Working With Rails

Do you have an actual problem or are you looking for a tutorial?

Well, I’d say that most of the time you’re not going to want to test the associations themselves other than something rather superficial. ActiveRecord is very well tested and doing any sort of extensive testing on a relationship’s mechanics would probably be unnecessary.

That being said, if you wanted to test that a particular association exists and is working, let’s assume we have two classes, Tree and Fruit.

class Tree
  has_many :fruits
end

and

class Fruit
  beongs_to :tree
end

If you wanted to test that a Tree does indeed have many fruits,

it "should have fruit" do
  tree = Tree.create("....")
  tree.fruits << Fruit.new(:type => "Apple")
  tree.fruits << Fruit.new(:type => "Apple", :hasworms => true)
  tree.should have(2).fruits
end

etc…

If you want to test that the actual model associations are defined, then this is useful:
http://github.com/joshknowles/rspec-on-rails-matchers/tree

Something I’ve been using to test the presence of an association (remember, we’re writing the tests first) is:

it "should reflect the association" do
   Profile.reflect_on_association(:user).should_not be_nil
end

This of course is just a basic test to make sure that you have defined the association in the model.

I usually only check that the object responds to a given message because I normally don’t care if it’s from an association or a “manually” added method:

# in the post model
it "should have comments" do
  @post.should respond_to(:comments)
end