Unit Test Helpers

About

Unit Test Helpers (uth) is a simple library for Python containing some helper methods for unit testing.

I found myself writing a lot of setup code using unittest.mock.patch and unittest.TestCase.addCleanup:

class MyTestCase(unittest.TestCase):
    def setUp(self):
        patcher = unittest.mock.patch('module.function')
        patcher.start()
        self.addCleanup(patcher.stop)

        # Or if there was many functions and/or objects to patch
        # something like:
        for patcher in (
            unittest.mock.patch('function_a'),
            unittest.mock.patch('function_b'),
        ):
            patcher.start()
            self.addCleanup(patcher.stop)

Adding helper methods to TestCase classes (via mixin class) allows easier patching:

import unittest
import unittest.mock

import uth


def function_a():
    return None


class MyTestCase(unittest.TestCase, uth.MockMixin):
    def setUp(self):
        # The function function_a is immediately patched and patching is stopped
        # automatically after the test has run (using unittest.TestCase.addCleanup).
        mock = self.patched('{}.function_a'.format(__name__), return_value=self.sentinel.retval)

    def test_function_a(self):
        self.assertEqual(function_a(), self.sentinel.retval)

    def test_sentinel(self):
        self.assertEqual(self.sentinel.value, unittest.mock.sentinel.value)

    def test_mock(self):
        mock = self.mock(return_value=self.sentinel.retval)
        self.assertIsInstance(mock, unittest.mock.Mock)

The patched method is the only one that actually provides functionality not directly present in unittest.mock. The members mock, patch and sentinel are provided for convenience; you don't need to import unittest.mock and you can access mock related functionality through self.

API

uth.MockMixin

A mixin class for unittest.TestCase (or any other class from which you want to use Mock, sentinel and/or patch).

The following members are added:

• ANY

  unittest.mock.ANY

• sentinel (property)

  Access to unittest.mock.sentinel

• call(*args, **kwargs)

  unittest.mock.call

• mock(*args, **kwargs)

  Calls unittest.mock.Mock with given arguments

• magic_mock(*args, **kwargs)

  Calls unittest.mock.MagicMock with given arguments

• patch(*args, **kwargs)

  Calls unittest.mock.patch with given arguments

• patched(*args, **kwargs)

  Calls unittest.mock.patch with given arguments, starts the returned patcher, registers stopping the patcher using self.addCleanup and returns the return value of patcher.start (the Mock object).