title: How to ignore directories with Composer?
body: <p>I'd like to release a PHP library and submit it on <a href="https://packagist.org/">Packagist</a> to have it installable via <a href="http://getcomposer.org/">Composer</a>.</p>
  
  <p>My library has the following structure:</p>
  
  <pre><code>lib/
  tests/
  composer.json
  README.md
  </code></pre>
  
  <p>Basically, whenever I include this library in a project's <code>composer.json</code>, I'd like everything to be copied with the exception of the <code>tests</code> directory, which is cumbersome and is only needed when developing the library itself. It's just a waste of space otherwise (especially when packaging the project for production).</p>
  
  <p>Is it possible to exclude this directory from the library's <code>composer.json</code>?</p>