public async Task GivenFittingDate_WhenGetTotalBuysIsCalled_ThenReturnTotalPriceAsDecimal()
{
//Arrange
_mockOrderIitemsService.Setup(x => x.GetTotalBuys(new DateTime(2018, 5, 12))).ReturnsAsync(It.IsAny <decimal>());
var sut = new OrderItemsController(_mockOrderIitemsService.Object);
//Act
var result = await sut.GetTotalBuys(It.IsAny <DateTime>());
//Assert
Assert.AreEqual(It.IsAny <decimal>(), result);
Assert.IsInstanceOf <decimal>(result);
_mockOrderIitemsService.Verify(x => x.GetTotalBuys(It.IsAny <DateTime>()), Times.Exactly(1));
}