work on Python 3.10 (fixes https://bugs.python.org/issue12178)

README.rst

@@ -20,7 +20,7 @@ Improvements
 
 bpo-12178_
   broken round-trip with ``escapechar`` if your data contains a literal escape
-  character
+  character (fixed in Python 3.10)
 
 bpo-31590_
   broken round-trip with ``escapechar`` and embedded newlines under Python 2

setup.py

@@ -44,5 +44,6 @@
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
+        'Programming Language :: Python :: 3.10',
     ],
 )

tests/test_stdlib_csv.py

@@ -2,6 +2,7 @@
 
 import csv
 import io
+import sys
 
 import pytest
 
@@ -64,7 +65,8 @@ def test_csv_roundtrip(py2, quoting, quotechar, escapechar, doublequote, value):
     if quoting != csv.QUOTE_NONE and escapechar is not None and escapechar in value:
         # writer fails to escape escapechar
         assert row != expected
-        pytest.xfail(reason='https://bugs.python.org/issue12178')
+        if sys.version_info < (3, 10):
+            pytest.xfail(reason='https://bugs.python.org/issue12178')
     elif py2 and quoting == csv.QUOTE_NONE and escapechar is not None and '\n' in value:
         # reader fails to recognize escaped newline
         assert row != expected

tests/test_workarounds.py

@@ -2,12 +2,15 @@
 
 from __future__ import unicode_literals
 
+import sys
+
 import pytest
 
 from csv23._workarounds import issue12178, issue31590
 
 
-@pytest.mark.xfail(reason='https://bugs.python.org/issue12178')
+@pytest.mark.xfail(sys.version_info < (3, 10),
+                   reason='https://bugs.python.org/issue12178')
 def test_issue12178():
     assert not issue12178()