Database reset aftar testing in Laravel

I'm new at Testing, so i was following a tutorial. In the Database setting i was set into like this:

'sqlite' => [
            'driver'   => 'sqlite',
            'database' => ':memory:',
            'prefix'   => '',
        ],

and in the phpunit.xml i make configuration like this:

<php>
        <env name="APP_ENV" value="testing"/>
        <env name="DATABASE_CONNECTION" value="sqlite"/>
        <env name="CACHE_DRIVER" value="array"/>
        <env name="SESSION_DRIVER" value="array"/>
        <env name="QUEUE_DRIVER" value="sync"/>
    </php>

i'm not sure what going on, the database seed that i created using factory is always missing and the database tables either. left only a migration table. so what was happen and how can i fix it?