shoulda cheet sheet from https://github.com/robin/chitsheet/blob/master/rspec_shoulda.yml

Should cheet sheet

--- 
rspec_shoulda: |
  Shoulda Rspec Matchers
    For more information on rspec, rspec-rails, shoulda
      $ cheat rspec
      $ cheat rspec_on_rails_matchers
      $ cheat shoulda
    
  Models Matchers
    Data
      it { should_not have_db_column(:admin).of_type(:boolean) }
      it { should have_db_column(:salary).
            of_type(:decimal).
            with_options(:precision => 10, :scale => 2) }
      
    Associations
      it { should belong_to(:parent) }
      
      it { should have_many(:friends) }
      it { should have_many(:enemies).through(:friends) }
      it { should have_many(:enemies).dependent(:destroy) }
      
      it { should have_one(:god) }
      
      it { should have_and_belong_to_many(:posts) }
      
    Validation Matchers
      it { should validate_uniqueness_of(:keyword) }
      it { should validate_uniqueness_of(:keyword).with_message(/dup/) }
      it { should validate_uniqueness_of(:email).scoped_to(:name) }
      it { should validate_uniqueness_of(:email).
                    scoped_to(:first_name, :last_name) }
      it { should validate_uniqueness_of(:keyword).case_insensitive }
      
      it { should validate_presence_of(:name) }
      it { should validate_presence_of(:name).
                    with_message(/is not optional/) }
      
      it { should validate_numericality_of(:age) }
      
      it { should validate_format_of(:name).
                    with('12345').
                    with_message(/is not optional/) }
      it { should validate_format_of(:name).
                    not_with('12D45').
                    with_message(/is not optional/) }
      
      it { should validate_acceptance_of(:eula) }
      
      it { should have_readonly_attributes(:password) }
      it { should ensure_length_of(:password).
                    is_at_least(6).
                    is_at_most(20) }
      it { should ensure_length_of(:name).
                    is_at_least(3).
                    with_short_message(/not long enough/) }
      it { should ensure_length_of(:ssn).
                    is_equal_to(9).
                    with_message(/is invalid/) }
      
      it { should ensure_inclusion_of(:age).in_range(0..100) }
      it { should_not allow_mass_assignment_of(:password) }
      it { should allow_mass_assignment_of(:first_name) }
      
  Controller Matchers
    Assigns  
      it { should assign_to(:user)        }
      it { should assign_to(:user)        }
      it { should_not assign_to(:user)    }
      it { should assign_to(:user).with_kind_of(User) }
      it { should assign_to(:user).with(@user) }
      
    Sessions
      it { should set_session(:message) }
      it { should set_session(:user_id).to(@user.id) }
      it { should_not set_session(:user_id) }
      
    Flash
      it { should set_the_flash }
      it { should set_the_flash.to("Thank you for placing this order.") }
      it { should set_the_flash.to(/created/i) }
      it { should_not set_the_flash }
      
    Responses
      it { should respond_with(:success)  }
      it { should respond_with(:redirect) }
      it { should respond_with(:missing)  }
      it { should respond_with(:error)    }
      it { should respond_with(501)       }
      
    Content-Type Responses
      it { should respond_with_content_type(:xml)  }
      it { should respond_with_content_type(:csv)  }
      it { should respond_with_content_type(:atom) }
      it { should respond_with_content_type(:yaml) }
      it { should respond_with_content_type(:text) }
      it { should respond_with_content_type('application/rss+xml')  }
      it { should respond_with_content_type(/json/) }
      
    Rendering
      it { should render_template(:new)         }
      it { should render_with_layout            }
      it { should render_with_layout(:special)  }
      it { should_not render_with_layout        }
      
    Filter Parameter
      it { should filter_param(:password)       }
      
  Route Matchers
      it { should route(:get, "/posts/new").to(:action => :new) }
      it { should route(:put, "/posts/1").to(:action => :update, :id => 1) }