zippy-test.rb

# Put filenames on the pipe to have them loaded
# $ echo test/unit/foo_test.rb > zippy.pipe

require 'benchmark'
#
# load rails and the gems
result = Benchmark.realtime { require './config/application' }
puts "Loading gems took #{result}s"

# open pipe
pipe = open('zippy.pipe', 'r+')

loop do
  filename = pipe.gets.strip

  # create a process to run the tests
  fork do
    result = Benchmark.realtime { require File.expand_path(filename) }
    puts "Running test took #{result}s"
  end

  Process.wait
end