Fix merge error when Equality LHS is non-attribute.

This is reworking of rails/rails/pull/7380 made for rails 3.

1 files changed, 15 insertions, 0 deletions

diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index f14eee2eb8..39632075e8 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -668,6 +668,21 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal [developers(:poor_jamis)], dev_with_count.to_a
   end
 
+  def test_relation_merging_with_arel_equalities_keeps_last_equality
+   devs = Developer.where(Developer.arel_table[:salary].eq(80000)).merge(
+     Developer.where(Developer.arel_table[:salary].eq(9000))
+   )
+   assert_equal [developers(:poor_jamis)], devs.to_a
+ end
+
+  def test_relation_merging_with_arel_equalities_with_a_non_attribute_left_hand_ignores_non_attributes_when_discarding_equalities
+    salary_attr = Developer.arel_table[:salary]
+    devs = Developer.where(salary_attr.eq(80000)).merge(
+      Developer.where(salary_attr.eq(9000)).where(Arel::Nodes::NamedFunction.new('abs', [salary_attr]).eq(9000))
+    )
+    assert_equal [developers(:poor_jamis)], devs.to_a
+ end
+
   def test_relation_merging_with_eager_load
     relations = []
     relations << Post.order('comments.id DESC').merge(Post.eager_load(:last_comment)).merge(Post.scoped)