public async Task ClearAsyncTest()
        {
            DictionaryChange change = null;
            TransactedConcurrentDictionary <int, string> d = new TransactedConcurrentDictionary <int, string>(
                new Uri("test://mocks", UriKind.Absolute),
                (c) =>
            {
                change = c;
                return(true);
            }
                );

            using (var tx = _stateManager.CreateTransaction())
            {
                await d.AddAsync(tx, 1, "One");

                await tx.CommitAsync();

                Assert.AreEqual(1, await GetCount(d));
            }

            change = null;
            await d.ClearAsync();

            Assert.AreEqual(0, await GetCount(d));
            Assert.IsNull(change);
        }