Move test to the proper file

All preload tests are in the eager_test file

activerecord/test/cases/associations/eager_test.rb

@@ -1167,6 +1167,13 @@ def test_deep_including_through_habtm
     )
   end
 
+  test "deep preload"
+    post = Post.preload(author: :posts, comments: :post).first
+
+    assert_predicate post.author.association(:posts), :loaded?
+    assert_predicate post.comments.first.association(:post), :loaded?
+  end
+
   test "preloading does not cache has many association subset when preloaded with a through association" do
     author = Author.includes(:comments_with_order_and_conditions, :posts).first
     assert_no_queries { assert_equal 2, author.comments_with_order_and_conditions.size }

activerecord/test/cases/relations_test.rb

@@ -552,13 +552,6 @@ def test_find_with_preloaded_associations
     end
   end
 
-  def test_deep_preload
-    post = Post.preload(author: :posts, comments: :post).first
-
-    assert_predicate post.author.association(:posts), :loaded?
-    assert_predicate post.comments.first.association(:post), :loaded?
-  end
-
   def test_preload_applies_to_all_chained_preloaded_scopes
     assert_queries(3) do
       post = Post.with_comments.with_tags.first