Add ability to disable warnings being emitted

Provide a helpful fixture that can be used
to disable warnings being output, for testing, or other
purporses.

Closes-Bug: #1503918

Change-Id: I2e1fd6f427ff6ee6d0b11b86ac2ff1b75dc0548c

debtcollector/_utils.py

@@ -30,6 +30,7 @@ except AttributeError:
 # and see https://docs.python.org/2/reference/executionmodel.html (and likely
 # others)...
 _BUILTIN_MODULES = ('builtins', '__builtin__', '__builtins__', 'exceptions')
+_enabled = True
 
 
 def deprecation(message, stacklevel=None, category=None):
@@ -49,6 +50,8 @@ def deprecation(message, stacklevel=None, category=None):
     avoid doing by always giving at *least* N + 1 release for users to address
     the deprecation warnings).
     """
+    if not _enabled:
+        return
     if category is None:
         category = DeprecationWarning
     if stacklevel is None:

debtcollector/fixtures/disable.py

@@ -0,0 +1,39 @@
+# -*- coding: utf-8 -*-
+
+#    Copyright (C) 2015 Yahoo! Inc. 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 __future__ import absolute_import
+
+import fixtures
+
+from debtcollector import _utils
+
+
+class DisableFixture(fixtures.Fixture):
+    """Fixture that disables debtcollector triggered warnings.
+
+    This does **not** disable warnings calls emitted by other libraries.
+
+    This can be used like::
+
+        from debtcollector.fixtures import disable
+
+        with disable.DisableFixture():
+            <some code that calls into depreciated code>
+    """
+
+    def _setUp(self):
+        self.addCleanup(setattr, _utils, "_enabled", True)
+        _utils._enabled = False

debtcollector/tests/test_deprecation.py

@@ -15,6 +15,7 @@
 import warnings
 
 import debtcollector
+from debtcollector.fixtures import disable
 from debtcollector import moves
 from debtcollector import removals
 from debtcollector import renames
@@ -225,6 +226,19 @@ class MovedPropertyTest(test_base.TestCase):
         self.assertEqual(0, len(capture))
 
 
+class DisabledTest(test_base.TestCase):
+    def test_basics(self):
+        dog = WoofWoof()
+        c = KittyKat()
+        with warnings.catch_warnings(record=True) as capture:
+            warnings.simplefilter("always")
+            with disable.DisableFixture():
+                self.assertTrue(yellowish_sun())
+                self.assertEqual('woof', dog.berk)
+                self.assertEqual('supermeow', c.meow())
+        self.assertEqual(0, len(capture))
+
+
 class MovedFunctionTest(test_base.TestCase):
     def test_basics(self):
         self.assertTrue(yellowish_sun())

doc/source/api.rst

@@ -31,3 +31,8 @@ Removals
 --------
 
 .. automodule:: debtcollector.removals
+
+Fixtures
+--------
+
+.. automodule:: debtcollector.fixtures.disable

test-requirements.txt

@@ -13,4 +13,5 @@ oslotest>=1.10.0 # Apache-2.0
 testrepository>=0.0.18
 testscenarios>=0.4
 testtools>=1.4.0
+fixtures>=1.3.1
 doc8 # Apache-2.0