Add action to run tests

.github/workflows/test.yml

@@ -0,0 +1,15 @@
+name: Test
+
+on:
+  pull_request:
+    paths:
+      - '.github/workflows/test.yml'
+      - '**/*.swift'
+
+jobs:
+  SwiftLint:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: Run tests
+        run: swift test