Add CI job

Author: olafurpg

.github/workflows/test.yml

@@ -0,0 +1,33 @@
+name: Test
+on: 
+  push:
+    branches:
+      - main
+  pull_request:
+env:
+  DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
+  DOTNET_CLI_TELEMETRY_OPTOUT: true
+jobs:
+  format:
+    runs-on: ubuntu-latest
+    - uses: actions/checkout@v3
+    - uses: actions/setup-dotnet@v3
+      with:
+        dotnet-version: 6.0.x
+    - run: dotnet format --verify-no-changes
+    - run: dotnet format --verify-no-changes
+      working-directory: snapshots/input/syntax
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    name: Test
+    steps:
+    - uses: actions/checkout@v3
+    - uses: actions/setup-dotnet@v3
+      with:
+        dotnet-version: 6.0.x
+    - run: dotnet test
+