Recently one of the companies asked me to solve Vending Machine Kata given here (https://github.com/guyroyse/vending-machine-kata) as their first level of screening. Though I couldn’t solve it completely in less than three hours I have covered most of the usecases. You can find my solution here. (https://github.com/sanjuthomas/vending-machine) You will have to add logic to complete the coin inventory so that you can give change to the customer in case if the customer insert a higher amount than the price of the item selected.