Add a test fixture for translatable strings

Change-Id: I96aec806392672ff69a3af6c3e0a04a621656f78

doc/source/api.rst

@@ -31,3 +31,8 @@ oslo.i18n.log
 .. automodule:: oslo.i18n.log
    :members:
 
+oslo.i18n.fixture
+=================
+
+.. automodule:: oslo.i18n.fixture
+   :members:

oslo/i18n/fixture.py

@@ -0,0 +1,65 @@
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+"""Test fixtures for working with oslo.i18n.
+
+"""
+
+import fixtures
+import six
+
+from oslo.i18n import _message
+
+
+class Translation(fixtures.Fixture):
+    """Fixture for managing translatable strings.
+
+    This class provides methods for creating translatable strings
+    using both lazy translation and immediate translation. It can be
+    used to generate the different types of messages returned from
+    oslo.i18n to test code that may need to know about the type to
+    handle them differently (for example, error handling in WSGI apps,
+    or logging).
+
+    Use this class to generate messages instead of toggling the global
+    lazy flag and using the regular translation factory.
+
+    """
+
+    def __init__(self, domain='test-domain'):
+        """Initialize the fixture.
+
+        :param domain: The translation domain. This is not expected to
+                       coincide with an actual set of message
+                       catalogs, but it can.
+        :type domain: str
+        """
+        self.domain = domain
+
+    def lazy(self, msg):
+        """Return a lazily translated message.
+
+        :param msg: Input message string. May optionally include
+                    positional or named string interpolation markers.
+        :type msg: str or unicode
+
+        """
+        return _message.Message(msg, domain=self.domain)
+
+    def immediate(self, msg):
+        """Return a string as though it had been translated immediately.
+
+        :param msg: Input message string. May optionally include
+                    positional or named string interpolation markers.
+        :type msg: str or unicode
+
+        """
+        return six.text_type(msg)

tests/test_fixture.py

@@ -0,0 +1,38 @@
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from oslotest import base as test_base
+import six
+
+from oslo.i18n import _message
+from oslo.i18n import fixture
+
+
+class FixtureTest(test_base.BaseTestCase):
+
+    def setUp(self):
+        super(FixtureTest, self).setUp()
+        self.trans_fixture = self.useFixture(fixture.Translation())
+
+    def test_lazy(self):
+        msg = self.trans_fixture.lazy('this is a lazy message')
+        self.assertIsInstance(msg, _message.Message)
+        self.assertEqual(msg.msgid, 'this is a lazy message')
+
+    def test_immediate(self):
+        msg = self.trans_fixture.immediate('this is a lazy message')
+        # Python 2.6 does not have assertNotIsInstance
+        self.assertFalse(isinstance(msg, _message.Message))
+        self.assertIsInstance(msg, six.text_type)
+        self.assertEqual(msg, u'this is a lazy message')