Vending Machine Kata Solution

https://github.com/guyroyse/vending-machine-kata

Overview

There is no runtime environment at this point. The code is exercised via the RSpec tests. The integration specs in vending_machine_spec.rb demonstrate the functionality of each feature (accept coins, select product, etc)

VendingMachine provides the public interface of the vending machine. All other classes are internal implementation.

Steps to run the code

This code requires a standard Ruby development environment. The basic components are:

• Ruby 2.1 (or newer).
• Build tools. XCode or GCC and development libraries. Needed to build gems.
• Bundler 1.12 (or newer). This can be installed with gem install bundler

Start by installing dependencies.

cd [folder where you cloned the code]
bundle

Then run the tests

bin/rspec

Or use Guard to run the tests automatically as you work

bin/guard

TODO

Not all features of the vending machine have been implemented. Here's what's remaining.

Return Coins

CoinBox needs to track which coins have been inserted. A return_coins method will deposit these coins into the coin return. A "coin return" button should be added to VendingMachine and wired to CoinBox.

Alternatively, we could use CoinBox#make_change to return coins. While the customer would get back the amount they inserted, they may not get back the same coins.

Sold Out

ProductDispenser needs to track product inventory. dispense should return { status: :sold_out } when the product is unavailable. We also need to update Display and VendingMachine to handle this condition.

Exact Change Only

CoinBox needs to track the coins it has available for making change, removing coins from this inventory whenever make_change is called.

Assuming the products and prices are fixed, the most change the machine will need to make is $0.10 - for the case where the customer only has quarters and wants to buy candy. CoinBox will need 1 dime or 2 nickels for this. As long as CoinBox has 1 dime or 2 nickels, it can make change.

VendingMachine should check CoinBox after each transaction and update Display as needed.

This can be solved in a more general way. VendingMachine should give CoinBox the price list when it's initialized. Then CoinBox can calculate the price that's farthest away from the next increment of $0.25 and determine what coins are needed to make change.