def test_load_checkpoint_strict_loading(tmp_path):
    """Test that an error is raised if a key is requested to be restored but does not exist in the checkpoint."""
    strategy = SingleDeviceStrategy()  # surrogate class to test implementation in base class
    saved_state = {"a": 1, "b": 2}
    requested_state = {"a": 1, "b": 2, "c": 3}  # key `c` does not exist in the saved state
    load_checkpoint_mock = Mock(return_value=saved_state)
    strategy.checkpoint_io.load_checkpoint = load_checkpoint_mock
    with pytest.raises(KeyError, match="contains a key 'c' that does not exist"):
        strategy.load_checkpoint(tmp_path, requested_state, strict=True)
Test that an error is raised if a key is requested to be restored but does not exist in the checkpoint.
tests/tests_fabric/strategies/test_strategy.py