title: PHP: Composer auto-load not working
body: <p>Actually Iam new to PHP. I am running this from a nearly empty folder (actually following along a Lara-casts tutorial: Design a Fluent API with TDD).</p>
  
  <p>My directory structure looks like</p>
  
  <ul>
  <li>src
  
  <ul>
  <li>Expression.php</li>
  </ul></li>
  <li>tests
  
  <ul>
  <li>ExpressionTest.php</li>
  </ul></li>
  <li>vendor</li>
  <li>composer.json</li>
  <li>composer.lock</li>
  </ul>
  
  <p>Inside composer.json:</p>
  
  <pre><code>{    
      "require-dev": {
          "phpunit/phpunit": "^5.2"
      },
      "autoload": {
          "psr-4": {
              "": "src/"
          }
      }
  }
  </code></pre>
  
  <p>Inside ExpressionTest.php:
      
  
  <pre><code>class ExpressionTest extends PHPUnit_Framework_TestCase
  {
      /** @test */
      public function it_finds_a_string()
      {
          $regex = Expression::make()-&gt;find('www');
  
          $this-&gt;assertRegExp($regex, 'www');
      }
  }
  </code></pre>
  
  <p>Inside Expression.php</p>
  
  <pre><code>&lt;?php
  
  class Expression
  {
  
  }
  </code></pre>
  
  <p>I then run composer dump-autoload and run phpunit but I still get:</p>
  
  <pre><code> "Fatal error: Class 'Expression' not found in 
  C:\Users\nobis\code\testing2\tests\ExpressionTest.php on line 8"
  </code></pre>
  
  <p>Is there something wrong with my syntax? My understanding of Composer is very basic. Thanks in advance.</p>