# File lib/autotest.rb, line 239
  def run_tests
    hook :run_command

    new_mtime = self.find_files_to_test
    return unless new_mtime
    self.last_mtime = new_mtime

    cmd = self.make_test_cmd self.files_to_test
    return if cmd.empty?

    puts cmd unless $q

    old_sync = $stdout.sync
    $stdout.sync = true
    self.results = []
    line = []
    begin
      open("| #{cmd}", "r") do |f|
        until f.eof? do
          c = f.getc
          putc c
          line << c
          if c == ?\n then
            self.results << if RUBY_VERSION >= "1.9" then
                              line.join
                            else
                              line.pack "c*"
                            end
            line.clear
          end
        end
      end
    ensure
      $stdout.sync = old_sync
    end
    hook :ran_command
    self.results = self.results.join

    handle_results(self.results)
  end