Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/services/completion/completion_target_test.dart

Index: pkg/analysis_server/test/services/completion/completion_target_test.dart
diff --git a/pkg/analysis_server/test/services/completion/completion_target_test.dart b/pkg/analysis_server/test/services/completion/completion_target_test.dart
index ce023433eeeb77d456ecfc14d8942908e9f93569..80d4596183afd7dfa40a0958e6e948f0593fe919 100644
--- a/pkg/analysis_server/test/services/completion/completion_target_test.dart
+++ b/pkg/analysis_server/test/services/completion/completion_target_test.dart
@@ -7,15 +7,17 @@ library test.services.completion.target;
 import 'package:analysis_server/src/provisional/completion/dart/completion_target.dart';
 import 'package:analyzer/dart/ast/ast.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 '../../abstract_context.dart';
 import '../../utils.dart';
 
 main() {
   initializeTestEnvironment();
-  defineReflectiveTests(CompletionTargetTest);
+  defineReflectiveSuite(() {
+    defineReflectiveTests(CompletionTargetTest);
+  });
 }
 
 @reflectiveTest
@@ -45,6 +47,7 @@ class CompletionTargetTest extends AbstractContextTest {
           reason: 'containingNode');
       expect(target.argIndex, argIndex, reason: 'argIndex');
     }
+
     // Assert with parsed unit
     assertCommon();
     CompilationUnit unit =