Issue #16145: Support legacy strings in the _csv module.

1 files changed, 11 insertions, 0 deletions

diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py
index 55796a204a..96f8aa7ee1 100644
--- a/Lib/test/test_csv.py
+++ b/Lib/test/test_csv.py
@@ -197,6 +197,17 @@ class Test_Csv(unittest.TestCase):
             fileobj.seek(0)
             self.assertEqual(fileobj.read(), "a,b\r\nc,d\r\n")
 
+    @support.cpython_only
+    def test_writerows_legacy_strings(self):
+        import _testcapi
+
+        c = _testcapi.unicode_legacy_string('a')
+        with TemporaryFile("w+", newline='') as fileobj:
+            writer = csv.writer(fileobj)
+            writer.writerows([[c]])
+            fileobj.seek(0)
+            self.assertEqual(fileobj.read(), "a\r\n")
+
     def _read_test(self, input, expect, **kwargs):
         reader = csv.reader(input, **kwargs)
         result = list(reader)