diff --git a/tool/test_for_warn_bundled_gems/test_no_warn_sub_feature.rb b/tool/test_for_warn_bundled_gems/test_no_warn_sub_feature.rb
new file mode 100644
index 0000000000..7d62a2f9d0
--- /dev/null
+++ b/tool/test_for_warn_bundled_gems/test_no_warn_sub_feature.rb
@@ -0,0 +1,8 @@
+require "bundler/inline"
+
+gemfile do
+  source "https://rubygems.org"
+  gem "bigdecimal"
+end
+
+require "bigdecimal/util"
diff --git a/tool/test_for_warn_bundled_gems/test_warn_sub_feature.rb b/tool/test_for_warn_bundled_gems/test_warn_sub_feature.rb
new file mode 100644
index 0000000000..bf7eb3572d
--- /dev/null
+++ b/tool/test_for_warn_bundled_gems/test_warn_sub_feature.rb
@@ -0,0 +1,7 @@
+require "bundler/inline"
+
+gemfile do
+  source "https://rubygems.org"
+end
+
+require "bigdecimal/util"