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

tools/testing/dart/test_runner.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.
 
 /**
  * Classes and methods for executing tests.
  *
  * This module includes:
  * - Managing parallel execution of tests, including timeout checks.
  * - Evaluating the output of each test as pass/fail/crash/timeout.
@@ skipping 760 matching lines @@
     _executable = testCase.commands.last.executable;
     _batchArguments = testCase.batchRunnerArguments;
     _isWebDriver = testCase.usesWebDriver;
   }
 
   bool get active => _currentTest != null;
 
   void startTest(TestCase testCase) {
     Expect.isNull(_currentTest);
     _currentTest = testCase;
-    if (_process === null) {
+    if (_process == null) {
       // Start process if not yet started.
       _executable = testCase.commands.last.executable;
       _startProcess(() {
         doStartTest(testCase);
       });
     } else if (testCase.commands.last.executable != _executable) {
       // Restart this runner with the right executable for this test
       // if needed.
       _executable = testCase.commands.last.executable;
       _batchArguments = testCase.batchRunnerArguments;
@@ skipping 527 matching lines @@
         // the developer doesn't waste his or her time trying to fix a bunch of
         // tests that appear to be broken but were actually just flakes that
         // didn't get retried because there had already been one failure.
         bool allowRetry = _MAX_FAILED_NO_RETRY > _progress.numFailedTests;
         new RunningProcess(test, allowRetry, this).start();
       }
       _numProcesses++;
     }
   }
 }