(Just a small post mostly for myself, in case i forget) I've been playing a bit with ruby the last couple of days, mostly because i migth get to use it at work later on and a saw i short demo by Thomas Lundström on cucumber at the latest Alt.Net Öresund meeting. However his demo was on IronRuby testing .Net code and it was too slow to be useful . So here's a short summary of how to implement the example on the cucmber homepage. First the feature, just a plain text file defining the scenario we want to test:

Feature: Addition
  In order to aviod silly misstakes
  As a math idiot
  I want to be told the sum of two numbers

  Scenario: Add two numbers
    Given I have entered 50 into the calculator
    And I have entered 70 into the calculator
    When I press add
    Then The result should be 120 on the screen

Next is the parser, that parses the feature, so no magic here. Unless you think RegEx is magic.

require 'spec/expectations'

Before do
	@calculator = Calculator.new
end

Given /^I have entered (\d+) into the calculator$/ do |n|
  @calculator.push(n.to_i)
end

When /^I press (\w+)$/ do |op|
  @result = @calculator.op(op)
end

Then /^The result should be (\d+) on the screen$/ do |n|
  @result.should == n.to_f
end

Then the Implementation, this once just has a couple of methods, but can be extened with more if needed.

class Calculator
  def push(n)
    @args ||= []
    @args << n
  end

  def op(type)
	res = 0
	case type
		when "add"
				@args.each do |input|
				  res += input
				end
	end
	res
  end
end

So, to run it you need to have Cucubmer & RSpec installed, fastest way to install them is to do:

gem install cucumber
gem install rspec

When everything is installed just do

cucumber addition.feature

and your result should look something like this:

Feature: Addition
  In order to aviod silly misstakes
  As a math idiot
  I want to be told the sum of two numbers

  Scenario: Add two numbers                     # addition.feature:6
    Given I have entered 50 into the calculator # steps.rb:7
    And I have entered 70 into the calculator   # steps.rb:7
    When I press add                            # steps.rb:11
    Then The result should be 120 on the screen # steps.rb:15

1 scenario
4 passed steps

But all the lines starting with Given, And, When, Then should be in green if the test passed