diff --git a/tests/fixtures/layout.yaml b/tests/fixtures/layout.yaml
new file mode 100644
index 0000000..e01ebfd
--- /dev/null
+++ b/tests/fixtures/layout.yaml
@@ -0,0 +1,47 @@
+queues:
+  - name: check
+    manager: IndependentQueueManager
+    trigger:
+      - event: patchset-uploaded
+    success:
+      verified: 1
+    failure:
+      verified: -1
+
+  - name: post
+    manager: IndependentQueueManager
+    trigger:
+      - event: ref-updated
+        ref: ^(?!refs/).*$
+
+  - name: gate
+    manager: DependentQueueManager
+    trigger:
+      - event: comment-added
+        approval: 
+          - approved: 1
+    success:
+      verified: 2
+      submit: true
+    failure:
+      verified: -2
+    start:
+      verified: 0
+
+jobs:
+  - name: ^.*-merge$
+    failure-message: Unable to merge change
+    hold-following-changes: true
+
+projects:
+  - name: org/project
+    check:
+      - project-merge:
+        - project-test1
+        - project-test2
+    gate:
+      - project-merge:
+        - project-test1
+        - project-test2
+    post:
+      - project-post
diff --git a/tests/fixtures/zuul.conf b/tests/fixtures/zuul.conf
new file mode 100644
index 0000000..b66b489
--- /dev/null
+++ b/tests/fixtures/zuul.conf
@@ -0,0 +1,12 @@
+[jenkins]
+server=https://jenkins.example.com
+user=jenkins
+apikey=1234
+
+[gerrit]
+server=review.example.com
+user=jenkins
+sshkey=none
+
+[zuul]
+layout_config=layout.yaml
diff --git a/tests/test_scheduler.py b/tests/test_scheduler.py
new file mode 100644
index 0000000..3d9355f
--- /dev/null
+++ b/tests/test_scheduler.py
@@ -0,0 +1,466 @@
+#!/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 logging
+import json
+import threading
+import time
+import pprint
+import re
+
+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)
+
+
+class FakeChange(object):
+    categories = {'APRV': 'Approved',
+                  'CRVW': 'Code-Review',
+                  'VRFY': 'Verified'}
+
+    def __init__(self, number, project, branch, subject, status='NEW'):
+        self.patchsets = []
+        self.submit_records = []
+        self.number = number
+        self.project = project
+        self.branch = branch
+        self.subject = subject
+        self.latest_patchset = 0
+        self.data = {
+            'branch': branch,
+            'comments': [],
+            'commitMessage': subject,
+            'createdOn': time.time(),
+            'id': 'Iaa69c46accf97d0598111724a38250ae76a22c87',
+            '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': self.submit_records,
+            'url': 'https://hostname/%s' % number}
+
+        self.addPatchset()
+
+    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': self.latest_patchset,
+             'ref': 'refs/changes/1/%s/%s' % (self.number,
+                                              self.latest_patchset),
+             'revision':
+                 'aa69c46accf97d0598111724a38250ae76a22c87',
+             'uploader': {'email': 'user@example.com',
+                          'name': 'User name',
+                          'username': 'user'}}
+        self.data['currentPatchSet'] = d
+        self.patchsets.append(d)
+
+    def addApproval(self, category, value):
+        event = {'approvals': [{'description': self.categories[category],
+                                'type': category,
+                                'value': str(value)}],
+                 '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'}
+        return json.loads(json.dumps(event))
+
+    def query(self):
+        return json.loads(json.dumps(self.data))
+
+    def setMerged(self):
+        self.data['status'] = 'MERGED'
+        self.open = False
+
+
+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 = {}
+
+    def addFakeChange(self, project, branch, subject):
+        self.change_number += 1
+        c = FakeChange(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):
+        if 'submit' in action:
+            number, ps = changeid.split(',')
+            change = self.changes[int(number)]
+            change.setMerged()
+
+    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
+
+    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)
+        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']))
+        self.jenkins.fakeAddHistory(name=self.name, number=self.number,
+                                    result='SUCCESS')
+        self.callback.jenkins_endpoint(FakeJenkinsEvent(
+                self.name, self.number, self.parameters,
+                'COMPLETED', 'SUCCESS'))
+        self.callback.jenkins_endpoint(FakeJenkinsEvent(
+                self.name, self.number, self.parameters,
+                'FINISHED', 'SUCCESS'))
+        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.job_history = []
+        self.hold_jobs_in_queue = False
+        self.hold_jobs_in_build = False
+
+    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 build_job(self, name, parameters):
+        count = self.job_counter.get(name, 0)
+        count += 1
+        self.job_counter[name] = count
+        job = FakeJenkinsJob(self, self.callback, name, count, parameters)
+        self.all_jobs.append(job)
+        job.start()
+
+    def set_build_description(self, *args, **kw):
+        pass
+
+
+class FakeJenkinsCallback(zuul.launcher.jenkins.JenkinsCallback):
+    def start(self):
+        pass
+
+
+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
+
+        zuul.launcher.jenkins.ExtendedJenkins = jenkinsFactory
+        zuul.launcher.jenkins.JenkinsCallback = jenkinsCallbackFactory
+        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.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 test_jobs_launched(self):
+        "Test that jobs are launched and a change is merged"
+        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
+        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'
+
+    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')
+
+        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'