DRY up STI subclass logic

the newer method used for discriminating new records did not
use the older and more robust method used for instantiating
existing records, but did have a better post-check to ensure
the sublass was in the hierarchy. so move the descendants check
to find_sti_class, and then simply call find_sti_class from
subclass_from_attributes

now with fixed specs

3 files changed, 10 insertions, 3 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 5f52c65412..a53717d6c1 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -1117,10 +1117,10 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
 
   def test_has_many_through_with_default_scope_on_the_target
     person = people(:michael)
-    assert_equal [posts(:thinking)], person.first_posts
+    assert_equal [posts(:thinking).id], person.first_posts.map(&:id)
 
     readers(:michael_authorless).update(first_post_id: 1)
-    assert_equal [posts(:thinking)], person.reload.first_posts
+    assert_equal [posts(:thinking).id], person.reload.first_posts.map(&:id)
   end
 
   def test_has_many_through_with_includes_in_through_association_scope
diff --git a/activerecord/test/cases/batches_test.rb b/activerecord/test/cases/batches_test.rb
index 9e428098e4..24bab35b76 100644
--- a/activerecord/test/cases/batches_test.rb
+++ b/activerecord/test/cases/batches_test.rb
@@ -158,7 +158,7 @@ class EachTest < ActiveRecord::TestCase
     end
     # posts.first will be ordered using id only. Title order scope should not apply here
     assert_not_equal first_post, posts.first
-    assert_equal posts(:welcome), posts.first
+    assert_equal posts(:welcome).id, posts.first.id
   end
 
   def test_find_in_batches_should_not_ignore_the_default_scope_if_it_is_other_then_order
diff --git a/activerecord/test/models/post.rb b/activerecord/test/models/post.rb
index 052b1c9690..b92c67e85e 100644
--- a/activerecord/test/models/post.rb
+++ b/activerecord/test/models/post.rb
@@ -185,6 +185,7 @@ class SubStiPost < StiPost
 end
 
 class FirstPost < ActiveRecord::Base
+  self.inheritance_column = :disabled
   self.table_name = 'posts'
   default_scope { where(:id => 1) }
 
@@ -193,6 +194,7 @@ class FirstPost < ActiveRecord::Base
 end
 
 class PostWithDefaultInclude < ActiveRecord::Base
+  self.inheritance_column = :disabled
   self.table_name = 'posts'
   default_scope { includes(:comments) }
   has_many :comments, :foreign_key => :post_id
@@ -204,16 +206,19 @@ class PostWithSpecialCategorization < Post
 end
 
 class PostWithDefaultScope < ActiveRecord::Base
+  self.inheritance_column = :disabled
   self.table_name = 'posts'
   default_scope { order(:title) }
 end
 
 class SpecialPostWithDefaultScope < ActiveRecord::Base
+  self.inheritance_column = :disabled
   self.table_name = 'posts'
   default_scope { where(:id => [1, 5,6]) }
 end
 
 class PostThatLoadsCommentsInAnAfterSaveHook < ActiveRecord::Base
+  self.inheritance_column = :disabled
   self.table_name = 'posts'
   has_many :comments, class_name: "CommentThatAutomaticallyAltersPostBody", foreign_key: :post_id
 
@@ -223,6 +228,7 @@ class PostThatLoadsCommentsInAnAfterSaveHook < ActiveRecord::Base
 end
 
 class PostWithAfterCreateCallback < ActiveRecord::Base
+  self.inheritance_column = :disabled
   self.table_name = 'posts'
   has_many :comments, foreign_key: :post_id
 
@@ -232,6 +238,7 @@ class PostWithAfterCreateCallback < ActiveRecord::Base
 end
 
 class PostWithCommentWithDefaultScopeReferencesAssociation < ActiveRecord::Base
+  self.inheritance_column = :disabled
   self.table_name = 'posts'
   has_many :comment_with_default_scope_references_associations, foreign_key: :post_id
   has_one :first_comment, class_name: "CommentWithDefaultScopeReferencesAssociation", foreign_key: :post_id