public function test_join_inventory_scope()
{
$foo = Factory::create(new Product());
$bar = Factory::create(new Product());
Factory::create(new Inventory(), ['product_id' => $bar->id, 'quantity' => 5]);
$this->assertEquals(0, Product::joinInventory()->find($foo->id)->inventory);
$this->assertEquals(5, Product::joinInventory()->find($bar->id)->inventory);
}