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

pkg/logging/test/logging_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.
 
 
 library logging_test;
 
 // TODO(rnystrom): Use "package:" import when test.dart supports it (#4968).
 import '../lib/logging.dart';
 import '../../../pkg/unittest/lib/unittest.dart';
 
 main() {
   test('level comparison is a valid comparator', () {
     var level1 = const Level('NOT_REAL1', 253);
     expect(level1 == level1, isTrue);
     expect(level1 <= level1, isTrue);
     expect(level1 >= level1, isTrue);
     expect(level1 < level1, isFalse);
     expect(level1 > level1, isFalse);
 
     var level2 = const Level('NOT_REAL2', 455);
     expect(level1 <= level2, isTrue);
     expect(level1 < level2, isTrue);
     expect(level2 >= level1, isTrue);
     expect(level2 > level1, isTrue);
 
     var level3 = const Level('NOT_REAL3', 253);
-    expect(level1 !== level3, isTrue); // different instances
+    expect(!identical(level1, level3), isTrue); // different instances
     expect(level1 == level3, isTrue); // same value.
   });
 
   test('default levels are in order', () {
     final levels = const [
         Level.ALL, Level.FINEST, Level.FINER, Level.FINE, Level.CONFIG,
         Level.INFO, Level.WARNING, Level.SEVERE, Level.SHOUT, Level.OFF
       ];
 
     for (int i = 0; i < levels.length; i++) {
@@ skipping 56 matching lines @@
     expect(a == c.parent, isTrue);
     expect(a.children['b'] == b, isTrue);
     expect(a.children['c'] == c, isTrue);
   });
 
   test('loggers are singletons', () {
     Logger a1 = new Logger('a');
     Logger a2 = new Logger('a');
     Logger b = new Logger('a.b');
     Logger root = Logger.root;
-    expect(a1 === a2, isTrue);
-    expect(a1 === b.parent, isTrue);
-    expect(root === a1.parent, isTrue);
-    expect(root === new Logger(''), isTrue);
+    expect(identical(a1, a2), isTrue);
+    expect(identical(a1, b.parent), isTrue);
+    expect(identical(root, a1.parent), isTrue);
+    expect(identical(root, new Logger('')), isTrue);
   });
 
   group('mutating levels', () {
     Logger root = Logger.root;
     Logger a = new Logger('a');
     Logger b = new Logger('a.b');
     Logger c = new Logger('a.b.c');
     Logger d = new Logger('a.b.c.d');
     Logger e = new Logger('a.b.c.d.e');
 
@@ skipping 209 matching lines @@
             'SHOUT: 10']));
 
       expect(cMessages, equals([
             // 1 - 7 are lower in the hierarchy
             // 'FINE: 8' is not loggable
             'WARNING: 9',
             'SHOUT: 10']));
     });
   });
 }