String Calculator Kata TDD Workshop

This repo contains an exercise for our third workshop. This workshop is about TDD. For this session we have based our activities on Roy Osherove's String Calculator kata.

We've restructured the repository to provide a quick-start to TDD with RSpec and to mimic the setup we used last time. The code to be created is found in the lib/ directory, and we have supplied unit tests in the spec/ directory.

###Setup

Here are the steps to get you started with the repo. We assume, naturally, that you have a working development machine with Ruby 1.9 or better on it. At Ryatta Group we use rbenv, and so we've included some optional elements - just skip them if you're using rvm or are not versioning your Ruby.

% git clone git@github.com:k00ka/string-kata.git
% cd string-kata
% gem install bundler
Fetching: bundler-1.7.4.gem (100%)
Successfully installed bundler-1.7.4
1 gem installed
% bundle
Fetching gem metadata from https://rubygems.org/.........
Resolving dependencies...
Installing rake 10.3.2
...
Using bundler 1.7.4
Your bundle is complete!
Use `bundle show [gemname]` to see where a bundled gem is installed.

######Note: if you use rbenv...

% rbenv rehash

You are (almost) there!

###TDD If you want to learn (more) about TDD, there are plenty of online resources. For a quick primer, you can review our blog post from the previous workshop: [http://www.ryatta.com/refactoring-in-context/]

Tonight (or below if you're doing this kata on your own), I’m going to give you some directions for what your solution should do. In response to these requests, you are going to:

Write a test or tests that translate my request into code
Demonstrate to yourself that those test(s) fail
Implement modifications to make the tests pass
Share your implementation with the team

We'll iterate on this pattern about 11 times so you can practice the TDD workflow.

####Tips

Implement the simplest code you can imagine to make the tests pass.
Once the tests pass, refactor the code to simplify it.
Let earlier tests stand, they will catch regressions.
Discuss edge cases and obscure aspects with the customer or others on your team.

###How to test

There is an empty file (well, almost empty) in the lib/ directory. It is called string_calculator.rb. This is part 1 of your deliverable.

There is a unit test file in the spec/ directory called string_calculator_spec.rb. This is part 2 of your deliverable.

To "pass the String Kata", you need to make both files work together. To run the tests we have written against the code we've developed, do the following:

%rspec
F

Failures:

  1) StringCalculator#add returns 0 for empty string
     Failure/Error: expect("").to eq(0)
       
       expected: 0
            got: ""
       
       (compared using ==)
     # ./spec/string_calculator_spec.rb:11:in `block (2 levels) in <top (required)>'

Finished in 0.00108 seconds (files took 0.10543 seconds to load)
1 example, 1 failure

Failed examples:

rspec ./spec/string_calculator_spec.rb:10 # StringCalculator#add returns 0 for empty string

The text 1 failure means you're currently "failing the String Kata"! Now go fix some code and share what you've learned with the group.

###Final Notes

DHH has come out to say that he doesn't follow TDD [http://david.heinemeierhansson.com/2014/tdd-is-dead-long-live-testing.html]. His main concerns were with regard to the unintended impacts on system design that TDD were creating. His preferred approach is to focus on System Testing. Stay tuned to the Ryatta blog for an imformative post about this very topic (how timely!)

callunity/ruby_testing

String Calculator Kata TDD Workshop