I have a one-to many relationship in Rails:
class User < ActiveRecord::Base
has_many :activities, :order => "added_at DESC"
class Activity < ActiveRecord::Base
belongs_to :user
I have a method in Activity:
def self.test_message(user, message)
user.activities << Activity.create do |activity|
activity.message = message
activity.added_at = Time.now
end
end
and the following unit test:
require 'test_helper'
class ActivityTest < ActiveSupport::TestCase
def test_test_message
#From fixture
alice = User.find_by_name("alice")
assert_equal 0, alice.activities.count
Activity.test_message(alice, "Hello")
assert_equal 1, alice.activities.count
Activity.test_message(alice, "Goodbye")
assert_equal 2, alice.activities.count
assert_equal "Hello", alice.activities.find(:first).message
#The following line fails with: Goodbye expected but was Hello
assert_equal "Goodbye", alice.activities.find(:last).message,
acts = alice.activities
assert_equal 2, acts.count
assert_equal "Goodbye", acts[1].message
end
end
which fails on the indicated line, but I can't work out why.
Also, using activities.find(:last) works when using the development environment, but only fails under the test environment. I have dropped and rebuilt the database.
This seems to be an issue with using the :order flag in your association declaration. This post isn't the exact situation you're experiencing, but it recommends against the practice in general:
http://weblog.jamisbuck.org/2007/1/18/activerecord-association-scoping-pitfalls
(I'm not sure if these suggestions are still relevant, but I was seeing the same behavior as you in Rails 2.3.3 until I made the changes below.)
I set up your app locally and tried applying the technique from comment #4 by adding
def Activity.by_added_at
find :all, :order => 'added_at DESC'
end
and changing your find(:first) and find(:last) in the test to .by_added_at.first and .by_added_at.last, which returns more stable results.
One other suggestion -- your test is pretty big right now. You might consider splitting it out into multiple tests, each of which tests one or two conditions at most.