php - Laravel How to Test Static Query Builder Methods?

one text

I have the following single responsibility repository class

<?php
namespace App\Launches\Repositories\Customer;

use App\Launches\Models\Customer\Subscription;
use Illuminate\Support\Collection;

final class GetSubscriptionRepository
{
    /**
     * @param int $productId
     * @return Collection
     */
    public function byProductId(int $productId): Collection
    {
        return Subscription::where('product_id', $productId)->get();
    }
}

I want to be able to test that method, to make sure the object retrieve is the one I've asked. So I've done the following:

<?php
namespace Tests\Unit\Launches\Repository\Customer;

use App\Launches\Models\Customer\Subscription;
use Illuminate\Foundation\Testing\RefreshDatabase;
use Illuminate\Support\Collection;
use Tests\TestCase;
use App\Launches\Repositories\Customer\GetSubscriptionRepository;

class GetSubscriptionRepositoryTest extends TestCase
{
    use RefreshDatabase;

    /**
     * @var GetSubscriptionRepository
     */
    protected $getSubscriptionRepository;

    /**
     * @var Collection
     */
    protected $subscriptionCollection;

    public function setUp(): void
    {
        parent::setUp();

        $this->getSubscriptionRepository = new GetSubscriptionRepository();
        $this->subscriptionCollection = factory(Subscription::class, 20)->make();
    }

    /**
     * @covers GetSubscriptionRepository::byProductId
     */
    public function testSubscriptionIsPickedById()
    {
        $randomSubscription = $this->subscriptionCollection->random(1)->first()->toArray();
        $pickedSubscription = $this->getSubscriptionRepository->byProductId($randomSubscription['id']);
        
        $this->assertEquals($randomSubscription['id'], $pickedSubscription->get('id'));
    }
}

It's always returning null on $this->getSubscriptionRepository->byProductId($randomSubscription['id']);

It is obviously expecting stuff to be in the database, is there a way to test it without adding stuff to the database?