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

tests/standalone/io/process_stderr_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.
 //
 // Process test program to test process communication.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
@@ skipping 20 matching lines @@
     void readData() {
       buffer.addAll(err.read());
       for (int i = received;
            i < min(data.length, buffer.length) - 1;
            i++) {
         Expect.equals(data[i], buffer[i]);
       }
       received = buffer.length;
       if (received >= dataSize) {
         // We expect an extra character on windows due to carriage return.
-        if (13 === buffer[dataSize - 1] && dataSize + 1 === received) {
+        if (13 == buffer[dataSize - 1] && dataSize + 1 == received) {
           Expect.equals(13, buffer[dataSize - 1]);
           Expect.equals(10, buffer[dataSize]);
           buffer.removeLast();
         }
       }
     }
 
     process.stdout.onData = process.stdout.read;
     process.stdin.write(data);
     process.stdin.close();
     err.onData = readData;
   });
 }
 
 main() {
   // Run the test using the process_test binary.
   test(Process.start(getProcessTestFileName(),
                      const ["1", "1", "99", "0"]), 99);
 
   // Run the test using the dart binary with an echo script.
   // The test runner can be run from either the root or from runtime.
   var scriptFile = new File("tests/standalone/io/process_std_io_script.dart");
   if (!scriptFile.existsSync()) {
     scriptFile = new File("../tests/standalone/io/process_std_io_script.dart");
   }
   Expect.isTrue(scriptFile.existsSync());
   test(Process.start(new Options().executable, [scriptFile.name, "1"]), 0);
 }