example for rspec and rcov

Calc.rb

class Calc
  def initialize
    @value = 0
  end

  def add(value)
    @value += value
  end

  def sub(value)
    @value -= value
  end

  def div(value)
    @value /= value
  end

  attr_reader :value
end

Calc_spec.rb

require "Calc"

describe Calc do

  describe "when be made" do
    before :each do
      @calc = Calc.new
    end
    it "value should be zero" do
      @calc.value.should be_zero
    end
  end

  describe "when be made and add 10" do
    before :each do
      @calc = Calc.new
      @calc.add(10)
    end
    it "value should be ten" do
      @calc.value.should == 10
    end
  end

  describe "when be made and subtract 15" do
    before :each do
      @calc = Calc.new
      @calc.sub(15)
    end
    it "value should be minus fifteen" do
      @calc.value.should == -15
    end
  end

  describe "when be made, add 6 and divide by 2" do
    before :each do
      @calc = Calc.new
      @calc.add(6)
      @calc.div(2)
    end
    it "value should be three" do
      @calc.value.should == 3
    end
  end

end

Rakefile

require 'rake'
require 'spec/rake/spectask'

task :default => "rspec_with_rcov"

Spec::Rake::SpecTask.new('rspec_with_rcov') do |t|
  t.spec_files = FileList['**/*_spec.rb']
  t.libs << "./"
  t.rcov = true
  t.spec_opts = ['--format', 'nested', '--color']
  t.rcov_opts = ['--exclude', 'spec']
end