Issue 26207. Fix for renaming top-level functions with offset 0.

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/plugin/protocol/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 478 matching lines @@
 newName() {}
 foo() {}
 main() {
   print(newName);
   print(newName());
   foo();
 }
 ''');
   }
 
+  test_createChange_FunctionElement_imported() async {
+    indexUnit(
+        '/foo.dart',
+        r'''
+test() {}
+foo() {}
+''');
+    indexTestUnit('''
+import 'foo.dart';
+main() {
+  print(test);
+  print(test());
+  foo();
+}
+''');
+    // configure refactoring
+    createRenameRefactoringAtString('test);');
+    expect(refactoring.refactoringName, 'Rename Top-Level Function');
+    expect(refactoring.elementKindName, 'function');
+    expect(refactoring.oldName, 'test');
+    refactoring.newName = 'newName';
+    // validate change
+    await assertSuccessfulRefactoring('''
+import 'foo.dart';
+main() {
+  print(newName);
+  print(newName());
+  foo();
+}
+''');
+    assertFileChangeResult(
+        '/foo.dart',
+        '''
+newName() {}
+foo() {}
+''');
+  }
+
   test_createChange_PropertyAccessorElement_getter_declaration() {
     return _test_createChange_PropertyAccessorElement("test {}");
   }
 
   test_createChange_PropertyAccessorElement_getter_usage() {
     return _test_createChange_PropertyAccessorElement("test);");
   }
 
   test_createChange_PropertyAccessorElement_mix() {
     return _test_createChange_PropertyAccessorElement("test += 2");
@@ skipping 69 matching lines @@
     return assertSuccessfulRefactoring('''
 int newName = 0;
 main() {
   print(newName);
   newName = 1;
   newName += 2;
 }
 ''');
   }
 }