maya_listHistory_behavior.py

"""
  maya.cmds.listHistory() will always include the node itself when history is returned.
  Here we're testing whether it's always the first node returned, if not a RuntimeError is raised.
  
  We're also checking whether all nodes in the scene will return a valid history list, which isn't True.
  The 'defaultColorMgtGlobals' node returns None instead of an empty list.
"""

from maya import cmds

node_histories = {}
weird_non_listing_nodes = []

for node in mc.ls():
    history = cmds.listHistory(node, leaf=False)
    
    if history is None:
        weird_non_listing_nodes.append(node)
    else:
        if history[0] != node:
            raise RuntimeError()
        history =  history[1:] # remove the node itself from history
        node_histories[node] = history
        
import pprint

pprint.pprint(node_histories)
pprint.pprint(weird_non_listing_nodes)