add: add unit test workflow

.github/workflows/main.yml

@@ -0,0 +1,25 @@
+name: Unit Test CI
+on:
+  push:
+    branches: [ develop ]
+  pull_request:
+    branches: [ develop ]
+  workflow_dispatch:
+
+jobs:
+  unit-test:
+  runs-on: ubuntu-latest
+    steps:
+      - name: Checkout the code
+        uses: actions/checkout@v2
+
+      - name: Run tests
+        run: ./gradlew test
+
+      - name: Upload test report
+        uses: actions/upload-artifact@v2
+        with:
+          name: unit_test_report
+          path: app/build/reports/tests/testDebugUnitTest/
+
+