makolyte / srp

Single responsibility principle

This repository was made to find the best solution which does not violate SRP.

It started with these 2 tweets: @testdrivenio and jangiacomelli

Specifications

Let's say we have a forum for Python professionals. We have users which are monthly charged for the subscription and banned for 7 days if they misbehave.

SRP-violating pseudo-solution

import datetime


class User:
    def __init__(self, username, banned_until):
        self.username = username
        self.banned_until = banned_until

    def save(self):
        print('I am saving to PostgreSQL')

    def ban(self):
        self.banned_until = datetime.datetime.today() + datetime.timedelta(days=7)

    def charge(self):
        print('Charge credit card of user using Stripe')

Goal

We're trying to find the best solution that complies with SRP.

Setup

To install requirements:

(venv)$ pip install -r requirements.txt

To run tests:

(venv)$ pytest tests

To run tests - if you're getting "pytest" not found:

(venv)$ python -m pytest