chore(material): add unit tests for MdButton.

modules/angular2_material/test/test_url_resolver.dart

@@ -0,0 +1,21 @@
+library ng_material.test_url_resolver;
+
+import 'package:angular2/src/core/dom/browser_adapter.dart';
+import 'package:angular2/src/core/services/url_resolver.dart';
+
+void commonDemoSetup() {
+  BrowserDomAdapter.makeCurrent();
+}
+
+class TestUrlResolver extends UrlResolver {
+  @override
+  String resolve(String baseUrl, String url) {
+    const MATERIAL_PKG = 'package:angular2_material/';
+
+    if (url.startsWith(MATERIAL_PKG)) {
+      return '/packages/angular2_material/' +
+          url.substring(MATERIAL_PKG.length);
+    }
+    return super.resolve(baseUrl, url);
+  }
+}