Record ClassTypeAlias(s) as subtypes.

pkg/analyzer/test/src/dart/analysis/index_test.dart

 // Copyright (c) 2016, 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 'dart:async';
 import 'dart:convert';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
@@ skipping 898 matching lines @@
   A.foo({this.field});
   A.bar() : field = 5;
 }
 ''');
     FieldElement element = findElement('field', ElementKind.FIELD);
     assertThat(element)
       ..isWrittenAt('field})', true)
       ..isWrittenAt('field = 5', true);
   }
 
-  test_subtypes() async {
+  test_subtypes_classDeclaration() async {
     String libP = 'package:test/lib.dart;package:test/lib.dart';
     provider.newFile(
         _p('$testProject/lib.dart'),
         '''
 class A {}
 class B {}
 class C {}
 class D {}
 class E {}
 ''');
@@ skipping 38 matching lines @@
     }
 
     {
       AnalysisDriverSubtype Z =
           index.subtypes.singleWhere((t) => t.name == 'Z');
       expect(Z.supertypes, ['$libP;D', '$libP;E']);
       expect(Z.members, ['methodZ']);
     }
   }
 
+  test_subtypes_classTypeAlias() async {
+    String libP = 'package:test/lib.dart;package:test/lib.dart';
+    provider.newFile(
+        _p('$testProject/lib.dart'),
+        '''
+class A {}
+class B {}
+class C {}
+class D {}
+''');
+    await _indexTestUnit('''
+import 'lib.dart';
+
+class X = A with B, C;
+class Y = A with B implements C, D;
+''');
+
+    {
+      AnalysisDriverSubtype X =
+          index.subtypes.singleWhere((t) => t.name == 'X');
+      expect(X.supertypes, ['$libP;A', '$libP;B', '$libP;C']);
+      expect(X.members, isEmpty);
+    }
+
+    {
+      AnalysisDriverSubtype Y =
+          index.subtypes.singleWhere((t) => t.name == 'Y');
+      expect(Y.supertypes, ['$libP;A', '$libP;B', '$libP;C', '$libP;D']);
+      expect(Y.members, isEmpty);
+    }
+  }
+
   test_subtypes_dynamic() async {
     await _indexTestUnit('''
 class X extends dynamic {
   void foo() {}
 }
 ''');
 
     AnalysisDriverSubtype X = index.subtypes.singleWhere((t) => t.name == 'X');
     expect(X.supertypes, isEmpty);
     expect(X.members, ['foo']);
@@ skipping 340 matching lines @@
   final bool isQualified;
 
   _Relation(this.kind, this.offset, this.length, this.isQualified);
 
   @override
   String toString() {
     return '_Relation{kind: $kind, offset: $offset, length: $length, '
         'isQualified: $isQualified}lified)';
   }
 }