Add a warnings module capture fixure

Capturing the warnings module output (which is typically used
for deprecating code or functions or modules) is quite useful and
is a frequent operation that can be required to perform. So provide
a fixture that is similar (but not the same) as the warnings
``catch_warnings`` context manager that can be used to gather all
warnings emitted and allows people to later analyze them to ensure
they are as they expect.

1 files changed, 49 insertions, 0 deletions

diff --git a/fixtures/tests/_fixtures/test_warnings.py b/fixtures/tests/_fixtures/test_warnings.py
new file mode 100644
index 0000000..4731626
--- /dev/null
+++ b/fixtures/tests/_fixtures/test_warnings.py
@@ -0,0 +1,49 @@
+#  fixtures: Fixtures with cleanups for testing and convenience.
+#
+# Licensed under either the Apache License, Version 2.0 or the BSD 3-clause
+# license at the users choice. A copy of both licenses are available in the
+# project source as Apache-2.0 and BSD. You may not use this file except in
+# compliance with one of these two licences.
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under these licenses is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# license you chose for the specific language governing permissions and
+# limitations under that license.
+
+import warnings
+
+import testtools
+
+import fixtures
+
+
+class TestWarnings(testtools.TestCase, fixtures.TestWithFixtures):
+
+    def test_capture_reuse(self):
+        w = fixtures.WarningsCapture()
+        with w:
+            warnings.warn("test", DeprecationWarning)
+            self.assertEqual(1, len(w.captures))
+        with w:
+            self.assertEqual([], w.captures)
+
+    def test_capture_message(self):
+        w = self.useFixture(fixtures.WarningsCapture())
+        warnings.warn("hi", DeprecationWarning)
+        self.assertEqual(1, len(w.captures))
+        self.assertEqual("hi", str(w.captures[0].message))
+
+    def test_capture_category(self):
+        w = self.useFixture(fixtures.WarningsCapture())
+        categories = [
+            DeprecationWarning, Warning, UserWarning,
+            SyntaxWarning, RuntimeWarning,
+            UnicodeWarning, FutureWarning,
+        ]
+        for category in categories:
+            warnings.warn("test", category)
+        self.assertEqual(len(categories), len(w.captures))
+        for i, category in enumerate(categories):
+            c = w.captures[i]
+            self.assertEqual(category, c.category)