Add simple unit test job for PR on CI

.github/workflows/pr.yml

@@ -67,6 +67,28 @@ jobs:
       - name: Validate Lint
         run: ./gradlew lint
 
+  unit_tests:
+    runs-on: ubuntu-latest
+    steps:
+        - uses: actions/checkout@v4
+        - name: Set up JDK 17
+          uses: actions/[email protected]
+          with:
+              distribution: 'temurin'
+              java-version: '17'
+
+        - name: Mock google-services.json
+          run: |
+              cp .github/mock-google-services.json app/google-services.json
+              cp .github/mock-google-services.json wear/google-services.json
+              cp .github/mock-google-services.json automotive/google-services.json
+
+        - name: Setup Gradle
+          uses: gradle/actions/setup-gradle@v4
+
+        - name: Run test
+          run: ./gradlew test
+
   pr_build:
     runs-on: ubuntu-latest
     permissions: