[Rails] test a non active_record class in models directory in rails 3?

hi
i have a non active_record class in models dir which is like following:

class BuildSurvey

end

i want to test this class,so manually defined a test file which is like
following

require 'test_helper'
require 'build_survey'
class BuildSurveyTest < ActiveSupport::TestCase

end

but when i ran test,i got error like this:

undefined method '<' nil:NilClass

i want to know how to test a non active_record class in models directory
in rails 3.can you help me?

--
Posted via http://www.ruby-forum.com/.

--
You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group.
To post to this group, send email to rubyonrails-talk@googlegroups.com.
To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.