From f39b054b9c8cbbf884f53123eef028131789990c Mon Sep 17 00:00:00 2001
From: Kwak Byoung Min <67214970+doma17@users.noreply.github.com>
Date: Sun, 4 Oct 2026 13:53:35 +0900
Subject: [PATCH] Match CPython quotechar escaping when doublequote is disabled
 (#8953)

Let quote-only fields use the existing unquoted escaping path and enable
the existing CPython regression test.

Tested: test_csv, CSV snippet, 240 CPython comparisons, workspace and C-API tests, Clippy, prek
Assisted-by: Codex:gpt-6.1-sol
---
 Lib/test/test_csv.py     | 1 -
 crates/stdlib/src/csv.rs | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py
index 7e76f4bc1..21b02c2f0 100644
--- a/Lib/test/test_csv.py
+++ b/Lib/test/test_csv.py
@@ -228,7 +228,6 @@ class Test_Csv(unittest.TestCase):
         self._write_test(['a','',None,1], '"a","",,"1"',
                          quoting = csv.QUOTE_NOTNULL)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test_write_escape(self):
         self._write_test(['a',1,'p,q'], 'a,1,"p,q"',
                          escapechar='\\')
diff --git a/crates/stdlib/src/csv.rs b/crates/stdlib/src/csv.rs
index a0f75300e..b07f9c644 100644
--- a/crates/stdlib/src/csv.rs
+++ b/crates/stdlib/src/csv.rs
@@ -1246,7 +1246,7 @@ mod _csv {
     fn field_needs_quotes(data: &[u8], dialect: &PyDialect) -> bool {
         data.iter().any(|&byte| {
             byte == dialect.delimiter
-                || dialect.quotechar == Some(byte)
+                || (dialect.doublequote && dialect.quotechar == Some(byte))
                 || matches!(byte, b'\r' | b'\n')
         }) || data_contains_lineterminator_char(data, dialect)
     }