Check if string is empty instead of checking if it is equal to the empty string
Handle one number add correctly for all numbers
Moved int parsing to private function
Added test for two numbers
Added test for many numbers
Moved adding numbers to a private function
Added test for newline delimeter
Added test for multiple delimeters
Some refactoring
Added test for custom delimeter
Refactored splitNumbers into one function
Added test for negative numbers
Added test for one number, that is negative
Moved throwing error to seperate function
Refactored checking for negative numbers, and some more
Added test for numbers above 1000
Added test for variable length delimeter
Added test for a RegEx special character delimeter
Refactored checking for special characters
Added test for any multiple delimeters