[test] refactor test files

1 files changed, 700 insertions, 0 deletions

diff --git a/testing/tests/couch/test_sync.py b/testing/tests/couch/test_sync.py
new file mode 100644
index 00000000..bccbfe43
--- /dev/null
+++ b/testing/tests/couch/test_sync.py
@@ -0,0 +1,700 @@
+from leap.soledad.common.l2db import vectorclock
+from leap.soledad.common.l2db import errors as u1db_errors
+
+from testscenarios import TestWithScenarios
+
+from test_soledad import u1db_tests as tests
+from test_soledad.util import CouchDBTestCase
+from test_soledad.util import sync_via_synchronizer
+from test_soledad.u1db_tests import DatabaseBaseTests
+
+from common import simple_doc
+from common import COUCH_SCENARIOS
+
+
+sync_scenarios = []
+for name, scenario in COUCH_SCENARIOS:
+    scenario = dict(scenario)
+    scenario['do_sync'] = sync_via_synchronizer
+    sync_scenarios.append((name, scenario))
+    scenario = dict(scenario)
+
+
+# -----------------------------------------------------------------------------
+# The following tests come from `u1db.tests.test_sync`.
+# -----------------------------------------------------------------------------
+
+class CouchBackendSyncTests(
+        TestWithScenarios,
+        DatabaseBaseTests,
+        CouchDBTestCase):
+
+    scenarios = sync_scenarios
+
+    def create_database(self, replica_uid, sync_role=None):
+        if replica_uid == 'test' and sync_role is None:
+            # created up the chain by base class but unused
+            return None
+        db = self.create_database_for_role(replica_uid, sync_role)
+        if sync_role:
+            self._use_tracking[db] = (replica_uid, sync_role)
+        return db
+
+    def create_database_for_role(self, replica_uid, sync_role):
+        # hook point for reuse
+        return DatabaseBaseTests.create_database(self, replica_uid)
+
+    def copy_database(self, db, sync_role=None):
+        # DO NOT COPY OR REUSE THIS CODE OUTSIDE TESTS: COPYING U1DB DATABASES
+        # IS THE WRONG THING TO DO, THE ONLY REASON WE DO SO HERE IS TO TEST
+        # THAT WE CORRECTLY DETECT IT HAPPENING SO THAT WE CAN RAISE ERRORS
+        # RATHER THAN CORRUPT USER DATA. USE SYNC INSTEAD, OR WE WILL SEND
+        # NINJA TO YOUR HOUSE.
+        db_copy = self.copy_database_for_test(self, db)
+        name, orig_sync_role = self._use_tracking[db]
+        self._use_tracking[db_copy] = (
+            name + '(copy)', sync_role or orig_sync_role)
+        return db_copy
+
+    def sync(self, db_from, db_to, trace_hook=None,
+             trace_hook_shallow=None):
+        from_name, from_sync_role = self._use_tracking[db_from]
+        to_name, to_sync_role = self._use_tracking[db_to]
+        if from_sync_role not in ('source', 'both'):
+            raise Exception("%s marked for %s use but used as source" %
+                            (from_name, from_sync_role))
+        if to_sync_role not in ('target', 'both'):
+            raise Exception("%s marked for %s use but used as target" %
+                            (to_name, to_sync_role))
+        return self.do_sync(self, db_from, db_to, trace_hook,
+                            trace_hook_shallow)
+
+    def setUp(self):
+        self.db = None
+        self.db1 = None
+        self.db2 = None
+        self.db3 = None
+        self.db1_copy = None
+        self.db2_copy = None
+        self._use_tracking = {}
+        DatabaseBaseTests.setUp(self)
+
+    def tearDown(self):
+        for db in [
+            self.db, self.db1, self.db2,
+            self.db3, self.db1_copy, self.db2_copy
+        ]:
+            if db is not None:
+                self.delete_db(db._dbname)
+                db.close()
+        DatabaseBaseTests.tearDown(self)
+
+    def assertLastExchangeLog(self, db, expected):
+        log = getattr(db, '_last_exchange_log', None)
+        if log is None:
+            return
+        self.assertEqual(expected, log)
+
+    def test_sync_tracks_db_generation_of_other(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.assertEqual(0, self.sync(self.db1, self.db2))
+        self.assertEqual(
+            (0, ''), self.db1._get_replica_gen_and_trans_id('test2'))
+        self.assertEqual(
+            (0, ''), self.db2._get_replica_gen_and_trans_id('test1'))
+        self.assertLastExchangeLog(
+            self.db2,
+            {'receive': {'docs': [], 'last_known_gen': 0},
+             'return': {'docs': [], 'last_gen': 0}})
+
+    def test_sync_autoresolves(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        doc1 = self.db1.create_doc_from_json(simple_doc, doc_id='doc')
+        rev1 = doc1.rev
+        doc2 = self.db2.create_doc_from_json(simple_doc, doc_id='doc')
+        rev2 = doc2.rev
+        self.sync(self.db1, self.db2)
+        doc = self.db1.get_doc('doc')
+        self.assertFalse(doc.has_conflicts)
+        self.assertEqual(doc.rev, self.db2.get_doc('doc').rev)
+        v = vectorclock.VectorClockRev(doc.rev)
+        self.assertTrue(v.is_newer(vectorclock.VectorClockRev(rev1)))
+        self.assertTrue(v.is_newer(vectorclock.VectorClockRev(rev2)))
+
+    def test_sync_autoresolves_moar(self):
+        # here we test that when a database that has a conflicted document is
+        # the source of a sync, and the target database has a revision of the
+        # conflicted document that is newer than the source database's, and
+        # that target's database's document's content is the same as the
+        # source's document's conflict's, the source's document's conflict gets
+        # autoresolved, and the source's document's revision bumped.
+        #
+        # idea is as follows:
+        # A          B
+        # a1         -
+        #   `------->
+        # a1         a1
+        # v          v
+        # a2         a1b1
+        #   `------->
+        # a1b1+a2    a1b1
+        #            v
+        # a1b1+a2    a1b2 (a1b2 has same content as a2)
+        #   `------->
+        # a3b2       a1b2 (autoresolved)
+        #   `------->
+        # a3b2       a3b2
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db1.create_doc_from_json(simple_doc, doc_id='doc')
+        self.sync(self.db1, self.db2)
+        for db, content in [(self.db1, '{}'), (self.db2, '{"hi": 42}')]:
+            doc = db.get_doc('doc')
+            doc.set_json(content)
+            db.put_doc(doc)
+        self.sync(self.db1, self.db2)
+        # db1 and db2 now both have a doc of {hi:42}, but db1 has a conflict
+        doc = self.db1.get_doc('doc')
+        rev1 = doc.rev
+        self.assertTrue(doc.has_conflicts)
+        # set db2 to have a doc of {} (same as db1 before the conflict)
+        doc = self.db2.get_doc('doc')
+        doc.set_json('{}')
+        self.db2.put_doc(doc)
+        rev2 = doc.rev
+        # sync it across
+        self.sync(self.db1, self.db2)
+        # tadaa!
+        doc = self.db1.get_doc('doc')
+        self.assertFalse(doc.has_conflicts)
+        vec1 = vectorclock.VectorClockRev(rev1)
+        vec2 = vectorclock.VectorClockRev(rev2)
+        vec3 = vectorclock.VectorClockRev(doc.rev)
+        self.assertTrue(vec3.is_newer(vec1))
+        self.assertTrue(vec3.is_newer(vec2))
+        # because the conflict is on the source, sync it another time
+        self.sync(self.db1, self.db2)
+        # make sure db2 now has the exact same thing
+        self.assertEqual(self.db1.get_doc('doc'), self.db2.get_doc('doc'))
+
+    def test_sync_autoresolves_moar_backwards(self):
+        # here we test that when a database that has a conflicted document is
+        # the target of a sync, and the source database has a revision of the
+        # conflicted document that is newer than the target database's, and
+        # that source's database's document's content is the same as the
+        # target's document's conflict's, the target's document's conflict gets
+        # autoresolved, and the document's revision bumped.
+        #
+        # idea is as follows:
+        # A          B
+        # a1         -
+        #   `------->
+        # a1         a1
+        # v          v
+        # a2         a1b1
+        #   `------->
+        # a1b1+a2    a1b1
+        #            v
+        # a1b1+a2    a1b2 (a1b2 has same content as a2)
+        #   <-------'
+        # a3b2       a3b2 (autoresolved and propagated)
+        self.db1 = self.create_database('test1', 'both')
+        self.db2 = self.create_database('test2', 'both')
+        self.db1.create_doc_from_json(simple_doc, doc_id='doc')
+        self.sync(self.db1, self.db2)
+        for db, content in [(self.db1, '{}'), (self.db2, '{"hi": 42}')]:
+            doc = db.get_doc('doc')
+            doc.set_json(content)
+            db.put_doc(doc)
+        self.sync(self.db1, self.db2)
+        # db1 and db2 now both have a doc of {hi:42}, but db1 has a conflict
+        doc = self.db1.get_doc('doc')
+        rev1 = doc.rev
+        self.assertTrue(doc.has_conflicts)
+        revc = self.db1.get_doc_conflicts('doc')[-1].rev
+        # set db2 to have a doc of {} (same as db1 before the conflict)
+        doc = self.db2.get_doc('doc')
+        doc.set_json('{}')
+        self.db2.put_doc(doc)
+        rev2 = doc.rev
+        # sync it across
+        self.sync(self.db2, self.db1)
+        # tadaa!
+        doc = self.db1.get_doc('doc')
+        self.assertFalse(doc.has_conflicts)
+        vec1 = vectorclock.VectorClockRev(rev1)
+        vec2 = vectorclock.VectorClockRev(rev2)
+        vec3 = vectorclock.VectorClockRev(doc.rev)
+        vecc = vectorclock.VectorClockRev(revc)
+        self.assertTrue(vec3.is_newer(vec1))
+        self.assertTrue(vec3.is_newer(vec2))
+        self.assertTrue(vec3.is_newer(vecc))
+        # make sure db2 now has the exact same thing
+        self.assertEqual(self.db1.get_doc('doc'), self.db2.get_doc('doc'))
+
+    def test_sync_autoresolves_moar_backwards_three(self):
+        # same as autoresolves_moar_backwards, but with three databases (note
+        # all the syncs go in the same direction -- this is a more natural
+        # scenario):
+        #
+        # A          B          C
+        # a1         -          -
+        #   `------->
+        # a1         a1         -
+        #              `------->
+        # a1         a1         a1
+        # v          v
+        # a2         a1b1       a1
+        #  `------------------->
+        # a2         a1b1       a2
+        #              `------->
+        #            a2+a1b1    a2
+        #                       v
+        # a2         a2+a1b1    a2c1 (same as a1b1)
+        #  `------------------->
+        # a2c1       a2+a1b1    a2c1
+        #   `------->
+        # a2b2c1     a2b2c1     a2c1
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'both')
+        self.db3 = self.create_database('test3', 'target')
+        self.db1.create_doc_from_json(simple_doc, doc_id='doc')
+        self.sync(self.db1, self.db2)
+        self.sync(self.db2, self.db3)
+        for db, content in [(self.db2, '{"hi": 42}'),
+                            (self.db1, '{}'),
+                            ]:
+            doc = db.get_doc('doc')
+            doc.set_json(content)
+            db.put_doc(doc)
+        self.sync(self.db1, self.db3)
+        self.sync(self.db2, self.db3)
+        # db2 and db3 now both have a doc of {}, but db2 has a
+        # conflict
+        doc = self.db2.get_doc('doc')
+        self.assertTrue(doc.has_conflicts)
+        revc = self.db2.get_doc_conflicts('doc')[-1].rev
+        self.assertEqual('{}', doc.get_json())
+        self.assertEqual(self.db3.get_doc('doc').get_json(), doc.get_json())
+        self.assertEqual(self.db3.get_doc('doc').rev, doc.rev)
+        # set db3 to have a doc of {hi:42} (same as db2 before the conflict)
+        doc = self.db3.get_doc('doc')
+        doc.set_json('{"hi": 42}')
+        self.db3.put_doc(doc)
+        rev3 = doc.rev
+        # sync it across to db1
+        self.sync(self.db1, self.db3)
+        # db1 now has hi:42, with a rev that is newer than db2's doc
+        doc = self.db1.get_doc('doc')
+        rev1 = doc.rev
+        self.assertFalse(doc.has_conflicts)
+        self.assertEqual('{"hi": 42}', doc.get_json())
+        VCR = vectorclock.VectorClockRev
+        self.assertTrue(VCR(rev1).is_newer(VCR(self.db2.get_doc('doc').rev)))
+        # so sync it to db2
+        self.sync(self.db1, self.db2)
+        # tadaa!
+        doc = self.db2.get_doc('doc')
+        self.assertFalse(doc.has_conflicts)
+        # db2's revision of the document is strictly newer than db1's before
+        # the sync, and db3's before that sync way back when
+        self.assertTrue(VCR(doc.rev).is_newer(VCR(rev1)))
+        self.assertTrue(VCR(doc.rev).is_newer(VCR(rev3)))
+        self.assertTrue(VCR(doc.rev).is_newer(VCR(revc)))
+        # make sure both dbs now have the exact same thing
+        self.assertEqual(self.db1.get_doc('doc'), self.db2.get_doc('doc'))
+
+    def test_sync_puts_changes(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        doc = self.db1.create_doc_from_json(simple_doc)
+        self.assertEqual(1, self.sync(self.db1, self.db2))
+        self.assertGetDoc(self.db2, doc.doc_id, doc.rev, simple_doc, False)
+        self.assertEqual(1, self.db1._get_replica_gen_and_trans_id('test2')[0])
+        self.assertEqual(1, self.db2._get_replica_gen_and_trans_id('test1')[0])
+        self.assertLastExchangeLog(
+            self.db2,
+            {'receive': {'docs': [(doc.doc_id, doc.rev)],
+                         'source_uid': 'test1',
+                         'source_gen': 1, 'last_known_gen': 0},
+             'return': {'docs': [], 'last_gen': 1}})
+
+    def test_sync_pulls_changes(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        doc = self.db2.create_doc_from_json(simple_doc)
+        self.assertEqual(0, self.sync(self.db1, self.db2))
+        self.assertGetDoc(self.db1, doc.doc_id, doc.rev, simple_doc, False)
+        self.assertEqual(1, self.db1._get_replica_gen_and_trans_id('test2')[0])
+        self.assertEqual(1, self.db2._get_replica_gen_and_trans_id('test1')[0])
+        self.assertLastExchangeLog(
+            self.db2,
+            {'receive': {'docs': [], 'last_known_gen': 0},
+             'return': {'docs': [(doc.doc_id, doc.rev)],
+                        'last_gen': 1}})
+        self.assertGetDoc(self.db2, doc.doc_id, doc.rev, simple_doc, False)
+
+    def test_sync_pulling_doesnt_update_other_if_changed(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        doc = self.db2.create_doc_from_json(simple_doc)
+        # After the local side has sent its list of docs, before we start
+        # receiving the "targets" response, we update the local database with a
+        # new record.
+        # When we finish synchronizing, we can notice that something locally
+        # was updated, and we cannot tell c2 our new updated generation
+
+        def before_get_docs(state):
+            if state != 'before get_docs':
+                return
+            self.db1.create_doc_from_json(simple_doc)
+
+        self.assertEqual(0, self.sync(self.db1, self.db2,
+                                      trace_hook=before_get_docs))
+        self.assertLastExchangeLog(
+            self.db2,
+            {'receive': {'docs': [], 'last_known_gen': 0},
+             'return': {'docs': [(doc.doc_id, doc.rev)],
+                        'last_gen': 1}})
+        self.assertEqual(1, self.db1._get_replica_gen_and_trans_id('test2')[0])
+        # c2 should not have gotten a '_record_sync_info' call, because the
+        # local database had been updated more than just by the messages
+        # returned from c2.
+        self.assertEqual(
+            (0, ''), self.db2._get_replica_gen_and_trans_id('test1'))
+
+    def test_sync_doesnt_update_other_if_nothing_pulled(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db1.create_doc_from_json(simple_doc)
+
+        def no_record_sync_info(state):
+            if state != 'record_sync_info':
+                return
+            self.fail('SyncTarget.record_sync_info was called')
+        self.assertEqual(1, self.sync(self.db1, self.db2,
+                                      trace_hook_shallow=no_record_sync_info))
+        self.assertEqual(
+            1,
+            self.db2._get_replica_gen_and_trans_id(self.db1._replica_uid)[0])
+
+    def test_sync_ignores_convergence(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'both')
+        doc = self.db1.create_doc_from_json(simple_doc)
+        self.db3 = self.create_database('test3', 'target')
+        self.assertEqual(1, self.sync(self.db1, self.db3))
+        self.assertEqual(0, self.sync(self.db2, self.db3))
+        self.assertEqual(1, self.sync(self.db1, self.db2))
+        self.assertLastExchangeLog(
+            self.db2,
+            {'receive': {'docs': [(doc.doc_id, doc.rev)],
+                         'source_uid': 'test1',
+                         'source_gen': 1, 'last_known_gen': 0},
+             'return': {'docs': [], 'last_gen': 1}})
+
+    def test_sync_ignores_superseded(self):
+        self.db1 = self.create_database('test1', 'both')
+        self.db2 = self.create_database('test2', 'both')
+        doc = self.db1.create_doc_from_json(simple_doc)
+        doc_rev1 = doc.rev
+        self.db3 = self.create_database('test3', 'target')
+        self.sync(self.db1, self.db3)
+        self.sync(self.db2, self.db3)
+        new_content = '{"key": "altval"}'
+        doc.set_json(new_content)
+        self.db1.put_doc(doc)
+        doc_rev2 = doc.rev
+        self.sync(self.db2, self.db1)
+        self.assertLastExchangeLog(
+            self.db1,
+            {'receive': {'docs': [(doc.doc_id, doc_rev1)],
+                         'source_uid': 'test2',
+                         'source_gen': 1, 'last_known_gen': 0},
+             'return': {'docs': [(doc.doc_id, doc_rev2)],
+                        'last_gen': 2}})
+        self.assertGetDoc(self.db1, doc.doc_id, doc_rev2, new_content, False)
+
+    def test_sync_sees_remote_conflicted(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        doc1 = self.db1.create_doc_from_json(simple_doc)
+        doc_id = doc1.doc_id
+        doc1_rev = doc1.rev
+        new_doc = '{"key": "altval"}'
+        doc2 = self.db2.create_doc_from_json(new_doc, doc_id=doc_id)
+        doc2_rev = doc2.rev
+        self.assertTransactionLog([doc1.doc_id], self.db1)
+        self.sync(self.db1, self.db2)
+        self.assertLastExchangeLog(
+            self.db2,
+            {'receive': {'docs': [(doc_id, doc1_rev)],
+                         'source_uid': 'test1',
+                         'source_gen': 1, 'last_known_gen': 0},
+             'return': {'docs': [(doc_id, doc2_rev)],
+                        'last_gen': 1}})
+        self.assertTransactionLog([doc_id, doc_id], self.db1)
+        self.assertGetDoc(self.db1, doc_id, doc2_rev, new_doc, True)
+        self.assertGetDoc(self.db2, doc_id, doc2_rev, new_doc, False)
+
+    def test_sync_sees_remote_delete_conflicted(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        doc1 = self.db1.create_doc_from_json(simple_doc)
+        doc_id = doc1.doc_id
+        self.sync(self.db1, self.db2)
+        doc2 = self.make_document(doc1.doc_id, doc1.rev, doc1.get_json())
+        new_doc = '{"key": "altval"}'
+        doc1.set_json(new_doc)
+        self.db1.put_doc(doc1)
+        self.db2.delete_doc(doc2)
+        self.assertTransactionLog([doc_id, doc_id], self.db1)
+        self.sync(self.db1, self.db2)
+        self.assertLastExchangeLog(
+            self.db2,
+            {'receive': {'docs': [(doc_id, doc1.rev)],
+                         'source_uid': 'test1',
+                         'source_gen': 2, 'last_known_gen': 1},
+             'return': {'docs': [(doc_id, doc2.rev)],
+                        'last_gen': 2}})
+        self.assertTransactionLog([doc_id, doc_id, doc_id], self.db1)
+        self.assertGetDocIncludeDeleted(self.db1, doc_id, doc2.rev, None, True)
+        self.assertGetDocIncludeDeleted(
+            self.db2, doc_id, doc2.rev, None, False)
+
+    def test_sync_local_race_conflicted(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        doc = self.db1.create_doc_from_json(simple_doc)
+        doc_id = doc.doc_id
+        doc1_rev = doc.rev
+        self.sync(self.db1, self.db2)
+        content1 = '{"key": "localval"}'
+        content2 = '{"key": "altval"}'
+        doc.set_json(content2)
+        self.db2.put_doc(doc)
+        doc2_rev2 = doc.rev
+        triggered = []
+
+        def after_whatschanged(state):
+            if state != 'after whats_changed':
+                return
+            triggered.append(True)
+            doc = self.make_document(doc_id, doc1_rev, content1)
+            self.db1.put_doc(doc)
+
+        self.sync(self.db1, self.db2, trace_hook=after_whatschanged)
+        self.assertEqual([True], triggered)
+        self.assertGetDoc(self.db1, doc_id, doc2_rev2, content2, True)
+
+    def test_sync_propagates_deletes(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'both')
+        doc1 = self.db1.create_doc_from_json(simple_doc)
+        doc_id = doc1.doc_id
+        self.sync(self.db1, self.db2)
+        self.db3 = self.create_database('test3', 'target')
+        self.sync(self.db1, self.db3)
+        self.db1.delete_doc(doc1)
+        deleted_rev = doc1.rev
+        self.sync(self.db1, self.db2)
+        self.assertLastExchangeLog(
+            self.db2,
+            {'receive': {'docs': [(doc_id, deleted_rev)],
+                         'source_uid': 'test1',
+                         'source_gen': 2, 'last_known_gen': 1},
+             'return': {'docs': [], 'last_gen': 2}})
+        self.assertGetDocIncludeDeleted(
+            self.db1, doc_id, deleted_rev, None, False)
+        self.assertGetDocIncludeDeleted(
+            self.db2, doc_id, deleted_rev, None, False)
+        self.sync(self.db2, self.db3)
+        self.assertLastExchangeLog(
+            self.db3,
+            {'receive': {'docs': [(doc_id, deleted_rev)],
+                         'source_uid': 'test2',
+                         'source_gen': 2, 'last_known_gen': 0},
+             'return': {'docs': [], 'last_gen': 2}})
+        self.assertGetDocIncludeDeleted(
+            self.db3, doc_id, deleted_rev, None, False)
+
+    def test_sync_propagates_deletes_2(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db1.create_doc_from_json('{"a": "1"}', doc_id='the-doc')
+        self.sync(self.db1, self.db2)
+        doc1_2 = self.db2.get_doc('the-doc')
+        self.db2.delete_doc(doc1_2)
+        self.sync(self.db1, self.db2)
+        self.assertGetDocIncludeDeleted(
+            self.db1, 'the-doc', doc1_2.rev, None, False)
+
+    def test_sync_propagates_resolution(self):
+        self.db1 = self.create_database('test1', 'both')
+        self.db2 = self.create_database('test2', 'both')
+        doc1 = self.db1.create_doc_from_json('{"a": 1}', doc_id='the-doc')
+        self.db3 = self.create_database('test3', 'both')
+        self.sync(self.db2, self.db1)
+        self.assertEqual(
+            self.db1._get_generation_info(),
+            self.db2._get_replica_gen_and_trans_id(self.db1._replica_uid))
+        self.assertEqual(
+            self.db2._get_generation_info(),
+            self.db1._get_replica_gen_and_trans_id(self.db2._replica_uid))
+        self.sync(self.db3, self.db1)
+        # update on 2
+        doc2 = self.make_document('the-doc', doc1.rev, '{"a": 2}')
+        self.db2.put_doc(doc2)
+        self.sync(self.db2, self.db3)
+        self.assertEqual(self.db3.get_doc('the-doc').rev, doc2.rev)
+        # update on 1
+        doc1.set_json('{"a": 3}')
+        self.db1.put_doc(doc1)
+        # conflicts
+        self.sync(self.db2, self.db1)
+        self.sync(self.db3, self.db1)
+        self.assertTrue(self.db2.get_doc('the-doc').has_conflicts)
+        self.assertTrue(self.db3.get_doc('the-doc').has_conflicts)
+        # resolve
+        conflicts = self.db2.get_doc_conflicts('the-doc')
+        doc4 = self.make_document('the-doc', None, '{"a": 4}')
+        revs = [doc.rev for doc in conflicts]
+        self.db2.resolve_doc(doc4, revs)
+        doc2 = self.db2.get_doc('the-doc')
+        self.assertEqual(doc4.get_json(), doc2.get_json())
+        self.assertFalse(doc2.has_conflicts)
+        self.sync(self.db2, self.db3)
+        doc3 = self.db3.get_doc('the-doc')
+        self.assertEqual(doc4.get_json(), doc3.get_json())
+        self.assertFalse(doc3.has_conflicts)
+
+    def test_sync_supersedes_conflicts(self):
+        self.db1 = self.create_database('test1', 'both')
+        self.db2 = self.create_database('test2', 'target')
+        self.db3 = self.create_database('test3', 'both')
+        doc1 = self.db1.create_doc_from_json('{"a": 1}', doc_id='the-doc')
+        self.db2.create_doc_from_json('{"b": 1}', doc_id='the-doc')
+        self.db3.create_doc_from_json('{"c": 1}', doc_id='the-doc')
+        self.sync(self.db3, self.db1)
+        self.assertEqual(
+            self.db1._get_generation_info(),
+            self.db3._get_replica_gen_and_trans_id(self.db1._replica_uid))
+        self.assertEqual(
+            self.db3._get_generation_info(),
+            self.db1._get_replica_gen_and_trans_id(self.db3._replica_uid))
+        self.sync(self.db3, self.db2)
+        self.assertEqual(
+            self.db2._get_generation_info(),
+            self.db3._get_replica_gen_and_trans_id(self.db2._replica_uid))
+        self.assertEqual(
+            self.db3._get_generation_info(),
+            self.db2._get_replica_gen_and_trans_id(self.db3._replica_uid))
+        self.assertEqual(3, len(self.db3.get_doc_conflicts('the-doc')))
+        doc1.set_json('{"a": 2}')
+        self.db1.put_doc(doc1)
+        self.sync(self.db3, self.db1)
+        # original doc1 should have been removed from conflicts
+        self.assertEqual(3, len(self.db3.get_doc_conflicts('the-doc')))
+
+    def test_sync_stops_after_get_sync_info(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db1.create_doc_from_json(tests.simple_doc)
+        self.sync(self.db1, self.db2)
+
+        def put_hook(state):
+            self.fail("Tracehook triggered for %s" % (state,))
+
+        self.sync(self.db1, self.db2, trace_hook_shallow=put_hook)
+
+    def test_sync_detects_identical_replica_uid(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test1', 'target')
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id='doc1')
+        self.assertRaises(
+            u1db_errors.InvalidReplicaUID, self.sync, self.db1, self.db2)
+
+    def test_sync_detects_rollback_in_source(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id='doc1')
+        self.sync(self.db1, self.db2)
+        self.db1_copy = self.copy_database(self.db1)
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id='doc2')
+        self.sync(self.db1, self.db2)
+        self.assertRaises(
+            u1db_errors.InvalidGeneration, self.sync, self.db1_copy, self.db2)
+
+    def test_sync_detects_rollback_in_target(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id="divergent")
+        self.sync(self.db1, self.db2)
+        self.db2_copy = self.copy_database(self.db2)
+        self.db2.create_doc_from_json(tests.simple_doc, doc_id='doc2')
+        self.sync(self.db1, self.db2)
+        self.assertRaises(
+            u1db_errors.InvalidGeneration, self.sync, self.db1, self.db2_copy)
+
+    def test_sync_detects_diverged_source(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db3 = self.copy_database(self.db1)
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id="divergent")
+        self.db3.create_doc_from_json(tests.simple_doc, doc_id="divergent")
+        self.sync(self.db1, self.db2)
+        self.assertRaises(
+            u1db_errors.InvalidTransactionId, self.sync, self.db3, self.db2)
+
+    def test_sync_detects_diverged_target(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db3 = self.copy_database(self.db2)
+        self.db3.create_doc_from_json(tests.nested_doc, doc_id="divergent")
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id="divergent")
+        self.sync(self.db1, self.db2)
+        self.assertRaises(
+            u1db_errors.InvalidTransactionId, self.sync, self.db1, self.db3)
+
+    def test_sync_detects_rollback_and_divergence_in_source(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id='doc1')
+        self.sync(self.db1, self.db2)
+        self.db1_copy = self.copy_database(self.db1)
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id='doc2')
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id='doc3')
+        self.sync(self.db1, self.db2)
+        self.db1_copy.create_doc_from_json(tests.simple_doc, doc_id='doc2')
+        self.db1_copy.create_doc_from_json(tests.simple_doc, doc_id='doc3')
+        self.assertRaises(
+            u1db_errors.InvalidTransactionId, self.sync,
+            self.db1_copy, self.db2)
+
+    def test_sync_detects_rollback_and_divergence_in_target(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        self.db1.create_doc_from_json(tests.simple_doc, doc_id="divergent")
+        self.sync(self.db1, self.db2)
+        self.db2_copy = self.copy_database(self.db2)
+        self.db2.create_doc_from_json(tests.simple_doc, doc_id='doc2')
+        self.db2.create_doc_from_json(tests.simple_doc, doc_id='doc3')
+        self.sync(self.db1, self.db2)
+        self.db2_copy.create_doc_from_json(tests.simple_doc, doc_id='doc2')
+        self.db2_copy.create_doc_from_json(tests.simple_doc, doc_id='doc3')
+        self.assertRaises(
+            u1db_errors.InvalidTransactionId, self.sync,
+            self.db1, self.db2_copy)
+
+    def test_optional_sync_preserve_json(self):
+        self.db1 = self.create_database('test1', 'source')
+        self.db2 = self.create_database('test2', 'target')
+        cont1 = '{"a": 2}'
+        cont2 = '{"b": 3}'
+        self.db1.create_doc_from_json(cont1, doc_id="1")
+        self.db2.create_doc_from_json(cont2, doc_id="2")
+        self.sync(self.db1, self.db2)
+        self.assertEqual(cont1, self.db2.get_doc("1").get_json())
+        self.assertEqual(cont2, self.db1.get_doc("2").get_json())