##############################################################################
#
# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
import unittest
import warnings

import ZODB
import ZODB.FileStorage
from ZODB.POSException import ReadConflictError, ConflictError
from ZODB.POSException import TransactionFailedError
from ZODB.tests.warnhook import WarningsHook

from persistent import Persistent
from persistent.mapping import PersistentMapping
import transaction

# deprecated37  remove when subtransactions go away
# Don't complain about subtxns in these tests.
warnings.filterwarnings("ignore",
                        ".*\nsubtransactions are deprecated",
                        DeprecationWarning, __name__)

class P(Persistent):
    pass

class Independent(Persistent):

    def _p_independent(self):
        return 1

class DecoyIndependent(Persistent):

    def _p_independent(self):
        return 0

class ZODBTests(unittest.TestCase):

    def setUp(self):
        self._storage = ZODB.FileStorage.FileStorage(
            'ZODBTests.fs', create=1)
        self._db = ZODB.DB(self._storage)

    def populate(self):
        transaction.begin()
        conn = self._db.open()
        root = conn.root()
        root['test'] = pm = PersistentMapping()
        for n in range(100):
            pm[n] = PersistentMapping({0: 100 - n})
        transaction.get().note('created test data')
        transaction.commit()
        conn.close()

    def tearDown(self):
        self._db.close()
        self._storage.cleanup()

    def checkExportImport(self, abort_it=False):
        self.populate()
        conn = self._db.open()
        try:
            self.duplicate(conn, abort_it)
        finally:
            conn.close()
        conn = self._db.open()
        try:
            self.verify(conn, abort_it)
        finally:
            conn.close()

    def duplicate(self, conn, abort_it):
        transaction.begin()
        transaction.get().note('duplication')
        root = conn.root()
        ob = root['test']
        assert len(ob) > 10, 'Insufficient test data'
        try:
            import tempfile
            f = tempfile.TemporaryFile()
            ob._p_jar.exportFile(ob._p_oid, f)
            assert f.tell() > 0, 'Did not export correctly'
            f.seek(0)
            new_ob = ob._p_jar.importFile(f)
            self.assertEqual(new_ob, ob)
            root['dup'] = new_ob
            f.close()
            if abort_it:
                transaction.abort()
            else:
                transaction.commit()
        except:
            transaction.abort()
            raise

    def verify(self, conn, abort_it):
        transaction.begin()
        root = conn.root()
        ob = root['test']
        try:
            ob2 = root['dup']
        except KeyError:
            if abort_it:
                # Passed the test.
                return
            else:
                raise
        else:
            self.failUnless(not abort_it, 'Did not abort duplication')
        l1 = list(ob.items())
        l1.sort()
        l2 = list(ob2.items())
        l2.sort()
        l1 = map(lambda (k, v): (k, v[0]), l1)
        l2 = map(lambda (k, v): (k, v[0]), l2)
        self.assertEqual(l1, l2)
        self.assert_(ob._p_oid != ob2._p_oid)
        self.assertEqual(ob._p_jar, ob2._p_jar)
        oids = {}
        for v in ob.values():
            oids[v._p_oid] = 1
        for v in ob2.values():
            assert not oids.has_key(v._p_oid), (
                'Did not fully separate duplicate from original')
        transaction.commit()

    def checkExportImportAborted(self):
        self.checkExportImport(abort_it=True)

    def checkVersionOnly(self):
        # Make sure the changes to make empty transactions a no-op
        # still allow things like abortVersion().  This should work
        # because abortVersion() calls tpc_begin() itself.
        conn = self._db.open("version")
        try:
            r = conn.root()
            r[1] = 1
            transaction.commit()
        finally:
            conn.close()
        self._db.abortVersion("version")
        transaction.commit()

    def checkResetCache(self):
        # The cache size after a reset should be 0.  Note that
        # _resetCache is not a public API, but the resetCaches()
        # function is, and resetCaches() causes _resetCache() to be
        # called.
        self.populate()
        conn = self._db.open()
        conn.root()
        self.assert_(len(conn._cache) > 0)  # Precondition
        conn._resetCache()
        self.assertEqual(len(conn._cache), 0)

    def checkResetCachesAPI(self):
        # Checks the resetCaches() API.
        # (resetCaches used to be called updateCodeTimestamp.)
        self.populate()
        conn = self._db.open()
        conn.root()
        self.assert_(len(conn._cache) > 0)  # Precondition
        ZODB.Connection.resetCaches()
        conn.close()
        self.assert_(len(conn._cache) > 0)  # Still not flushed
        conn.open()  # simulate the connection being reopened
        self.assertEqual(len(conn._cache), 0)

    def checkExplicitTransactionManager(self):
        # Test of transactions that apply to only the connection,
        # not the thread.
        tm1 = transaction.TransactionManager()
        conn1 = self._db.open(transaction_manager=tm1)
        tm2 = transaction.TransactionManager()
        conn2 = self._db.open(transaction_manager=tm2)
        try:
            r1 = conn1.root()
            r2 = conn2.root()
            if r1.has_key('item'):
                del r1['item']
                tm1.get().commit()
            r1.get('item')
            r2.get('item')
            r1['item'] = 1
            tm1.get().commit()
            self.assertEqual(r1['item'], 1)
            # r2 has not seen a transaction boundary,
            # so it should be unchanged.
            self.assertEqual(r2.get('item'), None)
            conn2.sync()
            # Now r2 is updated.
            self.assertEqual(r2['item'], 1)

            # Now, for good measure, send an update in the other direction.
            r2['item'] = 2
            tm2.get().commit()
            self.assertEqual(r1['item'], 1)
            self.assertEqual(r2['item'], 2)
            conn1.sync()
            conn2.sync()
            self.assertEqual(r1['item'], 2)
            self.assertEqual(r2['item'], 2)
        finally:
            conn1.close()
            conn2.close()

    def checkReadConflict(self):
        self.obj = P()
        self.readConflict()

    def readConflict(self, shouldFail=True):
        # Two transactions run concurrently.  Each reads some object,
        # then one commits and the other tries to read an object
        # modified by the first.  This read should fail with a conflict
        # error because the object state read is not necessarily
        # consistent with the objects read earlier in the transaction.

        tm1 = transaction.TransactionManager()
        conn = self._db.open(mvcc=False, transaction_manager=tm1)
        r1 = conn.root()
        r1["p"] = self.obj
        self.obj.child1 = P()
        tm1.get().commit()

        # start a new transaction with a new connection
        tm2 = transaction.TransactionManager()
        cn2 = self._db.open(mvcc=False, transaction_manager=tm2)
        # start a new transaction with the other connection
        r2 = cn2.root()

        self.assertEqual(r1._p_serial, r2._p_serial)

        self.obj.child2 = P()
        tm1.get().commit()

        # resume the transaction using cn2
        obj = r2["p"]
        # An attempt to access obj should fail, because r2 was read
        # earlier in the transaction and obj was modified by the othe
        # transaction.
        if shouldFail:
            self.assertRaises(ReadConflictError, lambda: obj.child1)
            # And since ReadConflictError was raised, attempting to commit
            # the transaction should re-raise it.  checkNotIndependent()
            # failed this part of the test for a long time.
            self.assertRaises(ReadConflictError, tm2.get().commit)

            # And since that commit failed, trying to commit again should
            # fail again.
            self.assertRaises(TransactionFailedError, tm2.get().commit)
            # And again.
            self.assertRaises(TransactionFailedError, tm2.get().commit)
            # Etc.
            self.assertRaises(TransactionFailedError, tm2.get().commit)

        else:
            # make sure that accessing the object succeeds
            obj.child1
        tm2.get().abort()

    def checkReadConflictIgnored(self):
        # Test that an application that catches a read conflict and
        # continues can not commit the transaction later.
        root = self._db.open(mvcc=False).root()
        root["real_data"] = real_data = PersistentMapping()
        root["index"] = index = PersistentMapping()

        real_data["a"] = PersistentMapping({"indexed_value": 0})
        real_data["b"] = PersistentMapping({"indexed_value": 1})
        index[1] = PersistentMapping({"b": 1})
        index[0] = PersistentMapping({"a": 1})
        transaction.commit()

        # load some objects from one connection
        tm = transaction.TransactionManager()
        cn2 = self._db.open(mvcc=False, transaction_manager=tm)
        r2 = cn2.root()
        real_data2 = r2["real_data"]
        index2 = r2["index"]

        real_data["b"]["indexed_value"] = 0
        del index[1]["b"]
        index[0]["b"] = 1
        transaction.commit()

        del real_data2["a"]
        try:
            del index2[0]["a"]
        except ReadConflictError:
            # This is the crux of the text.  Ignore the error.
            pass
        else:
            self.fail("No conflict occurred")

        # real_data2 still ready to commit
        self.assert_(real_data2._p_changed)

        # index2 values not ready to commit
        self.assert_(not index2._p_changed)
        self.assert_(not index2[0]._p_changed)
        self.assert_(not index2[1]._p_changed)

        self.assertRaises(ReadConflictError, tm.get().commit)
        self.assertRaises(TransactionFailedError, tm.get().commit)
        tm.get().abort()

    def checkIndependent(self):
        self.obj = Independent()
        self.readConflict(shouldFail=False)

    def checkNotIndependent(self):
        self.obj = DecoyIndependent()
        self.readConflict()

    def checkSubtxnCommitDoesntGetInvalidations(self):
        # Prior to ZODB 3.2.9 and 3.4, Connection.tpc_finish() processed
        # invalidations even for a subtxn commit.  This could make
        # inconsistent state visible after a subtxn commit.  There was a
        # suspicion that POSKeyError was possible as a result, but I wasn't
        # able to construct a case where that happened.

        # Set up the database, to hold
        # root --> "p" -> value = 1
        #      --> "q" -> value = 2
        tm1 = transaction.TransactionManager()
        conn = self._db.open(transaction_manager=tm1)
        r1 = conn.root()
        p = P()
        p.value = 1
        r1["p"] = p
        q = P()
        q.value = 2
        r1["q"] = q
        tm1.commit()

        # Now txn T1 changes p.value to 3 locally (subtxn commit).
        p.value = 3
        tm1.commit(True)

        # Start new txn T2 with a new connection.
        tm2 = transaction.TransactionManager()
        cn2 = self._db.open(transaction_manager=tm2)
        r2 = cn2.root()
        p2 = r2["p"]
        self.assertEqual(p._p_oid, p2._p_oid)
        # T2 shouldn't see T1's change of p.value to 3, because T1 didn't
        # commit yet.
        self.assertEqual(p2.value, 1)
        # Change p.value to 4, and q.value to 5.  Neither should be visible
        # to T1, because T1 is still in progress.
        p2.value = 4
        q2 = r2["q"]
        self.assertEqual(q._p_oid, q2._p_oid)
        self.assertEqual(q2.value, 2)
        q2.value = 5
        tm2.commit()

        # Back to T1.  p and q still have the expected values.
        rt = conn.root()
        self.assertEqual(rt["p"].value, 3)
        self.assertEqual(rt["q"].value, 2)

        # Now do another subtxn commit in T1.  This shouldn't change what
        # T1 sees for p and q.
        rt["r"] = P()
        tm1.commit(True)

        # Doing that subtxn commit in T1 should not process invalidations
        # from T2's commit.  p.value should still be 3 here (because that's
        # what T1 subtxn-committed earlier), and q.value should still be 2.
        # Prior to ZODB 3.2.9 and 3.4, q.value was 5 here.
        rt = conn.root()
        try:
            self.assertEqual(rt["p"].value, 3)
            self.assertEqual(rt["q"].value, 2)
        finally:
            tm1.abort()

    def checkSavepointDoesntGetInvalidations(self):
        # Prior to ZODB 3.2.9 and 3.4, Connection.tpc_finish() processed
        # invalidations even for a subtxn commit.  This could make
        # inconsistent state visible after a subtxn commit.  There was a
        # suspicion that POSKeyError was possible as a result, but I wasn't
        # able to construct a case where that happened.
        # Subtxns are deprecated now, but it's good to check that the
        # same kind of thing doesn't happen when making savepoints either.

        # Set up the database, to hold
        # root --> "p" -> value = 1
        #      --> "q" -> value = 2
        tm1 = transaction.TransactionManager()
        conn = self._db.open(transaction_manager=tm1)
        r1 = conn.root()
        p = P()
        p.value = 1
        r1["p"] = p
        q = P()
        q.value = 2
        r1["q"] = q
        tm1.commit()

        # Now txn T1 changes p.value to 3 locally (subtxn commit).
        p.value = 3
        tm1.savepoint()

        # Start new txn T2 with a new connection.
        tm2 = transaction.TransactionManager()
        cn2 = self._db.open(transaction_manager=tm2)
        r2 = cn2.root()
        p2 = r2["p"]
        self.assertEqual(p._p_oid, p2._p_oid)
        # T2 shouldn't see T1's change of p.value to 3, because T1 didn't
        # commit yet.
        self.assertEqual(p2.value, 1)
        # Change p.value to 4, and q.value to 5.  Neither should be visible
        # to T1, because T1 is still in progress.
        p2.value = 4
        q2 = r2["q"]
        self.assertEqual(q._p_oid, q2._p_oid)
        self.assertEqual(q2.value, 2)
        q2.value = 5
        tm2.commit()

        # Back to T1.  p and q still have the expected values.
        rt = conn.root()
        self.assertEqual(rt["p"].value, 3)
        self.assertEqual(rt["q"].value, 2)

        # Now make another savepoint in T1.  This shouldn't change what
        # T1 sees for p and q.
        rt["r"] = P()
        tm1.savepoint()

        # Making that savepoint in T1 should not process invalidations
        # from T2's commit.  p.value should still be 3 here (because that's
        # what T1 savepointed earlier), and q.value should still be 2.
        # Prior to ZODB 3.2.9 and 3.4, q.value was 5 here.
        rt = conn.root()
        try:
            self.assertEqual(rt["p"].value, 3)
            self.assertEqual(rt["q"].value, 2)
        finally:
            tm1.abort()

    def checkReadConflictErrorClearedDuringAbort(self):
        # When a transaction is aborted, the "memory" of which
        # objects were the cause of a ReadConflictError during
        # that transaction should be cleared.
        root = self._db.open(mvcc=False).root()
        data = PersistentMapping({'d': 1})
        root["data"] = data
        transaction.commit()

        # Provoke a ReadConflictError.
        tm2 = transaction.TransactionManager()
        cn2 = self._db.open(mvcc=False, transaction_manager=tm2)
        r2 = cn2.root()
        data2 = r2["data"]

        data['d'] = 2
        transaction.commit()

        try:
            data2['d'] = 3
        except ReadConflictError:
            pass
        else:
            self.fail("No conflict occurred")

        # Explicitly abort cn2's transaction.
        tm2.get().abort()

        # cn2 should retain no memory of the read conflict after an abort(),
        # but 3.2.3 had a bug wherein it did.
        data_conflicts = data._p_jar._conflicts
        data2_conflicts = data2._p_jar._conflicts
        self.failIf(data_conflicts)
        self.failIf(data2_conflicts)  # this used to fail

        # And because of that, we still couldn't commit a change to data2['d']
        # in the new transaction.
        cn2.sync()  # process the invalidation for data2['d']
        data2['d'] = 3
        tm2.get().commit()  # 3.2.3 used to raise ReadConflictError

        cn2.close()

    def checkTxnBeginImpliesAbort(self):
        # begin() should do an abort() first, if needed.
        cn = self._db.open()
        rt = cn.root()
        rt['a'] = 1

        transaction.begin()  # should abort adding 'a' to the root
        rt = cn.root()
        self.assertRaises(KeyError, rt.__getitem__, 'a')

        # A longstanding bug:  this didn't work if changes were only in
        # subtransactions.
        transaction.begin()
        rt = cn.root()
        rt['a'] = 2
        transaction.commit(1)

        transaction.begin()
        rt = cn.root()
        self.assertRaises(KeyError, rt.__getitem__, 'a')

        # One more time, mixing "top level" and subtransaction changes.
        transaction.begin()
        rt = cn.root()
        rt['a'] = 3
        transaction.commit(1)
        rt['b'] = 4

        transaction.begin()
        rt = cn.root()
        self.assertRaises(KeyError, rt.__getitem__, 'a')
        self.assertRaises(KeyError, rt.__getitem__, 'b')

        # That used methods of the default transaction *manager*.  Alas,
        # that's not necessarily the same as using methods of the current
        # transaction, and, in fact, when this test was written,
        # Transaction.begin() didn't do anything (everything from here
        # down failed).
        # Later (ZODB 3.6):  Transaction.begin() no longer exists, so the
        # rest of this test was tossed.

    def checkFailingCommitSticks(self):
        # See also checkFailingSubtransactionCommitSticks.
        # See also checkFailingSavepointSticks.
        cn = self._db.open()
        rt = cn.root()
        rt['a'] = 1

        # Arrange for commit to fail during tpc_vote.
        poisoned = PoisonedObject(PoisonedJar(break_tpc_vote=True))
        transaction.get().register(poisoned)

        self.assertRaises(PoisonedError, transaction.get().commit)
        # Trying to commit again fails too.
        self.assertRaises(TransactionFailedError, transaction.commit)
        self.assertRaises(TransactionFailedError, transaction.commit)
        self.assertRaises(TransactionFailedError, transaction.commit)

        # The change to rt['a'] is lost.
        self.assertRaises(KeyError, rt.__getitem__, 'a')

        # Trying to modify an object also fails, because Transaction.join()
        # also raises TransactionFailedError.
        self.assertRaises(TransactionFailedError, rt.__setitem__, 'b', 2)

        # Clean up via abort(), and try again.
        transaction.abort()
        rt['a'] = 1
        transaction.commit()
        self.assertEqual(rt['a'], 1)

        # Cleaning up via begin() should also work.
        rt['a'] = 2
        transaction.get().register(poisoned)
        self.assertRaises(PoisonedError, transaction.commit)
        self.assertRaises(TransactionFailedError, transaction.commit)
        # The change to rt['a'] is lost.
        self.assertEqual(rt['a'], 1)
        # Trying to modify an object also fails.
        self.assertRaises(TransactionFailedError, rt.__setitem__, 'b', 2)
        # Clean up via begin(), and try again.
        transaction.begin()
        rt['a'] = 2
        transaction.commit()
        self.assertEqual(rt['a'], 2)

        cn.close()

    def checkFailingSubtransactionCommitSticks(self):
        cn = self._db.open()
        rt = cn.root()
        rt['a'] = 1
        transaction.commit(True)
        self.assertEqual(rt['a'], 1)

        rt['b'] = 2

        # Make a jar that raises PoisonedError when a subtxn commit is done.
        poisoned = PoisonedJar(break_savepoint=True)
        transaction.get().join(poisoned)
        # We're using try/except here instead of assertRaises so that this
        # module's attempt to suppress subtransaction deprecation wngs
        # works.
        try:
            transaction.commit(True)
        except PoisonedError:
            pass
        else:
            self.fail("expected PoisonedError")
        # Trying to subtxn-commit again fails too.
        try:
            transaction.commit(True)
        except TransactionFailedError:
            pass
        else:
            self.fail("expected TransactionFailedError")
        try:
            transaction.commit(True)
        except TransactionFailedError:
            pass
        else:
            self.fail("expected TransactionFailedError")
        # Top-level commit also fails.
        self.assertRaises(TransactionFailedError, transaction.commit)

        # The changes to rt['a'] and rt['b'] are lost.
        self.assertRaises(KeyError, rt.__getitem__, 'a')
        self.assertRaises(KeyError, rt.__getitem__, 'b')

        # Trying to modify an object also fails, because Transaction.join()
        # also raises TransactionFailedError.
        self.assertRaises(TransactionFailedError, rt.__setitem__, 'b', 2)

        # Clean up via abort(), and try again.
        transaction.abort()
        rt['a'] = 1
        transaction.commit()
        self.assertEqual(rt['a'], 1)

        # Cleaning up via begin() should also work.
        rt['a'] = 2
        transaction.get().join(poisoned)
        try:
            transaction.commit(True)
        except PoisonedError:
            pass
        else:
            self.fail("expected PoisonedError")
        # Trying to subtxn-commit again fails too.
        try:
            transaction.commit(True)
        except TransactionFailedError:
            pass
        else:
            self.fail("expected TransactionFailedError")

        # The change to rt['a'] is lost.
        self.assertEqual(rt['a'], 1)
        # Trying to modify an object also fails.
        self.assertRaises(TransactionFailedError, rt.__setitem__, 'b', 2)

        # Clean up via begin(), and try again.
        transaction.begin()
        rt['a'] = 2
        transaction.commit(True)
        self.assertEqual(rt['a'], 2)
        transaction.get().commit()

        cn2 = self._db.open()
        rt = cn.root()
        self.assertEqual(rt['a'], 2)

        cn.close()
        cn2.close()

    def checkFailingSavepointSticks(self):
        cn = self._db.open()
        rt = cn.root()
        rt['a'] = 1
        transaction.savepoint()
        self.assertEqual(rt['a'], 1)

        rt['b'] = 2

        # Make a jar that raises PoisonedError when making a savepoint.
        poisoned = PoisonedJar(break_savepoint=True)
        transaction.get().join(poisoned)
        self.assertRaises(PoisonedError, transaction.savepoint)
        # Trying to make a savepoint again fails too.
        self.assertRaises(TransactionFailedError, transaction.savepoint)
        self.assertRaises(TransactionFailedError, transaction.savepoint)
        # Top-level commit also fails.
        self.assertRaises(TransactionFailedError, transaction.commit)

        # The changes to rt['a'] and rt['b'] are lost.
        self.assertRaises(KeyError, rt.__getitem__, 'a')
        self.assertRaises(KeyError, rt.__getitem__, 'b')

        # Trying to modify an object also fails, because Transaction.join()
        # also raises TransactionFailedError.
        self.assertRaises(TransactionFailedError, rt.__setitem__, 'b', 2)

        # Clean up via abort(), and try again.
        transaction.abort()
        rt['a'] = 1
        transaction.commit()
        self.assertEqual(rt['a'], 1)

        # Cleaning up via begin() should also work.
        rt['a'] = 2
        transaction.get().join(poisoned)
        self.assertRaises(PoisonedError, transaction.savepoint)
        # Trying to make a savepoint again fails too.
        self.assertRaises(TransactionFailedError, transaction.savepoint)

        # The change to rt['a'] is lost.
        self.assertEqual(rt['a'], 1)
        # Trying to modify an object also fails.
        self.assertRaises(TransactionFailedError, rt.__setitem__, 'b', 2)

        # Clean up via begin(), and try again.
        transaction.begin()
        rt['a'] = 2
        transaction.savepoint()
        self.assertEqual(rt['a'], 2)
        transaction.commit()

        cn2 = self._db.open()
        rt = cn.root()
        self.assertEqual(rt['a'], 2)

        cn.close()
        cn2.close()

    def checkMultipleUndoInOneTransaction(self):
        # Verify that it's possible to perform multiple undo
        # operations within a transaction.  If ZODB performs the undo
        # operations in a nondeterministic order, this test will often
        # fail.

        conn = self._db.open()
        try:
            root = conn.root()

            # Add transactions that set root["state"] to (0..5)
            for state_num in range(6):
                transaction.begin()
                root['state'] = state_num
                transaction.get().note('root["state"] = %d' % state_num)
                transaction.commit()

            # Undo all but the first.  Note that no work is actually
            # performed yet.
            transaction.begin()
            log = self._db.undoLog()
            for i in range(5):
                self._db.undo(log[i]['id'])
            transaction.get().note('undo states 1 through 5')

            # Now attempt all those undo operations.
            transaction.commit()

            # Sanity check: we should be back to the first state.
            self.assertEqual(root['state'], 0)
        finally:
            transaction.abort()
            conn.close()

        

class PoisonedError(Exception):
    pass

# PoisonedJar arranges to raise PoisonedError from interesting places.
class PoisonedJar:
    def __init__(self, break_tpc_begin=False, break_tpc_vote=False,
                 break_savepoint=False):
        self.break_tpc_begin = break_tpc_begin
        self.break_tpc_vote = break_tpc_vote
        self.break_savepoint = break_savepoint

    def sortKey(self):
        return str(id(self))

    # A way that used to poison a subtransaction commit.  With the current
    # implementation of subtxns, pass break_savepoint=True instead.
    def tpc_begin(self, *args):
        if self.break_tpc_begin:
            raise PoisonedError("tpc_begin fails")

    # A way to poison a top-level commit.
    def tpc_vote(self, *args):
        if self.break_tpc_vote:
            raise PoisonedError("tpc_vote fails")

    # A way to poison a savepoint -- also a way to poison a subtxn commit.
    def savepoint(self):
        if self.break_savepoint:
            raise PoisonedError("savepoint fails")

    def commit(*args):
        pass

    def abort(*self):
        pass


class PoisonedObject:
    def __init__(self, poisonedjar):
        self._p_jar = poisonedjar

def test_suite():
    return unittest.makeSuite(ZODBTests, 'check')

if __name__ == "__main__":
    unittest.main(defaultTest="test_suite")
