【Python】unittestとmockの使い方を解説！

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import unittest
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# テスト対象の関数
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def add(a, b):
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    return a + b
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class TestMathOperations(unittest.TestCase):
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    def test_add(self):
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        self.assertEqual(add(2, 3), 5)
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        self.assertEqual(add(-1, 1), 0)
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        self.assertEqual(add(0, 0), 0)
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if __name__ == "__main__":
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    unittest.main()

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from unittest import TestCase
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from unittest.mock import patch
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import requests
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# テスト対象の関数
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def fetch_data(url):
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    response = requests.get(url)
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    return response.json()
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class TestFetchData(TestCase):
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    @patch("requests.get")
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    def test_fetch_data(self, mock_get):
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        mock_get.return_value.json.return_value = {"message": "Hello, world!"}
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        result = fetch_data("http://example.com")
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        self.assertEqual(result, {"message": "Hello, world!"})

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import unittest
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from unittest.mock import patch
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class MyClass:
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    def method(self):
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        return "real value"
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class TestMyClass(unittest.TestCase):
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    @patch.object(MyClass, "method", return_value="mocked value")
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    def test_method(self, mock_method):
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        obj = MyClass()
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        self.assertEqual(obj.method(), "mocked value")
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if __name__ == "__main__":
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    unittest.main()

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import unittest
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from unittest.mock import patch
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import requests
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class TestMyClass(unittest.TestCase):
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    def test_method(self):
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        with patch("requests.get") as mock_get:
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            mock_get.return_value.json.return_value = {"status": "ok"}
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            response = requests.get("http://example.com")
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            assert response.json() == {"status": "ok"}
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if __name__ == "__main__":
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    unittest.main()

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import unittest
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from unittest.mock import patch
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class Config:
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    def __init__(self):
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        self.api_key = "real_api_key"
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class Service:
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    def __init__(self, config):
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        self.config = config
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    def get_api_key(self):
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        return self.config.api_key
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class TestService(unittest.TestCase):
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    def test_get_api_key(self):
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        config = Config()
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        with patch.object(config, "api_key", new="mocked_api_key"):  # インスタンス変数をモック化
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            service = Service(config)
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            self.assertEqual(service.get_api_key(), "mocked_api_key")
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if __name__ == "__main__":
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    unittest.main()