buildbucket: add longest_pending_time API

appengine/cr-buildbucket/test/api_test.py

Index: appengine/cr-buildbucket/test/api_test.py
diff --git a/appengine/cr-buildbucket/test/api_test.py b/appengine/cr-buildbucket/test/api_test.py
index e751bcb2a2e2df601666a02e0e43ddf5911e9500..4679456313dec368c16b45e450183e85f0c74415 100644
--- a/appengine/cr-buildbucket/test/api_test.py
+++ b/appengine/cr-buildbucket/test/api_test.py
@@ -620,6 +620,18 @@ class ApiTests(object):
     service.get.side_effect = auth.AuthorizationError
     self.call_api('get', {'id': 123}, status=403)
 
+  ############################# LONGEST_PENDING_TIME ###########################
+
+  def test_longest_pending_time(self):
+    service.longest_pending_time.return_value = datetime.timedelta(seconds=42)
+    req = {
+      'bucket': 'chromium',
+      'builder': 'x',
+    }
+    res = self.call_api('longest_pending_time', req).json_body
+    self.assertEqual(res['longest_pending_time_sec'], 42)
+    service.longest_pending_time.assert_called_once_with('chromium', 'x')
+
 
 class EndpointsApiTest(testing.EndpointsTestCase, ApiTests):
   api_service_cls = api.BuildBucketApi