Move the addition of an onError handler to earlier (onInit instead of onStart), while still support…

pkg/unittest/html_config.dart

 // Copyright (c) 2011, 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 simple unit test library for running tests in a browser.
  */
 #library('unittest');
 
 #import('dart:html');
 #import('unittest.dart');
 
 #source('html_print.dart');
 
 class HtmlConfiguration extends Configuration {
   /** Whether this is run within dartium layout tests. */
   final bool _isLayoutTest;
   HtmlConfiguration(this._isLayoutTest);
 
   // TODO(rnystrom): Get rid of this if we get canonical closures for methods.
   EventListener _onErrorClosure;
 
+  void _installErrorHandler() {
+    if (_onErrorClosure == null) {
+      _onErrorClosure =
+          (e) => handleExternalError(e, '(DOM callback has errors)');
+      // Listen for uncaught errors.
+      window.on.error.add(_onErrorClosure);
+    }
+  }
+
+  void _removeErrorHandler() {

[Siggi Cherem (dart-lang), 2012/09/20 20:41:31]

maybe rename [_removeErrorHandler] to [_uninstallErrorHandler] (to
match/contrast the _install name above)

[gram, 2012/09/20 20:48:29]

Done.

+    if (_onErrorClosure != null) {
+      window.on.error.remove(_onErrorClosure);
+      _onErrorClosure = null;
+    }
+  }
+
   void onInit() {
-    _onErrorClosure =
-        (e) => handleExternalError(e, '(DOM callback has errors)');
+    _installErrorHandler();
   }
 
   void onStart() {
+    _installErrorHandler();
     window.postMessage('unittest-suite-wait-for-done', '*');
-    // Listen for uncaught errors.
-    window.on.error.add(_onErrorClosure);
   }
 
   void onTestResult(TestCase testCase) {}
 
   void onDone(int passed, int failed, int errors, List<TestCase> results,
       String uncaughtError) {
-    window.on.error.remove(_onErrorClosure);
+    _removeErrorHandler();

[Siggi Cherem (dart-lang), 2012/09/20 20:41:31]

since the idea of detaching/reataching it is mostly for the interactive config,
you could make that this config doesn't install/remove it on onStart/onDone, but
only sets it up once on onInit

[gram, 2012/09/20 20:48:29]

Done.

     _showResultsInPage(passed, failed, errors, results, _isLayoutTest,
         uncaughtError);
     window.postMessage('unittest-suite-done', '*');
   }
 }
 
 void useHtmlConfiguration([bool isLayoutTest = false]) {
   configure(new HtmlConfiguration(isLayoutTest));
 }