Enhance code-check step in GitHub Actions

Author: kappsegla

.github/workflows/classroom.yml

@@ -28,6 +28,8 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
 
       - name: Read assignment instructions
         id: instructions
@@ -180,19 +182,23 @@ jobs:
           java-version: '25'
 
       - name: Check for modified files and test presence
-        id: code-check
-        run: |
-          # Check for test files
-          has_tests=$(find src/test/java -type f -name "*.java" | grep -q . && echo "true" || echo "false")
-
-          # Check for modified files in src folders
-          git fetch origin main
-          changed_files=$(git diff --name-only origin/main...HEAD | grep -E '^src/(main|test)/java/.*\.java$' || true)
-          has_changes=$(test -n "$changed_files" && echo "true" || echo "false")
-
-          echo "has_tests=$has_tests" >> $GITHUB_OUTPUT
-          echo "has_changes=$has_changes" >> $GITHUB_OUTPUT
-           echo "should_grade=$([[ $has_tests == 'true' && $has_changes == 'true' ]] && echo 'true' || echo 'false')" >> $GITHUB_OUTPUT
+  id: code-check
+  run: |
+    # Ensure full history
+    git fetch origin main
+    git checkout ${{ github.ref_name }}
+    git branch --set-upstream-to=origin/main ${{ github.ref_name }}
+
+    # Check for test files
+    has_tests=$(find src/test/java -type f -name "*.java" | grep -q . && echo "true" || echo "false")
+
+    # Check for modified files
+    changed_files=$(git diff --name-only origin/main...HEAD | grep -E '^src/(main|test)/java/.*\.java$' || true)
+    has_changes=$(test -n "$changed_files" && echo "true" || echo "false")
+
+    echo "has_tests=$has_tests" >> $GITHUB_OUTPUT
+    echo "has_changes=$has_changes" >> $GITHUB_OUTPUT
+    echo "should_grade=$([[ $has_tests == 'true' && $has_changes == 'true' ]] && echo 'true' || echo 'false')" >> $GITHUB_OUTPUT
 
       - name: Compilation Check
         id: compilation-check