add github action for tests

.github/workflows/tests.yml

@@ -0,0 +1,35 @@
+name: Test Suite
+
+# Controls when the action will run. Triggers the workflow on push or pull request 
+# events but only for the master branch
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+# A workflow run is made up of one or more jobs that can run sequentially or in parallel
+jobs:
+  # This workflow contains a single job called "build"
+  build:
+    # The type of runner that the job will run on
+    runs-on: ubuntu-latest
+
+    # Steps represent a sequence of tasks that will be executed as part of the job
+    steps:
+    # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
+    - uses: actions/checkout@v2
+    
+    - name: Setup node
+      uses: actions/setup-node@v1
+      with:
+        node-version: 10
+
+    - name: Install
+      run: npm install
+
+    - name: Elm test suite
+      run: npm run test
+    
+    - name: Rendering test suite
+      run: npm run test-rendering