Image Intervention - PhpUnit - Encoding format (bin) is not supported

I wrote a test for a piece of my application (Laravel 5.1 / Vagrant homestead) :

<?php

use Illuminate\Foundation\Testing\WithoutMiddleware;
use Illuminate\Foundation\Testing\DatabaseMigrations;
use Illuminate\Foundation\Testing\DatabaseTransactions;

use Faker\Factory as Faker;

class NewAdTest extends TestCase
{
    use DatabaseTransactions;


    public function test_it_must_create_an_ad()
    {
        $faker = Faker::create();

        $this->visit('/awesome-segment')
            ->attach($faker->image(), 'avatar')
            ->press('submit')
            ->seePageIs('/awesome-segment')
            ->see('Are you awesome dude ?');

    }


}

In that piece of my application, I use Intervention to resize the avatar uploaded. Everything works like a charm in my browser, but when I run that test, Intervention becomes crazy and output me that:

Caused by
exception 'Intervention\Image\Exception\NotSupportedException' with message 'Encoding format (bin) is not supported.' in /home/vagrant/Code/http://ift.tt/1MHrr7G

Do someone has some leads ?

via Chebli Mohamed