public function test_get_billets()
{
$student = factory(Student::class)->create();
$billets = factory(Billet::class, 5)->create(['student_id' => $student->id]);
$repo = App::make(StudentRepository::class);
$student = $repo->getBillets($student->id);
$this->assertInstanceOf(Student::class, $student);
$this->assertInstanceOf(Billet::class, $student->billets->first());
foreach ($billets as $billet) {
$this->seeInDatabase('billets', ['id' => $billet->id, 'student_id' => $student->id]);
}
}