PHPUnit Laravel InvalidArgumentException: Unable to locate factory with name [default] [App\User]

I have a setup function in a test which does the following

function setUp()
{
    $this->user = factory(User::class)->create();
}

ofcourse I used "use App\User;" at the very top.

This is my model factory

/** @var \Illuminate\Database\Eloquent\Factory $factory */
$factory->define(App\User::class, function (Faker\Generator $faker) {
    static $password;

    return [
        'name' => $faker->name,
        'email' => $faker->unique()->safeEmail,
        'password' => $password ?: $password = bcrypt('secret'),
        'remember_token' => str_random(10),
    ];
});

When runnning phpunit i get the error

InvalidArgumentException: Unable to locate factory with name [default] [App\User].

HOWEVER: If I go to php artisan tinker an run

factory(User::class)->create();

it works ... I tried App\User::class and other stuff and even putting it inside the test directly instead of the setUp method. The weird part is that another factory within the same file is working.