public function registerContextClass($contextClass, array $arguments = null)
    {
        if (!class_exists($contextClass)) {
            throw new ContextNotFoundException(sprintf(
                '`%s` context class not found and can not be used.',
                $contextClass
            ), $contextClass);
        }

        $reflClass = new \ReflectionClass($contextClass);

        if (!$reflClass->implementsInterface('Behat\Behat\Context\Context')) {
            throw new WrongContextClassException(sprintf(
                'Every context class must implement Behat Context interface, but `%s` does not.',
                $contextClass
            ), $contextClass);
        }

        $this->contextClasses[$contextClass] = $arguments ? : array();
    }