public void Can_enumerate_and_add_to_journal_concurrently() { var source = new SpeechJournalSource(); var journal = new SpeechJournal(source, null); source.AddMessage("name", "first message", new ObjectId(0), 0); using (var enumerator = journal.GetEnumerator()) { enumerator.MoveNext().Should().BeTrue(); enumerator.Current.Message.Should().Be("first message"); source.AddMessage("name", "second, concurrently added message", new ObjectId(0), 0); enumerator.MoveNext().Should().BeFalse(); } }