Unittesting Python class

Question

class Car:
 def __init__(self):
     self.__engine_size = 2.0
     self.__colour = str
 @property # getter
 def engine_size(self):
     return self.__engine_size
 @property # getter
 def colour(self):
     return self.__colour
 @colour.setter
 def colour(self, value):
     self.__colour = value
 def start(self):
     return 'Engine started!!....ggggrrrrrr'
 def stop(self):
     return 'Engine stopped!!...'

Hey guys, trying to perform a test on this piece of code but can't think of ways. See bellow what I did and suggest other ways if known.

import unittest

from car import __init__

class TestCarMethods(unittest.TestCase):

    # case assertion no1
    '''

    '''

    def test_car_colour(self):

        # arrange
        __engine_size = 3.2
        __colour = 'red'

        # act
        result = ('red')

        # assert
        self.assertEqual(result, 'red')



       if __name__ == '__main__':
         unittest.main()

Don't use a property if the getter/setters just provide unrestricted or unmodified access to the underlying attribute; just use the attribute directly. — chepner
– chepner, Commented Dec 16, 2019 at 22:09
tests come out naturally by defining what should it do , but not true when you try saying how does it do. for your piece of code . valid test would be the return values of start/stop, exception checking can be addwed too. — James Li
– James Li, Commented Dec 16, 2019 at 23:03

chepner · Accepted Answer · 2019-12-16 22:38:06Z

1

You need to create and work with an instance of your class.

class TestCarMethods(unittest.TestCase):
    def setUp(self):
        self.car = Car()

    def test_car_color(self):
        self.assertEqual(self.car.color, 'red')  # If the default is, in fact, red

    def test_set_color(self):
        self.car.color = 'blue'

        self.assertEqual(self.car.color, 'blue')

    def test_start(self):
        self.assertEqual(self.car.start(), 'Engine started!!....ggggrrrrrr')

edited Dec 16, 2019 at 22:38

answered Dec 16, 2019 at 22:11

chepner

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3 Comments

danH Over a year ago

Appreciated, and makes a lot of sense setting up, I get blocked in trying to perform a test on start / stop.

chepner Over a year ago

See update; it's just a matter of calling the method and checking what it returns.

danH Over a year ago

Gosh, I think I need a break :))) thanks man. for a weird reason I was complicating it thinking that the functions start/ stop is called after color is set .....

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