Add test workflow.

.github/workflows/test.yml

@@ -0,0 +1,49 @@
+name: Test
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [2.7, 3.4, 3.5, 3.6, 3.7, 3.8, 'pypy2', 'pypy3']
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+
+    - name: Get pip cache dir
+      id: pip-cache
+      run: |
+        echo "::set-output name=dir::$(pip cache dir)"
+
+    - name: Cache
+      uses: actions/cache@v2
+      with:
+        path: ${{ steps.pip-cache.outputs.dir }}
+        key:
+          test-${{ matrix.python-version }}-v1-${{ hashFiles('**/setup.py') }}
+        restore-keys: |
+          test-${{ matrix.python-version }}-v1-
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install --upgrade tox tox-gh-actions
+
+    - name: Tox tests
+      shell: bash
+      run: |
+        tox
+      env:
+        TARGET: ${{ matrix.target }}
+
+    - name: Upload coverage to Coveralls
+      uses: coverallsapp/github-action@master
+      with:
+        github-token: ${{ secrets.COVERALLS_GITHUB_TOKEN }}