[refactor] move tests to root of repository

Tests entrypoint was in a testing/ subfolder in the root of the
repository. This was made mainly because we had some common files for
tests and we didn't want to ship them (files in testing/test_soledad,
which is itself a python package. This sometimes causes errors when
loading tests (it seems setuptools is confused with having one python
package in a subdirectory of another).

This commit moves the tests entrypoint to the root of the repository.

Closes: #8952

10 files changed, 1723 insertions, 0 deletions

diff --git a/tests/couch/__init__.py b/tests/couch/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/tests/couch/__init__.py
diff --git a/tests/couch/common.py b/tests/couch/common.py
new file mode 100644
index 00000000..3c272f6e
--- /dev/null
+++ b/tests/couch/common.py
@@ -0,0 +1,75 @@
+from uuid import uuid4
+from six.moves.urllib.parse import urljoin
+from couchdb.client import Server
+
+from leap.soledad.common import couch
+from leap.soledad.common.document import ServerDocument
+
+from test_soledad import u1db_tests as tests
+
+
+simple_doc = tests.simple_doc
+nested_doc = tests.nested_doc
+
+
+def make_couch_database_for_test(test, replica_uid):
+    dbname = ('test-%s' % uuid4().hex)
+    db = couch.CouchDatabase.open_database(
+        urljoin(test.couch_url, dbname),
+        create=True,
+        replica_uid=replica_uid or 'test')
+    test.addCleanup(test.delete_db, dbname)
+    return db
+
+
+def copy_couch_database_for_test(test, db):
+    couch_url = test.couch_url
+    new_dbname = db._dbname + '_copy'
+    new_db = couch.CouchDatabase.open_database(
+        urljoin(couch_url, new_dbname),
+        create=True,
+        replica_uid=db._replica_uid or 'test')
+    # copy all docs
+    session = couch.Session()
+    old_couch_db = Server(couch_url, session=session)[db._dbname]
+    new_couch_db = Server(couch_url, session=session)[new_dbname]
+    for doc_id in old_couch_db:
+        doc = old_couch_db.get(doc_id)
+        # bypass u1db_config document
+        if doc_id == 'u1db_config':
+            pass
+        # copy u1db docs
+        elif 'u1db_rev' in doc:
+            new_doc = {
+                '_id': doc['_id'],
+                'u1db_rev': doc['u1db_rev']
+            }
+            attachments = []
+            if ('u1db_conflicts' in doc):
+                new_doc['u1db_conflicts'] = doc['u1db_conflicts']
+                for c_rev in doc['u1db_conflicts']:
+                    attachments.append('u1db_conflict_%s' % c_rev)
+            new_couch_db.save(new_doc)
+            # save conflict data
+            attachments.append('u1db_content')
+            for att_name in attachments:
+                att = old_couch_db.get_attachment(doc_id, att_name)
+                if (att is not None):
+                    new_couch_db.put_attachment(new_doc, att,
+                                                filename=att_name)
+        elif doc_id.startswith('gen-'):
+            new_couch_db.save(doc)
+    # cleanup connections to prevent file descriptor leaking
+    return new_db
+
+
+def make_document_for_test(test, doc_id, rev, content, has_conflicts=False):
+    return ServerDocument(
+        doc_id, rev, content, has_conflicts=has_conflicts)
+
+
+COUCH_SCENARIOS = [
+    ('couch', {'make_database_for_test': make_couch_database_for_test,
+               'copy_database_for_test': copy_couch_database_for_test,
+               'make_document_for_test': make_document_for_test, }),
+]
diff --git a/tests/couch/test_atomicity.py b/tests/couch/test_atomicity.py
new file mode 100644
index 00000000..48e1c01d
--- /dev/null
+++ b/tests/couch/test_atomicity.py
@@ -0,0 +1,370 @@
+# -*- coding: utf-8 -*-
+# test_couch_operations_atomicity.py
+# Copyright (C) 2013, 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Test atomicity of couch operations.
+"""
+import os
+import pytest
+import threading
+
+from six.moves.urllib.parse import urljoin
+from twisted.internet import defer
+from uuid import uuid4
+
+from leap.soledad.client import Soledad
+from leap.soledad.common.couch.state import CouchServerState
+from leap.soledad.common.couch import CouchDatabase
+
+from test_soledad.util import (
+    make_token_soledad_app,
+    make_soledad_document_for_test,
+    soledad_sync_target,
+)
+from test_soledad.util import CouchDBTestCase
+from test_soledad.u1db_tests import TestCaseWithServer
+
+
+REPEAT_TIMES = 20
+
+
+@pytest.mark.usefixtures('method_tmpdir')
+class CouchAtomicityTestCase(CouchDBTestCase, TestCaseWithServer):
+
+    @staticmethod
+    def make_app_after_state(state):
+        return make_token_soledad_app(state)
+
+    make_document_for_test = make_soledad_document_for_test
+
+    sync_target = soledad_sync_target
+
+    def _soledad_instance(self, user=None, passphrase=u'123',
+                          prefix='',
+                          secrets_path='secrets.json',
+                          local_db_path='soledad.u1db', server_url='',
+                          cert_file=None, auth_token=None):
+        """
+        Instantiate Soledad.
+        """
+        user = user or self.user
+
+        # this callback ensures we save a document which is sent to the shared
+        # db.
+        def _put_doc_side_effect(doc):
+            self._doc_put = doc
+
+        soledad = Soledad(
+            user,
+            passphrase,
+            secrets_path=os.path.join(self.tempdir, prefix, secrets_path),
+            local_db_path=os.path.join(
+                self.tempdir, prefix, local_db_path),
+            server_url=server_url,
+            cert_file=cert_file,
+            auth_token=auth_token,
+            shared_db=self.get_default_shared_mock(_put_doc_side_effect))
+        self.addCleanup(soledad.close)
+        return soledad
+
+    def make_app(self):
+        self.request_state = CouchServerState(self.couch_url)
+        return self.make_app_after_state(self.request_state)
+
+    def setUp(self):
+        TestCaseWithServer.setUp(self)
+        CouchDBTestCase.setUp(self)
+        self.user = ('user-%s' % uuid4().hex)
+        self.db = CouchDatabase.open_database(
+            urljoin(self.couch_url, 'user-' + self.user),
+            create=True,
+            replica_uid='replica')
+        self.startTwistedServer()
+
+    def tearDown(self):
+        self.db.delete_database()
+        self.db.close()
+        CouchDBTestCase.tearDown(self)
+        TestCaseWithServer.tearDown(self)
+
+    #
+    # Sequential tests
+    #
+
+    def test_correct_transaction_log_after_sequential_puts(self):
+        """
+        Assert that the transaction_log increases accordingly with sequential
+        puts.
+        """
+        doc = self.db.create_doc({'ops': 0})
+        docs = [doc.doc_id]
+        for i in range(0, REPEAT_TIMES):
+            self.assertEqual(
+                i + 1, len(self.db._get_transaction_log()))
+            doc.content['ops'] += 1
+            self.db.put_doc(doc)
+            docs.append(doc.doc_id)
+
+        # assert length of transaction_log
+        transaction_log = self.db._get_transaction_log()
+        self.assertEqual(
+            REPEAT_TIMES + 1, len(transaction_log))
+
+        # assert that all entries in the log belong to the same doc
+        self.assertEqual(REPEAT_TIMES + 1, len(docs))
+        for doc_id in docs:
+            self.assertEqual(
+                REPEAT_TIMES + 1,
+                len(filter(lambda t: t[0] == doc_id, transaction_log)))
+
+    def test_correct_transaction_log_after_sequential_deletes(self):
+        """
+        Assert that the transaction_log increases accordingly with sequential
+        puts and deletes.
+        """
+        docs = []
+        for i in range(0, REPEAT_TIMES):
+            doc = self.db.create_doc({'ops': 0})
+            self.assertEqual(
+                2 * i + 1, len(self.db._get_transaction_log()))
+            docs.append(doc.doc_id)
+            self.db.delete_doc(doc)
+            self.assertEqual(
+                2 * i + 2, len(self.db._get_transaction_log()))
+
+        # assert length of transaction_log
+        transaction_log = self.db._get_transaction_log()
+        self.assertEqual(
+            2 * REPEAT_TIMES, len(transaction_log))
+
+        # assert that each doc appears twice in the transaction_log
+        self.assertEqual(REPEAT_TIMES, len(docs))
+        for doc_id in docs:
+            self.assertEqual(
+                2,
+                len(filter(lambda t: t[0] == doc_id, transaction_log)))
+
+    @defer.inlineCallbacks
+    def test_correct_sync_log_after_sequential_syncs(self):
+        """
+        Assert that the sync_log increases accordingly with sequential syncs.
+        """
+        sol = self._soledad_instance(
+            auth_token='auth-token',
+            server_url=self.getURL())
+        source_replica_uid = sol._dbpool.replica_uid
+
+        def _create_docs():
+            deferreds = []
+            for i in xrange(0, REPEAT_TIMES):
+                deferreds.append(sol.create_doc({}))
+            return defer.gatherResults(deferreds)
+
+        def _assert_transaction_and_sync_logs(results, sync_idx):
+            # assert sizes of transaction and sync logs
+            self.assertEqual(
+                sync_idx * REPEAT_TIMES,
+                len(self.db._get_transaction_log()))
+            gen, _ = self.db._get_replica_gen_and_trans_id(source_replica_uid)
+            self.assertEqual(sync_idx * REPEAT_TIMES, gen)
+
+        def _assert_sync(results, sync_idx):
+            gen, docs = results
+            self.assertEqual((sync_idx + 1) * REPEAT_TIMES, gen)
+            self.assertEqual((sync_idx + 1) * REPEAT_TIMES, len(docs))
+            # assert sizes of transaction and sync logs
+            self.assertEqual((sync_idx + 1) * REPEAT_TIMES,
+                             len(self.db._get_transaction_log()))
+            target_known_gen, target_known_trans_id = \
+                self.db._get_replica_gen_and_trans_id(source_replica_uid)
+            # assert it has the correct gen and trans_id
+            conn_key = sol._dbpool._u1dbconnections.keys().pop()
+            conn = sol._dbpool._u1dbconnections[conn_key]
+            sol_gen, sol_trans_id = conn._get_generation_info()
+            self.assertEqual(sol_gen, target_known_gen)
+            self.assertEqual(sol_trans_id, target_known_trans_id)
+
+        # sync first time and assert success
+        results = yield _create_docs()
+        _assert_transaction_and_sync_logs(results, 0)
+        yield sol.sync()
+        results = yield sol.get_all_docs()
+        _assert_sync(results, 0)
+
+        # create more docs, sync second time and assert success
+        results = yield _create_docs()
+        _assert_transaction_and_sync_logs(results, 1)
+        yield sol.sync()
+        results = yield sol.get_all_docs()
+        _assert_sync(results, 1)
+
+    #
+    # Concurrency tests
+    #
+
+    class _WorkerThread(threading.Thread):
+
+        def __init__(self, params, run_method):
+            threading.Thread.__init__(self)
+            self._params = params
+            self._run_method = run_method
+
+        def run(self):
+            self._run_method(self)
+
+    def test_correct_transaction_log_after_concurrent_puts(self):
+        """
+        Assert that the transaction_log increases accordingly with concurrent
+        puts.
+        """
+        pool = threading.BoundedSemaphore(value=1)
+        threads = []
+        docs = []
+
+        def _run_method(self):
+            doc = self._params['db'].create_doc({})
+            pool.acquire()
+            self._params['docs'].append(doc.doc_id)
+            pool.release()
+
+        for i in range(0, REPEAT_TIMES):
+            thread = self._WorkerThread(
+                {'docs': docs, 'db': self.db},
+                _run_method)
+            thread.start()
+            threads.append(thread)
+
+        for thread in threads:
+            thread.join()
+
+        # assert length of transaction_log
+        transaction_log = self.db._get_transaction_log()
+        self.assertEqual(
+            REPEAT_TIMES, len(transaction_log))
+
+        # assert all documents are in the log
+        self.assertEqual(REPEAT_TIMES, len(docs))
+        for doc_id in docs:
+            self.assertEqual(
+                1,
+                len(filter(lambda t: t[0] == doc_id, transaction_log)))
+
+    def test_correct_transaction_log_after_concurrent_deletes(self):
+        """
+        Assert that the transaction_log increases accordingly with concurrent
+        puts and deletes.
+        """
+        threads = []
+        docs = []
+        pool = threading.BoundedSemaphore(value=1)
+
+        # create/delete method that will be run concurrently
+        def _run_method(self):
+            doc = self._params['db'].create_doc({})
+            pool.acquire()
+            docs.append(doc.doc_id)
+            pool.release()
+            self._params['db'].delete_doc(doc)
+
+        # launch concurrent threads
+        for i in range(0, REPEAT_TIMES):
+            thread = self._WorkerThread({'db': self.db}, _run_method)
+            thread.start()
+            threads.append(thread)
+
+        # wait for threads to finish
+        for thread in threads:
+            thread.join()
+
+        # assert transaction log
+        transaction_log = self.db._get_transaction_log()
+        self.assertEqual(
+            2 * REPEAT_TIMES, len(transaction_log))
+        # assert that each doc appears twice in the transaction_log
+        self.assertEqual(REPEAT_TIMES, len(docs))
+        for doc_id in docs:
+            self.assertEqual(
+                2,
+                len(filter(lambda t: t[0] == doc_id, transaction_log)))
+
+    def test_correct_sync_log_after_concurrent_puts_and_sync(self):
+        """
+        Assert that the sync_log is correct after concurrent syncs.
+        """
+        docs = []
+
+        sol = self._soledad_instance(
+            auth_token='auth-token',
+            server_url=self.getURL())
+
+        def _save_doc_ids(results):
+            for doc in results:
+                docs.append(doc.doc_id)
+
+        # create documents in parallel
+        deferreds = []
+        for i in range(0, REPEAT_TIMES):
+            d = sol.create_doc({})
+            deferreds.append(d)
+
+        # wait for documents creation and sync
+        d = defer.gatherResults(deferreds)
+        d.addCallback(_save_doc_ids)
+        d.addCallback(lambda _: sol.sync())
+
+        def _assert_logs(results):
+            transaction_log = self.db._get_transaction_log()
+            self.assertEqual(REPEAT_TIMES, len(transaction_log))
+            # assert all documents are in the remote log
+            self.assertEqual(REPEAT_TIMES, len(docs))
+            for doc_id in docs:
+                self.assertEqual(
+                    1,
+                    len(filter(lambda t: t[0] == doc_id, transaction_log)))
+
+        d.addCallback(_assert_logs)
+        d.addCallback(lambda _: sol.close())
+
+        return d
+
+    @defer.inlineCallbacks
+    def test_concurrent_syncs_do_not_fail(self):
+        """
+        Assert that concurrent attempts to sync end up being executed
+        sequentially and do not fail.
+        """
+        docs = []
+
+        sol = self._soledad_instance(
+            auth_token='auth-token',
+            server_url=self.getURL())
+
+        deferreds = []
+        for i in xrange(0, REPEAT_TIMES):
+            d = sol.create_doc({})
+            d.addCallback(lambda doc: docs.append(doc.doc_id))
+            d.addCallback(lambda _: sol.sync())
+            deferreds.append(d)
+        yield defer.gatherResults(deferreds, consumeErrors=True)
+
+        transaction_log = self.db._get_transaction_log()
+        self.assertEqual(REPEAT_TIMES, len(transaction_log))
+        # assert all documents are in the remote log
+        self.assertEqual(REPEAT_TIMES, len(docs))
+        for doc_id in docs:
+            self.assertEqual(
+                1,
+                len(filter(lambda t: t[0] == doc_id, transaction_log)))
diff --git a/tests/couch/test_backend.py b/tests/couch/test_backend.py
new file mode 100644
index 00000000..9dfa22ac
--- /dev/null
+++ b/tests/couch/test_backend.py
@@ -0,0 +1,111 @@
+# -*- coding: utf-8 -*-
+# test_couch.py
+# Copyright (C) 2013-2016 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Test ObjectStore and Couch backend bits.
+"""
+
+from uuid import uuid4
+from six.moves.urllib.parse import urljoin
+from testscenarios import TestWithScenarios
+from twisted.trial import unittest
+
+from leap.soledad.common import couch
+
+from test_soledad.util import CouchDBTestCase
+from test_soledad.u1db_tests import test_backends
+
+from .common import COUCH_SCENARIOS
+
+
+# -----------------------------------------------------------------------------
+# The following tests come from `u1db.tests.test_common_backend`.
+# -----------------------------------------------------------------------------
+
+class TestCouchBackendImpl(CouchDBTestCase):
+
+    def test__allocate_doc_id(self):
+        db = couch.CouchDatabase.open_database(
+            urljoin(self.couch_url, 'test-%s' % uuid4().hex),
+            create=True)
+        doc_id1 = db._allocate_doc_id()
+        self.assertTrue(doc_id1.startswith('D-'))
+        self.assertEqual(34, len(doc_id1))
+        int(doc_id1[len('D-'):], 16)
+        self.assertNotEqual(doc_id1, db._allocate_doc_id())
+        self.delete_db(db._dbname)
+
+
+# -----------------------------------------------------------------------------
+# The following tests come from `u1db.tests.test_backends`.
+# -----------------------------------------------------------------------------
+
+class CouchTests(
+        TestWithScenarios, test_backends.AllDatabaseTests, CouchDBTestCase):
+
+    scenarios = COUCH_SCENARIOS
+
+
+class CouchBackendTests(
+        TestWithScenarios,
+        test_backends.LocalDatabaseTests,
+        CouchDBTestCase):
+
+    scenarios = COUCH_SCENARIOS
+
+
+class CouchValidateGenNTransIdTests(
+        TestWithScenarios,
+        test_backends.LocalDatabaseValidateGenNTransIdTests,
+        CouchDBTestCase):
+
+    scenarios = COUCH_SCENARIOS
+
+
+class CouchValidateSourceGenTests(
+        TestWithScenarios,
+        test_backends.LocalDatabaseValidateSourceGenTests,
+        CouchDBTestCase):
+
+    scenarios = COUCH_SCENARIOS
+
+
+class CouchWithConflictsTests(
+        TestWithScenarios,
+        test_backends.LocalDatabaseWithConflictsTests,
+        CouchDBTestCase):
+
+        scenarios = COUCH_SCENARIOS
+
+
+# Notice: the CouchDB backend does not have indexing capabilities, so we do
+# not test indexing now.
+
+# class CouchIndexTests(test_backends.DatabaseIndexTests, CouchDBTestCase):
+#
+#     scenarios = COUCH_SCENARIOS
+#
+#     def tearDown(self):
+#         self.db.delete_database()
+#         test_backends.DatabaseIndexTests.tearDown(self)
+
+
+class DatabaseNameValidationTest(unittest.TestCase):
+
+    def test_database_name_validation(self):
+        inject = couch.state.is_db_name_valid("user-deadbeef | cat /secret")
+        self.assertFalse(inject)
+        self.assertTrue(couch.state.is_db_name_valid("user-cafe1337"))
diff --git a/tests/couch/test_command.py b/tests/couch/test_command.py
new file mode 100644
index 00000000..9fb2c153
--- /dev/null
+++ b/tests/couch/test_command.py
@@ -0,0 +1,31 @@
+from twisted.trial import unittest
+
+from leap.soledad.common.couch import state as couch_state
+from leap.soledad.common.l2db import errors as u1db_errors
+
+from mock import Mock
+
+
+class CommandBasedDBCreationTest(unittest.TestCase):
+
+    def test_ensure_db_using_custom_command(self):
+        state = couch_state.CouchServerState(
+            "url", create_cmd="/bin/echo", check_schema_versions=False)
+        mock_db = Mock()
+        mock_db.replica_uid = 'replica_uid'
+        state.open_database = Mock(return_value=mock_db)
+        db, replica_uid = state.ensure_database("user-1337")  # works
+        self.assertEquals(mock_db, db)
+        self.assertEquals(mock_db.replica_uid, replica_uid)
+
+    def test_raises_unauthorized_on_failure(self):
+        state = couch_state.CouchServerState(
+            "url", create_cmd="inexistent", check_schema_versions=False)
+        self.assertRaises(u1db_errors.Unauthorized,
+                          state.ensure_database, "user-1337")
+
+    def test_raises_unauthorized_by_default(self):
+        state = couch_state.CouchServerState("url",
+                                             check_schema_versions=False)
+        self.assertRaises(u1db_errors.Unauthorized,
+                          state.ensure_database, "user-1337")
diff --git a/tests/couch/test_ddocs.py b/tests/couch/test_ddocs.py
new file mode 100644
index 00000000..3937f2de
--- /dev/null
+++ b/tests/couch/test_ddocs.py
@@ -0,0 +1,60 @@
+from uuid import uuid4
+
+from leap.soledad.common import couch
+
+from test_soledad.util import CouchDBTestCase
+
+
+class CouchDesignDocsTests(CouchDBTestCase):
+
+    def setUp(self):
+        CouchDBTestCase.setUp(self)
+        self.create_db()
+
+    def create_db(self, dbname=None):
+        if not dbname:
+            dbname = ('test-%s' % uuid4().hex)
+        if dbname not in self.couch_server:
+            self.couch_server.create(dbname)
+        self.db = couch.CouchDatabase(
+            (self.couch_url),
+            dbname)
+
+    def tearDown(self):
+        self.db.delete_database()
+        self.db.close()
+        CouchDBTestCase.tearDown(self)
+
+    def test_ensure_security_doc(self):
+        """
+        Ensure_security creates a _security ddoc to ensure that only soledad
+        will have the lowest privileged access to an user db.
+        """
+        self.assertFalse(self.db._database.resource.get_json('_security')[2])
+        self.db.ensure_security_ddoc()
+        security_ddoc = self.db._database.resource.get_json('_security')[2]
+        self.assertIn('admins', security_ddoc)
+        self.assertFalse(security_ddoc['admins']['names'])
+        self.assertIn('members', security_ddoc)
+        self.assertIn('soledad', security_ddoc['members']['names'])
+
+    def test_ensure_security_from_configuration(self):
+        """
+        Given a configuration, follow it to create the security document
+        """
+        configuration = {'members': ['user1', 'user2'],
+                         'members_roles': ['role1', 'role2'],
+                         'admins': ['admin'],
+                         'admins_roles': ['administrators']
+                         }
+        self.db.ensure_security_ddoc(configuration)
+
+        security_ddoc = self.db._database.resource.get_json('_security')[2]
+        self.assertEquals(configuration['admins'],
+                          security_ddoc['admins']['names'])
+        self.assertEquals(configuration['admins_roles'],
+                          security_ddoc['admins']['roles'])
+        self.assertEquals(configuration['members'],
+                          security_ddoc['members']['names'])
+        self.assertEquals(configuration['members_roles'],
+                          security_ddoc['members']['roles'])
diff --git a/tests/couch/test_soledad b/tests/couch/test_soledad
new file mode 120000
index 00000000..c1a35d32
--- /dev/null
+++ b/tests/couch/test_soledad
@@ -0,0 +1 @@
+../test_soledad
\ No newline at end of file
diff --git a/tests/couch/test_state.py b/tests/couch/test_state.py
new file mode 100644
index 00000000..e5ac3704
--- /dev/null
+++ b/tests/couch/test_state.py
@@ -0,0 +1,32 @@
+import pytest
+from leap.soledad.common.couch import CONFIG_DOC_ID
+from leap.soledad.common.couch import SCHEMA_VERSION
+from leap.soledad.common.couch import SCHEMA_VERSION_KEY
+from leap.soledad.common.couch.state import CouchServerState
+from uuid import uuid4
+
+from leap.soledad.common.errors import WrongCouchSchemaVersionError
+from leap.soledad.common.errors import MissingCouchConfigDocumentError
+from test_soledad.util import CouchDBTestCase
+
+
+class CouchDesignDocsTests(CouchDBTestCase):
+
+    def setUp(self):
+        CouchDBTestCase.setUp(self)
+        self.db = self.couch_server.create('user-' + uuid4().hex)
+        self.addCleanup(self.delete_db, self.db.name)
+
+    def test_wrong_couch_version_raises(self):
+        wrong_schema_version = SCHEMA_VERSION + 1
+        self.db.create(
+            {'_id': CONFIG_DOC_ID, SCHEMA_VERSION_KEY: wrong_schema_version})
+        with pytest.raises(WrongCouchSchemaVersionError):
+            CouchServerState(self.couch_url, create_cmd='/bin/echo',
+                             check_schema_versions=True)
+
+    def test_missing_config_doc_raises(self):
+        self.db.create({})
+        with pytest.raises(MissingCouchConfigDocumentError):
+            CouchServerState(self.couch_url, create_cmd='/bin/echo',
+                             check_schema_versions=True)
diff --git a/tests/couch/test_sync.py b/tests/couch/test_sync.py
new file mode 100644
index 00000000..c353518e
--- /dev/null
+++ b/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())
diff --git a/tests/couch/test_sync_target.py b/tests/couch/test_sync_target.py
new file mode 100644
index 00000000..0370a6d1
--- /dev/null
+++ b/tests/couch/test_sync_target.py
@@ -0,0 +1,343 @@
+import json
+
+from leap.soledad.common.l2db import SyncTarget
+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 make_local_db_and_target
+from test_soledad.u1db_tests import DatabaseBaseTests
+
+from .common import simple_doc
+from .common import nested_doc
+from .common import COUCH_SCENARIOS
+
+
+target_scenarios = [
+    ('local', {'create_db_and_target': make_local_db_and_target}), ]
+
+
+class CouchBackendSyncTargetTests(
+        TestWithScenarios,
+        DatabaseBaseTests,
+        CouchDBTestCase):
+
+    # TODO: implement _set_trace_hook(_shallow) in CouchSyncTarget so
+    #       skipped tests can be succesfully executed.
+
+    # whitebox true means self.db is the actual local db object
+    # against which the sync is performed
+    whitebox = True
+
+    scenarios = (tests.multiply_scenarios(COUCH_SCENARIOS, target_scenarios))
+
+    def set_trace_hook(self, callback, shallow=False):
+        setter = (self.st._set_trace_hook if not shallow else
+                  self.st._set_trace_hook_shallow)
+        try:
+            setter(callback)
+        except NotImplementedError:
+            self.skipTest("%s does not implement _set_trace_hook"
+                          % (self.st.__class__.__name__,))
+
+    def setUp(self):
+        CouchDBTestCase.setUp(self)
+        # other stuff
+        self.db, self.st = self.create_db_and_target(self)
+        self.other_changes = []
+
+    def tearDown(self):
+        self.db.close()
+        CouchDBTestCase.tearDown(self)
+
+    def receive_doc(self, doc, gen, trans_id):
+        self.other_changes.append(
+            (doc.doc_id, doc.rev, doc.get_json(), gen, trans_id))
+
+    def test_sync_exchange_returns_many_new_docs(self):
+        # This test was replicated to allow dictionaries to be compared after
+        # JSON expansion (because one dictionary may have many different
+        # serialized representations).
+        doc = self.db.create_doc_from_json(simple_doc)
+        doc2 = self.db.create_doc_from_json(nested_doc)
+        self.assertTransactionLog([doc.doc_id, doc2.doc_id], self.db)
+        new_gen, _ = self.st.sync_exchange(
+            [], 'other-replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertTransactionLog([doc.doc_id, doc2.doc_id], self.db)
+        self.assertEqual(2, new_gen)
+        self.assertEqual(
+            [(doc.doc_id, doc.rev, json.loads(simple_doc), 1),
+             (doc2.doc_id, doc2.rev, json.loads(nested_doc), 2)],
+            [c[:-3] + (json.loads(c[-3]), c[-2]) for c in self.other_changes])
+        if self.whitebox:
+            self.assertEqual(
+                self.db._last_exchange_log['return'],
+                {'last_gen': 2, 'docs':
+                 [(doc.doc_id, doc.rev), (doc2.doc_id, doc2.rev)]})
+
+    def test_get_sync_target(self):
+        self.assertIsNot(None, self.st)
+
+    def test_get_sync_info(self):
+        self.assertEqual(
+            ('test', 0, '', 0, ''), self.st.get_sync_info('other'))
+
+    def test_create_doc_updates_sync_info(self):
+        self.assertEqual(
+            ('test', 0, '', 0, ''), self.st.get_sync_info('other'))
+        self.db.create_doc_from_json(simple_doc)
+        self.assertEqual(1, self.st.get_sync_info('other')[1])
+
+    def test_record_sync_info(self):
+        self.st.record_sync_info('replica', 10, 'T-transid')
+        self.assertEqual(
+            ('test', 0, '', 10, 'T-transid'), self.st.get_sync_info('replica'))
+
+    def test_sync_exchange(self):
+        docs_by_gen = [
+            (self.make_document('doc-id', 'replica:1', simple_doc), 10,
+             'T-sid')]
+        new_gen, trans_id = self.st.sync_exchange(
+            docs_by_gen, 'replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertGetDoc(self.db, 'doc-id', 'replica:1', simple_doc, False)
+        self.assertTransactionLog(['doc-id'], self.db)
+        last_trans_id = self.getLastTransId(self.db)
+        self.assertEqual(([], 1, last_trans_id),
+                         (self.other_changes, new_gen, last_trans_id))
+        self.assertEqual(10, self.st.get_sync_info('replica')[3])
+
+    def test_sync_exchange_deleted(self):
+        doc = self.db.create_doc_from_json('{}')
+        edit_rev = 'replica:1|' + doc.rev
+        docs_by_gen = [
+            (self.make_document(doc.doc_id, edit_rev, None), 10, 'T-sid')]
+        new_gen, trans_id = self.st.sync_exchange(
+            docs_by_gen, 'replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertGetDocIncludeDeleted(
+            self.db, doc.doc_id, edit_rev, None, False)
+        self.assertTransactionLog([doc.doc_id, doc.doc_id], self.db)
+        last_trans_id = self.getLastTransId(self.db)
+        self.assertEqual(([], 2, last_trans_id),
+                         (self.other_changes, new_gen, trans_id))
+        self.assertEqual(10, self.st.get_sync_info('replica')[3])
+
+    def test_sync_exchange_push_many(self):
+        docs_by_gen = [
+            (self.make_document('doc-id', 'replica:1', simple_doc), 10, 'T-1'),
+            (self.make_document('doc-id2', 'replica:1', nested_doc), 11,
+             'T-2')]
+        new_gen, trans_id = self.st.sync_exchange(
+            docs_by_gen, 'replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertGetDoc(self.db, 'doc-id', 'replica:1', simple_doc, False)
+        self.assertGetDoc(self.db, 'doc-id2', 'replica:1', nested_doc, False)
+        self.assertTransactionLog(['doc-id', 'doc-id2'], self.db)
+        last_trans_id = self.getLastTransId(self.db)
+        self.assertEqual(([], 2, last_trans_id),
+                         (self.other_changes, new_gen, trans_id))
+        self.assertEqual(11, self.st.get_sync_info('replica')[3])
+
+    def test_sync_exchange_refuses_conflicts(self):
+        doc = self.db.create_doc_from_json(simple_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        new_doc = '{"key": "altval"}'
+        docs_by_gen = [
+            (self.make_document(doc.doc_id, 'replica:1', new_doc), 10,
+             'T-sid')]
+        new_gen, _ = self.st.sync_exchange(
+            docs_by_gen, 'replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        self.assertEqual(
+            (doc.doc_id, doc.rev, simple_doc, 1), self.other_changes[0][:-1])
+        self.assertEqual(1, new_gen)
+        if self.whitebox:
+            self.assertEqual(self.db._last_exchange_log['return'],
+                             {'last_gen': 1, 'docs': [(doc.doc_id, doc.rev)]})
+
+    def test_sync_exchange_ignores_convergence(self):
+        doc = self.db.create_doc_from_json(simple_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        gen, txid = self.db._get_generation_info()
+        docs_by_gen = [
+            (self.make_document(doc.doc_id, doc.rev, simple_doc), 10, 'T-sid')]
+        new_gen, _ = self.st.sync_exchange(
+            docs_by_gen, 'replica', last_known_generation=gen,
+            last_known_trans_id=txid, return_doc_cb=self.receive_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        self.assertEqual(([], 1), (self.other_changes, new_gen))
+
+    def test_sync_exchange_returns_new_docs(self):
+        doc = self.db.create_doc_from_json(simple_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        new_gen, _ = self.st.sync_exchange(
+            [], 'other-replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        self.assertEqual(
+            (doc.doc_id, doc.rev, simple_doc, 1), self.other_changes[0][:-1])
+        self.assertEqual(1, new_gen)
+        if self.whitebox:
+            self.assertEqual(self.db._last_exchange_log['return'],
+                             {'last_gen': 1, 'docs': [(doc.doc_id, doc.rev)]})
+
+    def test_sync_exchange_returns_deleted_docs(self):
+        doc = self.db.create_doc_from_json(simple_doc)
+        self.db.delete_doc(doc)
+        self.assertTransactionLog([doc.doc_id, doc.doc_id], self.db)
+        new_gen, _ = self.st.sync_exchange(
+            [], 'other-replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertTransactionLog([doc.doc_id, doc.doc_id], self.db)
+        self.assertEqual(
+            (doc.doc_id, doc.rev, None, 2), self.other_changes[0][:-1])
+        self.assertEqual(2, new_gen)
+        if self.whitebox:
+            self.assertEqual(self.db._last_exchange_log['return'],
+                             {'last_gen': 2, 'docs': [(doc.doc_id, doc.rev)]})
+
+    def test_sync_exchange_getting_newer_docs(self):
+        doc = self.db.create_doc_from_json(simple_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        new_doc = '{"key": "altval"}'
+        docs_by_gen = [
+            (self.make_document(doc.doc_id, 'test:1|z:2', new_doc), 10,
+             'T-sid')]
+        new_gen, _ = self.st.sync_exchange(
+            docs_by_gen, 'other-replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertTransactionLog([doc.doc_id, doc.doc_id], self.db)
+        self.assertEqual(([], 2), (self.other_changes, new_gen))
+
+    def test_sync_exchange_with_concurrent_updates_of_synced_doc(self):
+        expected = []
+
+        def before_whatschanged_cb(state):
+            if state != 'before whats_changed':
+                return
+            cont = '{"key": "cuncurrent"}'
+            conc_rev = self.db.put_doc(
+                self.make_document(doc.doc_id, 'test:1|z:2', cont))
+            expected.append((doc.doc_id, conc_rev, cont, 3))
+
+        self.set_trace_hook(before_whatschanged_cb)
+        doc = self.db.create_doc_from_json(simple_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        new_doc = '{"key": "altval"}'
+        docs_by_gen = [
+            (self.make_document(doc.doc_id, 'test:1|z:2', new_doc), 10,
+             'T-sid')]
+        new_gen, _ = self.st.sync_exchange(
+            docs_by_gen, 'other-replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertEqual(expected, [c[:-1] for c in self.other_changes])
+        self.assertEqual(3, new_gen)
+
+    def test_sync_exchange_with_concurrent_updates(self):
+
+        def after_whatschanged_cb(state):
+            if state != 'after whats_changed':
+                return
+            self.db.create_doc_from_json('{"new": "doc"}')
+
+        self.set_trace_hook(after_whatschanged_cb)
+        doc = self.db.create_doc_from_json(simple_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        new_doc = '{"key": "altval"}'
+        docs_by_gen = [
+            (self.make_document(doc.doc_id, 'test:1|z:2', new_doc), 10,
+             'T-sid')]
+        new_gen, _ = self.st.sync_exchange(
+            docs_by_gen, 'other-replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertEqual(([], 2), (self.other_changes, new_gen))
+
+    def test_sync_exchange_converged_handling(self):
+        doc = self.db.create_doc_from_json(simple_doc)
+        docs_by_gen = [
+            (self.make_document('new', 'other:1', '{}'), 4, 'T-foo'),
+            (self.make_document(doc.doc_id, doc.rev, doc.get_json()), 5,
+             'T-bar')]
+        new_gen, _ = self.st.sync_exchange(
+            docs_by_gen, 'other-replica', last_known_generation=0,
+            last_known_trans_id=None, return_doc_cb=self.receive_doc)
+        self.assertEqual(([], 2), (self.other_changes, new_gen))
+
+    def test_sync_exchange_detect_incomplete_exchange(self):
+        def before_get_docs_explode(state):
+            if state != 'before get_docs':
+                return
+            raise u1db_errors.U1DBError("fail")
+        self.set_trace_hook(before_get_docs_explode)
+        # suppress traceback printing in the wsgiref server
+        # self.patch(simple_server.ServerHandler,
+        #           'log_exception', lambda h, exc_info: None)
+        doc = self.db.create_doc_from_json(simple_doc)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        self.assertRaises(
+            (u1db_errors.U1DBError, u1db_errors.BrokenSyncStream),
+            self.st.sync_exchange, [], 'other-replica',
+            last_known_generation=0, last_known_trans_id=None,
+            return_doc_cb=self.receive_doc)
+
+    def test_sync_exchange_doc_ids(self):
+        sync_exchange_doc_ids = getattr(self.st, 'sync_exchange_doc_ids', None)
+        if sync_exchange_doc_ids is None:
+            self.skipTest("sync_exchange_doc_ids not implemented")
+        db2 = self.create_database('test2')
+        doc = db2.create_doc_from_json(simple_doc)
+        new_gen, trans_id = sync_exchange_doc_ids(
+            db2, [(doc.doc_id, 10, 'T-sid')], 0, None,
+            return_doc_cb=self.receive_doc)
+        self.assertGetDoc(self.db, doc.doc_id, doc.rev, simple_doc, False)
+        self.assertTransactionLog([doc.doc_id], self.db)
+        last_trans_id = self.getLastTransId(self.db)
+        self.assertEqual(([], 1, last_trans_id),
+                         (self.other_changes, new_gen, trans_id))
+        self.assertEqual(10, self.st.get_sync_info(db2._replica_uid)[3])
+
+    def test__set_trace_hook(self):
+        called = []
+
+        def cb(state):
+            called.append(state)
+
+        self.set_trace_hook(cb)
+        self.st.sync_exchange([], 'replica', 0, None, self.receive_doc)
+        self.st.record_sync_info('replica', 0, 'T-sid')
+        self.assertEqual(['before whats_changed',
+                          'after whats_changed',
+                          'before get_docs',
+                          'record_sync_info',
+                          ],
+                         called)
+
+    def test__set_trace_hook_shallow(self):
+        st_trace_shallow = self.st._set_trace_hook_shallow
+        target_st_trace_shallow = SyncTarget._set_trace_hook_shallow
+        same_meth = st_trace_shallow == self.st._set_trace_hook
+        same_fun = st_trace_shallow.im_func == target_st_trace_shallow.im_func
+        if (same_meth or same_fun):
+            # shallow same as full
+            expected = ['before whats_changed',
+                        'after whats_changed',
+                        'before get_docs',
+                        'record_sync_info',
+                        ]
+        else:
+            expected = ['sync_exchange', 'record_sync_info']
+
+        called = []
+
+        def cb(state):
+            called.append(state)
+
+        self.set_trace_hook(cb, shallow=True)
+        self.st.sync_exchange([], 'replica', 0, None, self.receive_doc)
+        self.st.record_sync_info('replica', 0, 'T-sid')
+        self.assertEqual(expected, called)