In Laravel, how can I clear my database after my test class is done running?

Question

I have a really large database that I want to introduce testing into and I have been experimenting on ways to approach it.

If I were to run the full migrate:fresh it would take about a minute to create the entire schema. To seed this database it would likely take >5 minutes. My thought was to preload a DB schema into a test database ahead of time, before the tests even start running. Then I was thinking I would seed portions of data as I need it.

This project has multiple domains and it is a DDD design. I'm currently thinking that each domain will have at least one testcase that extends laravels BaseTestcase.

The problem I'm having is that I am not able to clear the data from the database. Here's an example of what a testcase might look like for one of my domains:

    use CreatesApplication;
    use RefreshDatabase;
    use ActingAsUser;
    use HasTestHelpers;

    /**
     * Refresh a conventional test database.
     *
     * @return void
     */
    protected function refreshTestDatabase()
    {
        if (! RefreshDatabaseState::$migrated) {
            $this->artisan('db:seed --class=CourseTestSeeder');

            $this->app[Kernel::class]->setArtisan(null);

            RefreshDatabaseState::$migrated = true;
        }

        $this->beginDatabaseTransaction();
    }

    public static function tearDownAfterClass(): void
    {
        CourseTestSeeder::clear();
    }

This particular domains depends on Course data. I put together a CourseTestSeeder that will seed all the data needed for this domain. This part works great. The problem is that when I try to do a tearDownAfterClass I receive the following error:

Exception in tearDownAfterClass
  Target class [db] does not exist.

  at vendor/phpunit/phpunit/phpunit:98
     94▕ unset($options);
     95▕
     96▕ require PHPUNIT_COMPOSER_INSTALL;
     97▕
  ➜  98▕ PHPUnit\TextUI\Command::main();
     99▕

How can I clear the db after my tests run? Is there a better way to do this?

If this is not a good approach, I also welcome feedback on that.