Add static ensure() methods to unmodifiable views.

tests/corelib/map_test.dart

 // Copyright (c) 2011, 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 map_test;
 import "package:expect/expect.dart";
 import 'dart:collection';
 import 'dart:convert' show JSON;
 
 Map newJsonMap()
@@ skipping 105 matching lines @@
                                   hashCode: (int v) => v.hashCode,
                                   isValidKey: (v) => v is int));
   testOtherKeys(new MapBaseMap<int, int>());
   testOtherKeys(new MapMixinMap<int, int>());
   testOtherKeys(newJsonMap());
   testOtherKeys(newJsonMapCustomReviver());
 
   testUnmodifiableMap(const {1 : 37});
   testUnmodifiableMap(new UnmodifiableMapView({1 : 37}));
   testUnmodifiableMap(new UnmodifiableMapBaseMap([1, 37]));
+  testUnmodifiableMap(UnmodifiableMapView.ensure({1 : 37}));

[Lasse Reichstein Nielsen, 2015/08/27 07:59:04]

Also test that UnmodifiableMapView.ensure called with unmodifiable maps return
the original map.

[nweiz, 2015/08/27 19:25:38]

It does that in the body of [testUnmodifiableMap] below.

 
   testFrom();
 }
 
 
 void test(Map map) {
   testDeletedElement(map);
   testMap(map, 1, 2, 3, 4, 5, 6, 7, 8);
   map.clear();
   testMap(map, "value1", "value2", "value3", "value4", "value5",
@@ skipping 607 matching lines @@
 void testUnmodifiableMap(Map map) {
   Expect.isTrue(map.containsKey(1));
   testLength(1, map);
   Expect.equals(1, map.keys.first);
   Expect.equals(37, map.values.first);
 
   Expect.throws(map.clear);
   Expect.throws(() { map.remove(1); });
   Expect.throws(() { map[2] = 42; });
   Expect.throws(() { map.addAll({2 : 42}); });
+
+  Expect.isTrue(identical(map, UnmodifiableMapView.ensure(map)));
 }
 
 class Customer {
   final int id;
   final int secondId;
   const Customer(this.id, this.secondId);
   int get hashCode => id;
   bool operator==(Object other) {
     if (other is! Customer) return false;
     Customer otherCustomer = other;
@@ skipping 179 matching lines @@
   Map<Interface, Interface> interfaceMap = <Interface, Interface>{sub: sub};
   expectMap(superMap, new Map<Super, Super>.from(interfaceMap));
   expectMap(superMap, new Map<Interface, Interface>.from(superMap));
   expectMap(superMap, new HashMap<Super, Super>.from(interfaceMap));
   expectMap(superMap, new HashMap<Interface, Interface>.from(superMap));
   expectMap(superMap, new LinkedHashMap<Super, Super>.from(interfaceMap));
   expectMap(superMap, new LinkedHashMap<Interface, Interface>.from(superMap));
   expectMap(superMap, new SplayTreeMap<Super, Super>.from(interfaceMap));
   expectMap(superMap, new SplayTreeMap<Interface, Interface>.from(superMap));
 }