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

tests/standalone/io/socket_exception_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.
 //
 // Tests socket exceptions.
 
 #import("dart:isolate");
 #import("dart:io");
 
 class SocketExceptionTest {
 
   static const PORT = 0;
   static const HOST = "127.0.0.1";
 
   static void serverSocketExceptionTest() {
     bool exceptionCaught = false;
     bool wrongExceptionCaught = false;
 
     ServerSocket server = new ServerSocket(HOST, PORT, 10);
-    Expect.equals(true, server !== null);
+    Expect.equals(true, server != null);
     server.close();
     try {
       server.close();
     } on SocketIOException catch(ex) {
       exceptionCaught = true;
     } on Exception catch (ex) {
       wrongExceptionCaught = true;
     }
     Expect.equals(false, exceptionCaught);
     Expect.equals(true, !wrongExceptionCaught);
 
     // Test invalid host.
     Expect.throws(() => new ServerSocket("__INVALID_HOST__", PORT, 10),
                   (e) => e is SocketIOException);
   }
 
   static void clientSocketExceptionTest() {
     bool exceptionCaught = false;
     bool wrongExceptionCaught = false;
 
     ServerSocket server = new ServerSocket(HOST, PORT, 10);
-    Expect.equals(true, server !== null);
+    Expect.equals(true, server != null);
     int port = server.port;
     Socket client = new Socket(HOST, port);
     client.onConnect = () {
-      Expect.equals(true, client !== null);
+      Expect.equals(true, client != null);
       InputStream input = client.inputStream;
       OutputStream output = client.outputStream;
       client.close();
       try {
         client.close();
       } on SocketIOException catch(ex) {
         exceptionCaught = true;
       } on Exception catch (ex) {
         wrongExceptionCaught = true;
       }
@@ skipping 56 matching lines @@
 
       server.close();
     };
   }
 
   static void indexOutOfRangeExceptionTest() {
     bool exceptionCaught = false;
     bool wrongExceptionCaught = false;
 
     ServerSocket server = new ServerSocket(HOST, PORT, 10);
-    Expect.equals(true, server !== null);
+    Expect.equals(true, server != null);
     int port = server.port;
     Socket client = new Socket(HOST, port);
     client.onConnect = () {
-      Expect.equals(true, client !== null);
+      Expect.equals(true, client != null);
       try {
         List<int> buffer = new List<int>(10);
         client.readList(buffer, -1, 1);
       } on RangeError catch (ex) {
         exceptionCaught = true;
       } on Exception catch (ex) {
         wrongExceptionCaught = true;
       }
       Expect.equals(true, exceptionCaught);
       Expect.equals(true, !wrongExceptionCaught);
@@ skipping 54 matching lines @@
     clientSocketExceptionTest();
     indexOutOfRangeExceptionTest();
     unknownHostTest();
   }
 }
 
 main() {
   SocketExceptionTest.testMain();
 }