dependency_grapher: handle dependencies on SDK.

pkg/front_end/test/dependency_grapher_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 'package:front_end/compiler_options.dart';
 import 'package:front_end/dependency_grapher.dart';
 import 'package:front_end/memory_file_system.dart';
 import 'package:path/path.dart' as pathos;
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DependencyGrapherTest);
   });
 }
 
 @reflectiveTest
 class DependencyGrapherTest {
   LibraryNode checkLibrary(LibraryCycleNode cycle, String uri,
-      {List<String> dependencies: const [], List<String> parts: const []}) {
+      {List<String> dependencies: const ['dart:core'],
+      List<String> parts: const []}) {
     var library = cycle.libraries[Uri.parse(uri)];
     expect('${library.uri}', uri);
     expect(library.dependencies.map((dep) => '${dep.uri}'),
         unorderedEquals(dependencies));
     expect(library.parts.map((part) => '$part'), unorderedEquals(parts));
     return library;
   }
 
   Future<List<LibraryCycleNode>> getCycles(Map<String, String> contents,
       {List<String> startingPoints, String packagesFilePath = ''}) async {
@@ skipping 16 matching lines @@
 
   /// Sort the given library cycles into a deterministic order based on their
   /// URIs for easier unit testing.
   List<LibraryCycleNode> sortCycles(Iterable<LibraryCycleNode> cycles) {
     var result = cycles.toList();
     String sortKey(LibraryCycleNode node) => node.libraries.keys.join(',');
     result.sort((a, b) => Comparable.compare(sortKey(a), sortKey(b)));
     return result;
   }
 
+  test_explicitCoreDependency() async {
+    // If "dart:core" is explicitly imported, there shouldn't be two imports of
+    // "dart:core", just one.
+    var cycles = await getCycles({'/foo.dart': 'import "dart:core";'});
+    expect(cycles, hasLength(1));
+    expect(cycles[0].libraries, hasLength(1));
+    checkLibrary(cycles[0], 'file:///foo.dart');
+  }
+
   test_exportDependency() async {
     var cycles =
         await getCycles({'/foo.dart': 'export "bar.dart";', '/bar.dart': ''});
     expect(cycles, hasLength(2));
     expect(cycles[0].libraries, hasLength(1));
     checkLibrary(cycles[0], 'file:///bar.dart');
     expect(cycles[1].libraries, hasLength(1));
     checkLibrary(cycles[1], 'file:///foo.dart',
-        dependencies: ['file:///bar.dart']);
+        dependencies: ['file:///bar.dart', 'dart:core']);
   }
 
   test_importDependency() async {
     var cycles =
         await getCycles({'/foo.dart': 'import "bar.dart";', '/bar.dart': ''});
     expect(cycles, hasLength(2));
     expect(cycles[0].libraries, hasLength(1));
     checkLibrary(cycles[0], 'file:///bar.dart');
     expect(cycles[1].libraries, hasLength(1));
     checkLibrary(cycles[1], 'file:///foo.dart',
-        dependencies: ['file:///bar.dart']);
+        dependencies: ['file:///bar.dart', 'dart:core']);
   }
 
   test_multipleStartingPoints() async {
     var cycles = await getCycles({
       '/a.dart': 'import "c.dart";',
       '/b.dart': 'import "c.dart";',
       '/c.dart': ''
     }, startingPoints: [
       '/a.dart',
       '/b.dart'
     ]);
     expect(cycles, hasLength(3));
     expect(cycles[0].libraries, hasLength(1));
     checkLibrary(cycles[0], 'file:///c.dart');
     // The other two cycles might be in any order, so sort them for
     // reproducibility.
     List<LibraryCycleNode> otherCycles = sortCycles(cycles.sublist(1));
     checkLibrary(otherCycles[0], 'file:///a.dart',
-        dependencies: ['file:///c.dart']);
+        dependencies: ['file:///c.dart', 'dart:core']);
     checkLibrary(otherCycles[1], 'file:///b.dart',
-        dependencies: ['file:///c.dart']);
+        dependencies: ['file:///c.dart', 'dart:core']);
   }
 
   test_packages() async {
     var cycles = await getCycles({
       '/foo.dart': 'import "package:foo/bar.dart";',
       '/.packages': 'foo:pkg/foo/lib\nbar:pkg/bar/lib\n',
       '/pkg/foo/lib/bar.dart': 'import "package:bar/baz.dart";',
       '/pkg/bar/lib/baz.dart': ''
     }, packagesFilePath: '/.packages');
     expect(cycles, hasLength(3));
     expect(cycles[0].libraries, hasLength(1));
     checkLibrary(cycles[0], 'package:bar/baz.dart');
     expect(cycles[1].libraries, hasLength(1));
     checkLibrary(cycles[1], 'package:foo/bar.dart',
-        dependencies: ['package:bar/baz.dart']);
+        dependencies: ['package:bar/baz.dart', 'dart:core']);
     expect(cycles[2].libraries, hasLength(1));
     checkLibrary(cycles[2], 'file:///foo.dart',
-        dependencies: ['package:foo/bar.dart']);
+        dependencies: ['package:foo/bar.dart', 'dart:core']);
   }
 
   test_parts() async {
     var cycles = await getCycles({
       '/foo.dart': 'library foo; part "a.dart"; part "b.dart";',
       '/a.dart': 'part of foo;',
       '/b.dart': 'part of foo;'
     });
     expect(cycles, hasLength(1));
     expect(cycles[0].libraries, hasLength(1));
     checkLibrary(cycles[0], 'file:///foo.dart',
         parts: ['file:///a.dart', 'file:///b.dart']);
   }
 
   test_relativeUris() async {
     var cycles = await getCycles({
       '/a.dart': 'import "b/c.dart";',
       '/b/c.dart': 'import "d/e.dart";',
       '/b/d/e.dart': 'import "../f.dart";',
       '/b/f.dart': ''
     });
     expect(cycles, hasLength(4));
     expect(cycles[0].libraries, hasLength(1));
     checkLibrary(cycles[0], 'file:///b/f.dart');
     expect(cycles[1].libraries, hasLength(1));
     checkLibrary(cycles[1], 'file:///b/d/e.dart',
-        dependencies: ['file:///b/f.dart']);
+        dependencies: ['file:///b/f.dart', 'dart:core']);
     expect(cycles[2].libraries, hasLength(1));
     checkLibrary(cycles[2], 'file:///b/c.dart',
-        dependencies: ['file:///b/d/e.dart']);
+        dependencies: ['file:///b/d/e.dart', 'dart:core']);
     expect(cycles[3].libraries, hasLength(1));
     checkLibrary(cycles[3], 'file:///a.dart',
-        dependencies: ['file:///b/c.dart']);
+        dependencies: ['file:///b/c.dart', 'dart:core']);
+  }
+
+  test_sdkDependency() async {
+    // Dependencies on the SDK should be recorded even if SDK libraries aren't
+    // being included in the graph.
+    var cycles = await getCycles({'/foo.dart': 'import "dart:async";'});
+    expect(cycles, hasLength(1));
+    expect(cycles[0].libraries, hasLength(1));
+    checkLibrary(cycles[0], 'file:///foo.dart',
+        dependencies: ['dart:core', 'dart:async']);
   }
 
   test_simpleCycle() async {
     var cycles = await getCycles(
         {'/foo.dart': 'import "bar.dart";', '/bar.dart': 'import "foo.dart";'});
     expect(cycles, hasLength(1));
     expect(cycles[0].libraries, hasLength(2));
     var foo = checkLibrary(cycles[0], 'file:///foo.dart',
-        dependencies: ['file:///bar.dart']);
+        dependencies: ['file:///bar.dart', 'dart:core']);
     var bar = checkLibrary(cycles[0], 'file:///bar.dart',
-        dependencies: ['file:///foo.dart']);
+        dependencies: ['file:///foo.dart', 'dart:core']);
     expect(foo.dependencies[0], same(bar));
     expect(bar.dependencies[0], same(foo));
   }
 
   test_singleFile() async {
     var cycles = await getCycles({'/foo.dart': ''});
     expect(cycles, hasLength(1));
     expect(cycles[0].libraries, hasLength(1));
     checkLibrary(cycles[0], 'file:///foo.dart');
   }
 }