def METHOD_NAME(db_session, user_rincewind) -> None:
    """`AuthClient` can have empty scope."""
    auth_client = models.AuthClient(
        account=user_rincewind,
        title="Test client",
        confidential=True,
        website='http://localhost',
        scope=None,
    )
    db_session.add(auth_client)
    assert auth_client.scope == ()
    # Scope can be assigned a string value, but will return as a tuple
    auth_client.scope = 'test'
    assert auth_client.scope == ('test',)
    # Whitespace separators in strings will be parsed as distinct scope tokens
    auth_client.scope = 'test scope'
    # ...and will always be sorted
    assert auth_client.scope == ('scope', 'test')
    assert auth_client._scope == 'scope test'
    auth_client.scope = 'also\tscope'
    assert auth_client.scope == ('also', 'scope')
    assert auth_client._scope == 'also scope'
    # Any kind of iterable is okay
    auth_client.scope = ['another', 'scope']
    assert auth_client.scope == ('another', 'scope')
    assert auth_client._scope == 'another scope'
    # Scope can be reset to None in models that allow it (only AuthClient)
    auth_client.scope = None
    assert auth_client.scope == ()
    assert auth_client._scope is None
    auth_client.scope = ''
    assert auth_client.scope == ()
    assert auth_client._scope is None
    auth_client.scope = ()
    assert auth_client.scope == ()
    assert auth_client._scope is None