Improve unit test workflow file

- Update checkout action to version v3
- Use new docker layer caching version
- Simplify commands to handle docker compose shell commands
- Update codecov action

.github/workflows/unit-tests.yml

@@ -0,0 +1,48 @@
+name: Unit tests
+on: push
+jobs:
+  unit-test-job:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v3
+      with:
+        submodules: recursive
+
+    - name: Pull docker image
+      run: docker compose pull
+      working-directory: docker/development
+
+    # In this step, this action saves a list of existing images,
+    # the cache is created without them in the post run.
+    # It also restores the cache if it exists.
+    # https://github.com/jpribyl/action-docker-layer-caching
+    - uses: jpribyl/action-docker-layer-caching@v0.1.1
+      continue-on-error: true
+
+    - name: Build docker image
+      run: docker compose build
+      working-directory: docker/development
+
+    - name: Create database
+      working-directory: docker/development
+      run: |
+          docker compose exec mampf RAILS_ENV=test rails db:create
+          docker compose exec mampf RAILS_ENV=test rails db:migrate
+          docker compose exec mampf RAILS_ENV=test rails db:test:prepare
+
+    - name: Reindex sunspot
+      working-directory: docker/development
+      run: |
+          docker compose run mampf RAILS_ENV=test rake sunspot:reindex
+
+    - name: Run unit tests
+      working-directory: docker/development
+      run: docker compose exec mampf RAILS_ENV=test rails spec
+
+    - name: Send test coverage report to Codecov
+      uses: codecov/codecov-action@v3
+      with:
+        directory: ./coverage
+        fail_ci_if_error: true
+        verbose: true