接上文，好不容易配置好phpunit 一运行命令：
phpunit tests/feature/exampletest
报错：
ErrorException: Declaration of Illuminate\Testing\Assert::assertArraySubset($subset, $array, bool $checkForIdentity = false, string $msg = ‘‘): void should be compatible with PHPUnit\Framework\Assert::assertArraySubset($subset, $array, $strict = false, $message = ‘‘)
解决办法：推测是因为 phpunit 版本跟 laravel 所需的版本不匹配，而且是低于 laravel 所需的版本，更新 phpunit.phar 可以解决
查看phpunit版本命令：
$ phpunit --version PHPUnit x.y.z by Sebastian Bergmann and contributors.
重新下载最新版本的phpunit 8.5.8.phar，复制到之前安装phpunit的目录覆盖
之后重新输入命令：
$ phpunit --version PHPUnit 8.5.8 by Sebastian Bergmann and contributors.
成功了，现在我们再来单元测试：
$ phpunit tests/feature/exampletest PHPUnit 8.5.8 by Sebastian Bergmann and contributors. Warning: Invocation with class name is deprecated . 1 / 1 (100%) Time: 213 ms, Memory: 24.00 MB OK (1 test, 1 assertion)
搞定，收工！