class Shoulda::Matchers::ActiveModel::ExceptionMessageFinder

def allow_description(allowed_values)
  "doesn't raise when #{@attribute} is set to #{allowed_values}"
end

def expected_message_from(attribute_message)
  "#{human_attribute_name} #{attribute_message}"
end

def has_messages?
  messages.any?
end

def human_attribute_name
  @instance.class.human_attribute_name(@attribute)
end

def initialize(instance, attribute)
  @instance = instance
  @attribute = attribute
end

def messages
  @messages ||= validate_and_rescue
end

def messages_description
  if has_messages?
    messages.join
  else
    'no exception'
  end
end

def source_description
  'exception'
end

def validate_and_rescue
  @instance.valid?
  []
rescue ::ActiveModel::StrictValidationFailed => exception
  [exception.message]
end