class Shoulda::Matchers::ActiveModel::ValidateAcceptanceOfMatcher

def description
  "require #{@attribute} to be accepted"
end

def matches?(subject)
  super(subject)
  @expected_message ||= :accepted
  disallows_value_of(false, @expected_message)
end

def with_message(message)
  if message
    @expected_message = message
  end
  self
end