Method test_function_back_compat

test/test_fx.py:4055–4081

Test backward compatibility for function signatures with @compatibility(is_backward_compatible=True). Currently this checks for exact signature matches, which may lead to false positives. If this becomes too annoying, we can refine this check to actually parse out

(self)

    def test_function_back_compat(self):
        """
        Test backward compatibility for function signatures with
        @compatibility(is_backward_compatible=True). Currently this checks for
        exact signature matches, which may lead to false positives. If this
        becomes too annoying, we can refine this check to actually parse out
        the saved schema strings and check if the change is truly backward-
        incompatible.
        """
        signature_strs = []

        for obj in _BACK_COMPAT_OBJECTS:
            if not isinstance(obj, type):
                signature_strs.append(self._fn_to_stable_annotation_str(obj))

        signature_strs.sort()

        try:
            self.assertExpected('\n'.join(signature_strs) + '\n', 'fx_backcompat_function_signatures')
        except AssertionError as e:
            msg = f"{e}\n****** ERROR ******\nAn FX function that has been marked " \
                  f"as backwards-compatible has experienced a signature change. See the " \
                  f"above exception context for more information. If this change was " \
                  f"unintended, please revert it. If it was intended, check with the FX " \
                  f"team to ensure that the proper deprecation protocols have been followed " \
                  f"and subsequently --accept the change."
            raise AssertionError(msg)  # noqa: TRY200

    def test_class_member_back_compat(self):
        """