public async void UpdatebyProduct_CallsUpdatebyProductOnMockRepo_ReturnsCreatedObjectResult()
{
//Arrange
int productId = 1;
var newProduct = new Product()
{
};
mockRepo.Setup(repo => repo.UpdatebyProduct(newProduct)).Returns(Task.FromResult <Product>(newProduct));
//Act
var result = await controller.UpdatebyProduct(productId, newProduct);
var resultObj = result as OkObjectResult;
//Asset
mockRepo.Verify(repo => repo.UpdatebyProduct(newProduct), Times.Once);
Assert.NotNull(resultObj);
Assert.Equal(200, resultObj.StatusCode);
}