title: PHPUnit fails on Travis-CI but passes locally
body: <p>I'm having some trouble getting PHPUnit to work on Travis-CI when it works fine on my local machine. I'm using the same PHP version and PHPUnit version.</p>
  
  <p>My codebase is at <a href="https://github.com/lncd/OAuth2" rel="nofollow">https://github.com/lncd/OAuth2</a><br>
  Travis-CI output is at <a href="https://travis-ci.org/lncd/OAuth2" rel="nofollow">https://travis-ci.org/lncd/OAuth2</a></p>
  
  <p>Executing <code>phpunit -c build/phpunit.xml</code> from the root of the repository works fine locally and tests execute as expected.</p>
  
  <p>The log for Travis is:</p>
  
  <pre><code>$ cd ~/builds
  $ git clone --branch=develop --depth=100 --quiet git://github.com/lncd/OAuth2.git lncd/OAuth2
  $ cd lncd/OAuth2
  $ git checkout -qf 1c3b319aa6c8f5521d5123f0e6affca94ee35010
  $ phpenv global 5.3
  $ php --version
  PHP 5.3.19 (cli) (built: Dec 20 2012 09:57:38) 
  Copyright (c) 1997-2012 The PHP Group
  Zend Engine v2.3.0, Copyright (c) 1998-2012 Zend Technologies
      with Xdebug v2.2.1, Copyright (c) 2002-2012, by Derick Rethans
  $ phpunit -c build/phpunit.xml
  PHP Warning:  require_once(src/OAuth2/Authentication/Server.php): failed to open stream: No such file or directory in /home/travis/builds/lncd/OAuth2/tests/authentication/server_test.php on line 3
  PHP Stack trace:
  PHP   1. {main}() /home/travis/.phpenv/versions/5.3.19/bin/phpunit:0
  PHP   2. PHPUnit_TextUI_Command::main() /home/travis/.phpenv/versions/5.3.19/bin/phpunit:46
  PHP   3. PHPUnit_TextUI_Command-&gt;run() /home/travis/.phpenv/versions/5.3.19/share/pyrus/.pear/php/PHPUnit/TextUI/Command.php:129
  PHP   4. PHPUnit_TextUI_Command-&gt;handleArguments() /home/travis/.phpenv/versions/5.3.19/share/pyrus/.pear/php/PHPUnit/TextUI/Command.php:138
  PHP   5. PHPUnit_Util_Configuration-&gt;getTestSuiteConfiguration() /home/travis/.phpenv/versions/5.3.19/share/pyrus/.pear/php/PHPUnit/TextUI/Command.php:657
  PHP   6. PHPUnit_Util_Configuration-&gt;getTestSuite() /home/travis/.phpenv/versions/5.3.19/share/pyrus/.pear/php/PHPUnit/Util/Configuration.php:784
  PHP   7. PHPUnit_Framework_TestSuite-&gt;addTestFiles() /home/travis/.phpenv/versions/5.3.19/share/pyrus/.pear/php/PHPUnit/Util/Configuration.php:860
  PHP   8. PHPUnit_Framework_TestSuite-&gt;addTestFile() /home/travis/.phpenv/versions/5.3.19/share/pyrus/.pear/php/PHPUnit/Framework/TestSuite.php:416
  PHP   9. PHPUnit_Util_Fileloader::checkAndLoad() /home/travis/.phpenv/versions/5.3.19/share/pyrus/.pear/php/PHPUnit/Framework/TestSuite.php:355
  PHP  10. PHPUnit_Util_Fileloader::load() /home/travis/.phpenv/versions/5.3.19/share/pyrus/.pear/php/PHPUnit/Util/Fileloader.php:76
  PHP  11. include_once() /home/travis/.phpenv/versions/5.3.19/share/pyrus/.pear/php/PHPUnit/Util/Fileloader.php:92
  </code></pre>
  
  <p>I've played around with altering the <code>require_once</code> to load<code>require_once '../../src/OAuth2/Authentication/Server.php';</code> (i.e. two directories down from the executing file) but that doesn't work on Travis or my local setup.</p>
  
  <p>What am I doing wrong? Or is it a bug with Travis?</p>
  
  <p>Thank you</p>
  
  <hr>
  
  <p><strong>EDIT:</strong></p>
  
  <p>To clarify this is the directory structure:</p>
  
  <pre><code>build
      /phpunit.xml
  src
      /OAuth2
          /Authentication
              /Database.php
              /Server.php
          /Resource
              /Database.php
              /Server.php
  tests
      /authentication
          /database_mock.php
          /server_test.php
      /resource
          /database_mock.php
          /server_test.php
  </code></pre>
  
  <p>Both files called <code>server_test.php</code> under directories in /tests are trying to load respective <code>Server.php</code> and <code>Database.php</code> files from directories under /src</p>