What should I write to do Unit testing (like test cases, how to run the unit testing)??? code- (python)

def checkout(request): data = cartData(request) cartItems = data['cartItems'] order = data['order'] items = data['items'] context = {'items':items, 'order':order, 'cartItems':cartItems} return render(request, 'store/checkout.html', context) (Please answer within today if possible)