Fix issue 4227 - unittest.dart silently consumes exceptions when expectAsync is active.

lib/unittest/unittest.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 library for writing dart unit tests.
  *
  * To import this library, specify the relative path to
  * lib/unittest/unittest.dart.
  *
@@ skipping 704 matching lines @@
       // If a random exception is thrown from within a test, we consider that
       // a test failure too. A test case implicitly has an expectation that it
       // will run to completion without an uncaught exception being thrown.
       _tests[_currentTest].fail('Caught $e',
           trace == null ? '' : trace.toString());
     } else if (_state != _UNCAUGHT_ERROR) {
       _tests[_currentTest].error('Caught $e',
           trace == null ? '' : trace.toString());
     }
   }
+  _nextTestCase();

[Siggi Cherem (dart-lang), 2012/08/01 00:11:16]

I'm thinking more about this, and I don't know if this is entirely correct - for
example, if we have 2 async tests one after another, this will possibly advance
to a later test that is not related to where the failure happened:

#library('foo_test');
#import('dart:html');
#import('../../../lib/unittest/unittest.dart');
#import('../../../lib/unittest/html_config.dart');

void main() {
  useHtmlConfiguration();
  test('one', () {
    var f = expectAsync0(() {});
    window.setTimeout(() => expect(false), 0);

    // 'two' will be marked as failed because of this
    window.setTimeout(() => expect(false), 0);
  });

  test('two', () {
    window.setTimeout(expectAsync0(() {}), 60);
  });
}

 }
 
 /**
  * Runs a batch of tests, yielding whenever an asynchronous test starts
  * running. Tests will resume executing when such asynchronous test calls
  * [done] or if it fails with an exception.
  */
 _nextBatch() {
   while (_currentTest < _tests.length) {
     final testCase = _tests[_currentTest];
@@ skipping 97 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 void TestFunction();