How to patch a property with mocker in pytest

Question

I have a project that I need to mock a property using the mocker fixture. Its using pytest and pytest-mock:

pip install pytest pytest-mock

A simple example of the problem:

I have the foo class in the foo.py file:

class Foo:
    @property
    def bar(self):
        return "x"

And I have to test it mocking the property bar:

import foo

def test_foo(mocker):
    mocker.patch("foo.Foo.bar", return_value="y")
    f = foo.Foo()
    assert f.bar == "y"

But when I patch it, the bar behaves like a callable and not like an attribute, how to fix this?

Have you tried using [PropertyMock](https://docs.python.org/3/library/unittest.mock.html#unittest.mock.PropertyMock) yet? — idjaw, Aug 06 '21 at 18:35
Just used and worked, if you post the answer I will accept it. — Cristiano Araujo, Aug 06 '21 at 18:37

score 5 · Accepted Answer · answered Aug 06 '21 at 18:52

I was able to so using the mocker.PropertyMock just like @idjaw comment.

import foo


def test_foo(mocker):
    mocker.patch('foo.Foo.bar', return_value="y", new_callable=mocker.PropertyMock)
    f = foo.Foo()
    assert f.bar == "y"

This made the test work.

How to patch a property with mocker in pytest

1 Answers1