# Unit testing rails model validation? - why bother? what's ra **URL:** \ **Category:** Ruby\ **Created:** [June 11, 2007, 8:16am UTC](https://www.ruby-forum.com/t/unit-testing-rails-model-validation-why-bother-whats-ra/106488 "2007-06-11T08:16:56Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\ **Post date:** [June 11, 2007, 8:16am UTC](https://www.ruby-forum.com/t/unit-testing-rails-model-validation-why-bother-whats-ra/106488/1 "2007-06-11T08:16:56Z")
Hi all, Is there any need to write unit test cases for model validation when such validation is implemented by a single rails validate\_\* line in the model? e.g. “validates\_presence\_of :email”. Conservatively I would say ‘yes’ however applying the following arguments below I’d actually re-consider and say ‘no’: [1] Any test should clearly have a clear objective in terms of what it is trying to test. In this case what is really being tested in the rails framework “validates\_” command and associated rails framework that handles this. If you take this as already been tested as part of the Rails release process then there is no reason to focus re-testing this. In other words why write a test for a situation for which you wrote no code yourself. [2] Any DRY? - By writing test cases you are really breaking the DRY (don’t repeat yourself content) by everytime you put a simple rails framework line (i.e. a validates\_\* in a model) you have to put extra straight-forward lines in test cases. Also would such test cases focused at testing such Rails commands already be present in the rails code base. Comments? What’s best practice here. Should we be writing test cases for such cases? Greg ---
**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\ **Post date:** [June 11, 2007, 2:18pm UTC](https://www.ruby-forum.com/t/unit-testing-rails-model-validation-why-bother-whats-ra/106488/2 "2007-06-11T14:18:53Z")
On Jun 11, 2007, at 1:16 AM, Greg H. wrote: > Is there any need to write unit test cases for model validation > when such > validation is implemented by a single rails validate\_\* line in the > model? > e.g. “validates\_presence\_of :email”. It doesn’t have anything to do with how easy it is to implement. It’s about validating your business logic. If a client tells me, “An email address is required,” writing that test ensures I’m meeting the specification. It’s also plenty common to add a custom validation method or two, which generally require more than one line of code. Surely you would want to test those. Finally, I’ve occasionally had tests show an unexpected interplay of many validation rules. Things like that are what unit tests are so good at uncovering. James Edward G. II ---
**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\ **Post date:** [June 11, 2007, 7:36pm UTC](https://www.ruby-forum.com/t/unit-testing-rails-model-validation-why-bother-whats-ra/106488/3 "2007-06-11T19:36:59Z")
On Jun 11, 2007, at 1:16 AM, Greg H. wrote: > below I’d actually re-consider and say ‘no’: > why write a test for a situation for which you wrote no code yourself. > > Comments? What’s best practice here. Should we be writing test > cases for > such cases? > > Greg > Yes, yes and yes. > Unit testing is the best way to ensure your results are what you > expect them to be. Unit testing can of course be as exhaustive or > minimal as you like. > Better to create them and run them now than to rely on faith. > Especially when it comes to data originating from external sources. > Unit test like mad to make sure it is sanitized. ---
**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\ **Post date:** [June 12, 2007, 10:27am UTC](https://www.ruby-forum.com/t/unit-testing-rails-model-validation-why-bother-whats-ra/106488/4 "2007-06-12T10:27:06Z")
On Jun 10, 2007, at 23:16, Greg H. wrote: > [1] Any test should clearly have a clear objective in terms of what > it is > trying to test. In this case what is really being tested in the rails > framework “validates\_” command and associated rails framework that > handles > this. No. You need to assert that you have validates\_presence\_of :email in your model. > If you take this as already been tested as part of the Rails release > process then there is no reason to focus re-testing this. In other > words > why write a test for a situation for which you wrote no code yourself. You don’t need to exhaustively test it, only assert the failing case. > [2] Any DRY? - By writing test cases you are really breaking the > DRY (don’t > repeat yourself content) by everytime you put a simple rails > framework line > (i.e. a validates\_\* in a model) you have to put extra straight- > forward lines > in test cases. Also would such test cases focused at testing such > Rails > commands already be present in the rails code base. Your implementation shouldn’t repeat itself, your tests shouldn’t repeat themselves, but if your tests repeat your implementation, that’s probably ok. Your tests are your project’s safety net. If you don’t have a test for a line of code I can come along and delete it and not know I broke something. Broken software sucks almost as much as falling off the high wire with a half set-up safety net. PS: If you don’t want to wait for me to delete the line of code, run heckle. It’ll delete it for you. [http://seattlerb.rubyforge.org/heckle/](http://seattlerb.rubyforge.org/heckle/)