4yfn-kata

Coding kata for the 2018 4yfn event. The following is a TDD Kata, an exercise in coding, refactoring and test-first.

Before you start

• Try not to read ahead.
• Do one task at a time. The trick is to learn to work incrementally.
• Make sure you only test for correct inputs. There is no need to test for invalid inputs for this kata.
• There are several folders , each one belonging to a specific language or technology in which you can solve the exercise.
• Follow the red-green-refactor approach

Instructions

• Please create a separate git branch from master with your solution

  • git checkout master
  • git pull origin master
  • git checkout -b <your_branch_name> ( to create a branch from master). As branch name we suggest you to use your name and surname separated by underscores( e.g. markus_wallace)

• Commit each one of the requested tasks separately :

  • git add -u .
  • git commit -m "<message regarding the task you are solving>"

• Push your changes :

  • git push origin <your_branch_name>
  • The user and passwords if required will be given at the momment of solving the exercise

The kata

Step 1: the simplest thing

Create a simple String calculator with a method int add(String numbers).

• The string argument can contain 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".
• Start with the simplest test case of an empty string and move to one and two numbers.
• Remember to solve things as simply as possible so that you force yourself to write tests you did not think about.
• Remember to refactor after each passing test.

Step 2: handle an unknown amount of numbers

Allow the add() method to handle an unknown amount of numbers.

Step 3: handle new lines between numbers

Allow the add() method to handle new lines between numbers (instead of commas).

• the following input is ok: "1\n2,3" (will equal 6)
• the following input is NOT ok: "1,\n" (not need to prove it - just clarifying)

Step 4: negative numbers

Calling add() with a negative number will throw an exception "negatives not allowed" - and the negative that was passed.

For example add("1,4,-1") should throw an exception with the message "negatives not allowed: -1".

If there are multiple negatives, show all of them in the exception message.

Step 5: ignore big numbers

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