tests/test_scheduler.py

#!/usr/bin/env python

# Copyright 2012 Hewlett-Packard Development Company, L.P.
#
# 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.

import unittest
import ConfigParser
import os
import Queue
import hashlib
import logging
import random
import json
import threading
import time
import pprint
import re
import urllib2
import urlparse

import zuul
import zuul.scheduler
import zuul.launcher.jenkins
import zuul.trigger.gerrit

FIXTURE_DIR = os.path.join(os.path.dirname(__file__),
                           'fixtures')
CONFIG = ConfigParser.ConfigParser()
CONFIG.read(os.path.join(FIXTURE_DIR, "zuul.conf"))

CONFIG.set('zuul', 'layout_config',
           os.path.join(FIXTURE_DIR, "layout.yaml"))

logging.basicConfig(level=logging.DEBUG)


def random_sha1():
    return hashlib.sha1(str(random.random())).hexdigest()


class FakeChange(object):
    categories = {'APRV': ('Approved', -1, 1),
                  'CRVW': ('Code-Review', -2, 2),
                  'VRFY': ('Verified', -2, 2)}

    def __init__(self, gerrit, number, project, branch, subject, status='NEW'):
        self.gerrit = gerrit
        self.reported = 0
        self.queried = 0
        self.patchsets = []
        self.number = number
        self.project = project
        self.branch = branch
        self.subject = subject
        self.latest_patchset = 0
        self.depends_on_change = None
        self.needed_by_changes = []
        self.data = {
            'branch': branch,
            'comments': [],
            'commitMessage': subject,
            'createdOn': time.time(),
            'id': 'I' + random_sha1(),
            'lastUpdated': time.time(),
            'number': str(number),
            'open': True,
            'owner': {'email': 'user@example.com',
                      'name': 'User Name',
                      'username': 'username'},
            'patchSets': self.patchsets,
            'project': project,
            'status': status,
            'subject': subject,
            'submitRecords': [],
            'url': 'https://hostname/%s' % number}

        self.addPatchset()
        self.data['submitRecords'] = self.getSubmitRecords()

    def addPatchset(self, files=None):
        self.latest_patchset += 1
        d = {'approvals': [],
             'createdOn': time.time(),
             'files': [{'file': '/COMMIT_MSG',
                        'type': 'ADDED'},
                       {'file': 'README',
                        'type': 'MODIFIED'}],
             'number': str(self.latest_patchset),
             'ref': 'refs/changes/1/%s/%s' % (self.number,
                                              self.latest_patchset),
             'revision': random_sha1(),
             'uploader': {'email': 'user@example.com',
                          'name': 'User name',
                          'username': 'user'}}
        self.data['currentPatchSet'] = d
        self.patchsets.append(d)
        self.data['submitRecords'] = self.getSubmitRecords()

    def addApproval(self, category, value):
        approval = {'description': self.categories[category][0],
                    'type': category,
                    'value': str(value)}
        self.patchsets[-1]['approvals'].append(approval)
        event = {'approvals': [approval],
                 'author': {'email': 'user@example.com',
                            'name': 'User Name',
                            'username': 'username'},
                 'change': {'branch': self.branch,
                            'id': 'Iaa69c46accf97d0598111724a38250ae76a22c87',
                            'number': str(self.number),
                            'owner': {'email': 'user@example.com',
                                      'name': 'User Name',
                                      'username': 'username'},
                            'project': self.project,
                            'subject': self.subject,
                            'topic': 'master',
                            'url': 'https://hostname/459'},
                 'comment': '',
                 'patchSet': self.patchsets[-1],
                 'type': 'comment-added'}
        self.data['submitRecords'] = self.getSubmitRecords()
        return json.loads(json.dumps(event))

    def getSubmitRecords(self):
        status = {}
        for cat in self.categories.keys():
            status[cat] = 0

        for a in self.patchsets[-1]['approvals']:
            cur = status[a['type']]
            cat_min, cat_max = self.categories[a['type']][1:]
            new = int(a['value'])
            if new == cat_min:
                cur = new
            elif abs(new) > abs(cur):
                cur = new
            status[a['type']] = cur

        labels = []
        ok = True
        for typ, cat in self.categories.items():
            cur = status[typ]
            cat_min, cat_max = cat[1:]
            if cur == cat_min:
                value = 'REJECT'
                ok = False
            elif cur == cat_max:
                value = 'OK'
            else:
                value = 'NEED'
                ok = False
            labels.append({'label': cat[0], 'status': value})
        if ok:
            return [{'status': 'OK'}]
        return [{'status': 'NOT_READY',
                 'labels': labels}]

    def setDependsOn(self, other, patchset):
        self.depends_on_change = other
        d = {'id': other.data['id'],
             'number': other.data['number'],
             'ref': other.patchsets[patchset - 1]['ref']
             }
        self.data['dependsOn'] = [d]

        other.needed_by_changes.append(self)
        needed = other.data.get('neededBy', [])
        d = {'id': self.data['id'],
             'number': self.data['number'],
             'ref': self.patchsets[patchset - 1]['ref'],
             'revision': self.patchsets[patchset - 1]['revision']
             }
        needed.append(d)
        other.data['neededBy'] = needed

    def query(self):
        self.queried += 1
        d = self.data.get('dependsOn')
        if d:
            d = d[0]
            if (self.depends_on_change.patchsets[-1]['ref'] == d['ref']):
                d['isCurrentPatchSet'] = True
            else:
                d['isCurrentPatchSet'] = False
        return json.loads(json.dumps(self.data))

    def setMerged(self):
        self.data['status'] = 'MERGED'
        self.open = False
        branch_heads = self.gerrit.heads[self.project]
        branch_heads[self.branch] = self.patchsets[-1]['revision']

    def setReported(self):
        self.reported += 1


class FakeGerrit(object):
    def __init__(self, *args, **kw):
        self.event_queue = Queue.Queue()
        self.fixture_dir = os.path.join(FIXTURE_DIR, 'gerrit')
        self.change_number = 0
        self.changes = {}
        self.heads = {}

    def addFakeChange(self, project, branch, subject):
        branch_heads = self.heads.get(project, {})
        if branch not in branch_heads:
            branch_heads[branch] = random_sha1()
        self.heads[project] = branch_heads

        self.change_number += 1
        c = FakeChange(self, self.change_number, project, branch, subject)
        self.changes[self.change_number] = c
        return c

    def addEvent(self, data):
        return self.event_queue.put(data)

    def getEvent(self):
        return self.event_queue.get()

    def eventDone(self):
        self.event_queue.task_done()

    def review(self, project, changeid, message, action):
        number, ps = changeid.split(',')
        change = self.changes[int(number)]
        if 'submit' in action:
            change.setMerged()
        if message:
            change.setReported()

    def query(self, number):
        change = self.changes[int(number)]
        return change.query()

    def startWatching(self, *args, **kw):
        pass


class FakeJenkinsEvent(object):
    def __init__(self, name, number, parameters, phase, status=None):
        data = {'build':
                     {'full_url': 'https://server/job/%s/%s/' % (name, number),
                      'number': number,
                      'parameters': parameters,
                      'phase': phase,
                      'url': 'job/%s/%s/' % (name, number)},
                     'name': name,
                     'url': 'job/%s/' % name}
        if status:
            data['build']['status'] = status
        self.body = json.dumps(data)


class FakeJenkinsJob(threading.Thread):
    log = logging.getLogger("zuul.test")

    def __init__(self, jenkins, callback, name, number, parameters):
        threading.Thread.__init__(self)
        self.jenkins = jenkins
        self.callback = callback
        self.name = name
        self.number = number
        self.parameters = parameters
        self.wait_condition = threading.Condition()
        self.waiting = False
        self.aborted = False
        self.canceled = False
        self.created = time.time()

    def release(self):
        self.wait_condition.acquire()
        self.wait_condition.notify()
        self.waiting = False
        self.log.debug("Job %s released" % (self.parameters['UUID']))
        self.wait_condition.release()

    def isWaiting(self):
        self.wait_condition.acquire()
        if self.waiting:
            ret = True
        else:
            ret = False
        self.wait_condition.release()
        return ret

    def _wait(self):
        self.wait_condition.acquire()
        self.waiting = True
        self.log.debug("Job %s waiting" % (self.parameters['UUID']))
        self.wait_condition.wait()
        self.wait_condition.release()

    def run(self):
        self.jenkins.fakeEnqueue(self)
        if self.jenkins.hold_jobs_in_queue:
            self._wait()
        self.jenkins.fakeDequeue(self)
        if self.canceled:
            self.jenkins.all_jobs.remove(self)
            return
        self.callback.jenkins_endpoint(FakeJenkinsEvent(
                self.name, self.number, self.parameters,
                'STARTED'))
        if self.jenkins.hold_jobs_in_build:
            self._wait()
        self.log.debug("Job %s continuing" % (self.parameters['UUID']))

        result = 'SUCCESS'
        if self.jenkins.fakeShouldFailTest(
            self.name,
            self.parameters['GERRIT_CHANGES']):
            result = 'FAILURE'
        if self.aborted:
            result = 'ABORTED'

        self.jenkins.fakeAddHistory(name=self.name, number=self.number,
                                    result=result)
        self.callback.jenkins_endpoint(FakeJenkinsEvent(
                self.name, self.number, self.parameters,
                'COMPLETED', result))
        self.callback.jenkins_endpoint(FakeJenkinsEvent(
                self.name, self.number, self.parameters,
                'FINISHED', result))
        self.jenkins.all_jobs.remove(self)


class FakeJenkins(object):
    log = logging.getLogger("zuul.test")

    def __init__(self, *args, **kw):
        self.queue = []
        self.all_jobs = []
        self.job_counter = {}
        self.queue_counter = 0
        self.job_history = []
        self.hold_jobs_in_queue = False
        self.hold_jobs_in_build = False
        self.fail_tests = {}

    def fakeEnqueue(self, job):
        self.queue.append(job)

    def fakeDequeue(self, job):
        self.queue.remove(job)

    def fakeAddHistory(self, **kw):
        self.job_history.append(kw)

    def fakeRelease(self, regex=None):
        all_jobs = self.all_jobs[:]
        self.log.debug("releasing jobs %s (%s)" % (regex, len(self.all_jobs)))
        for job in all_jobs:
            if not regex or re.match(regex, job.name):
                self.log.debug("releasing job %s" % (job.parameters['UUID']))
                job.release()
            else:
                self.log.debug("not releasing job %s" % (
                        job.parameters['UUID']))
        self.log.debug("done releasing jobs %s (%s)" % (regex,
                                                        len(self.all_jobs)))

    def fakeAllWaiting(self, regex=None):
        all_jobs = self.all_jobs[:]
        for job in all_jobs:
            self.log.debug("job %s %s" % (job.parameters['UUID'],
                                          job.isWaiting()))
            if not job.isWaiting():
                return False
        return True

    def fakeAddFailTest(self, name, change):
        l = self.fail_tests.get(name, [])
        l.append(change)
        self.fail_tests[name] = l

    def fakeShouldFailTest(self, name, changes):
        l = self.fail_tests.get(name, [])
        for change in l:
            if change in changes:
                return True
        return False

    def build_job(self, name, parameters):
        count = self.job_counter.get(name, 0)
        count += 1
        self.job_counter[name] = count

        queue_count = self.queue_counter
        self.queue_counter += 1
        job = FakeJenkinsJob(self, self.callback, name, count, parameters)
        job.queue_id = queue_count

        self.all_jobs.append(job)
        job.start()

    def stop_build(self, name, number):
        for job in self.all_jobs:
            if job.name == name and job.number == number:
                job.aborted = True
                job.release()
                return

    def cancel_queue(self, id):
        for job in self.queue:
            if job.queue_id == id:
                job.canceled = True
                job.release()
                return

    def get_queue_info(self):
        items = []
        for job in self.queue:
            paramstr = ''
            paramlst = []
            d = {'actions': [{'parameters': paramlst},
                             {'causes': [{'shortDescription':
                                          'Started by user Jenkins',
                                          'userId': 'jenkins',
                                          'userName': 'Jenkins'}]}],
                 'blocked': False,
                 'buildable': True,
                 'buildableStartMilliseconds': (job.created * 1000) + 5,
                 'id': job.queue_id,
                 'inQueueSince': (job.created * 1000),
                 'params': paramstr,
                 'stuck': False,
                 'task': {'color': 'blue',
                          'name': job.name,
                          'url': 'https://server/job/%s/' % job.name},
                 'why': 'Waiting for next available executor'}
            for k, v in job.parameters.items():
                paramstr += "\n(StringParameterValue) %s='%s'" % (k, v)
                pd = {'name': k, 'value': v}
                paramlst.append(pd)
            items.append(d)
        return items

    def set_build_description(self, *args, **kw):
        pass


class FakeJenkinsCallback(zuul.launcher.jenkins.JenkinsCallback):
    def start(self):
        pass


class FakeURLOpener(object):
    def __init__(self, fake_gerrit, url):
        self.fake_gerrit = fake_gerrit
        self.url = url

    def read(self):
        res = urlparse.urlparse(self.url)
        path = res.path
        project = '/'.join(path.split('/')[2:-2])
        heads = self.fake_gerrit.heads[project]
        ret = ''
        for change in self.fake_gerrit.changes.values():
            for ps in change.patchsets:
                ret += ps['revision'] + '\t' + ps['ref'] + '\n'
        for head, ref in heads.items():
            ret += ref + '\trefs/heads/' + head + '\n'
        return ret


class testScheduler(unittest.TestCase):
    log = logging.getLogger("zuul.test")

    def setUp(self):
        self.config = CONFIG
        self.sched = zuul.scheduler.Scheduler()

        def jenkinsFactory(*args, **kw):
            self.fake_jenkins = FakeJenkins()
            return self.fake_jenkins

        def jenkinsCallbackFactory(*args, **kw):
            self.fake_jenkins_callback = FakeJenkinsCallback(*args, **kw)
            return self.fake_jenkins_callback

        def URLOpenerFactory(*args, **kw):
            args = [self.fake_gerrit] + list(args)
            return FakeURLOpener(*args, **kw)

        zuul.launcher.jenkins.ExtendedJenkins = jenkinsFactory
        zuul.launcher.jenkins.JenkinsCallback = jenkinsCallbackFactory
        urllib2.urlopen = URLOpenerFactory
        self.jenkins = zuul.launcher.jenkins.Jenkins(self.config, self.sched)
        self.fake_jenkins.callback = self.fake_jenkins_callback

        zuul.lib.gerrit.Gerrit = FakeGerrit

        self.gerrit = zuul.trigger.gerrit.Gerrit(self.config, self.sched)
        self.gerrit.replication_timeout = 1.5
        self.gerrit.replication_retry_interval = 0.5
        self.fake_gerrit = self.gerrit.gerrit

        self.sched.setLauncher(self.jenkins)
        self.sched.setTrigger(self.gerrit)

        self.sched.start()
        self.sched.reconfigure(self.config)
        self.sched.resume()

    def tearDown(self):
        self.jenkins.stop()
        self.gerrit.stop()
        self.sched.stop()
        self.sched.join()

    def waitUntilSettled(self):
        self.log.debug("Waiting until settled...")
        start = time.time()
        while True:
            if time.time() - start > 10:
                print 'queue status:',
                print self.sched.trigger_event_queue.empty(),
                print self.sched.result_event_queue.empty(),
                print self.fake_gerrit.event_queue.empty(),
                raise Exception("Timeout waiting for Zuul to settle")
            self.fake_gerrit.event_queue.join()
            self.sched.queue_lock.acquire()
            if (self.sched.trigger_event_queue.empty() and
                self.sched.result_event_queue.empty() and
                self.fake_gerrit.event_queue.empty() and
                self.fake_jenkins.fakeAllWaiting()):
                self.sched.queue_lock.release()
                self.log.debug("...settled.")
                return
            self.sched.queue_lock.release()
            self.sched.wake_event.wait(0.1)

    def countJobResults(self, jobs, result):
        jobs = filter(lambda x: x['result'] == result, jobs)
        return len(jobs)

    def test_jobs_launched(self):
        "Test that jobs are launched and a change is merged"
        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
        A.addApproval('CRVW', 2)
        self.fake_gerrit.addEvent(A.addApproval('APRV', 1))
        self.waitUntilSettled()
        jobs = self.fake_jenkins.job_history
        job_names = [x['name'] for x in jobs]
        assert 'project-merge' in job_names
        assert 'project-test1' in job_names
        assert 'project-test2' in job_names
        assert jobs[0]['result'] == 'SUCCESS'
        assert jobs[1]['result'] == 'SUCCESS'
        assert jobs[2]['result'] == 'SUCCESS'
        assert A.data['status'] == 'MERGED'
        assert A.reported == 2

    def test_parallel_changes(self):
        "Test that changes are tested in parallel and merged in series"
        self.fake_jenkins.hold_jobs_in_build = True
        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
        B = self.fake_gerrit.addFakeChange('org/project', 'master', 'B')
        C = self.fake_gerrit.addFakeChange('org/project', 'master', 'C')
        A.addApproval('CRVW', 2)
        B.addApproval('CRVW', 2)
        C.addApproval('CRVW', 2)

        self.fake_gerrit.addEvent(A.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(B.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(C.addApproval('APRV', 1))

        self.waitUntilSettled()
        jobs = self.fake_jenkins.all_jobs
        assert len(jobs) == 1
        assert jobs[0].name == 'project-merge'
        assert (jobs[0].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')

        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()
        assert len(jobs) == 3
        assert jobs[0].name == 'project-test1'
        assert (jobs[0].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')
        assert jobs[1].name == 'project-test2'
        assert (jobs[1].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')
        assert jobs[2].name == 'project-merge'
        assert (jobs[2].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1^'
                'org/project:master:refs/changes/1/2/1')

        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()
        assert len(jobs) == 5
        assert jobs[0].name == 'project-test1'
        assert (jobs[0].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')
        assert jobs[1].name == 'project-test2'
        assert (jobs[1].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')

        assert jobs[2].name == 'project-test1'
        assert (jobs[2].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1^'
                'org/project:master:refs/changes/1/2/1')
        assert jobs[3].name == 'project-test2'
        assert (jobs[3].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1^'
                'org/project:master:refs/changes/1/2/1')

        assert jobs[4].name == 'project-merge'
        assert (jobs[4].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1^'
                'org/project:master:refs/changes/1/2/1^'
                'org/project:master:refs/changes/1/3/1')

        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()
        assert len(jobs) == 6
        assert jobs[0].name == 'project-test1'
        assert (jobs[0].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')
        assert jobs[1].name == 'project-test2'
        assert (jobs[1].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')

        assert jobs[2].name == 'project-test1'
        assert (jobs[2].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1^'
                'org/project:master:refs/changes/1/2/1')
        assert jobs[3].name == 'project-test2'
        assert (jobs[3].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1^'
                'org/project:master:refs/changes/1/2/1')

        assert jobs[4].name == 'project-test1'
        assert (jobs[4].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1^'
                'org/project:master:refs/changes/1/2/1^'
                'org/project:master:refs/changes/1/3/1')
        assert jobs[5].name == 'project-test2'
        assert (jobs[5].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1^'
                'org/project:master:refs/changes/1/2/1^'
                'org/project:master:refs/changes/1/3/1')

        self.fake_jenkins.hold_jobs_in_build = False
        self.fake_jenkins.fakeRelease()
        self.waitUntilSettled()
        assert len(jobs) == 0

        jobs = self.fake_jenkins.job_history
        assert len(jobs) == 9
        assert A.data['status'] == 'MERGED'
        assert B.data['status'] == 'MERGED'
        assert C.data['status'] == 'MERGED'
        assert A.reported == 2
        assert B.reported == 2
        assert C.reported == 2

    def test_failed_changes(self):
        "Test that a change behind a failed change is retested"
        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
        B = self.fake_gerrit.addFakeChange('org/project', 'master', 'B')
        A.addApproval('CRVW', 2)
        B.addApproval('CRVW', 2)

        self.fake_gerrit.addEvent(A.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(B.addApproval('APRV', 1))

        self.fake_jenkins.fakeAddFailTest(
            'project-test1',
            'org/project:master:refs/changes/1/1/1')

        self.waitUntilSettled()
        jobs = self.fake_jenkins.job_history
        assert len(jobs) > 6
        assert A.data['status'] == 'NEW'
        assert B.data['status'] == 'MERGED'
        assert A.reported == 2
        assert B.reported == 2

    def test_independent_queues(self):
        "Test that changes end up in the right queues"
        self.fake_jenkins.hold_jobs_in_build = True
        A = self.fake_gerrit.addFakeChange('org/project',  'master', 'A')
        B = self.fake_gerrit.addFakeChange('org/project1', 'master', 'B')
        C = self.fake_gerrit.addFakeChange('org/project2', 'master', 'C')
        A.addApproval('CRVW', 2)
        B.addApproval('CRVW', 2)
        C.addApproval('CRVW', 2)

        self.fake_gerrit.addEvent(A.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(B.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(C.addApproval('APRV', 1))

        jobs = self.fake_jenkins.all_jobs
        self.waitUntilSettled()

        # There should be one merge job at the head of each queue running
        assert len(jobs) == 2
        assert jobs[0].name == 'project-merge'
        assert (jobs[0].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')
        assert jobs[1].name == 'project1-merge'
        assert (jobs[1].parameters['GERRIT_CHANGES'] ==
                'org/project1:master:refs/changes/1/2/1')

        # Release the current merge jobs
        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()
        # Release the merge job for project2 which is behind project1
        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()

        # All the test jobs should be running:
        # project1 (3) + project2 (3) + project (2) = 8
        assert len(jobs) == 8

        self.fake_jenkins.fakeRelease()
        self.waitUntilSettled()
        assert len(jobs) == 0

        jobs = self.fake_jenkins.job_history
        assert len(jobs) == 11
        assert A.data['status'] == 'MERGED'
        assert B.data['status'] == 'MERGED'
        assert C.data['status'] == 'MERGED'
        assert A.reported == 2
        assert B.reported == 2
        assert C.reported == 2

    def test_failed_change_at_head(self):
        "Test that if a change at the head fails, jobs behind it are canceled"
        self.fake_jenkins.hold_jobs_in_build = True

        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
        B = self.fake_gerrit.addFakeChange('org/project', 'master', 'B')
        C = self.fake_gerrit.addFakeChange('org/project', 'master', 'C')
        A.addApproval('CRVW', 2)
        B.addApproval('CRVW', 2)
        C.addApproval('CRVW', 2)

        self.fake_jenkins.fakeAddFailTest(
            'project-test1',
            'org/project:master:refs/changes/1/1/1')

        self.fake_gerrit.addEvent(A.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(B.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(C.addApproval('APRV', 1))

        self.waitUntilSettled()
        jobs = self.fake_jenkins.all_jobs
        finished_jobs = self.fake_jenkins.job_history

        assert len(jobs) == 1
        assert jobs[0].name == 'project-merge'
        assert (jobs[0].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')

        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()
        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()
        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()

        assert len(jobs) == 6
        assert jobs[0].name == 'project-test1'
        assert jobs[1].name == 'project-test2'
        assert jobs[2].name == 'project-test1'
        assert jobs[3].name == 'project-test2'
        assert jobs[4].name == 'project-test1'
        assert jobs[5].name == 'project-test2'

        jobs[0].release()
        self.waitUntilSettled()

        assert len(jobs) == 1  # project-test2
        assert self.countJobResults(finished_jobs, 'ABORTED') == 4

        self.fake_jenkins.hold_jobs_in_build = False
        self.fake_jenkins.fakeRelease()
        self.waitUntilSettled()

        assert len(jobs) == 0
        assert len(finished_jobs) == 15
        assert A.data['status'] == 'NEW'
        assert B.data['status'] == 'MERGED'
        assert C.data['status'] == 'MERGED'
        assert A.reported == 2
        assert B.reported == 2
        assert C.reported == 2

    def test_failed_change_at_head_with_queue(self):
        "Test that if a change at the head fails, queued jobs are canceled"
        self.fake_jenkins.hold_jobs_in_queue = True

        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
        B = self.fake_gerrit.addFakeChange('org/project', 'master', 'B')
        C = self.fake_gerrit.addFakeChange('org/project', 'master', 'C')
        A.addApproval('CRVW', 2)
        B.addApproval('CRVW', 2)
        C.addApproval('CRVW', 2)

        self.fake_jenkins.fakeAddFailTest(
            'project-test1',
            'org/project:master:refs/changes/1/1/1')

        self.fake_gerrit.addEvent(A.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(B.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(C.addApproval('APRV', 1))

        self.waitUntilSettled()
        jobs = self.fake_jenkins.all_jobs
        finished_jobs = self.fake_jenkins.job_history
        queue = self.fake_jenkins.queue

        assert len(jobs) == 1
        assert len(queue) == 1
        assert jobs[0].name == 'project-merge'
        assert (jobs[0].parameters['GERRIT_CHANGES'] ==
                'org/project:master:refs/changes/1/1/1')

        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()
        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()
        self.fake_jenkins.fakeRelease('.*-merge')
        self.waitUntilSettled()

        assert len(jobs) == 6
        assert len(queue) == 6
        assert jobs[0].name == 'project-test1'
        assert jobs[1].name == 'project-test2'
        assert jobs[2].name == 'project-test1'
        assert jobs[3].name == 'project-test2'
        assert jobs[4].name == 'project-test1'
        assert jobs[5].name == 'project-test2'

        jobs[0].release()
        self.waitUntilSettled()

        assert len(jobs) == 1  # project-test2
        assert len(queue) == 1
        assert self.countJobResults(finished_jobs, 'ABORTED') == 0

        self.fake_jenkins.hold_jobs_in_queue = False
        self.fake_jenkins.fakeRelease()
        self.waitUntilSettled()

        assert len(jobs) == 0
        assert len(finished_jobs) == 11
        assert A.data['status'] == 'NEW'
        assert B.data['status'] == 'MERGED'
        assert C.data['status'] == 'MERGED'
        assert A.reported == 2
        assert B.reported == 2
        assert C.reported == 2

    def test_patch_order(self):
        "Test that dependent patches are tested in the right order"
        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
        B = self.fake_gerrit.addFakeChange('org/project', 'master', 'B')
        C = self.fake_gerrit.addFakeChange('org/project', 'master', 'C')
        A.addApproval('CRVW', 2)
        B.addApproval('CRVW', 2)
        C.addApproval('CRVW', 2)

        M2 = self.fake_gerrit.addFakeChange('org/project', 'master', 'M2')
        M1 = self.fake_gerrit.addFakeChange('org/project', 'master', 'M1')
        M2.setMerged()
        M1.setMerged()

        # C -> B -> A -> M1 -> M2
        # 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.

        C.setDependsOn(B, 1)
        B.setDependsOn(A, 1)
        A.setDependsOn(M1, 1)
        M1.setDependsOn(M2, 1)

        self.fake_gerrit.addEvent(C.addApproval('APRV', 1))

        self.waitUntilSettled()

        assert A.data['status'] == 'NEW'
        assert B.data['status'] == 'NEW'
        assert C.data['status'] == 'NEW'

        self.fake_gerrit.addEvent(B.addApproval('APRV', 1))
        self.fake_gerrit.addEvent(A.addApproval('APRV', 1))

        self.waitUntilSettled()
        assert M2.queried == 0
        assert A.data['status'] == 'MERGED'
        assert B.data['status'] == 'MERGED'
        assert C.data['status'] == 'MERGED'
        assert A.reported == 2
        assert B.reported == 2
        assert C.reported == 2

    def test_can_merge(self):
        "Test that whether a change is ready to merge"
        # TODO: move to test_gerrit (this is a unit test!)
        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
        a = self.sched.trigger.getChange(1, 2, 'gate')
        assert not a.can_merge

        A.addApproval('CRVW', 2)
        a = self.sched.trigger.getChange(1, 2, 'gate')
        assert not a.can_merge

        A.addApproval('APRV', 1)
        a = self.sched.trigger.getChange(1, 2, 'gate')
        assert a.can_merge

        return True