public void CanAddProduct_NullProduct_ThrowsException()
        {
            // Arrange
            ProductValidator productValidator = new ProductValidator();
            Product          product          = null;

            // Act
            // Assert
            Assert.ThrowsException <ArgumentNullException>(() => productValidator.CanAddProduct(product));
        }
        public void CanAddProduct_ProductHasEmptyPrice_ReturnErrorMessage()
        {
            // Arrange
            ProductValidator productValidator = new ProductValidator();
            Product          product          = new Product();

            product.Name        = "Name";
            product.Description = "Description";
            // Act
            List <KeyValuePair <string, string> > result = productValidator.CanAddProduct(product);

            // Assert
            Assert.IsNotNull(result);
            Assert.AreEqual(1, result.Count);
            Assert.AreEqual("Price", result[0].Key);
        }