unittest

@patch (from unittest.mock) Explanation

@patch is used to replace objects/functions with mock versions during tests. It is part of Python’s unittest.mock module.

Example & Usage

python

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from unittest.mock import patch def fetch_data(): """Simulated function that fetches data from an API""" return "Real Data" @patch("__main__.fetch_data", return_value="Mocked Data") def test_fetch_data(mock_fetch): assert fetch_data() == "Mocked Data"

🔹 How it works:

• @patch("__main__.fetch_data", return_value="Mocked Data") replaces fetch_data() with a mocked version returning "Mocked Data".
• Inside the test, fetch_data() will always return "Mocked Data" instead of calling the real function.

Why use @patch?

• Prevents tests from making actual API/database calls.
• Speeds up testing by mocking expensive operations.
• Allows control over return values and side effects.

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Your Case:

• @pytest.fixture is used to provide reusable test data (mock_files).
• @patch is used to:
  • Mock file operations (builtins.open, os.walk).
  • Mock function calls (process_file, log_action, write_updated_file).
  • Prevent real file modifications while testing.