Laraval - Tests on MySQL database

I'm learning Laravel and Functional tests. On laravast we have in phpunit.xml:

<php>
        <env name="DB_CONNECTION" value="sqlite"/>
        <env name="DB_DATABASE" value=":memory:"/>
</php>

I can not test on mysql database because when I switch my DB_CONNECTION param to "mysql" I have error "PDOException: SQLSTATE[HY000] [1049] Unknown database ':memory:'".

When I dont use memory all tables are removed from my database: My Test Class looks like that:

class ThreadsTest extends TestCase
{

    use DatabaseMigrations;

    /** @test */
    public function a_user_can_browse_threads()
    {
        $response = $this->get('/threads');
        $response->assertStatus(200);
    }
}

Does anybody know how can I test in memory with MySQL ? I can't find any information

Thanks