Python mock call_args_list unpacking tuples for assertion on arguments

Python mock call_args_list unpacking tuples for assertion on arguments

In Python's unittest.mock library, you can use the call_args_list attribute to access the list of call objects made to a mock object. Each call object contains information about the call, including the arguments passed. If you want to assert on the arguments of the calls stored in call_args_list, you can unpack the tuples using tuple unpacking.

Here's an example:

from unittest.mock import Mock # Create a mock object mock_obj = Mock() # Make some calls to the mock object mock_obj(1, 2, 3) mock_obj('a', 'b', 'c') mock_obj(4, 5, 6) # Access call_args_list and assert on arguments call_args_list = mock_obj.call_args_list for call_args in call_args_list: args, kwargs = call_args print("Arguments:", args) print("Keyword Arguments:", kwargs) print("=" * 20)

In this example, the call_args_list contains the call objects with their arguments and keyword arguments. You can unpack the tuples returned by the call objects using tuple unpacking to access the arguments and then perform assertions or other operations as needed.

If you want to perform assertions on the arguments, you can do something like:

expected_calls = [ ((1, 2, 3), {}), (('a', 'b', 'c'), {}), ((4, 5, 6), {}), ] for expected_args, expected_kwargs in expected_calls: assert call_args_list.pop(0) == (expected_args, expected_kwargs)

This will check if the actual calls match the expected calls in terms of arguments and keyword arguments. Keep in mind that this approach assumes the calls are in the order you expect. If order doesn't matter, you can use a more flexible assertion method like assertIn() or assertIsInstance() to verify that each call is present in the call_args_list.

Examples

  1. How to use call_args_list to assert function arguments in Python with unittest.mock?

    • Description: This query discusses how to use call_args_list from unittest.mock to check the arguments with which a mocked function was called, typically for assertion purposes in unit tests.
    # Install the pytest library if needed !pip install pytest 
    from unittest.mock import MagicMock import pytest def some_function(x, y): return x + y mock_function = MagicMock() # Simulate calling the function with specific arguments mock_function(1, 2) mock_function(3, 4) # Check the call arguments assert mock_function.call_args_list == [ ((1, 2), {}), ((3, 4), {}) ]

  2. How to extract specific arguments from call_args_list in Python's unittest.mock?

    • Description: This query explores how to extract specific arguments from call_args_list to validate their values, including both positional and keyword arguments.
    from unittest.mock import MagicMock def some_function(name, age, country="USA"): pass # Function that we will mock mock_function = MagicMock() mock_function("Alice", 30, country="UK") mock_function("Bob", 25) # Get arguments from call_args_list first_call_positional, first_call_keywords = mock_function.call_args_list[0] second_call_positional, second_call_keywords = mock_function.call_args_list[1] # Assertions on extracted arguments assert first_call_positional == ("Alice", 30) # Positional arguments assert first_call_keywords == {"country": "UK"} # Keyword arguments assert second_call_positional == ("Bob", 25) assert second_call_keywords == {} # No keyword arguments in second call

  3. How to assert argument values within call_args_list in Python's unittest.mock?

    • Description: This query demonstrates how to assert specific argument values within call_args_list, ensuring the correct arguments were passed to the mocked function.
    from unittest.mock import MagicMock def add_numbers(x, y): return x + y # Example function mock_function = MagicMock() mock_function(10, 20) # Mocked function call # Unpack the first call's positional arguments args, kwargs = mock_function.call_args_list[0] # Assert specific argument values assert args == (10, 20) assert kwargs == {} # No keyword arguments

  4. How to use call_args_list to assert multiple function calls in Python's unittest.mock?

    • Description: This query explores how to assert multiple function calls using call_args_list, checking for the expected sequence of calls and their arguments.
    from unittest.mock import MagicMock def process_data(data): pass # Function that will be mocked mock_function = MagicMock() # Simulate calling the function with different arguments mock_function("data1") mock_function("data2") mock_function("data3") # Validate the sequence of function calls expected_calls = [ (("data1",), {}), (("data2",), {}), (("data3",), {}), ] assert mock_function.call_args_list == expected_calls

  5. How to assert specific keyword arguments in call_args_list with unittest.mock?

    • Description: This query explores how to check specific keyword arguments in call_args_list and assert their values.
    from unittest.mock import MagicMock def save_to_db(data, table="default"): pass # Function that we will mock mock_function = MagicMock() mock_function(data="record1", table="users") mock_function(data="record2") # Get keyword arguments from call_args_list first_call_positional, first_call_keywords = mock_function.call_args_list[0] second_call_positional, second_call_keywords = mock_function.call_args_list[1] # Assert specific keyword arguments assert first_call_keywords == {"data": "record1", "table": "users"} assert second_call_keywords == {"data": "record2", "table": "default"} # Default table

  6. How to use call_args_list to validate optional arguments in unittest.mock?

    • Description: This query discusses how to validate optional arguments in call_args_list, ensuring that specific arguments are provided or defaulted.
    from unittest.mock import MagicMock def create_user(username, role="user"): pass # Mocked function mock_function = MagicMock() mock_function("john_doe", role="admin") mock_function("jane_doe") # Uses default role # Validate role arguments from call_args_list first_call_positional, first_call_keywords = mock_function.call_args_list[0] second_call_positional, second_call_keywords = mock_function.call_args_list[1] assert first_call_keywords["role"] == "admin" # Custom role assert second_call_keywords["role"] == "user" # Default role

  7. How to assert argument types with call_args_list in unittest.mock?

    • Description: This query explores checking the types of arguments passed to a mocked function using call_args_list and asserting expected types.
    from unittest.mock import MagicMock def log_message(level, message): pass # Function to be mocked mock_function = MagicMock() mock_function("INFO", "Starting process") mock_function("ERROR", "An error occurred") # Validate argument types first_call_args, _ = mock_function.call_args_list[0] second_call_args, _ = mock_function.call_args_list[1] assert isinstance(first_call_args[0], str) # Check type of first argument assert isinstance(first_call_args[1], str) # Check type of second argument

  8. How to use call_args_list to assert nested function calls with unittest.mock?

    • Description: This query discusses how to assert nested function calls using call_args_list, ensuring that specific nested calls are made with expected arguments.
    from unittest.mock import MagicMock def outer_function(inner_function, value): inner_function(value) mock_inner_function = MagicMock() outer_function(mock_inner_function, "Test Value") # Call the outer function # Assert that the inner function was called with expected arguments assert mock_inner_function.call_args_list == [ (("Test Value",), {}), ]

  9. How to use call_args_list to check call count and assert order of function calls in unittest.mock?

    • Description: This query explores using call_args_list to assert the call count and verify the order of function calls.
    from unittest.mock import MagicMock def send_email(subject, body): pass # Function to be mocked mock_function = MagicMock() mock_function("Subject 1", "Body 1") mock_function("Subject 2", "Body 2") mock_function("Subject 3", "Body 3") # Check call count and call order assert mock_function.call_count == 3 # Assert total call count # Assert order of calls assert mock_function.call_args_list == [ (("Subject 1", "Body 1"), {}), (("Subject 2", "Body 2"), {}), (("Subject 3", "Body 3"), {}), ]

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