PhpSpec\Locator\PSR0\PSR0Locator::isPSR4 PHP Method

    public function isPSR4()
    {
        return $this->psr4Prefix !== null;
    }

 /**
  * @return string
  */
 public function getSpecFilename()
 {
     if ($this->locator->isPSR4()) {
         return $this->locator->getFullSpecPath() . implode(DIRECTORY_SEPARATOR, $this->parts) . 'Spec.php';
     }
     $nsParts = $this->parts;
     $classname = array_pop($nsParts);
     $parts = array_merge($nsParts, explode('_', $classname));
     return $this->locator->getFullSpecPath() . implode(DIRECTORY_SEPARATOR, $parts) . 'Spec.php';
 }