$ cat << EOF > buggylocking.py

  > """A small extension that tests our developer warnings

  > """

  > 

  > from mercurial import cmdutil, repair, revset

  > 

  > cmdtable = {}

  > command = cmdutil.command(cmdtable)

  > 

  > @command('buggylocking', [], '')

  > def buggylocking(ui, repo):

  >     lo = repo.lock()

  >     wl = repo.wlock()

  >     wl.release()

  >     lo.release()

  > 

  > @command('buggytransaction', [], '')

  > def buggylocking(ui, repo):

  >     tr = repo.transaction('buggy')

  >     # make sure we rollback the transaction as we don't want to rely on the__del__

  >     tr.release()

  > 

  > @command('properlocking', [], '')

  > def properlocking(ui, repo):

  >     """check that reentrance is fine"""

  >     wl = repo.wlock()

  >     lo = repo.lock()

  >     tr = repo.transaction('proper')

  >     tr2 = repo.transaction('proper')

  >     lo2 = repo.lock()

  >     wl2 = repo.wlock()

  >     wl2.release()

  >     lo2.release()

  >     tr2.close()

  >     tr.close()

  >     lo.release()

  >     wl.release()

  > 

  > @command('nowaitlocking', [], '')

  > def nowaitlocking(ui, repo):

  >     lo = repo.lock()

  >     wl = repo.wlock(wait=False)

  >     wl.release()

  >     lo.release()

  > 

  > @command('stripintr', [], '')

  > def stripintr(ui, repo):

  >     lo = repo.lock()

  >     tr = repo.transaction('foobar')

  >     try:

  >         repair.strip(repo.ui, repo, [repo['.'].node()])

  >     finally:

  >         lo.release()

  > @command('oldanddeprecated', [], '')

  > def oldanddeprecated(ui, repo):

  >     """test deprecation warning API"""

  >     def foobar(ui):

  >         ui.deprecwarn('foorbar is deprecated, go shopping', '42.1337')

  >     foobar(ui)

  > 

  > def oldstylerevset(repo, subset, x):

  >     return list(subset)

  > 

  > revset.symbols['oldstyle'] = oldstylerevset

  > EOF

  $ cat << EOF >> $HGRCPATH

  > [extensions]

  > buggylocking=$TESTTMP/buggylocking.py

  > mock=$TESTDIR/mockblackbox.py

  > blackbox=

  > [devel]

  > all-warnings=1

  > EOF

  $ hg init lock-checker

  $ cd lock-checker

  $ hg buggylocking

  devel-warn: "wlock" acquired after "lock" at: $TESTTMP/buggylocking.py:* (buggylocking) (glob)

  $ cat << EOF >> $HGRCPATH

  > [devel]

  > all=0

  > check-locks=1

  > EOF

  $ hg buggylocking

  devel-warn: "wlock" acquired after "lock" at: $TESTTMP/buggylocking.py:* (buggylocking) (glob)

  $ hg buggylocking --traceback

  devel-warn: "wlock" acquired after "lock" at:

   */hg:* in * (glob)

   */mercurial/dispatch.py:* in run (glob)

   */mercurial/dispatch.py:* in dispatch (glob)

   */mercurial/dispatch.py:* in _runcatch (glob)

   */mercurial/dispatch.py:* in callcatch (glob)

   */mercurial/scmutil.py* in callcatch (glob)

   */mercurial/dispatch.py:* in _runcatchfunc (glob)

   */mercurial/dispatch.py:* in _dispatch (glob)

   */mercurial/dispatch.py:* in runcommand (glob)

   */mercurial/dispatch.py:* in _runcommand (glob)

   */mercurial/dispatch.py:* in <lambda> (glob)

   */mercurial/util.py:* in check (glob)

   $TESTTMP/buggylocking.py:* in buggylocking (glob)

  $ hg properlocking

  $ hg nowaitlocking

  $ echo a > a

  $ hg add a

  $ hg commit -m a

  $ hg stripintr

  saved backup bundle to $TESTTMP/lock-checker/.hg/strip-backup/*-backup.hg (glob)

  abort: programming error: cannot strip from inside a transaction

  (contact your extension maintainer)

  [255]

  $ hg log -r "oldstyle()" -T '{rev}\n'

  devel-warn: revset "oldstyle" uses list instead of smartset

  (compatibility will be dropped after Mercurial-3.9, update your code.) at: *mercurial/revset.py:* (mfunc) (glob)

  0

  $ hg oldanddeprecated

  devel-warn: foorbar is deprecated, go shopping

  (compatibility will be dropped after Mercurial-42.1337, update your code.) at: $TESTTMP/buggylocking.py:* (oldanddeprecated) (glob)

  $ hg oldanddeprecated --traceback

  devel-warn: foorbar is deprecated, go shopping

  (compatibility will be dropped after Mercurial-42.1337, update your code.) at:

   */hg:* in <module> (glob)

   */mercurial/dispatch.py:* in run (glob)

   */mercurial/dispatch.py:* in dispatch (glob)

   */mercurial/dispatch.py:* in _runcatch (glob)

   */mercurial/dispatch.py:* in callcatch (glob)

   */mercurial/scmutil.py* in callcatch (glob)

   */mercurial/dispatch.py:* in _runcatchfunc (glob)

   */mercurial/dispatch.py:* in _dispatch (glob)

   */mercurial/dispatch.py:* in runcommand (glob)

   */mercurial/dispatch.py:* in _runcommand (glob)

   */mercurial/dispatch.py:* in <lambda> (glob)

   */mercurial/util.py:* in check (glob)

   $TESTTMP/buggylocking.py:* in oldanddeprecated (glob)

  $ hg blackbox -l 9

  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> devel-warn: revset "oldstyle" uses list instead of smartset

  (compatibility will be dropped after Mercurial-3.9, update your code.) at: *mercurial/revset.py:* (mfunc) (glob)

  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> oldanddeprecated

  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> devel-warn: foorbar is deprecated, go shopping

  (compatibility will be dropped after Mercurial-42.1337, update your code.) at: $TESTTMP/buggylocking.py:* (oldanddeprecated) (glob)

  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> oldanddeprecated exited 0 after * seconds (glob)

  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> oldanddeprecated --traceback

  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> devel-warn: foorbar is deprecated, go shopping

  (compatibility will be dropped after Mercurial-42.1337, update your code.) at:

   */hg:* in <module> (glob)

   */mercurial/dispatch.py:* in run (glob)

   */mercurial/dispatch.py:* in dispatch (glob)

   */mercurial/dispatch.py:* in _runcatch (glob)

   */mercurial/dispatch.py:* in callcatch (glob)

   */mercurial/scmutil.py* in callcatch (glob)

   */mercurial/dispatch.py:* in _runcatchfunc (glob)

   */mercurial/dispatch.py:* in _dispatch (glob)

   */mercurial/dispatch.py:* in runcommand (glob)

   */mercurial/dispatch.py:* in _runcommand (glob)

   */mercurial/dispatch.py:* in <lambda> (glob)

   */mercurial/util.py:* in check (glob)

   $TESTTMP/buggylocking.py:* in oldanddeprecated (glob)

  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> oldanddeprecated --traceback exited 0 after * seconds (glob)

  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> blackbox -l 9

Test programming error failure:

  $ hg buggytransaction 2>&1 | egrep -v '^  '

  ** Unknown exception encountered with possibly-broken third-party extension buggylocking

  ** which supports versions unknown of Mercurial.

  ** Please disable buggylocking and try your action again.

  ** If that fixes the bug please report it to the extension author.

  ** Python * (glob)

  ** Mercurial Distributed SCM (*) (glob)

  ** Extensions loaded: * (glob)

  Traceback (most recent call last):

  mercurial.error.ProgrammingError: transaction requires locking

  $ cd ..