Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/operation/test_all.dart

Index: pkg/analysis_server/test/operation/test_all.dart
diff --git a/pkg/analysis_server/test/operation/test_all.dart b/pkg/analysis_server/test/operation/test_all.dart
index 4296f3950acfa6d37d4c6ae7ef8700ab92928c24..701045107ca926a6666eec197307542cfab5c770 100644
--- a/pkg/analysis_server/test/operation/test_all.dart
+++ b/pkg/analysis_server/test/operation/test_all.dart
@@ -4,7 +4,7 @@
 
 library test.operation.all;
 
-import 'package:unittest/unittest.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../utils.dart';
 import 'operation_queue_test.dart' as operation_queue_test;
@@ -15,8 +15,8 @@ import 'operation_test.dart' as operation_test;
  */
 main() {
   initializeTestEnvironment();
-  group('operation', () {
+  defineReflectiveSuite(() {
     operation_queue_test.main();
     operation_test.main();
-  });
+  }, name: 'operation');
 }