/**
  * Loads an array of fixtures.
  *
  * @param string[] $fixtureClasses List of fixture class names
  * @param bool $append
  * @return $this
  * @throws \Exception
  */
 public function loadFixtures(array $fixtureClasses, $append = false)
 {
     $loader = new \Doctrine\Common\DataFixtures\Loader();
     foreach ($fixtureClasses as $fixtureClass) {
         if (!class_Exists($fixtureClass)) {
             throw new \Exception('Could not locate the fixture class ' . $fixtureClass . '. Ensure it is autoloadable');
         }
         $fixture = new $fixtureClass();
         $loader->addFixture($fixture);
     }
     $purger = new \Doctrine\Common\DataFixtures\Purger\ORMPurger();
     $executor = new \Doctrine\Common\DataFixtures\Executor\ORMExecutor($this->getEntityManager(), $purger);
     $executor->setReferenceRepository($this->getFixtureReferenceRepo());
     $executor->execute($loader->getFixtures(), $append);
     return $this;
 }