Can't mock a @property without calling it?

I’m using TestSlide version: 2.7.0

Given:

import testslide

class SampleClass:
    @property
    def prop(self) -> str:
        raise RuntimeError("must not be called")

    def meth(self) -> str:
        raise RuntimeError("must not be called")


class SampleTest(testslide.TestCase):
    def test_prop_attr(self) -> None:
        host = SampleClass()
        self.patch_attribute(host, "prop", "patched")
        self.assertEqual(host.prop, "patched")

    def test_prop_callable(self) -> None:
        host = SampleClass()
        self.mock_callable(host, "prop").to_return_value("patched")
        self.assertEqual(host.prop, "patched")

    def test_meth(self) -> None:
        host = SampleClass()
        self.mock_callable(host, "meth").to_return_value("patched")
        self.assertEqual(host.meth(), "patched")

When I run: testslide patch_test.py

I expected this to happen: prop() is not called

But, instead this happened: prop() is called, both when using patch_attribute and mock_callable.

patch_test.SampleTest
  test_meth
  test_prop_attr: RuntimeError: must not be called
  test_prop_callable: RuntimeError: must not be called

Failures:

  1) patch_test.SampleTest: test_prop_attr
    1) RuntimeError: must not be called
      File "patch_test.py", line 15, in test_prop_attr
        self.patch_attribute(host, "prop", "patched")
      File "patch_test.py", line 6, in prop
        raise RuntimeError("must not be called")

  2) patch_test.SampleTest: test_prop_callable
    1) RuntimeError: must not be called
      File "patch_test.py", line 20, in test_prop_callable
        self.mock_callable(host, "prop").to_return_value("patched")
      File "patch_test.py", line 6, in prop
        raise RuntimeError("must not be called")

[macisamuele]

@fornellas I can try working on this within the next 2 weeks. Internally I’ve already prepared a prototype of the possible fix and I need to reserve enough bandwidth to clean-it-up and fix tests as needed

[fornellas]

Hum… I see your point, that’s fair.

I think the way to address this is to add (yet) more complexity on top:

• When patching, check whether the attribute is a property.
• If it is, then save the property itself (to unpatch), and not the property value.

There are then 2 bugs to fix:

• Make the test below pass.
• Have mock_callable against a property / attribute fail.

import testslide

class SampleClass:
    @property
    def prop(self) -> str:
        raise RuntimeError("must not be called")

class SampleTest(testslide.TestCase):
    def test_prop_attr(self) -> None:
        host = SampleClass()
        self.patch_attribute(host, "prop", "patched")
        self.assertEqual(host.prop, "patched")