1 files changed, 40 insertions, 0 deletions
diff --git a/activerecord/test/cases/adapters/mysql2/optimizer_hints_test.rb b/activerecord/test/cases/adapters/mysql2/optimizer_hints_test.rb
new file mode 100644
index 0000000000..b9794c5710
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql2/optimizer_hints_test.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+require "models/post"
+
+if supports_optimizer_hints?
+  class Mysql2OptimzerHintsTest < ActiveRecord::Mysql2TestCase
+    fixtures :posts
+
+    def test_optimizer_hints
+      assert_sql(%r{\ASELECT /\*\+ NO_RANGE_OPTIMIZATION\(posts index_posts_on_author_id\) \*/}) do
+        posts = Post.optimizer_hints("NO_RANGE_OPTIMIZATION(posts index_posts_on_author_id)")
+        posts = posts.select(:id).where(author_id: [0, 1])
+        assert_includes posts.explain, "| index | index_posts_on_author_id | index_posts_on_author_id |"
+      end
+    end
+
+    def test_optimizer_hints_is_sanitized
+      assert_sql(%r{\ASELECT /\*\+ NO_RANGE_OPTIMIZATION\(posts index_posts_on_author_id\) \*/}) do
+        posts = Post.optimizer_hints("/*+ NO_RANGE_OPTIMIZATION(posts index_posts_on_author_id) */")
+        posts = posts.select(:id).where(author_id: [0, 1])
+        assert_includes posts.explain, "| index | index_posts_on_author_id | index_posts_on_author_id |"
+      end
+
+      assert_sql(%r{\ASELECT /\*\+  `posts`\.\*,  \*/}) do
+        posts = Post.optimizer_hints("**// `posts`.*, //**")
+        posts = posts.select(:id).where(author_id: [0, 1])
+        assert_equal({ "id" => 1 }, posts.first.as_json)
+      end
+    end
+
+    def test_optimizer_hints_with_unscope
+      assert_sql(%r{\ASELECT `posts`\.`id`}) do
+        posts = Post.optimizer_hints("/*+ NO_RANGE_OPTIMIZATION(posts index_posts_on_author_id) */")
+        posts = posts.select(:id).where(author_id: [0, 1])
+        posts.unscope(:optimizer_hints).load
+      end
+    end
+  end
+end