build: Code Coverage for Nightly Build Workflows (#6635)

Added java coverage to the Nightly Check CI according to the following
contract:
- Coverage only runs on JVM 21
- Coverage runs on a schedule for any main repo branch
- Coverage runs On Push on any branch (including forks) that starts with
"coverage/"
- Coverage is collected from separate jobs into a combined report
uploaded as an Github artifact

.github/workflows/nightly-check-ci.yml

@@ -7,7 +7,7 @@ on:
     # 2AM EST == 6AM UTC
     - cron:  '0 6 * * *'
   push:
-    branches: [ 'nightly/**', 'release/v*', 'dependabot/**' ]
+    branches: [ 'nightly/**', 'release/v*', 'dependabot/**', 'coverage/**']
 
 jobs:
   nightly:
@@ -21,6 +21,8 @@ jobs:
     concurrency:
       group: ${{ matrix.gradle-task }}-${{ matrix.test-jvm-version }}-${{ github.workflow }}-${{ github.ref }}
       cancel-in-progress: true
+    env:
+      COVER: ${{ (github.event_name == 'schedule' || startsWith(github.ref_name, 'coverage/')) && matrix.test-jvm-version == '21' }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -66,8 +68,16 @@ jobs:
           .github/scripts/gradle-properties.sh >> gradle.properties
           cat gradle.properties
 
-      - name: Run gradle ${{ matrix.gradle-task }} on java ${{ matrix.test-jvm-version }}
-        run: ./gradlew --scan --continue --rerun-tasks ${{ matrix.gradle-task }} -PtestRuntimeVersion=${{ matrix.test-jvm-version }}
+      - name: Run gradle ${{ matrix.gradle-task }} on java ${{ matrix.test-jvm-version }} with coverage=${{ env.COVER }}
+        run: ./gradlew --scan --continue --rerun-tasks ${{ matrix.gradle-task }} -PtestRuntimeVersion=${{ matrix.test-jvm-version }} -Pcoverage.enabled=$COVER
+
+      - name: Upload Coverage Results
+        if: ${{ env.COVER == 'true' }}
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-${{ matrix.gradle-task }}-results
+          path: |
+            **/build/jacoco/*.exec
 
       - name: Upload Test Results
         uses: actions/upload-artifact@v4
@@ -111,3 +121,57 @@ jobs:
             }
         env:
           SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_NIGHTLY_FAILURE }}
+
+  combined-coverage-report:
+    if: ${{ github.event_name == 'schedule' || startsWith(github.ref_name, 'coverage/') }}
+    needs: nightly
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          lfs: true
+
+      - name: Download Coverage Results
+        uses: actions/download-artifact@v4
+        with:
+          pattern: coverage-*-results
+          merge-multiple: true
+
+      - name: Setup JDK 21
+        id: setup-java-21
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '21'
+
+      - name: Setup JDK 11
+        id: setup-java-11
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '11'
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v4
+
+      - name: Set JAVA_HOME
+        run: echo "JAVA_HOME=${{ steps.setup-java-11.outputs.path }}" >> $GITHUB_ENV
+
+      - name: Setup gradle properties
+        run: |
+          .github/scripts/gradle-properties.sh >> gradle.properties
+          cat gradle.properties
+          
+      - name: Run gradle ${{ matrix.gradle-task }}
+        run: |
+          ./gradlew -Pcoverage.enabled=true jacocoTestReport
+          ./gradlew -Pcoverage.enabled=true coverage:coverage-merge
+          
+      - name: Upload Combined Coverage Results
+        uses: actions/upload-artifact@v4
+        with:
+          name: combined-coverage-results
+          path: |
+            coverage/build/reports/jacoco/**
+            coverage/build/reports/coverage/**

coverage/gather-coverage.py

@@ -19,16 +19,17 @@
 os.makedirs(coverage_dir)
 
 # Aggregate and normalize coverage for java projects
+print("Aggregating Java Coverage")
 input_glob = proj_root_dir + '/build/reports/jacoco/jacoco-merge/jacoco-merge.csv'
 with open(f'{coverage_dir}/java-coverage.csv', 'w', newline='') as outfile:
     csv_writer = csv.writer(outfile)
-    csv_writer.writerow(['Language','Project','Package','Class','Missed','Covered'])
+    csv_writer.writerow(['Language','Package','Class','Missed','Covered'])
     for filename in glob.glob(input_glob, recursive = True):
         with open(filename, 'r') as csv_in:
             csv_reader = csv.reader(csv_in)
             next(csv_reader, None)
             for row in csv_reader:
-                new_row = ['java',row[0],row[1],row[2],row[3],row[4]]
+                new_row = ['java',row[1],row[2],row[3],row[4]]
                 csv_writer.writerow(new_row)
 
 # Load packages to be excluded from the aggregated coverage CSV
@@ -39,8 +40,10 @@
 with open(coverage_output_path, 'w', newline='') as outfile:
     csv_writer = csv.writer(outfile)
     for csv_file in glob.glob(coverage_input_glob):
+        if os.path.basename(csv_file) == "all-coverage.csv": continue
+        print('Merging', os.path.basename(csv_file))
         with open(csv_file, 'r') as csv_in:
             for row in csv.reader(csv_in):
-                if row[2] in excludes: continue
-                new_row = [row[0],row[1],row[2],row[3],row[4],row[5]]
+                if row[1] in excludes: continue
+                new_row = [row[0],row[1],row[2],row[3],row[4]]
                 csv_writer.writerow(new_row)