Descriptors should not give different results for different IChemObject implementations (data, nonotify, ...), e.g. caused by incorrect casting.
These patches provide some code clean up (0001, 0002) and the new tests (0003, 0004). Mind you, it does not catch all problems, like casting.
Patch 0003 tests of NNMolecule and Molecule give the same result.
Patch 0004 tests of descriptors can handle AtomContainer, as the API defines.