run tests in CI

.github/workflows/ci.yml

@@ -1,4 +1,4 @@
-name: Build
+name: CI
 
 on:
   push:
@@ -28,3 +28,20 @@ jobs:
       with:
         name: PackageViewer jar
         path: ./build/libs/PackageViewer*.jar
+
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+
+    - uses: actions/setup-java@v3
+      with:
+        distribution: 'temurin'
+        java-version: 17
+
+    - name: Run testsClassDiagram1
+      run: |
+        ./gradlew test