Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/services/correction/strings_test.dart

Index: pkg/analysis_server/test/services/correction/strings_test.dart
diff --git a/pkg/analysis_server/test/services/correction/strings_test.dart b/pkg/analysis_server/test/services/correction/strings_test.dart
index a5b4779b48c9f06717c76c020116675e00176770..2e98385b4ccc5bbd745c02f8d1ef52b30c98a50e 100644
--- a/pkg/analysis_server/test/services/correction/strings_test.dart
+++ b/pkg/analysis_server/test/services/correction/strings_test.dart
@@ -5,14 +5,16 @@
 library test.services.correction.strings;
 
 import 'package:analysis_server/src/services/correction/strings.dart';
+import 'package:test/test.dart' hide isEmpty;
 import 'package:test_reflective_loader/test_reflective_loader.dart';
-import 'package:unittest/unittest.dart' hide isEmpty;
 
 import '../../utils.dart';
 
 main() {
   initializeTestEnvironment();
-  defineReflectiveTests(StringsTest);
+  defineReflectiveSuite(() {
+    defineReflectiveTests(StringsTest);
+  });
 }
 
 @reflectiveTest
@@ -43,6 +45,7 @@ class StringsTest {
           oldStr.substring(diff.offset + diff.length);
       expect(applied, newStr);
     }
+
     assertDiff('', '');
     assertDiff('', 'a');
     assertDiff('abc', '');