Make actions run tests as well.

.github/workflows/run_tests.yml

@@ -1 +1,26 @@
 
+name: Tests
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  test:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up JDK 9
+      uses: actions/setup-java@v2
+      with:
+        java-version: '8'
+        distribution: 'adopt'
+        
+    - name: Grant execute permission for gradlew
+      run: chmod +x gradlew
+      
+    - name: Build with Gradle
+      run: ./gradlew test
+