Closes #14158: improved resilience to test files left behind.
diff --git a/Lib/test/test_base64.py b/Lib/test/test_base64.py
index 93c623c..ca94504 100644
--- a/Lib/test/test_base64.py
+++ b/Lib/test/test_base64.py
@@ -2,6 +2,7 @@
 from test import support
 import base64
 import binascii
+import os
 import sys
 import subprocess
 
@@ -227,6 +228,10 @@
 
 
 class TestMain(unittest.TestCase):
+    def tearDown(self):
+        if os.path.exists(support.TESTFN):
+            os.unlink(support.TESTFN)
+
     def get_output(self, *args, **options):
         args = (sys.executable, '-m', 'base64') + args
         return subprocess.check_output(args, **options)