Add tests, including test for issue

pkg/analyzer/test/generated/all_the_rest_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 analyzer.test.generated.all_the_rest_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/file_system/physical_file_system.dart';
@@ skipping 2469 matching lines @@
     FileBasedSource source3 = new FileBasedSource(file3);
     DirectoryBasedSourceContainer container =
         new DirectoryBasedSourceContainer.con1(dir);
     expect(container.contains(source1), isTrue);
     expect(container.contains(source2), isTrue);
     expect(container.contains(source3), isFalse);
   }
 }
 
 @reflectiveTest
-class ElementBuilderTest extends EngineTestCase {
+class ElementBuilderTest extends ParserTestCase {
+  void fail_visitMethodDeclaration_setter_duplicate() {
+    // https://github.com/dart-lang/sdk/issues/25601
+    String code = r'''
+class C {
+  set zzz(x) {}
+  set zzz(y) {}
+}
+''';
+    CompilationUnit unit = ParserTestCase.parseCompilationUnit(code);
+    ElementHolder holder = new ElementHolder();
+    ElementBuilder builder = new ElementBuilder(holder);
+    unit.accept(builder);
+    ClassElement classElement = holder.types[0];
+    for (PropertyAccessorElement accessor in classElement.accessors) {
+      expect(accessor.variable.setter, same(accessor));
+    }
+  }
+
   void test_visitCatchClause() {
     // } catch (e, s) {
     ElementHolder holder = new ElementHolder();
     ElementBuilder builder = new ElementBuilder(holder);
     String exceptionParameterName = "e";
     String stackParameterName = "s";
     CatchClause clause =
         AstFactory.catchClause2(exceptionParameterName, stackParameterName);
     clause.accept(builder);
 
@@ skipping 3519 matching lines @@
     expect(UriKind.fromEncoding(0x70), same(UriKind.PACKAGE_URI));
     expect(UriKind.fromEncoding(0x58), same(null));
   }
 
   void test_getEncoding() {
     expect(UriKind.DART_URI.encoding, 0x64);
     expect(UriKind.FILE_URI.encoding, 0x66);
     expect(UriKind.PACKAGE_URI.encoding, 0x70);
   }
 }