def setUpFaultyRename(self):
        """
        Set up a C{os.rename} that will fail with L{errno.EXDEV} on first call.
        This is used to simulate a cross-device rename failure.

        @return: a list of pair (src, dest) of calls to C{os.rename}
        @rtype: C{list} of C{tuple}
        """
        invokedWith = []
        def faultyRename(src, dest):
            invokedWith.append((src, dest))
            if len(invokedWith) == 1:
                raise OSError(errno.EXDEV, 'Test-induced failure simulating '
                                           'cross-device rename failure')
            return originalRename(src, dest)

        originalRename = os.rename
        self.patch(os, "rename", faultyRename)
        return invokedWith

        Set up a C{os.rename} that will fail with L{errno.EXDEV} on first call.
        This is used to simulate a cross-device rename failure.

        @return: a list of pair (src, dest) of calls to C{os.rename}
        @rtype: C{list} of C{tuple}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_paths.py