public void TestMicrowaveOven_WriteMessageMethod() { Mock <IWriter> writer = new Mock <IWriter>(); Mock <IRepository> repo = new Mock <IRepository>(); IClient microwave = new MicrowaveOven(writer.Object, repo.Object); microwave.WriteMessage(Msg); writer.Verify(w => w.WriteLine(It.Is <string>(s => s == Msg)), Times.Once, "Message hasn't been sent!"); }