Convert from unittest to test

test/plugin_impl_test.dart

Index: test/plugin_impl_test.dart
diff --git a/test/plugin_impl_test.dart b/test/plugin_impl_test.dart
index c8603afbcf5ca70a009d375cc1c69dd6df038a93..2221cf81ced78346808871cdc4260913d80df848 100644
--- a/test/plugin_impl_test.dart
+++ b/test/plugin_impl_test.dart
@@ -6,11 +6,9 @@ library test.operation;
 
 import 'package:plugin/plugin.dart';
 import 'package:plugin/src/plugin_impl.dart';
-import 'package:unittest/unittest.dart';
+import 'package:test/test.dart';
 
 main() {
-  groupSep = ' | ';
-
   group('ExtensionManager', () {
     test('processPlugins', () {
       TestPlugin plugin1 = new TestPlugin('plugin1');