module Shoulda::Matchers::ActiveModel

it { should ensure_exclusion_of(:age).in_range(30..60) }
Example:

translation for :exclusion.
errors.on(:attribute). Regexp or string. Defaults to the
* with_message - value the test expects to find in
* in_range - the range of not allowed values for this attribute
* in_array - the array of not allowed values for this attribute
Options:

Ensure that the attribute's value is not in the range specified

def ensure_exclusion_of(attr)
  EnsureExclusionOfMatcher.new(attr)
end