public void TestDispose1()
{
var filter = new EmptyLogLineFilter();
FilteredLogFile file = new FilteredLogFile(_taskScheduler, TimeSpan.Zero, _logFile.Object, filter, null);
_logFile.Verify(x => x.AddListener(It.Is <ILogFileListener>(y => Equals(y, file)),
It.IsAny <TimeSpan>(),
It.IsAny <int>()), Times.Once, "because the filtered log file should register itself as a listener with its source");
new Action(() => file.Dispose()).Should().NotThrow("because Dispose() must always succeed");
_logFile.Verify(x => x.RemoveListener(It.Is <ILogFileListener>(y => Equals(y, file))), Times.Once,
"because the filtered log file should unregister itself as a listener from its source when being disposed of");
}