admin\config\admin.php

<?php
return [
  'session_admin' => 'adminUser',
];

admin\Login.php

<?php
declare (strict_types = 1);
namespace app\admin\controller;
use app\BaseController;
use think\facade\View;
use app\common\model\mysql\AdminUser;

class Login extends BaseController{

    public function test()
    {
        halt(session(config("admin.session_admin")));
    }

    public function index(){
        return View::fetch();
    }

    public function check()
    {
        if (!$this->request->isPost()){
            return rData(config("code.error"),"请求方式错误");
        }

        $username = $this->request->param('username','','trim');
        $password = $this->request->param('password','','trim');
        $captcha = $this->request->param('captcha','','trim');

        if (empty($username) || empty($password) || empty($captcha)){
            return rData(config("code.error"),"参数不能为空");
        }
        //校验验证码
        if (!captcha_check($captcha)){
            return rData(config("code.error"),"验证码不正确");
        }

        try {
            $adminModel = new AdminUser;
            $adminUser = $adminModel->getAdminUserByUserName($username);

            if (empty($adminUser) || $adminUser->status != config("code.mysql.state_normal")) {
                return rData(config("code.error"), "管理员不存在");
            }
            $adminUser = $adminUser->toArray();

            if ($adminUser['password'] != password($password, $adminUser['encrypt'])) {
                return rData(config("code.error"), "管理员密码错误");
            }

            //记录登录信息
            $updateData = [
                "login_time" => time(),
                "login_ip" => request()->ip(),
                "update_time" => time(),
            ];
            $res = $adminModel->updateById($adminUser['id'], $updateData);
            if (empty($res)) {
                return rData(config("code.error"), "登录失败");
            }
        } catch (\Exception $e) {
            // todu 记录日志 $e->getMessage();
            return rData(config("code.error"), "内部异常，登录失败");
        }

        //记录session
        session(config("admin.session_admin",$adminUser));

        return rData(config("code.success"),"登录成功");
    }


}

访问 admin/login/test
输出null，请问老师哪里问题