bpo-43651: PEP 597: Fix EncodingWarning in some tests (GH-25145)

* test_asyncio
* test_bz2
* test_math
* test_cmath
* test_cmd_line
* test_cmd_line_script
* test_compile
* test_contextlib
* test_profile
* ctypes/test/test_find
* test_multiprocessing
* test_configparser
* test_csv
* test_dbm_dumb
* test_decimal
* test_difflib
* os.fdopen() calls io.text_encoding() to emit EncodingWarning for right place.

1 files changed, 5 insertions, 5 deletions

diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index fd3b4303f03..ead92cfa2ab 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -826,7 +826,7 @@ class _TestSubclassingProcess(BaseTestCase):
         proc = self.Process(target=self._test_stderr_flush, args=(testfn,))
         proc.start()
         proc.join()
-        with open(testfn, 'r') as f:
+        with open(testfn, encoding="utf-8") as f:
             err = f.read()
             # The whole traceback was printed
             self.assertIn("ZeroDivisionError", err)
@@ -836,14 +836,14 @@ class _TestSubclassingProcess(BaseTestCase):
     @classmethod
     def _test_stderr_flush(cls, testfn):
         fd = os.open(testfn, os.O_WRONLY | os.O_CREAT | os.O_EXCL)
-        sys.stderr = open(fd, 'w', closefd=False)
+        sys.stderr = open(fd, 'w', encoding="utf-8", closefd=False)
         1/0 # MARKER
 
 
     @classmethod
     def _test_sys_exit(cls, reason, testfn):
         fd = os.open(testfn, os.O_WRONLY | os.O_CREAT | os.O_EXCL)
-        sys.stderr = open(fd, 'w', closefd=False)
+        sys.stderr = open(fd, 'w', encoding="utf-8", closefd=False)
         sys.exit(reason)
 
     def test_sys_exit(self):
@@ -864,7 +864,7 @@ class _TestSubclassingProcess(BaseTestCase):
             join_process(p)
             self.assertEqual(p.exitcode, 1)
 
-            with open(testfn, 'r') as f:
+            with open(testfn, encoding="utf-8") as f:
                 content = f.read()
             self.assertEqual(content.rstrip(), str(reason))
 
@@ -1118,7 +1118,7 @@ class _TestQueue(BaseTestCase):
     def test_no_import_lock_contention(self):
         with os_helper.temp_cwd():
             module_name = 'imported_by_an_imported_module'
-            with open(module_name + '.py', 'w') as f:
+            with open(module_name + '.py', 'w', encoding="utf-8") as f:
                 f.write("""if 1:
                     import multiprocessing