Hi, I have the following situation. I have two models Item and Genre. A Item has a name and a description. The genres-table contains a list of possible genres wich can be associated to items. So a Item could be associated with many genres and a genre could be associated with many items. A typically n:m-relationship. I use the :has_many-:through association, because i want do to a kind of on-delete-cascade in Rails. My models look as follows: class Item < ActiveRecord::Base # n:m relationship between items and genres has_many :items_genres, :dependent => :destroy has_many :genres, :through => :items_genres validates_presence_of :name validate :must_have_at_least_one_associated_genre protected # valdation to ensure, that a item has at least one associated genre def must_have_at_least_one_associated_genre # add an error message to the default error messages errors.add(:genres, "must_be_choosen") if # if no genre is associated with this item genres.size <= 0 end end I put two validations to the Item. The statement at line 6 make the name arrtibute mandatory. In addition I would to ensure that a item has at least one associated genre. So I decided to write a own validation-method (line 10-17). class ItemsGenre < ActiveRecord::Base belongs_to :item belongs_to :genre end class Genre < ActiveRecord::Base # n:m relationship between genres and items has_many :items_genres, :dependent => :destroy has_many :items, :through => :items_genres end I added some unit-tests to ensure that the validation works as aspected. I wrote the following unit-test-methods. require 'test_helper' class ItemTest < ActiveSupport::TestCase def test_should_create_an_item item = Item.new( :name => "Item-Name", :description => "Item-Description" ) # Assert, that the item is not valid and cannot be saved, # because there are no genres associated with it assert !item.valid? assert !item.save # Associate two genres with this item item.genres = Genre.find_all_by_id([genres(:club).id, genres (:commedy).id]) # Assert, that the item is now valid and can be saved assert item.valid? assert item.save # Check if there are two genres associated with this item assert_equal 2, item.genres.size end def test_should_require_name # Create an item-object, but set name nil item = Item.new( :name => nil, :description => "Item-Description" ) # Assert, that the item is not valid and cannot be saved, # because the name is nil assert !item.valid? assert !item.save end def test_should_require_description # Create an item-object, but set name to nil item = Item.new( :name => "Item-Name", :description => nil ) # Assert, that the item is not valid and cannot be saved, # because the description is nil assert !item.valid? assert !item.save end end The amazing thing is that all tree test-methods pass. But I only have a validation for the name and the asscociated genres. I do not have a validation of the description, but the test method for the description passes. I found out another thing. If I remove the validate-call in line 8 of the Item-model, then all test-methods work as aspected. In this case the test_should_create_an_item- and the test_should_require_description-method both fail and the test_should_require_name-method passes. If I run the application and try to add a new item by the new-form, all validation works as exspected. So it seems that only the unit-test are faulty. I am at a loss. I don´t know what I am doing wrong. Can anyone reproduce this behavior? Or can anyone tell me how to write a validation-method to ensure that at least one genre is associated with an item. Maybe my test-method is wrong. I hope someone can help me out.
on 2009-04-28 12:29
on 2009-04-28 12:33
On Apr 28, 9:25 am, zeto <firstname.lastname@example.org> wrote: > assert !item.save > end > > end > > The amazing thing is that all tree test-methods pass. But I only have > a validation for the name and the asscociated genres. I do not have a > validation of the description, but the test method for the description > passes. In your test that description should be required you haven't created any genres, so even though you have no validation for description the validation on genres being present makes the item fail to save. Fred
on 2009-04-28 16:43
At first, thank you for your advise. I forgot to associate genres in the description_should_be_required-test-method. And you are right. This test method should fail, but it surprisingly passes. zeto
on 2009-04-28 17:21
You can always go into must_have_at_least_one_associated_genre with the debugger and find out why it is not failing. 2009/4/28 zeto <email@example.com>
on 2009-04-28 18:03
It is not the must_have_at_least_one_associated_genre-test-method. The test_should_require_description-test-method passes the test, but that method should fail.
on 2009-04-28 18:49
If I understand correctly you are saying that test_should_require_description is passing when it should fail. The fact that it passes appears to mean that the item is not valid. The question is why is it not valid? It may be that must_have_at_least_one_associated_genre is failing. I would check that first. You could just remove this validation to eliminate it. 2009/4/28 zeto <firstname.lastname@example.org>
on 2009-04-28 18:58
If I comment out the validation "validate :must_have_at_least_one_associated_genre" in line 8 of my Item-model all test methods work correctly. That means only the test_should_require_name -test-method passes the test. test_should_create_an_item --> fails, because the validation in line 8 of my Item-model is commented out test_should_require_description --> fails, because there is no validation for description yet Of course the failure is somewhere in the must_have_at_least_one_associated_genre-method in the Item-model, but I cannot figure out where the failure is.
on 2009-04-28 20:30
Go in with the debugger and have a look at the objects. 2009/4/28 zeto <email@example.com>