Update android.yml

.github/workflows/android.yml

@@ -3,8 +3,20 @@ name: Android CI
 on: [push]
 
 jobs:
-  build:
+  test:
+    name: Run Unit Tests
+    runs-on: ubuntu-18.04
 
+    steps:
+    - uses: actions/checkout@v1
+    - name: set up JDK 1.8
+      uses: actions/setup-java@v1
+      with:
+        java-version: 1.8
+    - name: Unit tests
+      run: bash ./gradlew test --stacktrace
+
+  build:
     runs-on: ubuntu-latest
 
     steps: