Merge pull request #8258 from kommen/eager_loading_with_select_test2

Add test to ensure preloading works as expected with "group", "select" and "includes".
Conflicts:
	activerecord/test/cases/relations_test.rb

Chery-pick a739340d3c9e66814429af6f3f410c01ff86810a:
Ensure ordering to make the test pass with postgresql

Conflicts:
	activerecord/test/cases/relations_test.rb

1 files changed, 14 insertions, 0 deletions

diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index b24df47efd..ada4294401 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1185,4 +1185,18 @@ class RelationTest < ActiveRecord::TestCase
     end
     assert_equal ['Foo', 'Foo'], query.uniq(true).uniq(false).map(&:name)
   end
+
+  test 'group with select and includes' do
+    authors_count = Post.select('author_id, COUNT(author_id) AS num_posts').
+      group('author_id').order('author_id').includes(:author).to_a
+
+    assert_no_queries do
+      result = authors_count.map do |post|
+        [post.num_posts.to_i, post.author.try(:name)]
+      end
+
+      expected = [[1, nil], [5, "David"], [3, "Mary"], [2, "Bob"]]
+      assert_equal expected, result
+    end
+  end
 end