Always activate testing using pytest fixture.

This is possibly the cleaner approach to the problem solved
in the previous commit.

The previous commit makes sure, that testing is enabled at
import time. While this one enables it just before the
individual test is run. So this one takes a bit more CPU.

Maybe revert the previous commit?

References: 0536306048daa0970d2e43411ba2a9bf073e570e

mediagoblin/tests/conftest.py

@@ -1,7 +1,25 @@
-from mediagoblin.tests import tools
+# GNU MediaGoblin -- federated, autonomous media hosting
+# Copyright (C) 2013 MediaGoblin contributors.  See AUTHORS.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import pytest
 
+from mediagoblin.tests import tools
+from mediagoblin.tools.testing import _activate_testing
+
+
 @pytest.fixture()
 def test_app(request):
     """
@@ -13,3 +31,11 @@ def test_app(request):
     in differently to get_app.
     """
     return tools.get_app(request)
+
+
+@pytest.fixture()
+def pt_fixture_enable_testing():
+    """
+    py.test fixture to enable testing mode in tools.
+    """
+    _activate_testing()

mediagoblin/tests/pytest.ini

@@ -1,2 +1,2 @@
 [pytest]
-usefixtures = tmpdir
+usefixtures = tmpdir pt_fixture_enable_testing