public void GetHello_ReturnsExpectedResult()
{
// Arrange
var mockMessageServiceReturn = "Hello World";
var mockService = new Mock <IMessageService>();
mockService.Setup(svc => svc.GetMessage())
.Returns(mockMessageServiceReturn);
var controller = new DemoController(mockService.Object);
// Act
var result = controller.GetHello();
var okResult = result as OkObjectResult;
// Assert
okResult.Should().NotBe(null);
okResult?.StatusCode.Should().Be(200);
okResult?.Value.Should().Be("Hello World");
}