require 'test/unit' class TestRedefinition < Test::Unit::TestCase def test_redefinition test_out, o = IO.pipe spawn(*@options[:ruby], "#{File.dirname(__FILE__)}/test4test_redefinition.rb", out: File::NULL, err: o) o.close assert_match /^test\/unit warning: method TestForTestRedefinition#test_redefinition is redefined$/, test_out.read test_out.close end end