simple-class-pytest.py

# cars.py
from datetime import date


class Car:

    def __init__(self, model, year):
        self.model = model
        self.year = year
        self._mileage = []

    def __str__(self):
        return f"Car: {self.model} ({self.year})"

    def drive(self, miles):
        self._mileage.append(miles)

    @property
    def is_flashy(self):
        return self.year == date.today().year

    @property
    def miles_driven(self):
        return sum(self._mileage)


if __name__ == "__main__":
    car = Car("Sierra", 2020)
    car.drive(2)
    car.drive(20)
    car.drive(33)
    print(car.miles_diven)


# test_cars.py

import pytest

from cars import Car


@pytest.fixture
def car():
    return Car("Sierra", 2020)


@pytest.fixture
def car2():
    return Car("Sierra old", 2018)


@pytest.fixture
def driving(car):
    for miles in (2, 3, 44, 66, 2, 1):
        car.drive(miles)


def test_init(car, car2):
    assert car.miles_driven == 0
    assert car2.miles_driven == 0


def test_str(car, car2):
    assert str(car) == 'Car: Sierra (2020)'
    assert str(car2) == 'Car: Sierra old (2018)'


def test_miles_driven(car, driving):
    assert car.miles_driven == 118


def test_flashy(car, car2):
    assert car.is_flashy is True
    assert car2.is_flashy is False