Add github test workflow.

.github/workflows/tests.yaml

@@ -0,0 +1,30 @@
+name: Pubs tests
+
+on: [push, pull_request]
+
+jobs:
+  unit-test:
+    strategy:
+      matrix:
+        os: [macos-latest, ubuntu-latest]
+        python-version: [3.6, 3.7, 3.8, 3.9]
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r dev_requirements.txt
+      - name: Test with pytest (mock API mode)
+        env:
+          PUBS_TESTS_MODE: MOCK
+        run: pytest
+      - name: Test with pytest (online API mode)
+        env:
+          PUBS_TESTS_MODE: COLLECT
+        run: pytest