Issue 23389. Report error in the renamed element be invisible after rename.

pkg/analysis_server/test/services/refactoring/rename_unit_member_test.dart

 // Copyright (c) 2014, 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.
 
 library test.services.refactoring.rename_unit_member;
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/correction/status.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 47 matching lines @@
   }
 }
 ''');
     createRenameRefactoringAtString('Test {}');
     // check status
     refactoring.newName = 'NewName';
     RefactoringStatus status = await refactoring.checkFinalConditions();
     assertRefactoringStatusOK(status);
   }
 
+  test_checkFinalConditions_publicToPrivate_usedInOtherLibrary() async {
+    indexTestUnit('''
+class Test {}
+''');
+    indexUnit('/lib.dart', '''
+library my.lib;
+import 'test.dart';
+
+main() {
+  new Test();
+}
+''');
+    createRenameRefactoringAtString('Test {}');
+    // check status
+    refactoring.newName = '_NewName';
+    RefactoringStatus status = await refactoring.checkFinalConditions();
+    assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR,
+        expectedMessage: "Renamed class will be invisible in 'my.lib'.");
+  }
+
   test_checkFinalConditions_shadowedBy_MethodElement() async {
     indexTestUnit('''
 class Test {}
 class A {
   void NewName() {}
   main() {
     new Test();
   }
 }
 ''');
@@ skipping 386 matching lines @@
     return assertSuccessfulRefactoring('''
 int newName = 0;
 main() {
   print(newName);
   newName = 1;
   newName += 2;
 }
 ''');
   }
 }