Fixing dynamic finders on associations to properly send arguments to …

…the find_by_* method. Closes issue #330.

Commit fdfc8e3 introduced a bugfix to prevent additional values passed
to a dynamic find_or_create_by_x methods from confusing the finder.
This patch also broke the essential behavior of this method on an
association by incorrectly sending arguments to the find_by_x methods.
The finder method would always see its inputs as a single array of
values instead of individual arguments, almost guaranteeing that the
finder call would be incorrect, and that we'd always create a new
record instead.

This patch adds a splat operator to the parameter array we send along to
the dynamic finder so that it receives its inputs correctly, and
includes an additional test to ensure that repeated calls to
find_or_create_by_x only creates one new record.

activerecord/lib/active_record/associations/association_collection.rb

@@ -381,7 +381,7 @@ def method_missing(method, *args, &block)
           when /^find_or_create_by_(.*)$/
             rest = $1
             find_args = pull_finder_args_from(DynamicFinderMatch.match(method).attribute_names, *args)
-            return  send("find_by_#{rest}", find_args) ||
+            return  send("find_by_#{rest}", *find_args) ||
                     method_missing("create_by_#{rest}", *args, &block)
           when /^create_by_(.*)$/
             return create($1.split('_and_').zip(args).inject({}) { |h,kv| k,v=kv ; h[k] = v ; h }, &block)

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -82,6 +82,15 @@ def test_find_or_create_by_with_additional_parameters
     assert_equal 4, post.comments.length
   end
 
+  def test_find_or_create_by_with_same_parameters_creates_a_single_record
+    author = Author.first
+    assert_difference "Post.count", +1 do
+      2.times do
+        author.posts.find_or_create_by_body_and_title('one', 'two')
+      end
+    end
+  end
+
   def test_find_or_create_by_with_block
     post = Post.create! :title => 'test_find_or_create_by_with_additional_parameters', :body => 'this is the body'
     comment = post.comments.find_or_create_by_body('other test comment body') { |comment| comment.type = 'test' }