Stateful test for parallel sessions

[dcherian]

Looks like it's catching a version of that bug.

E           Falsifying example:
E           state = SerialParallelStateMachine()
E           forking with pickle
E           state.fork_pickle()
E           merging forks to base session, merging 1→2→parallel
E           state.merge(two_to_one=False)
E           forking with pickle
E           state.fork_pickle()
E           merging forks to base session, merging 1→2→parallel
E           state.merge(two_to_one=False)
E           Draw 1: int8(1)
E           Adding array:  path='00'  shape=(1, 1, 1)  chunks=(1, 1, 1)
E           state.add_array(array_and_chunks=(array([[[0]]], dtype=int8), (1, 1, 1)), data=data(...), name='00')
E           Draw 2: int8(0)
E           Adding array:  path='0'  shape=(1,)  chunks=(1,)
E           state.add_array(array_and_chunks=(array([0], dtype=int8), (1,)), data=data(...), name='0')
E           forking with pickle
E           state.fork_pickle()
E           Draw 3: '00'
E           Draw 4: '0/0/0'
E           deleting chunk path='00/c/0/0/0'
E           Draw 5: ('parallel', <icechunk.session.Session object at 0x11476e570>)
E           executing on parallel
E           state.delete_chunk(data=data(...))
E           merging forks to base session, merging 1→2→parallel
E           state.merge(two_to_one=False)
E           verifying all arrays
E           state.verify_all_arrays()
E           state.teardown()

[dcherian]

This seems hard. I think we might need a different test that exercises rebase

[dcherian]

this is basically saying we expect the user to fork, merge, and then commit the "base" parallel session

[dcherian]

This is problematic. We could draw the same path on two draws which would model the case where parallel writers write to the same chunk and behaviour is undefined. I guess I can filter on chunk paths not in self.serial.status().updated_chunks[array]

[dcherian]

I should verify_all_arrays here because we expect the state on main and parallel to be identical after committing.