How to assert that an iterable is not empty on Unittest?

Depends exactly what you are looking for.

If you want to make sure the object is an iterable and it is not empty:

# TypeError: object of type 'NoneType' has no len()
# if my_iterable is None
self.assertTrue(len(my_iterable))

If it is OK for the object being tested to be None:

self.assertTrue(my_maybe_iterable)

Empty lists/dicts evaluate to False, so self.assertTrue(d) gets the job done.