public void Enter_WhenCompleted_LockIsAcquired()
{
_mutex.Enter(Key);
using (var cancellationTokenSource = new CancellationTokenSource(TimeSpan.FromSeconds(3)))
{
Assert.Throws <OperationCanceledException>(
() => _mutex.EnterAsync(Key, cancellationTokenSource.Token).GetAwaiter().GetResult());
}
_mutex.Exit(Key);
}