Suppress deprecation warnings while collecting modules

- closes #542

Author: mrbean-bremen

CHANGES.md

@@ -3,6 +3,10 @@ The released versions correspond to PyPi releases.
 
 ## Version 4.2.0 (as yet unreleased)
 
+#### Fixes
+  * suppress deprecation warnings while collecting modules
+   (see [#542](../../issues/542))
+
 ## [Version 4.1.0](https://pypi.python.org/pypi/pyfakefs/4.1.0)
 
 #### New Features

pyfakefs/fake_filesystem_unittest.py

@@ -503,13 +503,19 @@ def _def_values(self, item):
         elif inspect.isclass(item):
             # check for methods in class (nested classes are ignored for now)
             try:
-                for m in inspect.getmembers(item,
-                                            predicate=inspect.isfunction):
-                    m = m[1]
-                    if m.__defaults__:
-                        for i, d in enumerate(m.__defaults__):
-                            if self._is_fs_function(d):
-                                yield m, i, d
+                with warnings.catch_warnings():
+                    # ignore deprecation warnings, see #542
+                    warnings.filterwarnings(
+                        'ignore',
+                        category=DeprecationWarning
+                    )
+                    for m in inspect.getmembers(item,
+                                                predicate=inspect.isfunction):
+                        m = m[1]
+                        if m.__defaults__:
+                            for i, d in enumerate(m.__defaults__):
+                                if self._is_fs_function(d):
+                                    yield m, i, d
             except Exception:
                 # Ignore any exception, examples:
                 # ImportError: No module named '_gdbm'

pyfakefs/tests/fake_filesystem_unittest_test.py

@@ -25,6 +25,7 @@
 import sys
 import tempfile
 import unittest
+import warnings
 from distutils.dir_util import copy_tree, remove_tree
 from unittest import TestCase
 
@@ -659,5 +660,20 @@ def test_cwd(self, fs):
         self.assertTrue(dot_abs.exists())
 
 
+class TestDeprecationSuppression(fake_filesystem_unittest.TestCase):
+    def test_no_deprecation_warning(self):
+        """Ensures that deprecation warnings are suppressed during module
+        lookup, see #542.
+        """
+
+        from pyfakefs.tests.fixtures.deprecated_property import \
+            DeprecationTest  # noqa: F401
+
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("error", DeprecationWarning)
+            self.setUpPyfakefs()
+            self.assertEqual(0, len(w))
+
+
 if __name__ == "__main__":
     unittest.main()

pyfakefs/tests/fixtures/deprecated_property.py

@@ -0,0 +1,28 @@
+# 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.
+
+"""Used for testing suppression of deprecation warnings while iterating
+over modules. The code is modeled after code in xmlbuilder.py in Python 3.6.
+See issue #542.
+"""
+import warnings
+
+
+class DeprecatedProperty:
+
+    def __get__(self, instance, cls):
+        warnings.warn("async is deprecated", DeprecationWarning)
+        return instance
+
+
+class DeprecationTest:
+    locals()['async'] = DeprecatedProperty()