public void Incidents_AddAttachment() { var anAttachment = new Attachment { Id = 0 }; var parameters = new Dictionary <string, object> { { "file_name", anAttachment.FileName }, { "description", anAttachment.Description }, }; // Set test Create method w/o parameters request.Setup(m => m.Post <Response <Attachment> >("incidents/666/attachments", anAttachment.Data, parameters)).Returns(new Response <Attachment> { Data = new Attachment { Id = 1234 } }); // Test Get method var result = incidentsProxy.AddAttachment(666, anAttachment); // Verify test Assert.IsNotNull(result); Assert.IsTrue(result.IsSuccessful); Assert.AreEqual(1234, result.Data.Id); }