--- a/cubicweb/devtools/fake.py	Thu Nov 17 10:53:04 2016 +0100
+++ b/cubicweb/devtools/fake.py	Thu Nov 17 10:15:11 2016 +0100
@@ -55,12 +55,20 @@
         return {'system': {'db-driver': 'sqlite'}}
 
 
+class FakeCWRegistryStore(CWRegistryStore):
+
+    def property_value(self, key):
+        if key == 'ui.language':
+            return 'en'
+        assert False
+
+
 class FakeRequest(ConnectionCubicWebRequestBase):
     """test implementation of an cubicweb request object"""
 
     def __init__(self, *args, **kwargs):
         if not (args or 'vreg' in kwargs):
-            kwargs['vreg'] = CWRegistryStore(FakeConfig(), initlog=False)
+            kwargs['vreg'] = FakeCWRegistryStore(FakeConfig(), initlog=False)
         kwargs['https'] = False
         self._http_method = kwargs.pop('method', 'GET')
         self._url = kwargs.pop('url', None)
@@ -134,7 +142,7 @@
         if vreg is None:
             vreg = getattr(self.repo, 'vreg', None)
         if vreg is None:
-            vreg = CWRegistryStore(FakeConfig(), initlog=False)
+            vreg = FakeCWRegistryStore(FakeConfig(), initlog=False)
         self.vreg = vreg
         self.cnxset = FakeConnectionsSet()
         self.user = user or FakeUser()
@@ -176,7 +184,7 @@
         self._count = 0
         self.schema = schema
         self.config = config or FakeConfig()
-        self.vreg = vreg or CWRegistryStore(self.config, initlog=False)
+        self.vreg = vreg or FakeCWRegistryStore(self.config, initlog=False)
         self.vreg.schema = schema
 
     def internal_session(self):

--- a/cubicweb/req.py	Thu Nov 17 10:53:04 2016 +0100
+++ b/cubicweb/req.py	Thu Nov 17 10:15:11 2016 +0100
@@ -96,7 +96,15 @@
         Raises :exc:`KeyError` if translation doesn't exist.
         """
         self.lang = lang
-        gettext, pgettext = self.vreg.config.translations[lang]
+        try:
+            gettext, pgettext = self.vreg.config.translations[lang]
+        except KeyError:
+            assert self.vreg.config.mode == 'test'
+            gettext = text_type
+
+            def pgettext(x, y):
+                return text_type(y)
+
         # use _cw.__ to translate a message without registering it to the catalog
         self._ = self.__ = gettext
         self.pgettext = pgettext

--- a/cubicweb/web/request.py	Thu Nov 17 10:53:04 2016 +0100
+++ b/cubicweb/web/request.py	Thu Nov 17 10:15:11 2016 +0100
@@ -146,10 +146,9 @@
         #: Header used for the final response
         self.headers_out = Headers()
         #: HTTP status use by the final response
-        self.status_out  = 200
-        # set up language based on request headers or site default (we don't
-        # have a user yet, and might not get one)
-        self.set_user_language(None)
+        self.status_out = 200
+        # set up language based on site default (we don't have a user yet, and might not get one)
+        self.set_language(vreg.property_value('ui.language'))
         #: dictionary that may be used to store request data that has to be
         #: shared among various components used to publish the request (views,
         #: controller, application...)
@@ -929,18 +928,6 @@
                 return lang
         return None
 
-    def set_user_language(self, user):
-        vreg = self.vreg
-        if user is not None:
-            try:
-                lang = vreg.typed_value('ui.language', user.properties['ui.language'])
-                self.set_language(lang)
-                return
-            except KeyError:
-                pass
-        # site's default language
-        self.set_default_language(vreg)
-
 
 def _cnx_func(name):
     def proxy(req, *args, **kwargs):
@@ -993,25 +980,15 @@
         self.cnx = cnx
         self.session = cnx.session
         self._set_user(cnx.user)
-        self.set_user_language(cnx.user)
+        # set language according to the one defined on the connection which consider user's
+        # preference
+        self.set_language(cnx.lang)
 
     def execute(self, *args, **kwargs):
         rset = self.cnx.execute(*args, **kwargs)
         rset.req = self
         return rset
 
-    def set_default_language(self, vreg):
-        try:
-            lang = vreg.property_value('ui.language')
-        except Exception: # property may not be registered
-            lang = 'en'
-        try:
-            self.set_language(lang)
-        except KeyError:
-            # this occurs usually during test execution
-            self._ = self.__ = text_type
-            self.pgettext = lambda x, y: text_type(y)
-
     entity_metas = _cnx_func('entity_metas')  # XXX deprecated
     entity_type = _cnx_func('entity_type')
     source_defs = _cnx_func('source_defs')

--- a/cubicweb/web/test/unittest_request.py	Thu Nov 17 10:53:04 2016 +0100
+++ b/cubicweb/web/test/unittest_request.py	Thu Nov 17 10:15:11 2016 +0100
@@ -6,7 +6,7 @@
 
 from six import text_type
 
-from cubicweb.devtools.fake import FakeConfig
+from cubicweb.devtools.fake import FakeConfig, FakeCWRegistryStore
 
 from cubicweb.web.request import (CubicWebRequestBase, _parse_accept_header,
                                   _mimetype_sort_key, _mimetype_parser, _charset_sort_key)
@@ -72,8 +72,7 @@
 class WebRequestTC(unittest.TestCase):
 
     def test_base_url(self):
-        dummy_vreg = type('DummyVreg', (object,), {})()
-        dummy_vreg.config = FakeConfig()
+        dummy_vreg = FakeCWRegistryStore(FakeConfig(), initlog=False)
         dummy_vreg.config['base-url'] = 'http://babar.com/'
         dummy_vreg.config['https-url'] = 'https://toto.com/'
 
@@ -88,8 +87,7 @@
         self.assertEqual('https://toto.com/', req.base_url(True))
 
     def test_negotiated_language(self):
-        vreg = type('DummyVreg', (object,), {})()
-        vreg.config = FakeConfig()
+        vreg = FakeCWRegistryStore(FakeConfig(), initlog=False)
         vreg.config.translations = {'fr': (None, None), 'en': (None, None)}
         headers = {
             'Accept-Language': 'fr,fr-fr;q=0.8,en-us;q=0.5,en;q=0.3',
@@ -98,7 +96,7 @@
         self.assertEqual(req.negotiated_language(), 'fr')
 
     def test_build_url_language_from_url(self):
-        vreg = type('DummyVreg', (object,), {'config': FakeConfig()})()
+        vreg = FakeCWRegistryStore(FakeConfig(), initlog=False)
         vreg.config['base-url'] = 'http://testing.fr/cubicweb/'
         vreg.config['language-mode'] = 'url-prefix'
         vreg.config.translations['fr'] = text_type, text_type