Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/services/linter/linter_test.dart

Index: pkg/analysis_server/test/services/linter/linter_test.dart
diff --git a/pkg/analysis_server/test/services/linter/linter_test.dart b/pkg/analysis_server/test/services/linter/linter_test.dart
index 1017bd6b243f86ca91a87fc55dd34c1384d7d713..d4e2eac5d9999faea8047bbfabe0e22c9f7de3d3 100644
--- a/pkg/analysis_server/test/services/linter/linter_test.dart
+++ b/pkg/analysis_server/test/services/linter/linter_test.dart
@@ -9,14 +9,16 @@ import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/source/analysis_options_provider.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
+import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
-import 'package:unittest/unittest.dart';
 
 import '../../utils.dart';
 
 main() {
   initializeTestEnvironment();
-  defineReflectiveTests(LinterRuleOptionsValidatorTest);
+  defineReflectiveSuite(() {
+    defineReflectiveTests(LinterRuleOptionsValidatorTest);
+  });
 }
 
 @reflectiveTest