From 7ef275160953f00b4303149df6d919c0afe763cb Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Fri, 15 May 2020 09:22:54 -0700
Subject: [PATCH] bpo-40055: test_distutils leaves warnings filters unchanged
 (GH-20095)

distutils.tests now saves/restores warnings filters to leave them
unchanged. Importing tests imports docutils which imports
pkg_resources which adds a warnings filter.
(cherry picked from commit 6e57237faf0da8904e0130a11350cae3c5062b82)

Co-authored-by: Victor Stinner <vstinner@python.org>
---
 Lib/distutils/tests/__init__.py                             | 6 ++++++
 .../next/Tests/2020-05-15-01-21-44.bpo-40055.Xp4aP9.rst     | 3 +++
 2 files changed, 9 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Tests/2020-05-15-01-21-44.bpo-40055.Xp4aP9.rst

diff --git a/Lib/distutils/tests/__init__.py b/Lib/distutils/tests/__init__.py
index 1b939cbd5db2bf..5d2e69e3e6a8f6 100644
--- a/Lib/distutils/tests/__init__.py
+++ b/Lib/distutils/tests/__init__.py
@@ -15,6 +15,7 @@
 import os
 import sys
 import unittest
+import warnings
 from test.support import run_unittest
 
 
@@ -22,6 +23,7 @@
 
 
 def test_suite():
+    old_filters = warnings.filters[:]
     suite = unittest.TestSuite()
     for fn in os.listdir(here):
         if fn.startswith("test") and fn.endswith(".py"):
@@ -29,6 +31,10 @@ def test_suite():
             __import__(modname)
             module = sys.modules[modname]
             suite.addTest(module.test_suite())
+    # bpo-40055: Save/restore warnings filters to leave them unchanged.
+    # Importing tests imports docutils which imports pkg_resources which adds a
+    # warnings filter.
+    warnings.filters[:] = old_filters
     return suite
 
 
diff --git a/Misc/NEWS.d/next/Tests/2020-05-15-01-21-44.bpo-40055.Xp4aP9.rst b/Misc/NEWS.d/next/Tests/2020-05-15-01-21-44.bpo-40055.Xp4aP9.rst
new file mode 100644
index 00000000000000..edb01182c3a5ce
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2020-05-15-01-21-44.bpo-40055.Xp4aP9.rst
@@ -0,0 +1,3 @@
+distutils.tests now saves/restores warnings filters to leave them unchanged.
+Importing tests imports docutils which imports pkg_resources which adds a
+warnings filter.