RSpec matcher to test associations

gistfile1.rb

RSpec::Matchers.define :have_association do |association|
  @association = association

  match_for_should do |record|
    @record = record
    matches_against?(true)
  end

  match_for_should_not do |record|
    @record = record
    matches_against?(false)
  end

  def matches_against?(compare)
    raise "The have_association matcher requires an association and attribute; use subject.should have_association(:association).on(:attribute)" unless @association && @attribute
    
    return (false == compare) unless (attribute = @record.class.reflect_on_association(@attribute.to_sym))
    (attribute.macro == @association.to_sym) == compare
  end
  
  chain :on do |attribute|
    @attribute = attribute
  end

  failure_message_for_should do |actual|
    "expect to have_association #{@association.inspect} on #{@attribut.inspect}"
  end

  failure_message_for_should_not do |actual|
    "expect to not have_association #{@association.inspect} on #{@attribute.inspect}"
  end

  description do
    "have association #{association.inspect} on #{@attribute.inspect}"
  end
end