public void CalculateTrolley_ReturnsOk_WithDecimal()
        {
            _mockManager.Setup(x => x.CalculateTrolleyTotalAsync(It.IsAny <TrolleyVM>()))
            .ReturnsAsync((decimal)40.5);

            IActionResult result = _controller.CalculateTrolley(GetTrolley());

            var objectResult = Assert.IsType <OkObjectResult>(result);

            Assert.IsType <decimal>(objectResult.Value);
        }