Trying to format a diffForHumans for Laravel Carbon instance

Question

Inside my feature test I am trying to add some time specific dates and then I'm trying to get the exact time difference. Currently its rounding to the highest level so in this case months.

Feature Test

$title->champions()->attach([$champion1->id => ['champion_from' => Carbon::create(2016, 6), 'champion_to' => Carbon::create(2016, 7, 26)]]);

Model

public function getLengthOfTitleReignAttribute()
{
    return Carbon::parse($this->pivot->champion_from)->diffForHumans(Carbon::parse($this->pivot->champion_to), true);
}