Question

I am only looking for answers from senior/more experienced Ruby/Rails developers on this one, since I think this is a bit more advanced of a question.

I have a gem I am working on that adds some behavior to AR models. I have to test it for a lot of different associations (has_many, habtm, has_one etc), and I also have to test behavior when different options are passed for the associations (e.g. :foreign_key). Now with all these different models, I can use the same table in the database because the fields themselves do not need to change, only behavior specified through has_many, belongs_to and so on.
Keep in mind there are a lot of different options, so the number of models is quite large.

First I don’t think it would be bad practice to have the definition of the models next to / in the test itself, for readability purposes (if I have multiple tests that use the same model then I would group them together and use the before method). So this is one of my goals, and you can comment on this if you don’t agree.

The second thing I am not sure of is I wanted to keep the simple/same name of the model in all the tests, for example “Task”, instead of TaskWithManySubtasksAndForeignKey or something ugly like that. The problem is there are so many models it’s hard to come up with meaningful and simple names. I’m not quite sure about this – using the same name, since it’s a constant, is a little problematic. I have a solution with a proxy class but I don’t think this is the optimal solution. I was considering using variables (with the let method) like “taskModel”, but it seemed a little verbose and unusual.

One other option that comes to mind, but I am not sure is possible to do easily, is to remove an existing association and then define a new one. So e.g. add a has_many and then remove it, add a habtm…

How would you go about doing this?

Answer 1

Defining unique models in the spec files is not necessarily a bad idea since it makes it easy to see exactly how each model is defined. The obvious problem with this approach is if you want to reuse the models in other test files. The Rails approach to this is to define all the models in separate files and then just require them in the tests that need it.

I think it really just depends on how many models you have and how much you want to reuse. In one of my gems, I took the approach of defining the models in the spec file, in another gem, I defined them in the spec helper, and in yet another I took the Rails approach and used a separate directory for them. If you asked me which one I preferred, I’d probably go with the spec that also contains the models because it’s all in one place. Definitely a subjective problem though.

Another approach I’ve taken on occasion is to create an anonymous class that’s guaranteed to only be around for the life of that test:

describe 'my test' do
  let(:my_class) do
    Class.new(Task) do
      has_many :things
      belongs_to :something_else
    end
  end

  it 'should have many things' do
    my_class.should have(100).things
  end
end