diff --git a/tests/unit/test_gerrit_crd.py b/tests/unit/test_gerrit_crd.py
new file mode 100644
index 0000000..7a61eec
--- /dev/null
+++ b/tests/unit/test_gerrit_crd.py
@@ -0,0 +1,633 @@
+#!/usr/bin/env python
+
+# Copyright 2012 Hewlett-Packard Development Company, L.P.
+# Copyright 2018 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from tests.base import (
+    ZuulTestCase,
+    simple_layout,
+)
+
+
+class TestGerritCRD(ZuulTestCase):
+    tenant_config_file = 'config/single-tenant/main.yaml'
+
+    def setUp(self):
+        raise self.skipTest("Feature not yet implemented")
+
+    def test_crd_gate(self):
+        "Test cross-repo dependencies"
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+        A.addApproval('Code-Review', 2)
+        B.addApproval('Code-Review', 2)
+
+        AM2 = self.fake_gerrit.addFakeChange('org/project1', 'master', 'AM2')
+        AM1 = self.fake_gerrit.addFakeChange('org/project1', 'master', 'AM1')
+        AM2.setMerged()
+        AM1.setMerged()
+
+        BM2 = self.fake_gerrit.addFakeChange('org/project2', 'master', 'BM2')
+        BM1 = self.fake_gerrit.addFakeChange('org/project2', 'master', 'BM1')
+        BM2.setMerged()
+        BM1.setMerged()
+
+        # A -> AM1 -> AM2
+        # B -> BM1 -> BM2
+        # A Depends-On: B
+        # M2 is here to make sure it is never queried.  If it is, it
+        # means zuul is walking down the entire history of merged
+        # changes.
+
+        B.setDependsOn(BM1, 1)
+        BM1.setDependsOn(BM2, 1)
+
+        A.setDependsOn(AM1, 1)
+        AM1.setDependsOn(AM2, 1)
+
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+
+        for connection in self.connections.connections.values():
+            connection.maintainCache([])
+
+        self.executor_server.hold_jobs_in_build = True
+        B.addApproval('Approved', 1)
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.hold_jobs_in_build = False
+        self.executor_server.release()
+        self.waitUntilSettled()
+
+        self.assertEqual(AM2.queried, 0)
+        self.assertEqual(BM2.queried, 0)
+        self.assertEqual(A.data['status'], 'MERGED')
+        self.assertEqual(B.data['status'], 'MERGED')
+        self.assertEqual(A.reported, 2)
+        self.assertEqual(B.reported, 2)
+
+        changes = self.getJobFromHistory(
+            'project-merge', 'org/project1').changes
+        self.assertEqual(changes, '2,1 1,1')
+
+    def test_crd_branch(self):
+        "Test cross-repo dependencies in multiple branches"
+
+        self.create_branch('org/project2', 'mp')
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+        C1 = self.fake_gerrit.addFakeChange('org/project2', 'mp', 'C1')
+        C2 = self.fake_gerrit.addFakeChange('org/project2', 'mp', 'C2',
+                                            status='ABANDONED')
+        C1.data['id'] = B.data['id']
+        C2.data['id'] = B.data['id']
+
+        A.addApproval('Code-Review', 2)
+        B.addApproval('Code-Review', 2)
+        C1.addApproval('Code-Review', 2)
+
+        # A Depends-On: B+C1
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+
+        self.executor_server.hold_jobs_in_build = True
+        B.addApproval('Approved', 1)
+        C1.addApproval('Approved', 1)
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.hold_jobs_in_build = False
+        self.executor_server.release()
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'MERGED')
+        self.assertEqual(B.data['status'], 'MERGED')
+        self.assertEqual(C1.data['status'], 'MERGED')
+        self.assertEqual(A.reported, 2)
+        self.assertEqual(B.reported, 2)
+        self.assertEqual(C1.reported, 2)
+
+        changes = self.getJobFromHistory(
+            'project-merge', 'org/project1').changes
+        self.assertEqual(changes, '2,1 3,1 1,1')
+
+    def test_crd_multiline(self):
+        "Test multiple depends-on lines in commit"
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+        C = self.fake_gerrit.addFakeChange('org/project2', 'master', 'C')
+        A.addApproval('Code-Review', 2)
+        B.addApproval('Code-Review', 2)
+        C.addApproval('Code-Review', 2)
+
+        # A Depends-On: B+C
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\nDepends-On: %s\n' % (
+            A.subject, B.data['url'], C.data['url'])
+
+        self.executor_server.hold_jobs_in_build = True
+        B.addApproval('Approved', 1)
+        C.addApproval('Approved', 1)
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.hold_jobs_in_build = False
+        self.executor_server.release()
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'MERGED')
+        self.assertEqual(B.data['status'], 'MERGED')
+        self.assertEqual(C.data['status'], 'MERGED')
+        self.assertEqual(A.reported, 2)
+        self.assertEqual(B.reported, 2)
+        self.assertEqual(C.reported, 2)
+
+        changes = self.getJobFromHistory(
+            'project-merge', 'org/project1').changes
+        self.assertEqual(changes, '2,1 3,1 1,1')
+
+    def test_crd_unshared_gate(self):
+        "Test cross-repo dependencies in unshared gate queues"
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project', 'master', 'B')
+        A.addApproval('Code-Review', 2)
+        B.addApproval('Code-Review', 2)
+
+        # A Depends-On: B
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+
+        # A and B do not share a queue, make sure that A is unable to
+        # enqueue B (and therefore, A is unable to be enqueued).
+        B.addApproval('Approved', 1)
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+        self.assertEqual(A.reported, 0)
+        self.assertEqual(B.reported, 0)
+        self.assertEqual(len(self.history), 0)
+
+        # Enqueue and merge B alone.
+        self.fake_gerrit.addEvent(B.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.assertEqual(B.data['status'], 'MERGED')
+        self.assertEqual(B.reported, 2)
+
+        # Now that B is merged, A should be able to be enqueued and
+        # merged.
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'MERGED')
+        self.assertEqual(A.reported, 2)
+
+    def test_crd_gate_reverse(self):
+        "Test reverse cross-repo dependencies"
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+        A.addApproval('Code-Review', 2)
+        B.addApproval('Code-Review', 2)
+
+        # A Depends-On: B
+
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+
+        self.executor_server.hold_jobs_in_build = True
+        A.addApproval('Approved', 1)
+        self.fake_gerrit.addEvent(B.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+        self.executor_server.hold_jobs_in_build = False
+        self.executor_server.release()
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'MERGED')
+        self.assertEqual(B.data['status'], 'MERGED')
+        self.assertEqual(A.reported, 2)
+        self.assertEqual(B.reported, 2)
+
+        changes = self.getJobFromHistory(
+            'project-merge', 'org/project1').changes
+        self.assertEqual(changes, '2,1 1,1')
+
+    def test_crd_cycle(self):
+        "Test cross-repo dependency cycles"
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+        A.addApproval('Code-Review', 2)
+        B.addApproval('Code-Review', 2)
+
+        # A -> B -> A (via commit-depends)
+
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+        B.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            B.subject, A.data['url'])
+
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.assertEqual(A.reported, 0)
+        self.assertEqual(B.reported, 0)
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+
+    def test_crd_gate_unknown(self):
+        "Test unknown projects in dependent pipeline"
+        self.init_repo("org/unknown", tag='init')
+        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/unknown', 'master', 'B')
+        A.addApproval('Code-Review', 2)
+        B.addApproval('Code-Review', 2)
+
+        # A Depends-On: B
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+
+        B.addApproval('Approved', 1)
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        # Unknown projects cannot share a queue with any other
+        # since they don't have common jobs with any other (they have no jobs).
+        # Changes which depend on unknown project changes
+        # should not be processed in dependent pipeline
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+        self.assertEqual(A.reported, 0)
+        self.assertEqual(B.reported, 0)
+        self.assertEqual(len(self.history), 0)
+
+        # Simulate change B being gated outside this layout Set the
+        # change merged before submitting the event so that when the
+        # event triggers a gerrit query to update the change, we get
+        # the information that it was merged.
+        B.setMerged()
+        self.fake_gerrit.addEvent(B.addApproval('Approved', 1))
+        self.waitUntilSettled()
+        self.assertEqual(len(self.history), 0)
+
+        # Now that B is merged, A should be able to be enqueued and
+        # merged.
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'MERGED')
+        self.assertEqual(A.reported, 2)
+        self.assertEqual(B.data['status'], 'MERGED')
+        self.assertEqual(B.reported, 0)
+
+    def test_crd_check(self):
+        "Test cross-repo dependencies in independent pipelines"
+
+        self.executor_server.hold_jobs_in_build = True
+        self.gearman_server.hold_jobs_in_queue = True
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+
+        # A Depends-On: B
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        self.gearman_server.hold_jobs_in_queue = False
+        self.gearman_server.release()
+        self.waitUntilSettled()
+
+        self.executor_server.release('.*-merge')
+        self.waitUntilSettled()
+
+        self.assertTrue(self.builds[0].hasChanges(A, B))
+
+        self.executor_server.hold_jobs_in_build = False
+        self.executor_server.release()
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+        self.assertEqual(A.reported, 1)
+        self.assertEqual(B.reported, 0)
+
+        self.assertEqual(self.history[0].changes, '2,1 1,1')
+        tenant = self.sched.abide.tenants.get('tenant-one')
+        self.assertEqual(len(tenant.layout.pipelines['check'].queues), 0)
+
+    def test_crd_check_git_depends(self):
+        "Test single-repo dependencies in independent pipelines"
+        self.gearman_server.hold_jobs_in_build = True
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project1', 'master', 'B')
+
+        # Add two git-dependent changes and make sure they both report
+        # success.
+        B.setDependsOn(A, 1)
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        self.orderedRelease()
+        self.gearman_server.hold_jobs_in_build = False
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+        self.assertEqual(A.reported, 1)
+        self.assertEqual(B.reported, 1)
+
+        self.assertEqual(self.history[0].changes, '1,1')
+        self.assertEqual(self.history[-1].changes, '1,1 2,1')
+        tenant = self.sched.abide.tenants.get('tenant-one')
+        self.assertEqual(len(tenant.layout.pipelines['check'].queues), 0)
+
+        self.assertIn('Build succeeded', A.messages[0])
+        self.assertIn('Build succeeded', B.messages[0])
+
+    def test_crd_check_duplicate(self):
+        "Test duplicate check in independent pipelines"
+        self.executor_server.hold_jobs_in_build = True
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project1', 'master', 'B')
+        tenant = self.sched.abide.tenants.get('tenant-one')
+        check_pipeline = tenant.layout.pipelines['check']
+
+        # Add two git-dependent changes...
+        B.setDependsOn(A, 1)
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(len(check_pipeline.getAllItems()), 2)
+
+        # ...make sure the live one is not duplicated...
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(len(check_pipeline.getAllItems()), 2)
+
+        # ...but the non-live one is able to be.
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(len(check_pipeline.getAllItems()), 3)
+
+        # Release jobs in order to avoid races with change A jobs
+        # finishing before change B jobs.
+        self.orderedRelease()
+        self.executor_server.hold_jobs_in_build = False
+        self.executor_server.release()
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+        self.assertEqual(A.reported, 1)
+        self.assertEqual(B.reported, 1)
+
+        self.assertEqual(self.history[0].changes, '1,1 2,1')
+        self.assertEqual(self.history[1].changes, '1,1')
+        self.assertEqual(len(tenant.layout.pipelines['check'].queues), 0)
+
+        self.assertIn('Build succeeded', A.messages[0])
+        self.assertIn('Build succeeded', B.messages[0])
+
+    def _test_crd_check_reconfiguration(self, project1, project2):
+        "Test cross-repo dependencies re-enqueued in independent pipelines"
+
+        self.gearman_server.hold_jobs_in_queue = True
+        A = self.fake_gerrit.addFakeChange(project1, 'master', 'A')
+        B = self.fake_gerrit.addFakeChange(project2, 'master', 'B')
+
+        # A Depends-On: B
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        self.sched.reconfigure(self.config)
+
+        # Make sure the items still share a change queue, and the
+        # first one is not live.
+        tenant = self.sched.abide.tenants.get('tenant-one')
+        self.assertEqual(len(tenant.layout.pipelines['check'].queues), 1)
+        queue = tenant.layout.pipelines['check'].queues[0]
+        first_item = queue.queue[0]
+        for item in queue.queue:
+            self.assertEqual(item.queue, first_item.queue)
+        self.assertFalse(first_item.live)
+        self.assertTrue(queue.queue[1].live)
+
+        self.gearman_server.hold_jobs_in_queue = False
+        self.gearman_server.release()
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+        self.assertEqual(A.reported, 1)
+        self.assertEqual(B.reported, 0)
+
+        self.assertEqual(self.history[0].changes, '2,1 1,1')
+        self.assertEqual(len(tenant.layout.pipelines['check'].queues), 0)
+
+    def test_crd_check_reconfiguration(self):
+        self._test_crd_check_reconfiguration('org/project1', 'org/project2')
+
+    def test_crd_undefined_project(self):
+        """Test that undefined projects in dependencies are handled for
+        independent pipelines"""
+        # It's a hack for fake gerrit,
+        # as it implies repo creation upon the creation of any change
+        self.init_repo("org/unknown", tag='init')
+        self._test_crd_check_reconfiguration('org/project1', 'org/unknown')
+
+    @simple_layout('layouts/ignore-dependencies.yaml')
+    def test_crd_check_ignore_dependencies(self):
+        "Test cross-repo dependencies can be ignored"
+
+        self.gearman_server.hold_jobs_in_queue = True
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+        C = self.fake_gerrit.addFakeChange('org/project2', 'master', 'C')
+
+        # A Depends-On: B
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+        # C git-depends on B
+        C.setDependsOn(B, 1)
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.fake_gerrit.addEvent(C.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        # Make sure none of the items share a change queue, and all
+        # are live.
+        tenant = self.sched.abide.tenants.get('tenant-one')
+        check_pipeline = tenant.layout.pipelines['check']
+        self.assertEqual(len(check_pipeline.queues), 3)
+        self.assertEqual(len(check_pipeline.getAllItems()), 3)
+        for item in check_pipeline.getAllItems():
+            self.assertTrue(item.live)
+
+        self.gearman_server.hold_jobs_in_queue = False
+        self.gearman_server.release()
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+        self.assertEqual(C.data['status'], 'NEW')
+        self.assertEqual(A.reported, 1)
+        self.assertEqual(B.reported, 1)
+        self.assertEqual(C.reported, 1)
+
+        # Each job should have tested exactly one change
+        for job in self.history:
+            self.assertEqual(len(job.changes.split()), 1)
+
+    @simple_layout('layouts/three-projects.yaml')
+    def test_crd_check_transitive(self):
+        "Test transitive cross-repo dependencies"
+        # Specifically, if A -> B -> C, and C gets a new patchset and
+        # A gets a new patchset, ensure the test of A,2 includes B,1
+        # and C,2 (not C,1 which would indicate stale data in the
+        # cache for B).
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+        C = self.fake_gerrit.addFakeChange('org/project3', 'master', 'C')
+
+        # A Depends-On: B
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+
+        # B Depends-On: C
+        B.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            B.subject, C.data['url'])
+
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,1 2,1 1,1')
+
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,1 2,1')
+
+        self.fake_gerrit.addEvent(C.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,1')
+
+        C.addPatchset()
+        self.fake_gerrit.addEvent(C.getPatchsetCreatedEvent(2))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,2')
+
+        A.addPatchset()
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(2))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,2 2,1 1,2')
+
+    def test_crd_check_unknown(self):
+        "Test unknown projects in independent pipeline"
+        self.init_repo("org/unknown", tag='init')
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/unknown', 'master', 'D')
+        # A Depends-On: B
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+
+        # Make sure zuul has seen an event on B.
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(A.reported, 1)
+        self.assertEqual(B.data['status'], 'NEW')
+        self.assertEqual(B.reported, 0)
+
+    def test_crd_cycle_join(self):
+        "Test an updated change creates a cycle"
+        A = self.fake_gerrit.addFakeChange('org/project2', 'master', 'A')
+
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(A.reported, 1)
+
+        # Create B->A
+        B = self.fake_gerrit.addFakeChange('org/project1', 'master', 'B')
+        B.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            B.subject, A.data['url'])
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        # Dep is there so zuul should have reported on B
+        self.assertEqual(B.reported, 1)
+
+        # Update A to add A->B (a cycle).
+        A.addPatchset()
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['url'])
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(2))
+        self.waitUntilSettled()
+
+        # Dependency cycle injected so zuul should not have reported again on A
+        self.assertEqual(A.reported, 1)
+
+        # Now if we update B to remove the depends-on, everything
+        # should be okay.  B; A->B
+
+        B.addPatchset()
+        B.data['commitMessage'] = '%s\n' % (B.subject,)
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(2))
+        self.waitUntilSettled()
+
+        # Cycle was removed so now zuul should have reported again on A
+        self.assertEqual(A.reported, 2)
+
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(2))
+        self.waitUntilSettled()
+        self.assertEqual(B.reported, 2)