public function testChangingBelongsToSideOfHasManyRelation()
{
$k1 = new K();
$k2 = new K();
$i = new I();
$i->ks->add($k1);
$i->ks->add($k2);
$this->assertTrue($i->save());
$this->assertEquals(2, $i->ks->count());
$k1->i = null;
$this->assertTrue($k1->save());
$iId = $i->id;
$i->forget();
unset($i);
$i = I::getById($iId);
$this->assertEquals(1, $i->ks->count());
$i->ks->removeByIndex(0);
$this->assertTrue($i->save());
$this->assertEquals(0, $i->ks->count());
$k2Id = $k2->id;
$k2->forget();
unset($k2);
$k2 = K::getById($k2Id);
$this->assertTrue($k2->i->id < 0);
}