#16 new
James Mead

[#16775] Problem with stubbing find on AR associations

Reported by James Mead | January 1st, 2009 @ 07:29 PM

Date: 2008-01-02 19:50 Opener: Jonathan Leighton

I am having a problem where stubbing find on a has_many association doesn't appear to work. I don't know why and exactly what circumstances this occurs under, but I've made a test case for it. I know fixtures are evil but it requires a test database ;) (well maybe not but it's the easiest way to prove the problem for now as I don't actually know what causes it)

Comments and changes to this ticket

  • James Mead
  • James Mead

    James Mead January 1st, 2009 @ 07:31 PM

    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
    Finished in 0.032379 seconds.
      1) Failure:
        [/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:
    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...

  • James Mead

    James Mead January 1st, 2009 @ 07:35 PM

    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) }
          assert_equal room, house.rooms.find(6)

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

    Cheers, James.


  • James Mead

    James Mead January 1st, 2009 @ 07:36 PM

    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

  • James Mead

    James Mead January 1st, 2009 @ 07:36 PM

    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.


  • James Mead

    James Mead January 1st, 2009 @ 07:36 PM

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

    Hi James,

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


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