fix(ci): collect correct changed lines coverage

Signed-off-by: imeoer <yansong.ys@antgroup.com>

Author: imeoer

.github/workflows/coverage-comment.yml

@@ -26,22 +26,41 @@ jobs:
        github.event.workflow_run.conclusion == 'failure')
     steps:
       - name: Download coverage artifacts
+        id: download
+        continue-on-error: true
         uses: actions/download-artifact@v4
         with:
           name: coverage-report
+          path: coverage-artifact
           github-token: ${{ secrets.GITHUB_TOKEN }}
           # Download from the triggering workflow run, not the current one.
           run-id: ${{ github.event.workflow_run.id }}
 
       - name: Read PR number
         id: pr
         run: |
-          if [ -f pr-number.txt ]; then
-            echo "number=$(cat pr-number.txt)" >> "$GITHUB_OUTPUT"
+          if [ -f coverage-artifact/pr-number.txt ]; then
+            echo "number=$(cat coverage-artifact/pr-number.txt)" >> "$GITHUB_OUTPUT"
+          elif [ -n "${{ github.event.workflow_run.pull_requests[0].number }}" ]; then
+            echo "number=${{ github.event.workflow_run.pull_requests[0].number }}" >> "$GITHUB_OUTPUT"
           else
             echo "number=" >> "$GITHUB_OUTPUT"
           fi
 
+      - name: Prepare coverage comment body
+        run: |
+          if [ -f coverage-artifact/coverage-report.md ]; then
+            cp coverage-artifact/coverage-report.md coverage-report.md
+          else
+            cat > coverage-report.md <<EOF
+## 📊 Code Coverage Report
+
+Coverage workflow concluded with **${{ github.event.workflow_run.conclusion }}**, but no coverage report artifact was available.
+
+Triggering workflow run: ${{ github.event.workflow_run.html_url }}
+EOF
+          fi
+
       - name: Post coverage comment on PR
         if: steps.pr.outputs.number != ''
         uses: marocchino/sticky-pull-request-comment@v2

.github/workflows/coverage.yml

@@ -84,74 +84,118 @@ jobs:
           BASE=origin/${{ github.base_ref }}
           DIFF_OUTPUT=$(diff-cover coverage.xml \
             --compare-branch="${BASE}" \
+            --format json:diff-cover.json \
             --fail-under=${{ env.THRESHOLD_DIFF }} \
             2>&1) && DIFF_EXIT=0 || DIFF_EXIT=$?
 
-          DIFF_PCT=$(echo "$DIFF_OUTPUT" | grep -oP 'Diff coverage is \K[0-9.]+' || echo "N/A")
+          if [ -f diff-cover.json ]; then
+            DIFF_PCT=$(python3 - <<'PY'
+import json
+
+with open('diff-cover.json', encoding='utf-8') as f:
+    report = json.load(f)
+
+num_changed_lines = report.get('num_changed_lines', 0)
+total_num_lines = report.get('total_num_lines', 0)
+total_percent_covered = report.get('total_percent_covered', 'N/A')
+
+if num_changed_lines > 0 and total_num_lines == 0:
+    print('N/A')
+else:
+    print(total_percent_covered)
+PY
+)
+          else
+            DIFF_PCT="N/A"
+          fi
+
+          if [ "$DIFF_PCT" = "N/A" ]; then
+            DIFF_DISPLAY="N/A"
+          else
+            DIFF_DISPLAY="${DIFF_PCT}%"
+          fi
+
           echo "diff_pct=${DIFF_PCT}" >> "$GITHUB_OUTPUT"
+          echo "diff_display=${DIFF_DISPLAY}" >> "$GITHUB_OUTPUT"
           echo "$DIFF_OUTPUT"
 
-          if [ "$DIFF_EXIT" -ne 0 ]; then
+          if [ "$DIFF_EXIT" -ne 0 ] || [ "$DIFF_PCT" = "N/A" ]; then
             echo "diff_status=fail" >> "$GITHUB_OUTPUT"
+
+            if [ "$DIFF_PCT" = "N/A" ]; then
+              echo "❌ Changed-line coverage could not be computed because diff-cover found changed lines without matching coverage information."
+            fi
           else
             echo "diff_status=pass" >> "$GITHUB_OUTPUT"
           fi
 
       # ── Generate per-package coverage table ──────────────────────────────
       - name: Generate coverage report markdown
+        if: always()
         run: |
           {
             echo "## 📊 Code Coverage Report"
             echo ""
 
             TOTAL="${{ steps.total_coverage.outputs.total }}"
             STATUS="${{ steps.total_coverage.outputs.status }}"
+            [ -n "$TOTAL" ] || TOTAL="N/A"
             [ "$STATUS" = "pass" ] && ICON="✅" || ICON="❌"
 
             echo "| Metric | Coverage | Threshold | Status |"
             echo "|--------|----------|-----------|--------|"
             echo "| Overall | **${TOTAL}%** | ${{ env.THRESHOLD_TOTAL }}% | ${ICON} |"
 
             if [ "${{ github.event_name }}" = "pull_request" ]; then
-              DIFF_PCT="${{ steps.diff_coverage.outputs.diff_pct }}"
+              DIFF_DISPLAY="${{ steps.diff_coverage.outputs.diff_display }}"
               DIFF_STATUS="${{ steps.diff_coverage.outputs.diff_status }}"
+              [ -n "$DIFF_DISPLAY" ] || DIFF_DISPLAY="N/A"
               [ "$DIFF_STATUS" = "pass" ] && DIFF_ICON="✅" || DIFF_ICON="❌"
-              echo "| Changed lines | **${DIFF_PCT}%** | ${{ env.THRESHOLD_DIFF }}% | ${DIFF_ICON} |"
+              echo "| Changed lines | **${DIFF_DISPLAY}** | ${{ env.THRESHOLD_DIFF }}% | ${DIFF_ICON} |"
             fi
 
-            echo ""
-            echo "<details>"
-            echo "<summary>📦 Per-package breakdown</summary>"
-            echo ""
-            echo '```'
-            go tool cover -func=coverage.out | grep -v "^total:" | \
-              awk '{printf "%-80s %s\n", $1, $3}' | sort
-            echo ""
-            go tool cover -func=coverage.out | grep "^total:"
-            echo '```'
-            echo ""
-            echo "</details>"
+            if [ -f coverage.out ]; then
+              echo ""
+              echo "<details>"
+              echo "<summary>📦 Per-package breakdown</summary>"
+              echo ""
+              echo '```'
+              go tool cover -func=coverage.out | grep -v "^total:" | \
+                awk '{printf "%-80s %s\n", $1, $3}' | sort
+              echo ""
+              go tool cover -func=coverage.out | grep "^total:"
+              echo '```'
+              echo ""
+              echo "</details>"
+            else
+              echo ""
+              echo "Coverage artifacts were not generated because the workflow failed before coverage collection completed."
+            fi
           } > coverage-report.md
 
       # ── Write step summary ────────────────────────────────────────────────
       - name: Write job summary
+        if: always()
         run: cat coverage-report.md >> "$GITHUB_STEP_SUMMARY"
 
       # ── Save PR number so the comment workflow can find the right PR ──────
       - name: Save PR number
-        if: github.event_name == 'pull_request'
+        if: always() && github.event_name == 'pull_request'
         run: echo "${{ github.event.pull_request.number }}" > pr-number.txt
 
       # ── Upload artifacts (report + pr-number for comment workflow) ────────
       - name: Upload coverage artifacts
+        if: always()
         uses: actions/upload-artifact@v4
         with:
           name: coverage-report
           path: |
             coverage.out
             coverage.xml
+            diff-cover.json
             coverage-report.md
             pr-number.txt
+          if-no-files-found: warn
           retention-days: 14
 
       - name: Upload coverage to Codecov
@@ -176,6 +220,6 @@ jobs:
           github.event_name == 'pull_request' &&
           steps.diff_coverage.outputs.diff_status == 'fail'
         run: |
-          echo "❌ Changed-line coverage ${{ steps.diff_coverage.outputs.diff_pct }}% is below the required ${{ env.THRESHOLD_DIFF }}%"
+          echo "❌ Changed-line coverage ${{ steps.diff_coverage.outputs.diff_display }} is below the required ${{ env.THRESHOLD_DIFF }}%"
           exit 1