[#16775] Problem with stubbing find on AR associations

Date: 2008-01-02 19:53 Sender: Jonathan Leighton

This is the output from running the test:

$ ruby test/acceptance/rails_has_many_find_acceptance_test.rb 
Loaded suite test/acceptance/rails_has_many_find_acceptance_test
Started
F..
Finished in 0.032379 seconds.

  1) Failure:
test_find_stubbed_on_the_association_should_work(RailsHasManyFind
AcceptanceTest)
    [/home/turnip/Projects/mocha/test/test_runner.rb:24:in `assert_passed'
test/acceptance/rails_has_many_find_acceptance_test.rb:29:in `test_find_stubbed_on_the_association_should_work'
/home/turnip/Projects/mocha/lib/mocha/test_case_adapter.rb:19:in `__send__'
/home/turnip/Projects/mocha/lib/mocha/test_case_adapter.rb:19:in `run']:
Test failed unexpectedly with message: Error:
test_me():
ActiveRecord::RecordNotFound: Couldn't find Room with ID=6 AND (rooms.house_id = NULL)
   
/usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/base.rb:1267:in `find_one'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/base.rb:1250:in `find_from_ids'   
/usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/base.rb:504:in `find'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/associations/has_many_association.rb:66:in `find'
test/acceptance/rails_has_many_find_acceptance_test.rb:27:in `test_me'
/home/turnip/Projects/mocha/lib/mocha/test_case_adapter.rb:19:in `__send__'
/home/turnip/Projects/mocha/lib/mocha/test_case_adapter.rb:19:in `run'
/home/turnip/Projects/mocha/test/test_runner.rb:15:in `run_test'
test/acceptance/rails_has_many_find_acceptance_test.rb:24:in `test_find_stubbed_on_the_association_should_work'
/home/turnip/Projects/mocha/lib/mocha/test_case_adapter.rb:19:in `__send__'   
/home/turnip/Projects/mocha/lib/mocha/test_case_adapter.rb:19:in `run'.

3 tests, 1 assertions, 1 failures, 0 errors

Of course ActiveRecord::Base#find should actually be called because the method is stubbed out...

Date: 2008-01-02 23:24 Sender: James Mead

I haven't yet had a chance to run the tests you attached, but I think there have always been problems trying to stub directly on the ActiveRecord association proxies - they aren't normal objects. The simplest solution is to stub the proxy method generated by the association - in this case House#rooms to replace the proxy object itself.

Using the recently added block initializer code in Mocha, your first test could be something like this...

  def test_find_stubbed_on_the_association_should_work
    test_result = run_test do
      house, room = House.new, Room.new
      rooms = stub { stubs(:find).with(6).returns(room) }
      house.stubs(:rooms).returns(rooms)
      assert_equal room, house.rooms.find(6)
    end
    assert_passed(test_result)
  end

Again, I'm sorry but I haven't tested this thoroughly. Let me know if this doesn't solve your problem.

Cheers, James.

http://blog.floehopper.org

Date: 2008-01-02 23:38 Sender: Jonathan Leighton

Hi James,

Thanks for your speedy response. I figured it was probably something to do with AR's magic getting in the way. Stubbing the association proxy definitely does solve the problem (one of the tests I wrote shows this) but it would be lovely if that wasn't necessary :)

Cheers, Jon

Date: 2008-01-03 09:23 Sender: James Mead

Hi Jonathan,

My response was obviously a bit too speedy - I'm afraid I'd only looked at the failing test. BTW I really appreciate you taking the time to create failing tests for the bug report - they really help communication - especially if I were to read them properly!

Anyway, now that I understand the problem a bit better, I'll have a bit more of a think. One reason I haven't done anything about this previously is that there is a workaround which isn't too ugly and I'd like to avoid any Rails-specific code creeping into Mocha. If it's not possible to come up with a generic solution, it might be worth splitting the Mocha Rails plugin out into a separate project and adding the Rails-specific code in that.

Cheers, James.

http://blog.floehopper.org

Date: 2008-01-03 10:10 Sender: Jonathan Leighton

Hi James,

No problem, thanks for taking the time to look at it.

Jon