unittest.mock: Set custom attribute (variable) on specced mock object

Question

I am trying to mock an existing object from another library's class for unit tests with pytest. However, the attributes (not methods) from the other library are mostly set during runtime.

What I want to achieve

Get all the benefits of mocking the object with spec
Set the (nested) attributes (not methods) needed for my unittests to simulate as if they were set during object creation

from unittest.mock import Mock
from otherlib import ClassName

def test_stuff():
    mock_object = Mock(spec=ClassName)
    mock_object.data.outward.key = 12345

    assert mock_object.data.outward.key == 12345  # AttributeError: Mock object has no attribute 'data'

I made these attempts in code changes but with no success

...
def test_stuff():
    mock_object = Mock(spec=ClassName, **{'data.outward.key': 12345})

    assert mock_object.data.outward.key == 12345

...
def test_stuff():
    mock_object = Mock(spec=ClassName)
    attrs = {'data.outward.key': 12345}
    mock_object.configure_mock(**attrs)

    assert mock_object.data.outward.key == 12345

score -1 · Accepted Answer · answered May 14 '20 at 09:06

The best I came up with is using another Mock object to use when setting the main mock object's attributes. It works, but I guess there is a better solution for this...?

from unittest.mock import Mock
from otherlib import ClassName

def test_stuff():
    mock_data = Mock(spec=["outward"], key=12345)
    mock_object = Mock(spec=ClassName, data=mock_data)
    mock_object.data.outward.key = 12345

    assert mock_object.data.outward.key == 12345  # tests.py::test_stuff PASSED [100%]

unittest.mock: Set custom attribute (variable) on specced mock object

What I want to achieve

I made these attempts in code changes but with no success

1 Answers1