class Shoulda::ActiveRecord::Matchers::ValidateNumericalityOfMatcher

def description
  "only allow numeric values for #{@attribute}"
end

def matches?(subject)
  super(subject)
  @expected_message ||= :not_a_number
  disallows_value_of('abcd', @expected_message)
end

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