diff --git a/swh/web/ui/tests/test_app.py b/swh/web/ui/tests/test_app.py
index 19ced3717..3e21ed8b2 100644
--- a/swh/web/ui/tests/test_app.py
+++ b/swh/web/ui/tests/test_app.py
@@ -1,86 +1,88 @@
 # Copyright (C) 2015  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU Affero General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 # Functions defined here are NOT DESIGNED FOR PRODUCTION
 
 import unittest
 from swh.storage.api.client import RemoteStorage as Storage
 from swh.web.ui import renderers, main
 from flask.ext.testing import TestCase
 
 
 # Because the Storage's __init__ function does side effect at startup...
 class RemoteStorageAdapter(Storage):
     def __init__(self, base_url):
         self.base_url = base_url
 
 
 def _init_mock_storage(base_url='https://somewhere.org:4321'):
     """Instanciate a remote storage whose goal is to be mocked in a test
     context.
 
     NOT FOR PRODUCTION
 
     Returns:
         An instance of swh.storage.api.client.RemoteStorage destined to be
         mocked (it does not do any rest call)
 
     """
     return RemoteStorageAdapter(base_url)  # destined to be used as mock
 
 
 def create_app(base_url='https://somewhere.org:4321'):
     """Function to initiate a flask app with storage designed to be mocked.
 
     Returns:
         Tuple:
         - app test client (for testing api, client decorator from flask)
         - application's full configuration
         - the storage instance to stub and mock
         - the main app without any decoration
 
     NOT FOR PRODUCTION
 
     """
     storage = _init_mock_storage(base_url)
 
     # inject the mock data
     conf = {'storage': storage,
             'upload_folder': '/some/upload-dir',
             'upload_allowed_extensions': ['txt'],
             'max_upload_size': 1024}
 
-    main.app.config['TESTING'] = True
     main.app.config.update({'conf': conf})
     main.app.config['MAX_CONTENT_LENGTH'] = conf['max_upload_size']
     main.app.config['DEFAULT_RENDERERS'] = renderers.RENDERERS
-    main.load_controllers()
+
+    if not main.app.config['TESTING']:  # HACK: install controllers only once!
+        main.app.config['TESTING'] = True
+        main.load_controllers()
 
     return main.app.test_client(), main.app.config, storage, main.app
 
 
 class SWHApiTestCase(unittest.TestCase):
     """Testing API class.
 
     """
     @classmethod
     def setUpClass(cls):
         cls.app, cls.app_config, cls.storage, _ = create_app()
 
 
 class SWHViewTestCase(TestCase):
     """Testing view class.
 
     cf. http://pythonhosted.org/Flask-Testing/
     """
     # This inhibits template rendering
     # render_templates = False
     def create_app(self):
         """Initialize a Flask-Testing application instance to test view
         without template rendering
 
         """
         _, _, _, appToDecorate = create_app()
         return appToDecorate