MorphToMany relation doesn't work properly in my test - php

Question

In my laravel project I use morphToMany relation to connect costs to the orders and products of the orders.
I have this migration:
Schema::create('costables', function (Blueprint $table) {
$table->unsignedBigInteger('cost_id');
$table->morphs('costable');
$table->foreign('cost_id')
->references('id')->on('costs')
->onUpdate('cascade')
->onDelete('cascade');
});
This is the Order model, with costs() method in it:
namespace Domain\Webshop\Models;
use Domain\Customer\Models\Address;
use Domain\Customer\Models\Member;
use Domain\Product\Models\Cost;
use Domain\Webshop\Database\Factories\OrderFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\MorphToMany;
class Order extends Model
{
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = [
'member_id',
'shipping_address_id',
'billing_address_id',
'status',
];
public static $rules = [
'member_id' => 'required|integer',
'shipping_address_id' => 'sometimes|integer',
'billing_address_id' => 'nullable|integer',
'status' => 'required|integer',
];
protected $casts = [
'member_id' => 'integer',
'shipping_address_id' => 'integer',
'billing_address_id' => 'integer',
];
protected $hidden = ['created_at', 'updated_at', 'deleted_at'];
/**
* Create a new factory instance for the model.
*
* #return \Illuminate\Database\Eloquent\Factories\Factory
*/
protected static function newFactory(): OrderFactory
{
return OrderFactory::new();
}
public function member(): BelongsTo
{
return $this->belongsTo(Member::class, 'member_id');
}
public function shippingAddress(): BelongsTo
{
return $this->belongsTo(Address::class, 'shipping_address_id');
}
public function costs(): MorphToMany
{
return $this->morphToMany(Cost::class, 'costable');
}
}
And this is my phpunit test, for testing costs on the Order and OrderProduct models. The $this->model is the actual model, I use this as a trait:
/** #test */
public function shouldHasCosts()
{
$item = $this->model::factory()
->hasCosts(1)
->create();
$this->assertInstanceOf(
Cost::class,
$item->first()->costs()->first(),
"It should be defined a relation called costs on $this->model"
);
}
My problem is, the test success in the Order model case, but fails at the OrderProduct. What have I forgotten, or whats wrong in my code?

Answer 1

I found the problem myself: in the test's setup there was a factory create for the OrderProduct, so in that case there was two rows in the database, and the shouldHasCosts() test is examine the first(), so it was wrong. I deleted the unnecessary create, and it has solved the problem.