Test Downstream Packages (#528)

.github/workflows/downstream.yml

@@ -0,0 +1,42 @@
+name: Test downstream projects
+
+on:
+  push:
+    branches: '*'
+  pull_request:
+    branches: '*'
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+
+    - name: Set up Python 3.8
+      uses: actions/setup-python@v2
+      with:
+        python-version: 3.8
+
+    - name: Install dependencies
+      run: |
+        pip install --upgrade pip
+        pip install ".[test]"
+        pip install --pre --upgrade jupyterlab_server[test] jupyterlab[test] nbclassic[test]
+        pip freeze
+    - name: Run tests
+      run: |
+        pytest --pyargs jupyterlab_server
+        python -m jupyterlab.browser_check --no-browser-test
+
+        # Make sure we can start and kill the nbclassic server
+        jupyter nbclassic --no-browser &
+        TASK_PID=$!
+        # Make sure the task is running
+        ps -p $TASK_PID || exit 1
+        sleep 5
+        kill $TASK_PID
+        wait $TASK_PID
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v1