Allow mapping _ to lazy gettext path

Since nova has switched from using gettext.install for
importing the _ function to explicitly importing the _
function from gettextutils, we need to be able to enable
our deferred translation code path on the gettextutils._
function.

Change-Id: I7fec00810ea57c985e1f43c644913a9980b35655

2 files changed, 53 insertions, 1 deletions

diff --git a/openstack/common/gettextutils.py b/openstack/common/gettextutils.py
index bbf8fe9..321fdd0 100644
--- a/openstack/common/gettextutils.py
+++ b/openstack/common/gettextutils.py
@@ -38,10 +38,26 @@ _localedir = os.environ.get('oslo'.upper() + '_LOCALEDIR')
 _t = gettext.translation('oslo', localedir=_localedir, fallback=True)
 
 _AVAILABLE_LANGUAGES = []
+USE_LAZY = False
+
+
+def enable_lazy():
+    """Convenience function for configuring _() to use lazy gettext
+
+    Call this at the start of execution to enable the gettextutils._
+    function to use lazy gettext functionality. This is useful if
+    your project is importing _ directly instead of using the
+    gettextutils.install() way of importing the _ function.
+    """
+    global USE_LAZY
+    USE_LAZY = True
 
 
 def _(msg):
-    return _t.ugettext(msg)
+    if USE_LAZY:
+        return Message(msg, 'oslo')
+    else:
+        return _t.ugettext(msg)
 
 
 def install(domain, lazy=False):
diff --git a/tests/unit/test_gettext.py b/tests/unit/test_gettext.py
index d9cb9b8..ef16ac3 100644
--- a/tests/unit/test_gettext.py
+++ b/tests/unit/test_gettext.py
@@ -33,6 +33,42 @@ LOG = logging.getLogger(__name__)
 
 class GettextTest(utils.BaseTestCase):
 
+    def setUp(self):
+        super(GettextTest, self).setUp()
+        # remember so we can reset to it later
+        self._USE_LAZY = gettextutils.USE_LAZY
+
+    def tearDown(self):
+        # reset to value before test
+        gettextutils.USE_LAZY = self._USE_LAZY
+        super(GettextTest, self).tearDown()
+
+    def test_enable_lazy(self):
+        gettextutils.USE_LAZY = False
+
+        gettextutils.enable_lazy()
+        # assert now enabled
+        self.assertTrue(gettextutils.USE_LAZY)
+
+    def test_underscore_non_lazy(self):
+        # set lazy off
+        gettextutils.USE_LAZY = False
+
+        self.mox.StubOutWithMock(gettextutils._t, 'ugettext')
+        gettextutils._t.ugettext('blah').AndReturn('translated blah')
+        self.mox.ReplayAll()
+
+        result = gettextutils._('blah')
+        self.assertEqual('translated blah', result)
+
+    def test_underscore_lazy(self):
+        # set lazy off
+        gettextutils.USE_LAZY = False
+
+        gettextutils.enable_lazy()
+        result = gettextutils._('blah')
+        self.assertIsInstance(result, gettextutils.Message)
+
     def test_gettext_does_not_blow_up(self):
         LOG.info(gettextutils._('test'))