test: add backend tests for various controllers and services

.gitea/workflows/ci.yml

@@ -78,6 +78,32 @@ jobs:
         working-directory: ./backend
         run: gradle --stop
 
+  backend-test:
+    runs-on: ubuntu-latest
+    name: "Backend Tests"
+    needs: changed_files
+    if: ${{ needs.changed_files.outputs.backend == 'true' || needs.changed_files.outputs.workflow == 'true' }}
+    container:
+      image: "cimg/openjdk:23.0-node"
+    steps:
+      - name: "Checkout"
+        uses: actions/checkout@v4
+      - name: "Cache Gradle dependencies"
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: gradle-${{ runner.os }}-${{ hashFiles('backend/**/*.java', 'backend/build.gradle.kts', 'backend/settings.gradle.kts') }}
+          restore-keys: |
+            gradle-${{ runner.os }}-
+      - name: "Run backend tests"
+        working-directory: ./backend
+        run: ./gradlew test
+      - name: "Stop Gradle"
+        working-directory: ./backend
+        run: ./gradlew --stop
+
   validate-docker-frontend:
     runs-on: ubuntu-latest
     name: Docker frontend validation