example-top-down-unity/Assets/Scripts/Inventory/InventoryController.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class InventoryController : MonoBehaviour
{
    [SerializeField] Item item1;// not needed
    [SerializeField] Item item2;// not needed
    public Inventory inventory;
    [SerializeField] UI_Inventory uiInventory;
    private void Awake()
    {
        inventory = transform.GetComponent<Inventory>();
        inventory.createEmptyInventory(5);
        Debug.Log(inventory.addItemAt(0, item1, 8));
        Debug.Log(inventory.addItemAt(0, item1, 1));
        Debug.Log(inventory.addItemAt(3, item2, 15));
        Debug.Log(inventory.addItemAt(0, item2, 15));
        Debug.Log(inventory.getInventory[0].Count);

        uiInventory.setInventory(inventory);
    }
    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {

    }
}