Capturing stdout for tests in Ruby

I found this on Thinking Digitally that allows me to capture stdout and test that it is correct.

require 'stringio'

def capture_stdout
  out = StringIO.new
  $stdout = out
  yield
  return out
ensure
  $stdout = STDOUT
end

Which can be used as follows

class ATest < Test::Unit::TestCase
  def zxc(text, count)
    count.times {puts text.upcase}
  end

  def test_stdout_capture
     out = capture_stdout do
        zxc('yes', 3)
     end

     assert_equal "YES\nYES\nYES\n", out.string
  end
end