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My attempts at Roy Osherove's string calculator kata in Ruby.


Here's the description:

  1. Create a simple String calculator with a method int Add(string numbers)
    1. The method can take 0, 1 or 2 numbers, and will return their sum (for
       an empty string it will return 0) for example “” or “1” or “1,2”
    2. Start with the simplest test case of an empty string and move to 1 and
       two numbers
    3. Remember to solve things as simply as possible so that you force
       yourself to write tests you did not think about
    4. Remember to refactor after each passing test

  2. Allow the Add method to handle an unknown amount of numbers

  3. Allow the Add method to handle new lines between numbers (instead of
    1. the following input is ok:  “1\n2,3”  (will equal 6)
    2. the following input is NOT ok:  “1,\n”
    3. Make sure you only test for correct inputs. there is no need to test
       for invalid inputs for these katas

  4. Allow the Add method to handle a different delimiter:
    1. to change a delimiter, the beginning of the string will contain a
       separate line that looks like this:   “//[delimiter]\n[numbers…]”
       for example “//;\n1;2” should return three where the default
       delimiter is ‘;’ .
    2. the first line is optional. all existing scenarios should still be

  5. Calling Add with a negative number will throw an exception “negatives
     not allowed” - and the negative that was passed.if there are multiple
     negatives, show all of them in the exception message

  Stop here if you are a beginner. Continue if you can finish the steps so
  far in less than 30 minutes.

  6. Numbers bigger than 1000 should be ignored, so adding 2 + 1001  = 2

  7. Delimiters can be of any length with the following format:
     “//[delimiter]\n” for example: “//***\n1***2***3” should return 6

  8. Allow multiple delimiters like this:  “//[delim1][delim2]\n” for
     example “//[*][%]\n1*2%3” should return 6.

  9. make sure you can also handle multiple delimiters with length longer
     than one char

See branches for various versions.


This version (first_try):

Initial quick attempt (mostly on a train), with way too little refactoring
(in fact virtually none).

Passes the tests, but the intent of the code couldn't be much less clear.