title: How to use Test:Unit on a ruby file without classes (only methods)
body: <p>I have to write code for an homework and I wish to do TDD from the start.
  The homework consists of one ruby file with methods in it, no class.</p>
  
  <p>All examples I find on the Internet test against classes.  How could I test the following method?</p>
  
  <p><strong>homework.rb</strong></p>
  
  <pre><code>#!/usr/bin/env ruby
  
  def count_words(str)
    # SOME CODE HERE
  end
  </code></pre>
  
  <p>There is an auto-grading system that take one ruby file with the methods defined for the homework as an input.  So, I have to write my tests in a separate file (test_homework.rb) or comment out my test before submitting (which I found counter productive...). </p>
  
  <p>How will I test the count_words method using Test:Unit?</p>