redgreen.rb

# -*- coding: utf-8 -*-
class Test::Unit::UI::Console::RedGreenTestRunner < Test::Unit::UI::Console::TestRunner  
  def output_single(something, level=NORMAL)
    return unless (output?(level))
    something = case something
                when '.' then Color.green('.')
                when '☻' then Color.green('☻')
                when 'F' then Color.red("F")
                when 'E' then Color.yellow("E")
                else something
                end
    @io.write(something) 
    @io.flush
  end
end

test.rb

config.gem "redgreen"

test_helper.rb

require 'test/unit/ui/console/testrunner'
require File.join("#{RAILS_ROOT}/lib", 'patches/redgreen')
require File.join("#{RAILS_ROOT}/lib", 'patches/testrunner')