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

pkg/unittest/lib/mock.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.
 
 /**
  * A simple mocking/spy library.
  *
  * To create a mock objects for some class T, create a new class using:
  *
  *     class MockT extends Mock implements T {};
@@ skipping 180 matching lines @@
               arg6 = _noArg,
               arg7 = _noArg,
               arg8 = _noArg,
               arg9 = _noArg]) {
     if (name == null) {
       nameFilter = anything;
     } else {
       nameFilter = wrapMatcher(name);
     }
     argMatchers = new List<Matcher>();
-    if (arg0 === _noArg) return;
+    if (identical(arg0, _noArg)) return;
     argMatchers.add(wrapMatcher(arg0));
-    if (arg1 === _noArg) return;
+    if (identical(arg1, _noArg)) return;
     argMatchers.add(wrapMatcher(arg1));
-    if (arg2 === _noArg) return;
+    if (identical(arg2, _noArg)) return;
     argMatchers.add(wrapMatcher(arg2));
-    if (arg3 === _noArg) return;
+    if (identical(arg3, _noArg)) return;
     argMatchers.add(wrapMatcher(arg3));
-    if (arg4 === _noArg) return;
+    if (identical(arg4, _noArg)) return;
     argMatchers.add(wrapMatcher(arg4));
-    if (arg5 === _noArg) return;
+    if (identical(arg5, _noArg)) return;
     argMatchers.add(wrapMatcher(arg5));
-    if (arg6 === _noArg) return;
+    if (identical(arg6, _noArg)) return;
     argMatchers.add(wrapMatcher(arg6));
-    if (arg7 === _noArg) return;
+    if (identical(arg7, _noArg)) return;
     argMatchers.add(wrapMatcher(arg7));
-    if (arg8 === _noArg) return;
+    if (identical(arg8, _noArg)) return;
     argMatchers.add(wrapMatcher(arg8));
-    if (arg9 === _noArg) return;
+    if (identical(arg9, _noArg)) return;
     argMatchers.add(wrapMatcher(arg9));
   }
 
   /**
    * We keep our behavior specifications in a Map, which is keyed
    * by the [CallMatcher]. To make the keys unique and to get a
    * descriptive value for the [CallMatcher] we have this override
    * of [toString()].
    */
   String toString() {
@@ skipping 180 matching lines @@
       }
     }
     d.add(') ${action == Action.THROW ? "threw" : "returned"} ');
     d.addDescriptionOf(value);
     return d.toString();
   }
 }
 
 /** Utility function for optionally qualified method names */
 String _qualifiedName(owner, String method) {
-  if (owner == null || owner === anything) {
+  if (owner == null || identical(owner, anything)) {
     return method;
   } else if (owner is Matcher) {
     Description d = new StringDescription();
     d.addDescriptionOf(owner);
     d.add('.');
     d.add(method);
     return d.toString();
   } else {
     return '$owner.$method';
   }
@@ skipping 1033 matching lines @@
       }
     }
   }
 
   /** Clear both logs and behavior. */
   void reset() {
     resetBehavior();
     clearLogs();
   }
 }