[8.x] Allow a specific seeder to be used in tests

[patrickomeara]

It is quite common to have a seeder filled with dummy data that makes the developer experience closer to the production app, and a separate test suite seeder that provides the basics needed to get the app started; languages, permissions levels, oauth apps etc.

This PR enables the developer to specify a seeder to be used in the RefreshDatabase trait.

class TasksApiTest extends TestCase 
{
    use RefreshDatabase;

    protected $seeder = TestSuiteSeeder::class;

    // ...
}

[driesvints]

@patrickomeara thanks. Can you send in a PR to the docs as well?

[jasonmccreary]

I wonder if $seeders = [...] would have been more robust. While I appreciate you could make a seeder which runs the necessary seeders, keeping them separate provides greater flexibility through combination.

[driesvints]

@jasonmccreary the FreshCommand only allows for one seeder atm

[jasonmccreary]

I see. My bad. I didn't really look at the internals.