无法在Laravel中的测试的setUp()方法中使用factory()

我在重构Laravel测试时遇到了一个错误,在 setUp() 方法

<?php

namespace Tests\Feature;

use App\Models\Person;
use Tests\TestCase;

class MembershipTicketsTest extends TestCase
{

public function test_a_non_member_cannot_list_redeemable_events()
{
    $user = Person::factory()->create();

    $this->actingAs($user);

    $this->get(route('event.index'))->assertStatus(302)->assertRedirect(route('membership.create'));
}

其中,返回错误 Unknown formatter "firstName" :

<?php

namespace Tests\Feature;

use App\Models\Person;
use Tests\TestCase;

class MembershipTicketsTest extends TestCase
{
    protected $user;

    protected function setUp() : void
    {
        $this->user = Person::factory()->create();
    }

    public function test_a_non_member_cannot_list_redeemable_events()
    {

        $this->actingAs($this->user);

        $this->get(route('event.index'))->assertStatus(302)->assertRedirect(route('membership.create'));
    }

use Tests\TestCase; 在你的档案里,我就是这么做的。

设置() 拉威尔试验方法。这是真的吗?为什么是这样?