danielforgacs / VendingMachine

VendingMachine example implementation in Python for an interview.

Brief:

• Multiple item types available
• Can accept different coins e.g. 50p and two 20p's for a value of 90p
• The machine must be capable of handling change

Notes:

• I left a few unused standard files, like docker compose files, .env, ... in the repo. Those come from my automated git repo initialiser bash func. (See my .dotfiles repo)
• The actual vending machine logic is tiny. I focused on a framework design that other programmers can use in their tools.
• the tests use some hardcoded values. A configuarion update will break them. I wouldn't do that with actual code base.
• optional future directions:
  • items coming from a centralized DB with the vending machine tracking inventory across the company.
  • coins also stored in a DB.
  • singleton object, so it woulnd't matter where a developer instantiates the class.

Git branches:

• master: latest tested & approved code ready to be deployed
• staging/release.dddd: container branch to test multiple feature/ticket/etc... branches together before merging into master
• dev: wip branch

Setup

Python 3.8

start env:

$ pipenv shell

install dependencies:

# dev
$ pipenv install --dev

# live
$ pipenv install

test:

# in the project root dir:
$ python -m pytest

# if the project root is added to the PYTHONPATH:
$ pytest

docs:

The functional tests cover most use cases with examples.

# import the module:
import VendingMachine.vendmach as vendmach

# get an instance of the vending machine
# with the requested item and the budget:
machine = vendmach.VendingMachine(
    itemrequest='nuke license',
    coins=[20, 50],
)

# As part of a module it can make sense and it's possible
# to instantiate a machine without arguments and set those
# attrs when they became available:
machine = vendmach.VendingMachine()
machine.coins = [20, 10, 50, 50]
machine.itemrequest = 'nuke license'

# If the coins are enough the requested item
# is in the item attr:
print('requested item:', machine.item)

# The actual price of the item is in the cost attr:
print('requested item cost:', machine.cost)

# if the budget was enough, change is in the change attr:
print('change:', machine.change)

make targets:

makefile targets assume the project virtualenv is active.

• test: run all tests