Add UnlinkedUnit.isPartOf flag.

pkg/analyzer/test/src/summary/summary_common.dart

 // Copyright (c) 2015, 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.src.summary.summary_common;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/src/dart/scanner/reader.dart';
@@ skipping 9256 matching lines @@
   }
 
   test_public_namespace_of_part() {
     addNamedSource('/a.dart', 'part of foo; class C {}');
     serializeLibraryText('library foo; part "a.dart";');
     expect(unlinkedUnits[0].publicNamespace.names, isEmpty);
     expect(unlinkedUnits[1].publicNamespace.names, hasLength(1));
     expect(unlinkedUnits[1].publicNamespace.names[0].name, 'C');
   }
 
+  test_part_isPartOf() {
+    addNamedSource('/a.dart', 'part of foo; class C {}');
+    serializeLibraryText('library foo; part "a.dart";');
+    expect(unlinkedUnits[0].isPartOf, isFalse);
+    expect(unlinkedUnits[1].isPartOf, isTrue);
+  }
+
   test_reference_zero() {
     // Element zero of the references table should be populated in a standard
     // way.
     serializeLibraryText('');
     UnlinkedReference unlinkedReference0 = unlinkedUnits[0].references[0];
     expect(unlinkedReference0.name, '');
     expect(unlinkedReference0.prefixReference, 0);
     LinkedReference linkedReference0 = linked.units[0].references[0];
     expect(linkedReference0.containingReference, 0);
     expect(linkedReference0.dependency, 0);
@@ skipping 1057 matching lines @@
 class _PrefixExpectation {
   final ReferenceKind kind;
   final String name;
   final String absoluteUri;
   final String relativeUri;
   final int numTypeParameters;
 
   _PrefixExpectation(this.kind, this.name,
       {this.absoluteUri, this.relativeUri, this.numTypeParameters: 0});
 }