reconsider how to assert that expectations are used

[2bndy5]

Currently, the expectations are checked that they are all used upon destruction of the mocked object. However, pytest will ignore any exception thrown by a destructor. This leaves a traceback in the pytest output about "Ignored exception" when some exceptions were not used.

Possible solutions

1. let unused expectations go unchecked

   pros	cons
   The done() method can be called from the test code	This may cause a deviation from expected behavior

2. assert that done() is called upon destruction

   pros	cons
   This serves as reminder to update the test code	This seems to have poor behavior with the monkey_patch_sys_paths fixture because it is set to autouse=True (see also #9 )

Additional context

Because pytest manages setup and tear-down as an internal implementation detail, this is destructor approach is rather undesirable.

[2bndy5]

I'm inclined to go with option 1 because tests could expectedly fail (pytest.marks.xfail). Relying on a mock's destructor would force users' test code to overcompensate for a mock's behavior that asserts all expectations are used. It would be better to let a mock's done() be optionally invoked when appropriate.

As this library is largely influenced by embedded-hal-mock (for rust), going with option 1 is a serious deviation from that lib's design.