59 lines
1.3 KiB
Markdown
59 lines
1.3 KiB
Markdown
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---
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tags: [python]
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---
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An instance of the general Python `Mock` that is pre-configured with "magic"
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methods that the standard `Mock` lacks.
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These methods mean that it can automaticaly behave like the following objects
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without special configuration:
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- a [context manager](./Using_a_context_manager_in_Python.md)
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- supports `__enter__`, `__exit__` and `with` statement
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- a list or other container
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- supports `__iter__`, `__getitem`, `__len__`
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- calls to a methods
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## Example: mocking return from API call
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Mock:
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```py
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def get_user_data(api_client):
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response = api_client.get_user(id=123)
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return response
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```
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As follows:
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```py
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from unittest.mock import MagicMock
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def test_get_user_data():
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mock_api = MagicMock()
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mock_api.get_user.return_value = {"name": "Alice", "role": "Admin"}
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result = get_user_data(mock_api)
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assert result["name"] == "Alice"
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mock_api.get_user.assert_called_once_with(id=123)
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```
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## Example: testing behaviour of code that relies on context managers:
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```py
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def log_to_file(file_system):
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with file_system.open("log.txt") as f:
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f.write("Hello World")
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def test_log_to_file():
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mock_fs = MagicMock()
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log_to_file(mock_fs)
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mock_fs.open.assert_called_with("log.txt")
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mock_fs.open().__enter__().write.assert_called_with("Hello World")
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```
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