public async Task DismissGeneratesCorrectRequest()
        {
            NotificationClient client = null;

            client = GetClient(req =>
            {
                Assert.Equal(HttpMethod.Delete, req.Method);
                Assert.Equal(req.RequestUri.ToString(), client.NotificationUri("xxx", "dismiss").ToString());
                Assert.Equal("xxx", req.Headers.Authorization.Parameter);
                return(new HttpResponseMessage(HttpStatusCode.Accepted));
            });
            await client.Dismiss("xxx");
        }