Configure GitHub actions

Author: Wilfred

.github/workflows/test.yml

@@ -0,0 +1,30 @@
+name: Run test suite
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        emacs_version:
+          - '25.1'
+          - '26.1'
+          - '27.1'
+
+    steps:
+    - uses: purcell/setup-emacs@master
+      with:
+        version: ${{ matrix.emacs_version }}
+    - uses: conao3/setup-cask@master
+
+    - uses: actions/checkout@v2
+
+    - name: Test
+      run: |
+        cask install
+        cask exec ert-runner
+
+    - name: Test after byte-compilation
+      run: |
+        cask build
+        cask exec ert-runner