blocks=1
+
+        # Remove coverage data for system headers, lib files, and test files
+        lcov --remove coverage/coverage.info '/usr/*' '*/lib/*' '*/tests/*' --output-file coverage/coverage_filtered.info
+
+        # Generate HTML report
+        genhtml coverage/coverage_filtered.info --output-directory coverage/html
+
+        # Generate summary for CI
+        lcov --summary coverage/coverage_filtered.info
+
+    - name: Upload coverage reports
+      uses: actions/upload-artifact@v4
+      with:
+        name: coverage-report
+        path: coverage/
+
     - name: Show test results on failure
       if: failure()
       run: |