Merge lp:~gmb/launchpad/bug-1009712 into lp:launchpad

[Graham Binns]

test_set_feature_flags_raises_if_not_available() will no longer fail in parallel testing environments after being disabused of the assumption that no feature controller has been installed.

This branch fixes bug 1009712, which was caused by test_set_feature_flags_raises_if_not_available assuming that there is no feature controller when it gets run (hurrah for implied test isolation).

The fix was simple: I added a function that allows us to uninstall an existing feature controller from the thread and then called that from within the test. I also updated the test's docstring, which was pretty uninformative.

[Abel Deuring (adeuring)]

Aside from the "test_noise" noise, this looks good.

review: Approve (code)

=== modified file 'lib/lp/services/features/__init__.py'
--- lib/lp/services/features/__init__.py	2011-10-27 15:04:26 +0000
+++ lib/lp/services/features/__init__.py	2012-06-08 10:09:34 +0000
@@ -205,9 +205,16 @@
     per_thread.features = controller
 
 
+def uninstall_feature_controller():
+    """Remove the current feature controller from this thread.
+
+    This function is used to create a pristine environment in tests.
+    """
+    del per_thread.features
+
+
 def get_relevant_feature_controller():
     """Get a `FeatureController` for this thread."""
-
     # The noncommittal name "relevant" is because this function may change to
     # look things up from the current request or some other mechanism in
     # future.

=== modified file 'lib/lp/testing/tests/test_testing.py'
--- lib/lp/testing/tests/test_testing.py	2012-01-01 02:58:52 +0000
+++ lib/lp/testing/tests/test_testing.py	2012-06-08 10:09:34 +0000
@@ -9,7 +9,10 @@
 import tempfile
 
 from lp.services.config import config
-from lp.services.features import getFeatureFlag
+from lp.services.features import (
+    getFeatureFlag,
+    uninstall_feature_controller,
+    )
 from lp.testing import (
     feature_flags,
     NestedTempfile,
@@ -25,7 +28,13 @@
     layer = DatabaseFunctionalLayer
 
     def test_set_feature_flags_raises_if_not_available(self):
-        """set_feature_flags prevents mistakes mistakes by raising."""
+        """set_feature_flags raises an error if there is no feature
+        controller available for the current thread.
+        """
+        # Remove any existing feature controller for the sake of this
+        # test (other tests will re-add it). This prevents weird
+        # interactions in a parallel test environment.
+        uninstall_feature_controller()
         self.assertRaises(AssertionError, set_feature_flag, u'name', u'value')
 
     def test_flags_set_within_feature_flags_context(self):