CODEWITHSUNDEEP
pythonunit-testingmocking
drum
drum

Reputation: 5661

How to mock class instead of object?

How can I mock the following?

import os
from unittest import TestCase
from unittest.mock import patch

class A:
    VAR_A = os.environ.get("ABC")

    @classmethod
    def foo(cls):
       return cls.VAR_A

@patch.dict(os.environ, {'ABC': 'abc'})
class Test_A(TestCase):
    def test_foo(self):
        self.assertEqual(A.foo(), 'abc')

This VAR_A is not getting mocked. AssertionError: None != 'abc'

Upvotes: 0

Views: 62

Answers (1)

alberand
alberand

Reputation: 662

So, you want to test your foo() function. Instead of trying to change environment variable before class object definition try to mock already existing class's attribute. As class object is created before your test is run and VAR_A attribute is already initialized.

import os
from unittest import TestCase
from unittest.mock import patch

class A:
    VAR_A = os.environ.get("ABC")

    @classmethod
    def foo(cls):
       return cls.VAR_A

@patch.object(A, 'VAR_A', 'abc')
class Test_A(TestCase):
    def test_foo(self):
        self.assertEqual(A.foo(), 'abc')

Upvotes: 1

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