Working on the RPCFN: Shift Subtitle I found myself having to work with files input as a stream (or anyway that’s how I wanted to approach the problem; streams are efficient to me).  In order to give my code any sort of unit testing justice I needed to mock the file system.  The challenge expressly forbids any Ruby gems from being used in the script itself – and maybe by extension the unit tests as well – but I could not see devoting the time necessary to write a mocking framework for the file system.

I found a gem that does precisely what I needed named Construct.  Unfortunately there is a bug with Ruby 1.8.6 on Windows in regards to clean up of temp files.  The problem is that when attempting to clean up a Errno::EACCES is raised causing the unit test to fail (or you to write a lot of rescue blocks).

A workaround I came up with was to replace the rmtree method in the Pathname class within my unit test to perform no clean up.  Not the best approach I am sure, but it let me get on with my work.

# something_test.rb 

require "test/unit" 

require 'construct' 

require 'something'


class Pathname 

  # windows has problems with temp files created by Ruby
  # http://redmine.ruby-lang.org/issues/show/1494
  def rmtree
    nil
  end
end

class SomethingTest < Test::Unit::TestCase 

   # test methods...
end