Larave 单元测试，Call 方法传递的参数，Request 无法接收

<?php
use Illuminate\Foundation\Testing\WithoutMiddleware;
use Illuminate\Foundation\Testing\DatabaseMigrations;
use Illuminate\Foundation\Testing\DatabaseTransactions;

class TestUser extends TestCase
{
    /**
     * A basic test example.
     *
     * @return void
     */
    public function testStoreUser()
    {
        $response = $this->call('POST','/api/users',[
            'name'=>str_random(10),
            'true_name'=>str_random(5),
            'email'=>str_random('10').'@gmail.com',
            'department_id'=>0,
            'password'=>123456,
            'address'=>'',
            'phone'=>'0551-8959125',
            'mobile_phone'=>'13214789512',
            'usb_key'=>'',
        ]);
        $this->assertEquals(200,$response->getStatusCode());

        //$this->assertTrue(true);
    }
}

class UserController {
        public function store(Request $request)
        {
                //.....
                return $request->input('name')
        }
}

返回的却是如下图：

真是奇怪，不知道是什么原因？有遇到过的朋友吗？
PS：打印出来的log，获取的$request->all()也是空。