message vs value expection (for @RubyoffRails)

the_tests_and_specs.rb

describe Fixnum do

  it "should add 2 + 2 and return 4" do
    @two = 2
    result = @two+ @two
    result.should eq(4)
  end
end

class Calculator

  def self.slugify_the_words(words)
    words.join("-").downcase
  end

  def self.sum(values)
    values.inject(:+)
  end
end


class Person
  attr_reader :first_name, :last_name, :nerd

  def initialize(first_name, last_name, nerd)
    @first_name = first_name
    @last_name = last_name
    @nerd = nerd
  end

  def calculate_sum(numbers)
    Calculator.sum(numbers)
  end

  def nerd?
    @nerd == true
  end
end

describe Calculator do

  it "should slug the words" do
    result = Calculator.slugify_the_words(["The", "Words", "Are", "cool"])
    result.should eq("the-words-are-cool")
  end

  it "should add up all the numbers" do
    # value expectation
    Calculator.sum([5,10,25]).should eq(40)
  end
end


describe Person do
  it "should be a nerd if we tell it to" do
    person = Person.new("jeff", "corvette", true)
    # all value expectations
    person.nerd.should eq(true)
    person.nerd.should be_true
    person.should be_a_nerd
  end

  describe ":calculate_sum" do

    it "should use the calculator" do
      # message expectation!
      Calculator.should_receive(:sum).with([5,10,25])
      person = Person.new("jeff", "corvette", true)
      person.calculate_sum([5,10,25])
    end
  end
end