From b07b97057fba21cbccca9a81630173a88406175a Mon Sep 17 00:00:00 2001
From: Graham Turner <turnertgraham@gmail.com>
Date: Tue, 17 Apr 2018 21:56:33 -0400
Subject: Loaded associations should not run a new query when size is called

Already loaded associations were running an extra query when `size` was called on the association.
This fix ensures that an extra query is no longer run.

Update tests to use proper methods
---
 .../associations/has_many_associations_test.rb     | 74 ++++++++++++++++++++++
 1 file changed, 74 insertions(+)

(limited to 'activerecord/test')

diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 33fe5ccabc..feb7390e2c 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -993,6 +993,16 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal 1, post.readers.size
   end
 
+  def test_collection_empty_with_dirty_target
+    post = posts(:thinking)
+    assert_equal [], post.reader_ids
+    assert_empty post.readers
+    post.readers.reset
+    post.readers.build
+    assert_equal [], post.reader_ids
+    assert_not_empty post.readers
+  end
+
   def test_collection_size_twice_for_regressions
     post = posts(:thinking)
     assert_equal 0, post.readers.size
@@ -2573,6 +2583,70 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     end
   end
 
+  test "calling size on an association that has not been loaded performs a query" do
+    car = Car.create!
+    Bulb.create(car_id: car.id)
+
+    car_two = Car.create!
+
+    assert_queries(1) do
+      assert_equal 1, car.bulbs.size
+    end
+
+    assert_queries(1) do
+      assert_equal 0, car_two.bulbs.size
+    end
+  end
+
+  test "calling size on an association that has been loaded does not perform query" do
+    car = Car.create!
+    Bulb.create(car_id: car.id)
+    car.bulb_ids
+
+    car_two = Car.create!
+    car_two.bulb_ids
+
+    assert_no_queries do
+      assert_equal 1, car.bulbs.size
+    end
+
+    assert_no_queries do
+      assert_equal 0, car_two.bulbs.size
+    end
+  end
+
+  test "calling empty on an association that has not been loaded performs a query" do
+    car = Car.create!
+    Bulb.create(car_id: car.id)
+
+    car_two = Car.create!
+
+    assert_queries(1) do
+      assert_not_empty car.bulbs
+    end
+
+    assert_queries(1) do
+      assert_empty car_two.bulbs
+    end
+  end
+
+  test "calling empty on an association that has been loaded does not performs query" do
+    car = Car.create!
+    Bulb.create(car_id: car.id)
+    car.bulb_ids
+
+    car_two = Car.create!
+    car_two.bulb_ids
+
+    assert_no_queries do
+      assert_not_empty car.bulbs
+    end
+
+    assert_no_queries do
+      assert_empty car_two.bulbs
+    end
+  end
+
   class AuthorWithErrorDestroyingAssociation < ActiveRecord::Base
     self.table_name = "authors"
     has_many :posts_with_error_destroying,
-- 
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