public void Attachments_Update()
        {
            var anAttachment = new Attachment
            {
                Id = 1234
            };

            // Set test Create method w/o parameters
            request.Setup(m => m.Post <Response <Attachment> >("attachments/1234", anAttachment, null)).Returns(new Response <Attachment>
            {
                Data = anAttachment
            });

            // Test Get method
            var result = attachmentsProxy.Update(anAttachment);

            // Verify test
            Assert.IsNotNull(result);
            Assert.IsTrue(result.IsSuccessful);
            Assert.AreEqual(1234, result.Data.Id);
        }