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Mock Class Property in PyTest

It's easy to use Mock for a python method, staticmethod, classmethod, but for propery, it's not just to use Mock. Here are the example to mock a property of a class in python UT.

  • A simple class

    Python
    class Dog:
    @property
    def name(self):
        return "dog"

  • Test

    Python
    from unittest.mock import Mock, PropertyMock

from learn.animal.dog import Dog


def test_dog():
    dog = Dog()

    type(dog).name = PropertyMock(side_effect=["dog1", "dog2"])

    assert dog.name == "dog1"
    assert dog.name == "dog1"

We can see in the example, that we set the mock property to a PropertyMock by type(object).<property> = PropertyMock(). In the PropertyMock, we can use return_value or side_effect like what we use mocks for a method.