public void TestValidate_WithValidPageSize_NoValidationError(
            GetSalesOrdersQueryValidator sut,
            GetSalesOrdersQuery query
            )
        {
            //Act
            var result = sut.TestValidate(query);

            //Assert
            result.ShouldNotHaveValidationErrorFor(query => query.PageSize);
            result.ShouldNotHaveValidationErrorFor(query => query.PageIndex);
        }
        public void TestValidate_WithInvalidPageIndex_ValidationError(
            GetSalesOrdersQueryValidator sut,
            GetSalesOrdersQuery query
            )
        {
            //Arrange
            query.PageIndex = -1;

            //Act
            var result = sut.TestValidate(query);

            //Assert
            result.ShouldHaveValidationErrorFor(query => query.PageIndex)
            .WithErrorMessage("Page index must be 0 or positive");
        }
        public void TestValidate_WithInvalidPageSize_ValidationError(
            GetSalesOrdersQueryValidator sut,
            GetSalesOrdersQuery query
            )
        {
            //Arrange
            query.PageSize = 0;

            //Act
            var result = sut.TestValidate(query);

            //Assert
            result.ShouldHaveValidationErrorFor(query => query.PageSize)
            .WithErrorMessage("Page size must be positive");
        }