module Shoulda::ActiveRecord::Matchers

it { should validate_numericality_of(:age) }
Example:

translation for :not_a_number.
errors.on(:attribute). Regexp or string. Defaults to the
* with_message - value the test expects to find in
Options:

Ensure that the attribute is numeric

def validate_numericality_of(attr)
  ValidateNumericalityOfMatcher.new(attr)
end