def METHOD_NAME():
    # No explicit namespace
    group = SimpleGroup(namespace=None, variables={})
    with pytest.raises(KeyError):
        group._resolve("nonexisting_variable", {})
    # Empty explicit namespace
    group = SimpleGroup(namespace={}, variables={})
    with pytest.raises(KeyError):
        group._resolve("nonexisting_variable", {})
    # Illegal name
    with pytest.raises(ValueError):
        SimpleGroup(namespace={"_illegal": 3.0}, variables={})