it "always taints resulting strings when self or regexp is tainted" do
    strs = ["hello world"]
    strs += strs.map { |s| s.dup.taint }

    strs.each do |str|
      str = str.dup
      str.slice!(//, 0).tainted?.should == str.tainted?
      str.slice!(/hello/, 0).tainted?.should == str.tainted?

      tainted_re = /(.)(.)(.)/
      tainted_re.taint

      str.slice!(tainted_re, 1).tainted?.should == true
    end
  end