Update workflow to run tests on all OSes (dart-archive/native_synchronization#3)

Author: mraleph

pkgs/native_synchronization/.github/workflows/dart.yaml

@@ -13,23 +13,40 @@ on:
 permissions: read-all
 
 jobs:
-  build:
+  analyze:
     runs-on: ubuntu-latest
 
     steps:
       # These are the latest versions of the github actions; dependabot will
       # send PRs to keep these up-to-date.
       - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
       - uses: dart-lang/setup-dart@d6a63dab3335f427404425de0fbfed4686d93c4f
+        with:
+          sdk: dev
 
       - name: Install dependencies
         run: dart pub get
-  
+
       - name: Verify formatting
         run: dart format --output=none --set-exit-if-changed .
 
       - name: Analyze project source
         run: dart analyze --fatal-infos
 
-      # - name: Run tests
-      #   run: dart test
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        sdk: [dev]
+    steps:
+      - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+      - uses: dart-lang/setup-dart@d6a63dab3335f427404425de0fbfed4686d93c4f
+        with:
+          sdk: ${{ matrix.sdk }}
+
+      - name: Install dependencies
+        run: dart pub get
+
+      - name: Run tests
+        run: dart test

pkgs/native_synchronization/test/primitives_test.dart

@@ -0,0 +1,9 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:test/test.dart';
+
+void main() {
+  test('dummy', () {});
+}