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).
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
- 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
- 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 equal 6)
- the following input is NOT ok: “1,\n” (not need to prove it - just clarifying)
- 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
- 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.
- 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 return 6
- Allow multiple delimiters like this: “//[delim1][delim2]\n” for example “//[*][%]\n1*2%3” should return 6.
- make sure you can also handle multiple delimiters with length longer than one char
Online Training by Roy Osherove
- .NET: The Art of Unit Testing and TDD in .NET Online
- .NET: Legacy Code Hero (Advanced Refactoring Patterns)
Here are several run throughs of the kata by different people in various languages:
(want to show off your own version of this kata? video it and ping me)
- Java: The Kata done in Java and LamdaJ
- Java: another version in Java and Eclipse
- Ruby: Corey Haines does the kata in Ruby (here are my comments)
- Python: The Kata done in Python
- Scala: The Kata done in Scala
- C#: Andrew Woodward doing the kata mouseless in C# with NUnit
- Another C# version of the kata with NUnit
- The kata in C# with XUnit
- The Kata in C# with MSTest
- The kata in C# on LinqPad
- The kata in F# (with great music, I might add)
- TypeScript: The Kata in Typescript
- LUA: The Kata done in the lua language
- Erlang: The Kata done in Erlang
- C++: The Kata done in C++ with CPPUnit
- The Kata in C++ with Igloo
- Objective-C: The kata done in OCUnit with Objective-C
- Haskell: The Kata done in Haskell
- Scheme: The Kata done in Scheme
- ActionScript: The kata done in ActionScript 3 and Flex
- SmallTalk: The kata in Pharo SmallTalk
- AutoHotKey script (yeah, seriously) : The kata in AutoHotKey
- Perl: The kata in Perl
- PHP: The kata in PHP