Quench a bunch of warnings

setup.cfg

@@ -14,6 +14,7 @@ addopts = -ra
 testpaths = tests
 filterwarnings =
     once::Warning
+    ignore:::pympler[.*]
 
 
 [isort]

setup.py

@@ -41,7 +41,7 @@
         "coverage",
         "hypothesis",
         "pympler",
-        "pytest",
+        "pytest<3.9",
         "six",
         "zope.interface",
     ],

src/attr/_compat.py

@@ -20,6 +20,7 @@
 
 if PY2:
     from UserDict import IterableUserDict
+    from collections import Mapping, Sequence  # noqa
 
     # We 'bundle' isclass instead of using inspect as importing inspect is
     # fairly expensive (order of 10-15 ms for a modern machine in 2016)
@@ -89,8 +90,27 @@ def metadata_proxy(d):
         res.data.update(d)  # We blocked update, so we have to do it like this.
         return res
 
+    def just_warn(*args, **kw):  # pragma: nocover
+        """
+        We only warn on Python 3 because we are not aware of any concrete
+        consequences of not setting the cell on Python 2.
+        """
 
-else:
+
+else:  # Python 3 and later.
+    from collections.abc import Mapping, Sequence  # noqa
+
+    def just_warn(*args, **kw):
+        """
+        We only warn on Python 3 because we are not aware of any concrete
+        consequences of not setting the cell on Python 2.
+        """
+        warnings.warn(
+            "Missing ctypes.  Some features like bare super() or accessing "
+            "__class__ will not work with slots classes.",
+            RuntimeWarning,
+            stacklevel=2,
+        )
 
     def isclass(klass):
         return isinstance(klass, type)
@@ -113,30 +133,6 @@ def import_ctypes():
     return ctypes
 
 
-if not PY2:
-
-    def just_warn(*args, **kw):
-        """
-        We only warn on Python 3 because we are not aware of any concrete
-        consequences of not setting the cell on Python 2.
-        """
-        warnings.warn(
-            "Missing ctypes.  Some features like bare super() or accessing "
-            "__class__ will not work with slots classes.",
-            RuntimeWarning,
-            stacklevel=2,
-        )
-
-
-else:
-
-    def just_warn(*args, **kw):  # pragma: nocover
-        """
-        We only warn on Python 3 because we are not aware of any concrete
-        consequences of not setting the cell on Python 2.
-        """
-
-
 def make_set_closure_cell():
     """
     Moved into a function for testability.

tests/test_funcs.py

@@ -4,7 +4,7 @@
 
 from __future__ import absolute_import, division, print_function
 
-from collections import Mapping, OrderedDict, Sequence
+from collections import OrderedDict
 
 import pytest
 
@@ -14,7 +14,7 @@
 import attr
 
 from attr import asdict, assoc, astuple, evolve, fields, has
-from attr._compat import TYPE
+from attr._compat import TYPE, Mapping, Sequence, ordered_dict
 from attr.exceptions import AttrsAttributeNotFoundError
 from attr.validators import instance_of
 
@@ -163,10 +163,10 @@ def test_roundtrip(self, cls, dict_class):
     @given(simple_classes())
     def test_asdict_preserve_order(self, cls):
         """
-        Field order should be preserved when dumping to OrderedDicts.
+        Field order should be preserved when dumping to an ordered_dict.
         """
         instance = cls()
-        dict_instance = asdict(instance, dict_factory=OrderedDict)
+        dict_instance = asdict(instance, dict_factory=ordered_dict)
 
         assert [a.name for a in fields(cls)] == list(dict_instance.keys())
 

tox.ini

@@ -45,7 +45,7 @@ deps =
     black
 commands =
     flake8 src tests setup.py conftest.py docs/conf.py
-    black --check --verbose setup.py conftest.py src tests docs/conf.py
+    black --check setup.py conftest.py src tests docs/conf.py
 
 
 [testenv:pre-commit]