Merge lp:~lifeless/launchpad/malone into lp:launchpad

[Robert Collins]

Batch /bugs/bugtrackers

Batch the bug tracker lists - theres no point showing 1000 by default; the batching will also shrink the time massively; we can actually tune it later (this was sensible to do regardless and will give more headroom than just tuning it in the short term).

[Michael Hudson-Doyle (mwhudson)]

The change is basically fine, and clearly a good idea. I have a number of code clarity comments though, see below.

> === modified file 'lib/canonical/launchpad/webapp/batching.py'
> --- lib/canonical/launchpad/webapp/batching.py 2010-09-06 18:52:45 +0000
> +++ lib/canonical/launchpad/webapp/batching.py 2010-09-19 22:21:05 +0000
> @@ -77,6 +77,24 @@
> return self.batch.total() > self.batch.size
>
>
> +class ActiveBatchNavigator(BatchNavigator):
> + """A paginator for active items.
> +
> + Used when a view needs to display more than one BatchNavigator of items.
> + """
> + start_variable_name = 'active_start'
> + batch_variable_name = 'active_batch'
> +
> +
> +class InactiveBatchNavigator(BatchNavigator):
> + """A paginator for inactive items.
> +
> + Used when a view needs to display more than one BatchNavigator of items.
> + """
> + start_variable_name = 'inactive_start'
> + batch_variable_name = 'inactive_batch'
> +
> +

These are fine and clear enough -- are they generic enough to go in a
generic enough location though? Later: oh, I see you moved them from
other code. It's a shame you have to subclass to change these.

> class TableBatchNavigator(BatchNavigator):
> """See canonical.launchpad.interfaces.ITableBatchNavigator."""
> implements(ITableBatchNavigator)

> === modified file 'lib/lp/blueprints/browser/tests/test_specificationtarget.py'
> --- lib/lp/blueprints/browser/tests/test_specificationtarget.py 2010-09-17 14:04:29 +0000
> +++ lib/lp/blueprints/browser/tests/test_specificationtarget.py 2010-09-19 22:21:05 +0000
> @@ -3,11 +3,9 @@
>
> __metaclass__ = type
>
> -import unittest
>
> from zope.security.proxy import removeSecurityProxy
>
> -from canonical.launchpad.webapp.batching import BatchNavigator
> from canonical.launchpad.testing.pages import find_tag_by_id
> from canonical.testing.layers import DatabaseFunctionalLayer
> from lp.blueprints.interfaces.specificationtarget import (
> @@ -21,6 +19,7 @@
> login_person,
> TestCaseWithFactory,
> )
> +from lp.testing.matchers import IsConfiguredBatchNavigator
> from lp.testing.views import (
> create_view,
> create_initialized_view,
> @@ -108,22 +107,11 @@
> # subclass.
> person = self.factory.makePerson()
> view = create_initialized_view(person, name='+assignments')

Just up from here there's a comment:

        # Some pages turn up in very large contexts and patch. E.g.
        # Distro:+assignments which uses SpecificationAssignmentsView, a
        # subclass.

Is patch a typo for batch here?

> - self.assertIsInstance(view.specs_batched, BatchNavigator)
> -
> - def test_batch_headings(self):
> - person = self.factory.makePerson()
> - view = create_initialized_view(person, name='+assignments')
> - navigator = view.specs_batched
> - self.assertEqual('specification', navigator._singular_heading)
> - self.assertEqual('specifications', navigator._plural_heading)
> -
> - def test_batch_size(self):
> # Because +assignments is meant to provide an overview, we default to
> # 500 as the default batch size.
> - ...

review: Approve

[Robert Collins (lifeless)]

Thanks for the feedback will do most of it.

I have a few quirks though:
 - matchers inline - i agree, but the noddy style guide line wrapping
rules make it ugly. If you agree that inline is better even so, I'll
move it inline and wrap it the way I would in every other python
project.

 - the flavor comment is there because its a deprecated API. I think
the deprecation is a mistake until we actually don't need it.

Thanks,
Rob

[Michael Hudson-Doyle (mwhudson)]

For the first, I don't think:

        self.assertThat(
            view.specs_batched,
            IsConfiguredBatchNavigator(
                'specification', 'specifications', batch_size=500))

is too bad, but *shrug*, indent it however you like :)

For the second, fine.

=== modified file 'lib/canonical/launchpad/webapp/batching.py'
--- lib/canonical/launchpad/webapp/batching.py	2010-09-06 18:52:45 +0000
+++ lib/canonical/launchpad/webapp/batching.py	2010-09-20 05:15:57 +0000
@@ -77,6 +77,24 @@
         return self.batch.total() > self.batch.size
 
 
+class ActiveBatchNavigator(BatchNavigator):
+    """A paginator for active items.
+
+    Used when a view needs to display more than one BatchNavigator of items.
+    """
+    start_variable_name = 'active_start'
+    batch_variable_name = 'active_batch'
+
+
+class InactiveBatchNavigator(BatchNavigator):
+    """A paginator for inactive items.
+
+    Used when a view needs to display more than one BatchNavigator of items.
+    """
+    start_variable_name = 'inactive_start'
+    batch_variable_name = 'inactive_batch'
+
+
 class TableBatchNavigator(BatchNavigator):
     """See canonical.launchpad.interfaces.ITableBatchNavigator."""
     implements(ITableBatchNavigator)

=== modified file 'lib/lp/blueprints/browser/tests/test_specificationtarget.py'
--- lib/lp/blueprints/browser/tests/test_specificationtarget.py	2010-09-17 14:04:29 +0000
+++ lib/lp/blueprints/browser/tests/test_specificationtarget.py	2010-09-20 05:15:57 +0000
@@ -3,11 +3,9 @@
 
 __metaclass__ = type
 
-import unittest
 
 from zope.security.proxy import removeSecurityProxy
 
-from canonical.launchpad.webapp.batching import BatchNavigator
 from canonical.launchpad.testing.pages import find_tag_by_id
 from canonical.testing.layers import DatabaseFunctionalLayer
 from lp.blueprints.interfaces.specificationtarget import (
@@ -21,6 +19,7 @@
     login_person,
     TestCaseWithFactory,
     )
+from lp.testing.matchers import IsConfiguredBatchNavigator
 from lp.testing.views import (
     create_view,
     create_initialized_view,
@@ -103,27 +102,17 @@
             '<div id="involvement" class="portlet involvement">' in view())
 
     def test_specs_batch(self):
-        # Some pages turn up in very large contexts and patch. E.g.
+        # Some pages turn up in very large contexts and so batch. E.g.
         # Distro:+assignments which uses SpecificationAssignmentsView, a
         # subclass.
         person = self.factory.makePerson()
         view = create_initialized_view(person, name='+assignments')
-        self.assertIsInstance(view.specs_batched, BatchNavigator)
-
-    def test_batch_headings(self):
-        person = self.factory.makePerson()
-        view = create_initialized_view(person, name='+assignments')
-        navigator = view.specs_batched
-        self.assertEqual('specification', navigator._singular_heading)
-        self.assertEqual('specifications', navigator._plural_heading)
-
-    def test_batch_size(self):
         # Because +assignments is meant to provide an overview, we default to
         # 500 as the default batch size.
-        person = self.factory.makePerson()
-        view = create_initialized_view(person, name='+assignments')
-        navigator = view.specs_batched
-        self.assertEqual(500, view.specs_batched.default_size)
+        self.assertThat(
+            view.specs_batched,
+            IsConfiguredBatchNavigator(
+                'specification', 'specifications', batch_size=500))
 
 
 class TestAssignments(TestCaseWithFactory):
@@ -243,13 +232,3 @@
         login_person(project_group.owner)
         view = create_initialized_view(project_group, '+specs')
         self.assertEqual(False, view.can_configure_blueprints)
-
-
-def test_suite():
-    suite = unittest.TestSuite()
-    suite.addTest(unittest.TestLoader().loadTestsFromName(__name__))
-    return suite
-
-
-if __name__ == '__main__':
-    unittest.TextTestRunner().run(test_suite())

=== modified file 'lib/lp/bugs/browser/bugtracker.py'
--- lib/lp/bugs/browser/bugtracker.py	2010-09-03 15:02:39 +0000
+++ lib/lp/bugs/browser/bugtracker.py	2010-09-20 05:15:57 +0000
@@ -54,7 +54,11 @@
     structured,
     )
 from canonical.launchpad.webapp.authorization import check_permission
-from canonical.launchpad.webapp.batching import BatchNavigator
+from canonical.launchpad.webapp.batching import (
+    ActiveBatchNavigator,
+    BatchNavigator,
+    InactiveBatchNavigator,
+    )
 from canonical.launchpad.webapp.breadcrumb import Breadcrumb
 from canonical.launchpad.webapp.menu import NavigationMenu
 from canonical.lazr.utils import smartquote
@@ -154,21 +158,30 @@
     pillar_limit = 3
 
     def initialize(self):
-        # Sort the bug trackers into active and inactive lists so that
-        # we can display them separately.
-        all_bug_trackers = list(self.context)
-        self.active_bug_trackers = [
-            bug_tracker for bug_tracker in all_bug_trackers
-            if bug_tracker.active]
-        self.inactive_bug_trackers = [
-            bug_tracker for bug_tracker in all_bug_trackers
-            if not bug_tracker.active]
-
-        bugtrackerset = getUtility(IBugTrackerSet)
-        # The caching of bugtracker pillars here avoids us hitting the
-        # database multiple times for each bugtracker.
-        self._pillar_cache = bugtrackerset.getPillarsForBugtrackers(
-            all_bug_trackers)
+        # eager load related pillars. In future we should do this for
+        # just the rendered trackers, and also use group by to get
+        # bug watch counts per tracker. However the batching makes
+        # the inefficiency tolerable for now. Robert Collins 20100919.
+        self._pillar_cache = self.context.getPillarsForBugtrackers(
+            list(self.context.trackers()))
+
+    @property
+    def inactive_tracker_count(self):
+        return self.inactive_trackers.currentBatch().listlength
+
+    @cachedproperty
+    def active_trackers(self):
+        results = self.context.trackers(active=True)
+        navigator = ActiveBatchNavigator(results, self.request)
+        navigator.setHeadings('tracker', 'trackers')
+        return navigator
+
+    @cachedproperty
+    def inactive_trackers(self):
+        results = self.context.trackers(active=False)
+        navigator = InactiveBatchNavigator(results, self.request)
+        navigator.setHeadings('tracker', 'trackers')
+        return navigator
 
     def getPillarData(self, bugtracker):
         """Return dict of pillars and booleans indicating ellipsis.

=== modified file 'lib/lp/bugs/browser/tests/test_bugtracker_views.py'
--- lib/lp/bugs/browser/tests/test_bugtracker_views.py	2010-08-26 20:08:43 +0000
+++ lib/lp/bugs/browser/tests/test_bugtracker_views.py	2010-09-20 05:15:57 +0000
@@ -3,27 +3,61 @@
 
 """Tests for BugTracker views."""
 
+from __future__ import with_statement
+
 __metaclass__ = type
 
-import unittest
-
-from datetime import datetime, timedelta
-from pytz import utc
-
 from zope.component import getUtility
-from zope.security.interfaces import Unauthorized
 
-from canonical.launchpad.interfaces.launchpad import ILaunchpadCelebrities
+from canonical.launchpad.testing.pages import find_tag_by_id
+from canonical.launchpad.webapp import canonical_url
 from canonical.testing.layers import DatabaseFunctionalLayer
-
-from lp.bugs.browser.bugtracker import (
-    BugTrackerEditView)
+from lp.bugs.interfaces.bugtracker import IBugTrackerSet
 from lp.registry.interfaces.person import IPersonSet
-from lp.testing import login, TestCaseWithFactory
-from lp.testing.sampledata import ADMIN_EMAIL, NO_PRIVILEGE_EMAIL
+from lp.testing import (
+    login,
+    TestCaseWithFactory,
+    )
 from lp.testing.views import create_initialized_view
-
-
-
-def test_suite():
-    return unittest.TestLoader().loadTestsFromName(__name__)
+from lp.testing.matchers import IsConfiguredBatchNavigator
+from lp.testing import (
+    person_logged_in,
+    TestCaseWithFactory,
+    )
+from lp.testing.sampledata import ADMIN_EMAIL
+
+
+class TestBugTrackerSetView(TestCaseWithFactory):
+
+    layer = DatabaseFunctionalLayer
+
+    def test_trackers_are_batch_navigators(self):
+        trackers = getUtility(IBugTrackerSet)
+        view = create_initialized_view(trackers, name='+index')
+        matcher = IsConfiguredBatchNavigator('tracker', 'trackers')
+        self.assertThat(view.active_trackers, matcher)
+        self.assertThat(view.inactive_trackers, matcher)
+
+    def test_page_is_batched(self):
+        active_tracker1 = self.factory.makeBugTracker()
+        active_tracker2 = self.factory.makeBugTracker()
+        inactive_tracker1 = self.factory.makeBugTracker()
+        inactive_tracker2 = self.factory.makeBugTracker()
+        admin = getUtility(IPersonSet).find(ADMIN_EMAIL).any()
+        with person_logged_in(admin):
+            inactive_tracker1.active = False
+            inactive_tracker2.active = False
+        trackers = getUtility(IBugTrackerSet)
+        url = (canonical_url(trackers) +
+            "/+index?active_batch=1&inactive_batch=1")
+        browser = self.getUserBrowser(url)
+        content = browser.contents
+        # XXX RobertCollns 20100919 bug=642504. The support for multiple batches
+        # isn't complete and the id for the nav links gets duplicated.
+        #self.assertEqual('next',
+        #    find_tag_by_id(content, 'upper-batch-nav-batchnav-next')['class'])
+        #self.assertEqual('next',
+        #    find_tag_by_id(content, 'lower-batch-nav-batchnav-next')['class'])
+        # Instead we check the string appears.
+        self.assertTrue('upper-batch-nav-batchnav-next' in content)
+

=== modified file 'lib/lp/bugs/interfaces/bugtracker.py'
--- lib/lp/bugs/interfaces/bugtracker.py	2010-08-26 20:08:43 +0000
+++ lib/lp/bugs/interfaces/bugtracker.py	2010-09-20 05:15:57 +0000
@@ -432,6 +432,14 @@
     def getPillarsForBugtrackers(bug_trackers):
         """Return dict mapping bugtrackers to lists of pillars."""
 
+    def trackers(active=None):
+        """Return a ResultSet of bugtrackers.
+
+        :param active: If True, only active trackers are returned, if False
+            only inactive trackers are returned. All trackers are returned
+            by default.
+        """
+
 
 class IBugTrackerAlias(Interface):
     """Another URL for a remote bug system.

=== modified file 'lib/lp/bugs/model/bugtracker.py'
--- lib/lp/bugs/model/bugtracker.py	2010-08-26 20:08:43 +0000
+++ lib/lp/bugs/model/bugtracker.py	2010-09-20 05:15:57 +0000
@@ -8,7 +8,8 @@
     'BugTracker',
     'BugTrackerAlias',
     'BugTrackerAliasSet',
-    'BugTrackerSet']
+    'BugTrackerSet',
+    ]
 
 
 from datetime import datetime
@@ -66,6 +67,8 @@
     IBugTrackerSet,
     SINGLE_PRODUCT_BUGTRACKERTYPES,
     )
+from canonical.launchpad.webapp.interfaces import (
+        DEFAULT_FLAVOR, IStoreSelector, MAIN_STORE)
 from lp.bugs.interfaces.bugtrackerperson import BugTrackerPersonAlreadyExists
 from lp.bugs.model.bug import Bug
 from lp.bugs.model.bugmessage import BugMessage
@@ -577,6 +580,17 @@
         """See `IBugTrackerSet`."""
         return BugTracker.select()
 
+    def trackers(self, active=None):
+        # Without context, cannot tell what store flavour is desirable.
+        store = getUtility(IStoreSelector).get(MAIN_STORE, DEFAULT_FLAVOR)
+        if active is not None:
+            clauses = [BugTracker.active==active]
+        else:
+            clauses = []
+        results = store.find(BugTracker, *clauses)
+        results.order_by(BugTracker.name)
+        return results
+
     def ensureBugTracker(self, baseurl, owner, bugtrackertype,
         title=None, summary=None, contactdetails=None, name=None):
         """See `IBugTrackerSet`."""

=== modified file 'lib/lp/bugs/stories/bugtracker/bugtrackers-index.txt'
--- lib/lp/bugs/stories/bugtracker/bugtrackers-index.txt	2010-07-26 13:30:57 +0000
+++ lib/lp/bugs/stories/bugtracker/bugtrackers-index.txt	2010-09-20 05:15:57 +0000
@@ -39,11 +39,11 @@
     Email Address
     0
     ------------------------
-    GNU Savannah Bug Tracker
-    http://savannah.gnu.org/
-      --> http://savannah.gnu.org/
+    T'other Gnome GBugGTracker
+    http://bugzilla.gnome.org/
+      --> http://bugzilla.gnome.org/
     &mdash;
-    Savane
+    Bugzilla
     0
     ------------------------
     ...
@@ -68,6 +68,8 @@
     &mdash;
     Email Address
     0
+    ------------------------
+    ...
 
 The watch counts match the number of bugs listed, of course:
 

=== modified file 'lib/lp/bugs/templates/bugtrackers-index.pt'
--- lib/lp/bugs/templates/bugtrackers-index.pt	2009-09-01 16:24:52 +0000
+++ lib/lp/bugs/templates/bugtrackers-index.pt	2010-09-20 05:15:57 +0000
@@ -13,6 +13,7 @@
   </tal:comment>
   <metal:macros fill-slot="bogus">
     <metal:macro define-macro="tracker-table">
+      <tal:navigation content="structure trackers/@@+navigation-links-upper" />
       <table class="sortable listing" tal:attributes="id id">
         <thead>
           <tr>
@@ -24,7 +25,7 @@
           </tr>
         </thead>
         <tbody>
-          <tr tal:repeat="tracker trackers">
+          <tr tal:repeat="tracker trackers/currentBatch">
             <td>
               <a tal:replace="structure tracker/fmt:link" />
             </td>
@@ -53,6 +54,7 @@
           </tr>
         </tbody>
       </table>
+      <tal:navigation content="structure trackers/@@+navigation-links-lower" />
     </metal:macro>
   </metal:macros>
 
@@ -70,7 +72,7 @@
           the external status changes.
         </p>
         <tal:table define="id string:trackers;
-                           trackers view/active_bug_trackers">
+                           trackers view/active_trackers">
           <metal:table use-macro="template/macros/tracker-table" />
         </tal:table>
         <p style="margin-top: 1em"
@@ -81,11 +83,11 @@
         </p>
       </div>
     </div>
-    <div class="yui-u" tal:condition="view/inactive_bug_trackers">
+    <div class="yui-u" tal:condition="view/inactive_tracker_count">
       <div class="portlet">
         <h2>Inactive bug trackers</h2>
         <tal:table define="id string:inactive-trackers;
-                           trackers view/inactive_bug_trackers">
+                           trackers view/inactive_trackers">
           <metal:table use-macro="template/macros/tracker-table" />
         </tal:table>
       </div>

=== modified file 'lib/lp/bugs/tests/test_bugtracker.py'
--- lib/lp/bugs/tests/test_bugtracker.py	2010-08-26 20:08:43 +0000
+++ lib/lp/bugs/tests/test_bugtracker.py	2010-09-20 05:15:57 +0000
@@ -28,7 +28,10 @@
 
 from canonical.launchpad.ftests import login_person
 from canonical.launchpad.interfaces.launchpad import ILaunchpadCelebrities
-from canonical.testing import LaunchpadFunctionalLayer
+from canonical.testing import (
+    DatabaseFunctionalLayer,
+    LaunchpadFunctionalLayer,
+    )
 from lp.bugs.externalbugtracker import (
     BugTrackerConnectError,
     Mantis,
@@ -38,12 +41,36 @@
     BugTrackerType,
     IBugTracker,
     )
+from lp.bugs.model.bugtracker import BugTrackerSet
 from lp.bugs.tests.externalbugtracker import Urlib2TransportTestHandler
 from lp.registry.interfaces.person import IPersonSet
 from lp.testing import login, login_person, TestCaseWithFactory
 from lp.testing.sampledata import ADMIN_EMAIL
 
 
+class TestBugTrackerSet(TestCaseWithFactory):
+
+    layer = DatabaseFunctionalLayer
+
+    def test_trackers(self):
+        tracker = self.factory.makeBugTracker()
+        trackers = BugTrackerSet()
+        # Active trackers are in all trackers,
+        self.assertTrue(tracker in trackers.trackers())
+        # and active,
+        self.assertTrue(tracker in trackers.trackers(active=True))
+        # But not inactive.
+        self.assertFalse(tracker in trackers.trackers(active=False))
+        login(ADMIN_EMAIL)
+        tracker.active = False
+        # Inactive trackers are in all trackers
+        self.assertTrue(tracker in trackers.trackers())
+        # and inactive,
+        self.assertTrue(tracker in trackers.trackers(active=False))
+        # but not in active.
+        self.assertFalse(tracker in trackers.trackers(active=True))
+
+
 class BugTrackerTestCase(TestCaseWithFactory):
     """Unit tests for the `BugTracker` class."""
 

=== modified file 'lib/lp/registry/browser/person.py'
--- lib/lp/registry/browser/person.py	2010-09-15 16:44:41 +0000
+++ lib/lp/registry/browser/person.py	2010-09-20 05:15:57 +0000
@@ -194,7 +194,11 @@
     structured,
     )
 from canonical.launchpad.webapp.authorization import check_permission
-from canonical.launchpad.webapp.batching import BatchNavigator
+from canonical.launchpad.webapp.batching import (
+    ActiveBatchNavigator,
+    BatchNavigator,
+    InactiveBatchNavigator,
+    )
 from canonical.launchpad.webapp.breadcrumb import Breadcrumb
 from canonical.launchpad.webapp.interfaces import (
     ILaunchBag,
@@ -1385,24 +1389,6 @@
     links = ['profile', 'polls', 'members', 'ppas']
 
 
-class ActiveBatchNavigator(BatchNavigator):
-    """A paginator for active items.
-
-    Used when a view needs to display more than one BatchNavigator of items.
-    """
-    start_variable_name = 'active_start'
-    batch_variable_name = 'active_batch'
-
-
-class InactiveBatchNavigator(BatchNavigator):
-    """A paginator for inactive items.
-
-    Used when a view needs to display more than one BatchNavigator of items.
-    """
-    start_variable_name = 'inactive_start'
-    batch_variable_name = 'inactive_batch'
-
-
 class TeamMembershipView(LaunchpadView):
     """The view behind ITeam/+members."""
 

=== modified file 'lib/lp/registry/browser/team.py'
--- lib/lp/registry/browser/team.py	2010-09-17 18:32:23 +0000
+++ lib/lp/registry/browser/team.py	2010-09-20 05:15:57 +0000
@@ -829,8 +829,6 @@
         """
         results = self.mailing_list.getReviewableMessages()
         navigator = BatchNavigator(results, self.request)
-        # Subclasses often set the singular and plural headings,
-        # but we can use the generic class too.
         navigator.setHeadings('message', 'messages')
         return navigator
 

=== modified file 'lib/lp/registry/browser/tests/test_team.py'
--- lib/lp/registry/browser/tests/test_team.py	2010-09-14 00:21:04 +0000
+++ lib/lp/registry/browser/tests/test_team.py	2010-09-20 05:15:57 +0000
@@ -3,10 +3,10 @@
 
 __metaclass__ = type
 
-from canonical.launchpad.webapp.batching import BatchNavigator
 from canonical.testing import DatabaseFunctionalLayer
 from lp.registry.browser.person import TeamOverviewMenu
 from lp.testing import TestCaseWithFactory
+from lp.testing.matchers import IsConfiguredBatchNavigator
 from lp.testing.menu import check_menu_links
 from lp.testing.views import create_initialized_view
 
@@ -47,12 +47,6 @@
         team = self.factory.makeTeam()
         self.factory.makeMailingList(team, team.teamowner)
         view = create_initialized_view(team, name='+mailinglist-moderate')
-        self.assertIsInstance(view.held_messages, BatchNavigator)
-
-    def test_held_message_headings(self):
-        team = self.factory.makeTeam()
-        self.factory.makeMailingList(team, team.teamowner)
-        view = create_initialized_view(team, name='+mailinglist-moderate')
-        navigator = view.held_messages
-        self.assertEqual('message', navigator._singular_heading)
-        self.assertEqual('messages', navigator._plural_heading)
+        self.assertThat(
+            view.held_messages,
+            IsConfiguredBatchNavigator('message', 'messages'))

=== modified file 'lib/lp/testing/matchers.py'
--- lib/lp/testing/matchers.py	2010-08-25 20:04:40 +0000
+++ lib/lp/testing/matchers.py	2010-09-20 05:15:57 +0000
@@ -17,9 +17,12 @@
 from testtools.content import Content
 from testtools.content_type import UTF8_TEXT
 from testtools.matchers import (
+    Equals,
     Matcher,
     Mismatch,
+    MismatchesAll,
     )
+from testtools import matchers
 from zope.interface.exceptions import (
     BrokenImplementation,
     BrokenMethodImplementation,
@@ -31,6 +34,8 @@
     Proxy,
     )
 
+from canonical.launchpad.webapp.batching import BatchNavigator
+
 
 class DoesNotProvide(Mismatch):
     """An object does not provide an interface."""
@@ -220,3 +225,45 @@
         if not matchee.startswith(self.expected):
             return DoesNotStartWith(matchee, self.expected)
         return None
+
+
+class IsConfiguredBatchNavigator(Matcher):
+    """Check that an object is a batch navigator."""
+
+    def __init__(self, singular, plural, batch_size=None):
+        """Create a ConfiguredBatchNavigator.
+
+        :param singular: The singular header the batch should be using.
+        :param plural: The plural header the batch should be using.
+        :param batch_size: The batch size that should be configured by default.
+        """
+        self._single = Equals(singular)
+        self._plural = Equals(plural)
+        self._batch = None
+        if batch_size:
+            self._batch = Equals(batch_size)
+        self.matchers = dict(
+            _singular_heading=self._single, _plural_heading=self._plural)
+        if self._batch:
+            self.matchers['default_size'] = self._batch
+
+    def __str__(self):
+        if self._batch:
+            batch = ", %r" % self._batch.expected
+        else:
+            batch = ''
+        return "ConfiguredBatchNavigator(%r, %r%s)" % (
+            self._single.expected, self._plural.expected, batch)
+
+    def match(self, matchee):
+        if not isinstance(matchee, BatchNavigator):
+            # Testtools doesn't have an IsInstanceMismatch yet.
+            return matchers._BinaryMismatch(
+                BatchNavigator, 'isinstance', matchee)
+        mismatches = []
+        for attrname, matcher in self.matchers.items():
+            mismatch = matcher.match(getattr(matchee, attrname))
+            if mismatch is not None:
+                mismatches.append(mismatch)
+        if mismatches:
+            return MismatchesAll(mismatches)