Do not use this function in production code. For use in **unit tests**.
This function initialises a new Container [[SolidDataset]] with metadata as though the
Container has been retrieved from the given URL. The mock SolidDataset can be used in
unit tests that require persisted Containers; e.g., unit tests that call [[isContainer]].
This function initialises a new Container [[SolidDataset]] with metadata as though the Container has been retrieved from the given URL. The mock SolidDataset can be used in unit tests that require persisted Containers; e.g., unit tests that call [[isContainer]].