a === b -> identical(a, b)

tests/language/compile_time_constant_a_test.dart

 // Copyright (c) 2012, 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.
 
 const m1 = const { 'a': 400 + 99 };
 const m2 = const { 'a': 499, 'b': 42 };
 const m3 = const { 'm1': m1, 'm2': m2 };
 const m4 = const { 'z': 9, 'a': 8, 'm': 7 };
 const m5 = const { '': 499 };
 const m6 = const { 'a': 499 };
@@ skipping 55 matching lines @@
   Expect.throws(() => m2.remove('b'), isUnsupportedError);
   Expect.throws(() => m2.remove('c'), isUnsupportedError);
   Expect.throws(() => m2.clear(), isUnsupportedError);
   Expect.throws(() => m2['a'] = 499, isUnsupportedError);
   Expect.throws(() => m2['b'] = 42, isUnsupportedError);
   Expect.throws(() => m2['c'] = 499, isUnsupportedError);
   Expect.throws(() => m2.putIfAbsent('a', () => 499), isUnsupportedError);
   Expect.throws(() => m2.putIfAbsent('z', () => 499), isUnsupportedError);
   Expect.throws(() => m2['a'] = 499, isUnsupportedError);
 
-  Expect.isTrue(m3['m1'] === m1);
-  Expect.isTrue(m3['m2'] === m2);
+  Expect.isTrue(identical(m3['m1'], m1));

[Lasse Reichstein Nielsen, 2012/11/12 13:10:41]

Expect.identical

[floitsch, 2012/11/12 22:18:43]

Done.

+  Expect.isTrue(identical(m3['m2'], m2));
 
   Expect.listEquals(['z', 'a', 'm'], m4.keys);
   Expect.listEquals([9, 8, 7], m4.values);
   seenKeys = [];
   seenValues = [];
   m4.forEach((key, value) {
     seenKeys.add(key);
     seenValues.add(value);
   });
   Expect.listEquals(['z', 'a', 'm'], seenKeys);
   Expect.listEquals([9, 8, 7], seenValues);
 
   Expect.equals(499, m5['']);
   Expect.isTrue(m5.containsKey(''));
   Expect.equals(1, m5.length);
 
-  Expect.isTrue(m1 === m6);
+  Expect.isTrue(identical(m1, m6));
 
   Expect.isTrue(m7.isEmpty);
   Expect.equals(0, m7.length);
   Expect.equals(null, m7['b']);
   Expect.listEquals([], m7.keys);
   Expect.listEquals([], m7.values);
   Expect.isFalse(m7.containsKey('a'));
   Expect.isFalse(m7.containsKey('toString'));
   Expect.isFalse(m7.containsValue(499));
   Expect.isFalse(m7.containsValue(null));
   seenKeys = [];
   seenValues = [];
   m7.forEach((key, value) {
     seenKeys.add(key);
     seenValues.add(value);
   });
   Expect.listEquals([], seenKeys);
   Expect.listEquals([], seenValues);
   Expect.throws(() => m7.remove('a'), isUnsupportedError);
   Expect.throws(() => m7.remove('b'), isUnsupportedError);
   Expect.throws(() => m7.clear(), isUnsupportedError);
   Expect.throws(() => m7['b'] = 42, isUnsupportedError);
   Expect.throws(() => m7['a'] = 499, isUnsupportedError);
   Expect.throws(() => m7.putIfAbsent('a', () => 499),
                 isUnsupportedError);
   Expect.throws(() => m7.putIfAbsent('z', () => 499),
                 isUnsupportedError);
 }