pkg/unittest: config refactor

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.
 
 /**
  * A library for writing dart unit tests.
  *
  * To import this library, install the
  * [unittest package](http://pub.dartlang.org/packages/unittest) via the pub
  * package manager. See the [Getting Started](http://pub.dartlang.org/doc)
@@ skipping 138 matching lines @@
  *         });
  *       });
  *     }
  *
  */
 library unittest;
 
 import 'dart:async';
 import 'dart:isolate';
 import 'matcher.dart';
+import 'package:meta/meta.dart';
 export 'matcher.dart';
 
 // TODO(amouravski): We should not need to import mock here, but it's necessary
 // to enable dartdoc on the mock library, as it's not picked up normally.
 import 'mock.dart';
 
 part 'src/config.dart';
 part 'src/test_case.dart';
 
+Configuration _config;
+
 /** [Configuration] used by the unittest library. */
-Configuration _config = null;
-
 Configuration get config => _config;
 
 /**
- * Set the [Configuration] used by the unittest library. Returns any
- * previous configuration.
- * TODO: consider deprecating in favor of a setter now we have a getter.
+ * Sets the [Configuration] used by the unittest library.
+ *
+ * Throws an exception if a value has already been set to a different value.
  */
-Configuration configure(Configuration config) {
-  Configuration _oldConfig = _config;
-  _config = config;
-  return _oldConfig;
+void set config(Configuration value) {
+  if(!identical(_config, value)) {
+    if(_config != null) {
+      throw 'config has already been set';
+    }
+    _config = value;
+  }
+}
+
+/**
+ * Use [config] instead.
+ */
+@deprecated
+Configuration configure(Configuration value) {
+  var oldConfig = config;
+  config = value;
+  return oldConfig;
 }
 
 void logMessage(String message) => _config.logMessage(message);
 
 /**
  * Description text of the current test group. If multiple groups are nested,
  * this will contain all of their text concatenated.
  */
 String _currentGroup = '';
 
@@ skipping 608 matching lines @@
     return;
   }
   _initialized = true;
   // Hook our async guard into the matcher library.
   wrapAsync = (f, [id]) => expectAsync1(f, id: id);
 
   _tests = <TestCase>[];
   _uncaughtErrorMessage = null;
 
   if (_config == null) {
-    _config = new Configuration();
+    config = new Configuration();
   }
   _config.onInit();
 
   if (_config.autoStart) {
     // Immediately queue the suite up. It will run after a timeout (i.e. after
     // main() has returned).
     _defer(runTests);
   }
 }
 
@@ skipping 23 matching lines @@
 }
 
 /** Enable a test by ID. */
 void enableTest(int testId) => _setTestEnabledState(testId, true);
 
 /** Disable a test by ID. */
 void disableTest(int testId) => _setTestEnabledState(testId, false);
 
 /** Signature for a test function. */
 typedef dynamic TestFunction();