Fix collection= on hm:t join models when unsaved

If assigning to a has_many :through collection against an unsaved
object using the collection=[<array_of_items>] syntax, the join models
were not properly created, previously.

1 files changed, 5 insertions, 0 deletions

diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index 36e5ba9660..c591fd8532 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -838,6 +838,11 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     end
   end
 
+  def test_assign_array_to_new_record_builds_join_records
+    c = Category.new(:name => 'Fishing', :authors => [Author.first])
+    assert_equal 1, c.categorizations.size
+  end
+
   def test_create_bang_should_raise_exception_when_join_record_has_errors
     repair_validations(Categorization) do
       Categorization.validate { |r| r.errors[:base] << 'Invalid Categorization' }