=== modified file 'lib/lp/code/browser/tests/test_branch.py'
--- lib/lp/code/browser/tests/test_branch.py	2011-02-25 02:08:52 +0000
+++ lib/lp/code/browser/tests/test_branch.py	2011-02-25 02:29:04 +0000
@@ -19,6 +19,7 @@
 from canonical.config import config
 from canonical.database.constants import UTC_NOW
 from canonical.launchpad.helpers import truncate_text
+from canonical.launchpad.webapp.publisher import canonical_url
 from canonical.launchpad.webapp.servers import LaunchpadTestRequest
 from canonical.testing.layers import (
     DatabaseFunctionalLayer,
@@ -29,8 +30,6 @@
     find_tag_by_id,
     setupBrowser,
     )
-from canonical.launchpad.webapp.publisher import canonical_url
-
 from lp.app.interfaces.headings import IRootContext
 from lp.bugs.interfaces.bugtask import (
     BugTaskStatus,
@@ -58,6 +57,7 @@
     person_logged_in,
     TestCaseWithFactory,
     )
+from lp.testing.matchers import BrowsesWithQueryLimit
 from lp.testing.views import create_initialized_view


@@ -361,6 +361,28 @@
             self.assertTrue(
                 bug.bugtask.status in UNRESOLVED_BUGTASK_STATUSES)

+    def test_linked_bugs_branch_query_scaling(self):
+        # As we add linked bugs, the query count for a branch index page stays
+        # constant. We use a series branch to make sure we're capturing the
+        # overheads of shown *and* unshown bugs. Series branches only show
+        # open bugs, so adding bug links will add at least one new bug per
+        # call.
+        product = self.factory.makeProduct()
+        branch = self.factory.makeProductBranch(product=product)
+        browses_under_limit = BrowsesWithQueryLimit(54, branch.owner)
+        with person_logged_in(product.owner):
+            product.development_focus.branch = branch
+        # Start with some bugs, otherwise we might see a spurious increase
+        # depending on optimisations in eager loaders.
+        with person_logged_in(branch.owner):
+            self._addBugLinks(branch)
+            self.assertThat(branch, browses_under_limit)
+        with person_logged_in(branch.owner):
+            # Add plenty of bugs.
+            for _ in range(5):
+                self._addBugLinks(branch)
+            self.assertThat(branch, browses_under_limit)
+
     def _add_revisions(self, branch, nr_revisions=1):
         revisions = []
         for seq in range(1, nr_revisions+1):