code: private function getFixturesConfig($fixtures)
      {
          $config = [];
  
          foreach ($fixtures as $fixture) {
              $isNamespaced = (strpos($fixture, '\\') !== false);
              // replace linux' path slashes to namespace backslashes, in case if $fixture is non-namespaced relative path
              $fixture = str_replace('/', '\\', $fixture);
              $fullClassName = $isNamespaced ? $fixture : $this->namespace . '\\' . $fixture;
  
              if (class_exists($fullClassName)) {
                  $config[] = $fullClassName;
              } elseif (class_exists($fullClassName . 'Fixture')) {
                  $config[] = $fullClassName . 'Fixture';
              }
          }
  
          return $config;
      }
docs: Returns valid fixtures config that can be used to load them.
  @param array $fixtures fixtures to configure
  @return array