public void GenericRetvalAsync()
        {
            var handler    = CreateClass("MyService", "GenericRetvalAsync")(new[] { typeof(string), typeof(int) });
            var pureRetval = new Dictionary <string, int> {
                { "one", 1 }, { "two", 2 }
            };

            service.GenericRetvalAsync <string, int>().Returns(Task.FromResult(pureRetval));

            var retvalCodec  = codecContainer.GetManualCodecFor <Dictionary <string, int> >();
            var expectedData = retvalCodec.EncodeSingle(pureRetval);

            var resultingTask = handler.Handle(service, null, 0);

            Assert.That(resultingTask.Result, Is.EqualTo(expectedData));
        }