title: Why does this require fail from rake but succeed when ran explicitly?
body: <p>Help me understand why this project's tests run when executed directly but do not when run via rake. The error when run via a Rake TestTask:</p>
  
  <pre><code>** Execute test
  /home/myockey/.rvm/rubies/ruby-1.9.2-p136/bin/ruby -I"lib:test" "/home/myockey/.rvm/gems/ruby-1.9.2-p136/gems/rake-0.8.7/lib/rake/rake_test_loader.rb" "test/unit/data_test.rb" "test/unit/station_test.rb" "test/unit/raw_test.rb" "test/unit/parser_test.rb" "test/unit/report_test.rb" 
  &lt;internal:lib/rubygems/custom_require&gt;:29:in `require': no such file to load -- test/unit/../metar_test_helper.rb (LoadError)
      from &lt;internal:lib/rubygems/custom_require&gt;:29:in `require'
      from test/unit/data_test.rb:4:in `&lt;top (required)&gt;'
      from /home/myockey/.rvm/gems/ruby-1.9.2-p136/gems/rake-0.8.7/lib/rake/rake_test_loader.rb:5:in `load'
      from /home/myockey/.rvm/gems/ruby-1.9.2-p136/gems/rake-0.8.7/lib/rake/rake_test_loader.rb:5:in `block in &lt;main&gt;'
      from /home/myockey/.rvm/gems/ruby-1.9.2-p136/gems/rake-0.8.7/lib/rake/rake_test_loader.rb:5:in `each'
      from /home/myockey/.rvm/gems/ruby-1.9.2-p136/gems/rake-0.8.7/lib/rake/rake_test_loader.rb:5:in `&lt;main&gt;'
  rake aborted!
  </code></pre>
  
  <p>When I run the script directly I get the following:</p>
  
  <pre><code>myockey@myockey-K61IC:~/opt/joeyates-metar-parser-cdca19f/test/unit$ ruby data_test.rb 
  Loaded suite data_test
  Started
  ...................................................
  Finished in 0.084939 seconds.
  
  51 tests, 121 assertions, 0 failures, 0 errors, 0 skips
  </code></pre>
  
  <p>The top of the ruby files looks like this:</p>
  
  <pre><code>#!/usr/bin/env ruby
  # encoding: utf-8
  
  require File.dirname(__FILE__) + '/../metar_test_helper'
  
  class TestMetarData &lt; Test::Unit::TestCase
  </code></pre>
  
  <p>Note that I tried adding the .rb file extension to metar_test_helper to no avail. Rest assured that a file named metar_test_helper.rb exists in the parent directory of the file and that it has sufficient permissions to be accessible.</p>
  
  <p>Added a bounty. I know this must be a simple path issue, but I'd really appreciate some guidance solving it and helping me understand it.</p>