def test_coin_return():
vending_machine = VendingMachine()
vending_machine.insert_nickel()
vending_machine.insert_dime()
vending_machine.insert_quarter()
vending_machine.insert_dollar()
returned_coins: MoneyStack = vending_machine.coin_return()
assert returned_coins.dollars == 1
assert returned_coins.quarters == 1
assert returned_coins.dimes == 1
assert returned_coins.nickels == 1
def test_insert_dime():
vending_machine = VendingMachine()
vending_machine.insert_dime()
assert vending_machine.vending_stack.dimes == 1