The following is a TDD Kata- an exercise in coding, refactoring and test-first, that you should apply daily for at least 15 minutes (I do 30).
- 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
- Create a simple String calculator with a method int Add(string numbers)
- 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”
- Start with the simplest test case of an empty string and move to 1 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
- The method can take 0, 1 or 2 numbers, and will return their sum (for an empty string it will return 0) for example
- Allow the Add method to handle an unknown amount of numbers
- Allow the Add method to handle new lines between numbers (instead of commas).
- The following input is ok:
“1\n2,3”
(will equal6
) - The following input is NOT ok:
“1,\n”
- The following input is ok:
- Support different delimiters
- 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‘;’
. - The first line is optional. All existing scenarios should still be supported
- To change a delimiter, the beginning of the string will contain a separate line that looks like this:
- 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
N.B. Stop here if you are a beginner. Continue if you can finish the steps so far in less than 30 minutes.
- Numbers bigger than 1000 should be ignored, so adding
2 + 1001 = 2
- Delimiters can be of any length with the following format:
“//[delimiter]\n”
for example:“//[***]\n1***2***3”
should return6
- Allow multiple delimiters:
“//[delim1][delim2]\n”
- For example
“//[*][%]\n1*2%3”
should return6
.
- For example
- Make sure you can also handle multiple delimiters with length longer than one char
- Run
bundle install
- Run the tests with
ruby test/test_string_calculator.rb