Writing tests for AR validations

order.rb

class Order < ActiveRecord::Base

  ...
  
  validates :customer_id, 
            :company_id, 
            :credit_card_id, 
            :tip,
            :delivery_location, 
            presence: true

  ...
end

order_test.rb

class OrderTest < ActiveSupport::TestCase

  ...

  [ :customer_id, :credit_card_id, :delivery_location, :company_id, :tip ].each do |field|
    should validate_presence_of field
  end

  ...

end

IMHO if this is some sort of double check (like "am I really sure I should remove those validations because I would have to go modify the tests too") it's not something I would want to write.

I used to write lots of tests on AR, on the router, etc. None of these are actually worth the effort. What's worth the effort though is to isolate the app from the framework, and test the interactions. YMMV :-)