2 files changed, 14 insertions, 3 deletions
diff --git a/activerecord/test/cases/associations/nested_through_associations_test.rb b/activerecord/test/cases/associations/nested_through_associations_test.rb
index 6122098623..530f5212a2 100644
--- a/activerecord/test/cases/associations/nested_through_associations_test.rb
+++ b/activerecord/test/cases/associations/nested_through_associations_test.rb
@@ -356,11 +356,13 @@ class NestedThroughAssociationsTest < ActiveRecord::TestCase
     assert_equal categories(:general), members(:groucho).club_category
   end
 
-  def test_has_one_through_has_one_through_with_belongs_to_source_reflection_with_default_scope_preload_on_the_through_model
+  def test_joins_and_includes_from_through_models_not_included_in_association
     prev_default_scope = Club.default_scopes
-    Club.default_scopes = [Club.preload(:category)]
 
-    assert_equal categories(:general), members(:groucho).club_category
+    [:includes, :preload, :joins, :eager_load].each do |q|
+      Club.default_scopes = [Club.send(q, :category)]
+      assert_equal categories(:general), members(:groucho).reload.club_category
+    end
   ensure
     Club.default_scopes = prev_default_scope
   end
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index d840d38678..47bf2d007f 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -48,6 +48,15 @@ class FinderTest < ActiveRecord::TestCase
     assert Topic.exists?
   end
 
+  # exists? should handle nil for id's that come from URLs and always return false
+  # (example: Topic.exists?(params[:id])) where params[:id] is nil
+  def test_exists_with_nil_arg
+    assert !Topic.exists?(nil)
+    assert Topic.exists?
+    assert !Topic.first.replies.exists?(nil)
+    assert Topic.first.replies.exists?
+  end
+
   def test_does_not_exist_with_empty_table_and_no_args_given
     Topic.delete_all
     assert !Topic.exists?