gh-97825: fix AttributeError when calling subprocess.check_output(input=None) with encoding or errors args (GH-97826)

* fix AttributeError, add unit test
(cherry picked from commit db64fb9bbe92b212db7dd173f787ea3607ae971a)

Co-authored-by: andrei kulakov <andrei.avk@gmail.com>

2 files changed, 8 insertions, 1 deletions

diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index a414321..e5d7f09 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -411,7 +411,8 @@ def check_output(*popenargs, timeout=None, **kwargs):
     if 'input' in kwargs and kwargs['input'] is None:
         # Explicitly passing input=None was previously equivalent to passing an
         # empty string. That is maintained here for backwards compatibility.
-        if kwargs.get('universal_newlines') or kwargs.get('text'):
+        if kwargs.get('universal_newlines') or kwargs.get('text') or kwargs.get('encoding') \
+                or kwargs.get('errors'):
             empty = ''
         else:
             empty = b''
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index b91791a..ea02a9e 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -227,6 +227,12 @@ class ProcessTestCase(BaseTestCase):
                 input=None, universal_newlines=True)
         self.assertNotIn('XX', output)
 
+    def test_check_output_input_none_encoding_errors(self):
+        output = subprocess.check_output(
+                [sys.executable, "-c", "print('foo')"],
+                input=None, encoding='utf-8', errors='ignore')
+        self.assertIn('foo', output)
+
     def test_check_output_stdout_arg(self):
         # check_output() refuses to accept 'stdout' argument
         with self.assertRaises(ValueError) as c: