String Calculator

The goal of this project is to create two functions: Converter.toUnsignedInt() and Calculator.sum(). The development for these two functions will be done with TDD.

toUnsignedInt()

This function will take in a string that contains only not letters or special characters. Assume the frontend will limit the available input through a standard number input keyboard seen on the right in the below image.

Business Requirements

1. Input will limited on the front-end to contain only the following characters: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, _, -, ,
2. A unique exception should be thrown when the input contains a decimal (.)
3. A unique exception should be thrown when the input contains a dash (-)
4. A unique exception should be thrown when the input contains a underscore (_)
5. A unique exception should be thrown when the input contains a comma (,)
6. A unique exception should be thrown when the input is longer than 3 digits

sum()

Should compute the sum of an array of numbers, each represented in a string.

Business Requirements

1. When there are no inputs, return 0
   • sum([]) = 0
2. When there is one input, return that number
   • sum(["2"]) = 2
   • sum(["17"]) = 17
3. When there are two or more inputs, return the sum
   • sum(["1", "5"]) = 6
   • sum(["20", "3", "8"]) = 31
4. If any exception occurs, throw a CalculationException
   • sum(["-1", "3", "8"]) = !!CalculationException
   • sum(["4", ".25", "9"]) = !!CalculationException
   • sum(["_", "7"]) = !!CalculationException
   • sum([","]) = !!CalculationException
   • sum(["20", "3", "9108"]) = !!CalculationException