It's clear in hindsight that the connection only loads non-current
revisions for objects that have been invalidated.  Thus, we never need
to track them to invalidate stale objects; they'll be invalidated
anyway.  And loadBefore() will never return a current revision,
because it would only be called if the current revision could not be
used.

an unexpectedly live thread at the end.  That's been happening forever,
but never when I stare at it, and the more I stare at those tests the more
baffled I am that it ever fails this way.  So the point here is to get
more clues when nobody is staring at it <wink>.

exception), explicitly close the storage passed to it, then re-raise
the exception.  Otherwise the storage remains open.  Turns out that
accounted for why test_zeo_config left a ConnectThread daemon thread
running (Zope3's test.py has been pointing that out for a loooong time).

isImplementedByInstancesOf to implementedBy
  isImplementedBy            to providedBy

Add a limited mechanism to capture warnings instead of having them
printed to stderr.

Tests work in my local ZODB sandbox.  Need to check whether any Zope 2
or Zope 3 tests call the deprecated methods, which could affect the
test results.

Add a few comments.

Move some of the test framework code from .py to .txt, and add a more
detailed comment at the top about the contract between .txt and the
.py file that uses it.

Move the interface test into .txt.  I guess it's not so bad.

Change some tests that displayed the contents of __dict__.  Other
persistent implementations may have extra state in __dict__.

Remove B, it is unused.

Change DocFileSuite() to accept an explicit set of globals.

Remove the pickling/P2 test, because it was too hard to make work with
the framework.  Include comment explaining how such a test should be
added.

by src/persistent/tests/test_persistent.

I've included some code to convert a text file containing doctest
tests into a unittest.TestCase.  This code wants to be generic, but
I'm not sure if it's simple enough yet.

This shouldn't affect any user code, because False == 0 and True == 1.

Remove unittest boilerplate.

Add docstrings for public cache methods.