GraphQL\Error\Error::getLocations PHP Метод

    public function getLocations()
    {
        if (null === $this->locations) {
            $positions = $this->getPositions();
            $source = $this->getSource();
            if ($positions && $source) {
                $this->locations = array_map(function ($pos) use($source) {
                    return $source->getLocation($pos);
                }, $positions);
            } else {
                $this->locations = [];
            }
        }
        return $this->locations;
    }

 /**
  * @it converts source and positions to locations
  */
 public function testConvertsSourceAndPositionsToLocations()
 {
     $source = new Source('{
   field
 }');
     $e = new Error('msg', null, $source, [10]);
     $this->assertEquals(null, $e->nodes);
     $this->assertEquals($source, $e->getSource());
     $this->assertEquals([10], $e->getPositions());
     $this->assertEquals([new SourceLocation(2, 9)], $e->getLocations());
 }