in app/routes.php

gistfile1.php

// everything's creating fine. Positions and closure table, all's fine.
$Test = Test::create(array());
$child1 = $Test->appendChild(Test::make(), 0, true);
$child2 = $Test->appendChild(Test::make(), 1, true);
$child3 = $Test->appendChild(Test::make(), 2, true);
$child4 = $Test->appendChild(Test::make(), 3, true);

// this returns ids of $Test, $child1, $child2 and $child3...
dd($child4->prevSiblings()->lists('id'));

// returns id
dd($child4->getKey());

// then i do this
    /**
     * Build a part of the siblings query.
     * This part defines a sibling regardless of direction (prev or next) and position.
     *
     * @param array $columns
     * @return \Illuminate\Database\Eloquent\Builder
     */
    protected function buildSiblingsSubquery(array $columns = array('*'))
    {
        $dk = $this->getQualifiedDescendantKeyName();
        $dpk = $this->getQualifiedDepthKeyName();

        dd($this); //note this

        return $this->select($this->getSelectedColumns($columns))
            ->join($this->getClosure(), $dk, '=', $this->getQualifiedKeyName())
            ->where($dk, '<>', $this->getKey())
            ->where($dpk, '=', $this->getDepth());
    }

// that dd returns me this
object(Test)[123]
  protected 'table' => string 'tests' (length=5)
  public 'timestamps' => boolean false
  protected 'closure' => string 'tests_closure' (length=13)
  protected 'softDelete' => boolean true
  protected 'connection' => null
  protected 'primaryKey' => string 'id' (length=2)
  protected 'perPage' => int 15
  public 'incrementing' => boolean true
  protected 'attributes' => 
    array (size=0)
      empty
  protected 'original' => 
    array (size=0)
      empty
  protected 'relations' => 
    array (size=0)
      empty
  protected 'hidden' => 
    array (size=1)
      'depth' => int 0
  protected 'visible' => 
    array (size=0)
      empty
  protected 'appends' => 
    array (size=0)
      empty
  protected 'fillable' => 
    array (size=1)
      0 => string 'position' (length=8)
  protected 'guarded' => 
    array (size=1)
      0 => string '*' (length=1)
  protected 'dates' => 
    array (size=0)
      empty
  protected 'touches' => 
    array (size=0)
      empty
  protected 'with' => 
    array (size=0)
      empty
  public 'exists' => boolean false
  
  
// fucking what?!