public void Hello_Should_ReturnExpectedWelcomeMessage() { const string welcomeMessage = "TEST"; const string name = "Bob"; var expectedWelcome = $"{welcomeMessage} {name}"; var mockOptions = new Mock <IOptions <MessagesConfiguration> >(); mockOptions.Setup(x => x.Value).Returns(new MessagesConfiguration { WelcomeMessage = welcomeMessage }); var sut = new SampleController(mockOptions.Object, new NullLogger <SampleController>()); var actionResult = sut.Hello(name); var okResult = actionResult.Result.Should().BeAssignableTo <OkObjectResult>() .Which.Value.Should().BeAssignableTo <HelloOutputModel>() .Which.WelcomeMessage.Should().Be(expectedWelcome); }