Fix bug in the unittest's withTestEnvironment package and apply more feedback from nweiz.

pkg/unittest/lib/unittest.dart

 // Copyright (c) 2013, 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.
 
 /// Support for writing Dart unit tests.
 ///
 /// For information on installing and importing this library, see the
 /// [unittest package on pub.dartlang.org]
 /// (http://pub.dartlang.org/packages/unittest).
 ///
@@ skipping 144 matching lines @@
 
 const Symbol _UNITTEST_ENVIRONMENT = #unittest.environment;
 
 final _TestEnvironment _defaultEnvironment = new _TestEnvironment();
 
 /**
  * Internal getter for the current unittest config.
  */
 _TestEnvironment get _environment {
   var environment = Zone.current[_UNITTEST_ENVIRONMENT];
-  if (environment == null)
-    return _defaultEnvironment;
+  if (environment == null) return _defaultEnvironment;
   return environment;
 }
 
 // Convenience getter for the current environment's config.
 Configuration get _config => _environment.config;
 
 // Convenience setter for the current environment's config.
 void set _config(Configuration config) {
   _environment.config = config;
 }
@@ skipping 26 matching lines @@
 
 /// Can be called by tests to log status. Tests should use this
 /// instead of [print].
 void logMessage(String message) =>
     _config.onLogMessage(currentTestCase, message);
 
 /// Separator used between group names and test names.
 String groupSep = ' ';
 
 /// Tests executed in this suite.
-final List<TestCase> testCases =
+List<TestCase> get testCases =>
     new UnmodifiableListView<TestCase>(_environment.testCases);
 
 /// Interval (in msecs) after which synchronous tests will insert an async
 /// delay to allow DOM or other updates.
 const int BREATH_INTERVAL = 200;
 
 /// [TestCase] currently being executed.
 TestCase get currentTestCase =>
     (_environment.currentTestCaseIndex >= 0 &&
      _environment.currentTestCaseIndex < testCases.length)
@@ skipping 367 matching lines @@
 ///
 /// This allows for multiple invocations of the unittest library in the same
 /// application instance.
 /// This is useful when, for example, creating a test runner application which
 /// needs to create a new pristine test environment on each invocation to run
 /// a given set of test.
 dynamic withTestEnvironment(callback()) {
   return runZoned(callback,
       zoneValues: {_UNITTEST_ENVIRONMENT: new _TestEnvironment()});
 }