Consistently use unittest.mock in tests

 - Some tests used unittest.mock from the standard library
 - Some tests used mock from PyPI
 - Some tests tried to import unittest.mock with a fallback to mock
   (the import never fails on Python 3.7+, older Pythons are not supported)

changelog.d/3638.misc.rst

@@ -0,0 +1 @@
+Drop a test dependency on the ``mock`` package, always use :external+python:py:mod:`unittest.mock` -- by :user:`hroncok`

pkg_resources/tests/test_markers.py

@@ -1,4 +1,4 @@
-import mock
+from unittest import mock
 
 from pkg_resources import evaluate_marker
 

pkg_resources/tests/test_pkg_resources.py

@@ -9,10 +9,7 @@
 import distutils.dist
 import distutils.command.install_egg_info
 
-try:
-    from unittest import mock
-except ImportError:
-    import mock
+from unittest import mock
 
 from pkg_resources import (
     DistInfoDistribution, Distribution, EggInfoDistribution,

setup.cfg

@@ -59,7 +59,6 @@ testing =
 	pytest-perf
 
 	# local
-	mock
 	flake8-2020
 	virtualenv>=13.0.0
 	wheel

setuptools/tests/test_bdist_deprecations.py

@@ -1,7 +1,7 @@
 """develop tests
 """
-import mock
 import sys
+from unittest import mock
 
 import pytest
 

setuptools/tests/test_build_clib.py

@@ -1,6 +1,7 @@
+from unittest import mock
+
 import pytest
 
-import mock
 from distutils.errors import DistutilsSetupError
 from setuptools.command.build_clib import build_clib
 from setuptools.dist import Distribution

setuptools/tests/test_easy_install.py

@@ -12,14 +12,14 @@
 import distutils.errors
 import io
 import zipfile
-import mock
 import time
 import re
 import subprocess
 import pathlib
 import warnings
 from collections import namedtuple
 from pathlib import Path
+from unittest import mock
 
 import pytest
 from jaraco import path

setuptools/tests/test_packageindex.py

@@ -5,8 +5,8 @@
 import urllib.request
 import urllib.error
 import http.client
+from unittest import mock
 
-import mock
 import pytest
 
 import setuptools.package_index

setuptools/tests/test_register.py

@@ -2,10 +2,7 @@
 from setuptools.dist import Distribution
 from setuptools.errors import RemovedCommandError
 
-try:
-    from unittest import mock
-except ImportError:
-    import mock
+from unittest import mock
 
 import pytest
 

setuptools/tests/test_upload.py

@@ -2,10 +2,7 @@
 from setuptools.dist import Distribution
 from setuptools.errors import RemovedCommandError
 
-try:
-    from unittest import mock
-except ImportError:
-    import mock
+from unittest import mock
 
 import pytest