public function testDeleteSuccess()
 {
     $category = factory(Category::class)->create();
     $user = factory(App\User::class)->make(['hasRole' => true]);
     Auth::login($user);
     $res = $this->call('DELETE', "/categories/{$category->id}");
     $this->assertEquals(204, $res->getStatusCode());
     $exists = Category::find($category->id);
     $this->assertNull($exists);
 }