Author: Hugo Briand (briand@ekino.com)
Inheritance: extends Symfony\Component\HttpKernel\DependencyInjection\Extension
 /**
  * Asserts that an InvalidConfigurationException is thrown when not providing currency parameter.
  *
  * @expectedException \Symfony\Component\Config\Definition\Exception\InvalidConfigurationException
  */
 public function testCurrencyRequired()
 {
     $configuration = new ContainerBuilder();
     $loader = new SonataPriceExtension();
     $config = $this->getDefaultConfig();
     unset($config[0]['currency']);
     $loader->load($config, $configuration);
 }