class Shoulda::Matchers::ActiveRecord::AssociationMatchers::RequiredMatcher

def build_missing_option
  String.new('and for the record ').tap do |missing_option_string|
    missing_option_string <<
      if required
        'to '
      else
        'not to '
      end
    missing_option_string << (
      'fail validation if '\
      ":#{attribute_name} is unset; i.e., either the association "\
      'should have been defined with `required: '\
      "#{required.inspect}`, or there "
    )
    missing_option_string <<
      if required
        'should '
      else
        'should not '
      end
    missing_option_string << "be a presence validation on :#{attribute_name}"
  end
end

def description
  "required: #{required}"
end

def initialize(attribute_name, required)
  @attribute_name = attribute_name
  @required = required
  @submatcher = ActiveModel::DisallowValueMatcher.new(nil).
    for(attribute_name).
    with_message(validation_message_key)
  @missing_option = ''
end

def matches?(subject)
  if submatcher_passes?(subject)
    true
  else
    @missing_option = build_missing_option
    false
  end
end

def submatcher_passes?(subject)
  if required
    submatcher.matches?(subject)
  else
    submatcher.does_not_match?(subject)
  end
end

def validation_message_key
  :required
end