Issue #2147 has been updated by Mike Pomraning. This is also a problem unit testing anything derived from DelegateClass: AssertionMessage.delayed_diff calls a method, convert(), which may call pp, meaning that something as simple as: assert_equal [1,2,3], array_like_derived_from_delegateclass will fail with an internal NameError (!). ---------------------------------------- http://redmine.ruby-lang.org/issues/show/2147 ---------------------------------------- http://redmine.ruby-lang.org