---
name: unittest-skill
description: >
  Generates Python unittest tests. Built-in testing framework with TestCase,
  setUp/tearDown, and assertion methods. Use when user mentions "unittest",
  "TestCase", "self.assertEqual", "Python unittest". Triggers on: "unittest",
  "TestCase", "self.assertEqual", "Python unittest" (not pytest).
languages:
  - Python
category: unit-testing
license: MIT
metadata:
  author: TestMu AI
  version: "1.0"
---

# Python unittest Skill

## Core Patterns

### Basic Test

```python
import unittest

class TestCalculator(unittest.TestCase):
    def setUp(self):
        self.calc = Calculator()

    def test_add(self):
        self.assertEqual(self.calc.add(2, 3), 5)

    def test_divide_by_zero(self):
        with self.assertRaises(ZeroDivisionError):
            self.calc.divide(10, 0)

    def test_multiple_assertions(self):
        self.assertEqual(self.calc.add(2, 2), 4)
        self.assertEqual(self.calc.subtract(5, 3), 2)
        self.assertAlmostEqual(self.calc.divide(10, 3), 3.333, places=3)

    def tearDown(self):
        pass  # cleanup

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

### Assertions

```python
self.assertEqual(a, b)
self.assertNotEqual(a, b)
self.assertTrue(condition)
self.assertFalse(condition)
self.assertIsNone(obj)
self.assertIsNotNone(obj)
self.assertIs(a, b)              # same object
self.assertIn(item, collection)
self.assertNotIn(item, collection)
self.assertIsInstance(obj, cls)
self.assertAlmostEqual(a, b, places=5)
self.assertGreater(a, b)
self.assertLess(a, b)
self.assertRegex(str, r'\d+')
self.assertCountEqual(a, b)     # same elements, any order

# Exception
with self.assertRaises(ValueError) as ctx:
    raise ValueError("bad")
self.assertIn("bad", str(ctx.exception))

# Warning
with self.assertWarns(DeprecationWarning):
    deprecated_function()
```

### SubTest (Parameterized)

```python
def test_add_multiple(self):
    test_cases = [(2, 3, 5), (-1, 1, 0), (0, 0, 0)]
    for a, b, expected in test_cases:
        with self.subTest(a=a, b=b):
            self.assertEqual(self.calc.add(a, b), expected)
```

### Mocking

```python
from unittest.mock import patch, MagicMock, Mock

class TestUserService(unittest.TestCase):
    @patch('myapp.service.UserRepository')
    @patch('myapp.service.EmailService')
    def test_create_user(self, MockEmail, MockRepo):
        mock_repo = MockRepo.return_value
        mock_repo.save.return_value = User(1, 'Alice')

        service = UserService()
        result = service.create_user('alice@test.com', 'Alice')

        self.assertEqual(result.id, 1)
        mock_repo.save.assert_called_once()
        MockEmail.return_value.send_welcome.assert_called_with('alice@test.com')
```

### Lifecycle

```
setUpClass()    → Once before all tests (classmethod)
setUp()         → Before each test
test_method()   → Test
tearDown()      → After each test
tearDownClass() → Once after all tests (classmethod)
```

## Run: `python -m unittest` or `python -m unittest test_module.TestClass.test_method`
## Discover: `python -m unittest discover -s tests -p "test_*.py"`

## Deep Patterns

For advanced patterns, debugging guides, CI/CD integration, and best practices,
see `reference/playbook.md`.

## Source and license

Source: https://github.com/LambdaTest/agent-skills/blob/0491a3a29aa18558d2c3c64ff09367adb976c56f/unittest-skill/SKILL.md

MIT License

Copyright (c) 2025 TestMu AI / LambdaTest

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.