Laravel Testing reading many to many relationships

Ok so Im new to testing but I am trying to test if I can read from a db table which shares a many to many with another but only where certain conditions are met, IE Can I get all users who have role ID 1 or 2 .

My setup: -Roles and Users are the 2 tables which share a many to many connection.

• Roles is being filled through the use of a RoleSeeder:

public function run()
    {
        DB::table('roles')->delete();

        $roles = [
            ['id' => 1, 'name' => 'superuser'],
            ['id' => 2, 'name' => 'staff'],
            ['id' => 3, 'name' => 'venueadmin'],
            ['id' => 4, 'name' => 'venuestaff'],
        ];

        Role::insert($roles);
    }

• Users is being filled through this seeder:

public function run()
    {
        DB::table('users')->delete();
        DB::table('role_user')->delete();

        User::factory()
            ->count(100)
            ->create();

        $roles = Role::all();

        User::all()->each(function ($user) use ($roles) { 
            $user->roles()->attach(
                $roles->random(rand(1, 2))->pluck('id')->toArray()
            ); 
        });
    }

• the UsersController is being called via API
• The index function of UsersController looks like this:

public function index()
    {
        $users = User::whereHas('roles', function ($query) {
            $query->where('role_id', '1')
                  ->orWhere('role_id','2');
        })->with('roles')->get();
        return $users;
    }

Now, stop me if I'm wrong but here are my thought processes/assumptions:

1. Before I can read anything from Users, I need to enter some test data. This means calling the User factory.
2. This will only bring back users, not their relationships with roles
3. The users factory (I think) is not able to establish the relationship I need, only the seeder will
4. I can't call seeder from the test (Or can I?).

So, how can I enter a test user, with one or two roles and read it back testing that only users with certain roles are grabbed? Here is what I had so far in the test:

$this->withoutExceptionHandling();

        $this->postJson('/api/users', [
            'firstname' => 'Fake',
            'lastname' => 'Person',
            'email' => '[email protected]',
            'password' => 'yIXUNpkjO0rOQ5byMi.Ye4oKoEa3Ro9llC/.og/at2.uheWG/igi',
            'remember_token' => Str::random(10),
            'roles' => '1','2'
        ]);
        
        $user = $this->getJson('/api/users');

        dd($user);

That DD returned null