Question

Suppose I have this integration test

class TestClass(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        cls.key = '123'

    def test_01_create_acc(self):
       user = create_account(...)
       self.key = user.key

    def test_02_check_account(self):
       user = check_account(..)
       self.assertEqual(self.key, user.key)

It looks like the attribute self.key is not mutable. It stays with the old value from setUpClass. But isn’t setUpClass only called once?

The account function creates a key randomly for security reason, so I am not allowed to pass in my secret key. It returns the key, so I need to modify that attribute. Can I?

It looks like each test_ case is isolated.

my_gloabl = None

def setUpClass(cls):
    cls.key = my_global

If I change my_global in test1, test2 will get None.

Answer 1

The class is set up only once. But each test method is actually called from a different instance of that test.

You can demonstrate this using the id function, which will return a different number for each object:

import unittest

class TestClass(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        print "setup"

    def test_01_create_acc(self):
        print id(self)

    def test_02_check_account(self):
        print id(self)

unittest.main()

On my computer, this printed:

setup
4300479824
.4300479888

Note how the setup method was called only once, but the id of the instance for test1 and test2 are different.