with

    CorruptedError:  ... transaction with checkpoint flag set

on my box when doing the ZEO flavor of FileStorage.  This is like the
other pack-while-writing tests, but uses only 1 client thread that does
twice as much, and packs repeatedly for so long as that thread runs.  I
usually see it fail before the fourth pack attempt.

This makes the ZEO flavors of the tests much more likely to complete
without a "thread still alive" failure.

Forcing the output even when a test passes is interesting on my box.
When ZEO is involved, a single ClientThread tends to run all the way to
completion before another ClientThread manages to sneak in -- apart from
their first transactions, it's as if we ran one thread, then started the
next after the first finished (etc).  When ZEO isn't involved, threads
take turns.  When I see failures, they involve ZEO.  It's possible that
30 seconds just isn't long enough to wait on this box.

Drop several possible tasks that didn't seem relevant,
e.g. _p_independent() tests elsewhere should cover it just fine.

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.