Use `Enumerable#sum` on `ActiveRecord::Relation` when a block is given

This matches our behavior in other cases where useful enumerable methods
might have a different definition in `Relation`. Wanting to actually
enumerate over the records in this case is completely reasonable, and
wanting `.sum` is reasonable for the same reason it is on `Enumerable`
in the first place.

1 files changed, 10 insertions, 0 deletions

diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index cb4681109c..aa10817527 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -671,4 +671,14 @@ class CalculationsTest < ActiveRecord::TestCase
       developer.ratings.includes(comment: :post).where(posts: { id: 1 }).count
     end
   end
+
+  def test_sum_uses_enumerable_version_when_block_is_given
+    block_called = false
+    relation = Client.all.load
+
+    assert_no_queries do
+      assert_equal 0, relation.sum { block_called = true; 0 }
+    end
+    assert block_called
+  end
 end