gistfile1.rb

class User < ActiveRecord::Base
  def full_name
    "#{first_name} #{last_name if last_name.present?}".strip
  end
end

# Tests

# Without context
require 'spec_helper'

describe User do
  let(:user) { User.new first_name: "Bob", last_name: "Sieger" }
  
  describe "instance methods" do
    describe "#full_name" do
      
      it "has full_name equal to users first_name plus last_name" do
        user.full_name.should eq "Bob Sieger"
      end
  
      it "has full_name equal to user's first_name" do
        user.last_name = nil
        user.full_name.should eq "Bob"
      end
    end
    
  end
end

# With context
require 'spec_helper'

describe User do
  let(:user) { User.new first_name: "Bob", last_name: "Sieger" }
  
  describe "instance methods" do
    describe "#full_name" do
      
      context "when user has a first_name and last_name" do
        it "has full_name equal to user's first_name and last_name" do
          user.full_name.should eq "Bob Sieger"
        end
      end
      
      context "when user has only first_name" do
        it "has full_name equal to user's first_name" do
          user.last_name = nil
          user.full_name.should eq "Bob"
        end
      end
      
    end
  end
end