pub/validator/lib_test: use group instead of integration

utils/tests/pub/validator/lib_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:pathos/path.dart' as path;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../../../pub/entrypoint.dart';
 import '../../../pub/io.dart';
 import '../../../pub/validator.dart';
@@ skipping 16 matching lines @@
       d.dir(appPath, [
         d.libPubspec("test_pkg", "1.0.0"),
         d.dir("lib", [
           d.file("thing.txt", "woo hoo")
         ])
       ]).create();
       expectNoValidationError(lib);
     });
   });
 
-  integration('should consider a package invalid if it', () {
+  group('should consider a package invalid if it', () {
     setUp(d.validPackage.create);
 
     integration('has no lib directory', () {
       schedule(() => deleteEntry(path.join(sandboxDir, appPath, "lib")));
       expectValidationError(lib);
     });
 
     integration('has an empty lib directory', () {
       schedule(() =>
           deleteEntry(path.join(sandboxDir, appPath, "lib", "test_pkg.dart")));
       expectValidationError(lib);
     });
 
     integration('has a lib directory containing only src', () {
       schedule(() =>
           deleteEntry(path.join(sandboxDir, appPath, "lib", "test_pkg.dart")));
       d.dir(appPath, [
         d.dir("lib", [
           d.dir("src", [d.file("test_pkg.dart", "int i = 0;")])
         ])
       ]).create();
       expectValidationError(lib);
     });
   });
 }