class Shoulda::Matchers::ActiveModel::EnsureInclusionOfMatcher

def allows_blank_value?
  if @options.key?(:allow_blank)
    blank_values = ['', ' ', "\n", "\r", "\t", "\f"]
    @options[:allow_blank] == blank_values.all? { |value| allows_value_of(value) }
  else
    true
  end
end