1 files changed, 9 insertions, 0 deletions
diff --git a/activerecord/test/cases/counter_cache_test.rb b/activerecord/test/cases/counter_cache_test.rb
index 96a0edea34..1f5055b2a2 100644
--- a/activerecord/test/cases/counter_cache_test.rb
+++ b/activerecord/test/cases/counter_cache_test.rb
@@ -189,4 +189,13 @@ class CounterCacheTest < ActiveRecord::TestCase
     assert_equal 2, car.engines_count
     assert_equal 2, car.reload.engines_count
   end
+
+  test "counter caches are updated in memory when the default value is nil" do
+    car = Car.new(engines_count: nil)
+    car.engines = [Engine.new, Engine.new]
+    car.save!
+
+    assert_equal 2, car.engines_count
+    assert_equal 2, car.reload.engines_count
+  end
 end