public async Task Lock_DefaultGrantedAfterUpdateDowngrade()
{
Lock <int> l = new Lock <int>();
AcquireResult result;
result = await l.Acquire(1, LockMode.Update);
Assert.AreEqual(AcquireResult.Acquired, result);
var task = l.Acquire(2, LockMode.Default);
l.Downgrade(1);
result = await task;
Assert.AreEqual(AcquireResult.Acquired, result);
}