more TruffleRuby

Author: tenderlove

test/test_integration_ractor.rb

@@ -35,6 +35,8 @@ def test_ractor_share_database
   end
 
   def test_shareable_db
+    skip unless defined?(Ractor)
+
     # databases are shareable between ractors, but only if they're opened
     # in "full mutex" mode
     db = SQLite3::Database.new ":memory:",