public void SumByCategoryFilterShouldWork(string expected, Month month)
        {
            // Arrange
            // Act
            string actual = "";
            var    result = clientProcessor.SumByCategory(customers[0], month);

            foreach (var item in result)
            {
                actual += $"{item.Key.Name} {item.Value} ";
            }
            // Assert
            Assert.Equal(expected, actual);
        }