Test PRs for unit test coverage regression

.github/workflows/test_coverage_regression.yml

@@ -0,0 +1,203 @@
+name: Test for unit test coverage regression
+
+on:
+  pull_request:
+    branches: [ dev ]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pull-requests: write
+
+concurrency:
+  group: pr-coverage-${{ github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  coverage:
+    runs-on: ubuntu-24.04
+
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Install build dependencies
+        run: |
+          sudo ./INCHI-1-TEST/install_build_dependencies.sh
+
+      - name: Generate coverage report
+        uses: ./.github/actions/generate_coverage_report
+
+      - name: Test for unit test regression
+        run: |
+          set -euo pipefail
+          cd CMake_build/coverage_build
+
+          BASE_SUMMARY_URL="https://iupac-inchi.github.io/InChI/coverage/summary.txt"
+          BASE_SUMMARY_FILE="$(mktemp)"
+          PR_SUMMARY_FILE="coverage_reports/summary.txt"
+          COVERAGE_REPORT_MD="coverage_reports/coverage_report.md"
+
+          mkdir -p coverage_reports
+          trap 'rm -f "$BASE_SUMMARY_FILE"' EXIT
+
+          extract_pct() {
+            local metric="$1"
+            local file="$2"
+
+            awk -v metric="$metric" '
+              $0 ~ "^[[:space:]]*" metric "\\.*:" {
+                if (match($0, /[0-9]+([.][0-9]+)?%/)) {
+                  value = substr($0, RSTART, RLENGTH - 1)
+                  print value
+                }
+                exit
+              }
+            ' "$file"
+          }
+
+          parse_metrics() {
+            local prefix="$1"
+            local file="$2"
+            local parse_error="$3"
+            local lines branches
+
+            lines="$(extract_pct lines "$file")"
+            branches="$(extract_pct branches "$file")"
+
+            if [[ -n "$lines" && -n "$branches" ]]; then
+              printf -v "${prefix}_LINES" '%s' "$lines"
+              printf -v "${prefix}_BRANCHES" '%s' "$branches"
+              printf -v "${prefix}_AVAILABLE" 'true'
+            else
+              PROBLEMS+=("$parse_error")
+            fi
+          }
+
+          pct_diff() { awk -v pr="$1" -v base="$2" 'BEGIN {printf "%+.2f", pr-base}'; }
+          is_lt() { awk -v pr="$1" -v base="$2" 'BEGIN {exit !(pr < base)}'; }
+
+          PROBLEMS=()
+          PR_AVAILABLE=false
+          BASE_AVAILABLE=false
+          PR_LINES=""
+          PR_BRANCHES=""
+          BASE_LINES=""
+          BASE_BRANCHES=""
+
+          if lcov --summary coverage.lcov --branch-coverage --ignore-errors inconsistent > "$PR_SUMMARY_FILE"; then
+            parse_metrics PR "$PR_SUMMARY_FILE" "Unable to parse PR coverage metrics from $PR_SUMMARY_FILE"
+          else
+            PROBLEMS+=("Unable to generate PR coverage summary from coverage.lcov")
+          fi
+
+          if curl -fsSL --max-time 10 "$BASE_SUMMARY_URL" -o "$BASE_SUMMARY_FILE"; then
+            parse_metrics BASE "$BASE_SUMMARY_FILE" "Base summary fetched, but required metrics were incomplete"
+          else
+            PROBLEMS+=("Base summary fetch failed from $BASE_SUMMARY_URL")
+          fi
+
+          PR_LINES_DISPLAY="${PR_LINES:-N/A}"
+          PR_BRANCHES_DISPLAY="${PR_BRANCHES:-N/A}"
+          BASE_LINES_DISPLAY="${BASE_LINES:-N/A}"
+          BASE_BRANCHES_DISPLAY="${BASE_BRANCHES:-N/A}"
+          DIFF_LINES="N/A"
+          DIFF_BRANCHES="N/A"
+
+          if [[ "$PR_AVAILABLE" == true && "$BASE_AVAILABLE" == true ]]; then
+            DIFF_LINES="$(pct_diff "$PR_LINES" "$BASE_LINES")"
+            DIFF_BRANCHES="$(pct_diff "$PR_BRANCHES" "$BASE_BRANCHES")"
+          fi
+
+          {
+            echo "### Coverage Regression Summary"
+            echo
+            echo "| Metric | PR (%) | Base (%) | Difference (pp) |"
+            echo "| --- | ---: | ---: | ---: |"
+            echo "| Lines | ${PR_LINES_DISPLAY} | ${BASE_LINES_DISPLAY} | ${DIFF_LINES} |"
+            echo "| Branches | ${PR_BRANCHES_DISPLAY} | ${BASE_BRANCHES_DISPLAY} | ${DIFF_BRANCHES} |"
+            if [[ ${#PROBLEMS[@]} -gt 0 ]]; then
+              echo
+              echo "### Problems"
+              echo
+              printf -- "- %s\n" "${PROBLEMS[@]}"
+            fi
+            echo
+            echo "Find details on the base coverage at https://iupac-inchi.github.io/InChI/coverage/index.html"
+          } > "$COVERAGE_REPORT_MD"
+
+          if [[ "$PR_AVAILABLE" == false || "$BASE_AVAILABLE" == false ]]; then
+            echo "Coverage regression check skipped due to missing PR or base metrics."
+            exit 0
+          fi
+
+          FAIL=false
+          if is_lt "$PR_LINES" "$BASE_LINES"; then
+            echo "Line coverage regression: ${PR_LINES}% < base ${BASE_LINES}%"
+            FAIL=true
+          fi
+          if is_lt "$PR_BRANCHES" "$BASE_BRANCHES"; then
+            echo "Branch coverage regression: ${PR_BRANCHES}% < base ${BASE_BRANCHES}%"
+            FAIL=true
+          fi
+          if [[ "$FAIL" == true ]]; then
+            exit 1
+          fi
+
+          echo "Coverage OK: lines ${PR_LINES}% >= base ${BASE_LINES}%, branches ${PR_BRANCHES}% >= base ${BASE_BRANCHES}%"
+
+      - name: Upload coverage reports
+        uses: actions/upload-artifact@v7
+        if: always()
+        with:
+          name: coverage-reports-${{ github.run_id }}
+          path: CMake_build/coverage_build/coverage_reports/
+          retention-days: 30
+
+      - name: Post sticky PR comment (same-repo only)
+        if: always() && github.event.pull_request.head.repo.full_name == github.repository
+        uses: actions/github-script@v9
+        with:
+          script: |
+            const fs = require('fs');
+            const report = fs.readFileSync('CMake_build/coverage_build/coverage_reports/coverage_report.md', 'utf8');
+
+            // Build artifact link
+            const runId = context.runId;
+            const runUrl = `${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions/runs/${runId}`;
+            const artifactLink = `Find details on this PR's coverage by downloading [coverage-reports-${runId}](${runUrl}) and opening **html/index.html**`;
+
+            const body = `## Unit Test Coverage Report\n\n${report}\n\n${artifactLink}`;
+            const identifier = '<!-- InChI Unit Test Coverage Report -->';
+            const bodyWithId = `${identifier}\n${body}`;
+
+            // Search for existing comment with the identifier
+            const comments = await github.paginate(github.rest.issues.listComments, {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              per_page: 100,
+            });
+
+            const existingComment = comments.find(comment =>
+              comment.body.includes(identifier)
+            );
+
+            if (existingComment) {
+              // Update existing comment
+              await github.rest.issues.updateComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                comment_id: existingComment.id,
+                body: bodyWithId,
+              });
+              console.log('Updated existing comment:', existingComment.id);
+            } else {
+              // Create new comment
+              await github.rest.issues.createComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: context.issue.number,
+                body: bodyWithId,
+              });
+              console.log('Created new comment');
+            }

README.md

@@ -90,7 +90,7 @@ Please write your comments in the header files where possible.
 The Doxygen documentation syntax is quite powerful: you can include formulas, tables, and diagrams.
 For details see <https://www.doxygen.nl/manual>.
 
-The documentation is [built on every push](.github/workflows/deploy_docs.yml) to the default branch of this repository and hosted at <https://iupac-inchi.github.io/InChI/>.
+The documentation is [built on every push](.github/workflows/deploy_pages.yml) to the default branch of this repository and hosted at <https://iupac-inchi.github.io/InChI/docs/index.html>.
 That is, your comments will automatically be rendered to HTML and served as online documentation.
 
 ## Code quality
@@ -103,6 +103,10 @@ InChI is integrated into [Coverity Scan](https://scan.coverity.com/projects/inch
 
 InChI is integrated into [Google OSS-Fuzz](https://github.com/google/oss-fuzz/tree/master/projects/inchi), which runs continuous fuzz testing against the library. Fuzzing-related bugs are tracked at the [OSS-Fuzz issue tracker](https://bugs.chromium.org/p/oss-fuzz/issues/list?q=inchi).
 
+### Code coverage
+
+The unit test coverage is [evaluated on every push](.github/workflows/deploy_pages.yml) to the default branch of this repository and hosted at <https://iupac-inchi.github.io/InChI/coverage/index.html>. Every PR against the default branch is [tested for unit test coverage regressions](.github/workflows/test_coverage_regression.yml).
+
 ## Contents of this repository
 
 ### INCHI-1-DOC