python 3.x - Python3 Unittests, how to prevent private class variables from carrying over between tests

Question

I have two classes, Base and Rectangle. Rectangle inherits from base, and whenever an instance of either is created a private class variable increments (in most conditions) to count the number of instances.

class Base:
    """a class named base"""

    __nb_objects = 0

    def __init__(self, id=None):
        """constructs class"""
        if id is not None:
            self.id = id
        else:
            Base.__nb_objects += 1
            self.id = Base.__nb_objects

---

from models.base import Base


class Rectangle(Base):
    """a class named Rectangle that inherits from"""

    def __init__(self, width, height, x=0, y=0, id=None):
        """constructs class"""
        super().__init__(id)
        self.__width = width
        self.__height = height
        self.__x = x
        self.__y = y
    #more below, but irrelevant getters and setters for width, height, x, and y

I also have two separate test files that tests my classes. Run individually, both pass however when run together it fails due to the id's from the first test persisting to the next test.

class TestBaseInit(unittest.TestCase):
    """Testing init for base class"""

    def test_base_init(self):
        """adding simple instances"""
        b1 = Base()
        self.assertEqual(b1.id, 1)
        b2 = Base()
        self.assertEqual(b2.id, 2)
        b3 = Base()
        self.assertEqual(b3.id, 3)
        b4 = Base(12)
        self.assertEqual(b4.id, 12)
        b5 = Base()
        self.assertEqual(b5.id, 4)

---

import unittest
from models.rectangle import Rectangle

class TestRectangleInit(unittest.TestCase):
    """testing init for rectangle class"""

    def test_rectangle_init(self):
        """adding simple rect instances"""
        r1 = Rectangle(10, 2)
        self.assertEqual(r1.id, 1)
        r2 = Rectangle(2, 10)
        self.assertEqual(r2.id, 2)
        r3 = Rectangle(10, 2, 0, 0, 12)
        self.assertEqual(r3.id, 12)

Any tips? I want to make it so the difference tests on the two different files don't interfere with eachother (Somehow ensuring individual tests have their own instance of everything?).

question from:https://stackoverflow.com/questions/65853585/python3-unittests-how-to-prevent-private-class-variables-from-carrying-over-bet

Answer 1

Waitting for answers