izyim-api/database/factories/SoFactory.php

<?php

use Faker\Generator as Faker;

/*
|--------------------------------------------------------------------------
| Model Factories
|--------------------------------------------------------------------------
|
| This directory should contain each of the model factory definitions for
| your application. Factories provide a convenient way to generate new
| model instances for testing / seeding your application's database.
|
*/
// Manually creating the relationship tree.
$factory->define(App\So::class, function (Faker $faker) {
    return [
        'ff_id'=>'testing',
        'supplier_company_name'=>'testing',
        'supplier_contact_person'=>'testing',
        'supplier_contact_person_no'=>'12345',
        'delivery_id'=>'12345',
        'warehouse_id'=>'testing',
    ];
});