def patch(test_instance, object_to_patch, attr_name, new_value):
    """Override 'object_to_patch'.'attr_name' with 'new_value'.

    Also, add a cleanup procedure to 'test_instance' to restore
    'object_to_patch' value for 'attr_name'.
    The 'attr_name' should be a valid attribute for 'object_to_patch'.

    """
    # check that 'attr_name' is a real attribute for 'object_to_patch'
    # will raise AttributeError if it does not exist
    getattr(object_to_patch, attr_name)

    # keep a copy of the old value
    attr_is_local = False
    try:
        old_value = object_to_patch.__dict__[attr_name]
    except (AttributeError, __HOLE__):
        old_value = getattr(object_to_patch, attr_name, None)
    else:
        attr_is_local = True

    # restore the value when the test is done
    def cleanup():
        if attr_is_local:
            setattr(object_to_patch, attr_name, old_value)
        else:
            delattr(object_to_patch, attr_name)

    test_instance.addCleanup(cleanup)

    # actually override the attribute
    setattr(object_to_patch, attr_name, new_value)
dataset/ETHPy150Open OpenCobolIDE/OpenCobolIDE/open_cobol_ide/extlibs/future/backports/test/support.py/patch