chore: move SyntaxError regression test to extra_tests

Copilot · youknowone · Copilot · commit 9ba97e52ef70 · 2025-12-24T23:33:19.000Z
Co-authored-by: youknowone &lt;69878+youknowone@users.noreply.github.com&gt;
diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
@@ -130,7 +130,8 @@ repository's structure:
   - `stdlib`: Standard library parts implemented in rust.
 - `src`: using the other subcrates to bring rustpython to life.
 - `wasm`: Binary crate and resources for WebAssembly build
-- `extra_tests`: extra integration test snippets as a supplement to `Lib/test`
+- `extra_tests`: extra integration test snippets as a supplement to `Lib/test`.
+  Add new RustPython-only regression tests here; do not place new tests under `Lib/test`.
 
 ## Understanding Internals
 
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
@@ -2453,14 +2453,6 @@ def test_attributes_old_constructor(self):
         self.assertEqual(error, the_exception.text)
         self.assertEqual("bad bad", the_exception.msg)
 
-    def test_msg_attribute_writable(self):
-        err = SyntaxError("bad bad", ("bad.py", 1, 2, "abcdefg"))
-        err.msg = "changed"
-        self.assertEqual(err.msg, "changed")
-        self.assertEqual(str(err), "changed (bad.py, line 1)")
-        del err.msg
-        self.assertIsNone(err.msg)
-
     @unittest.expectedFailure # TODO: RUSTPYTHON
     def test_incorrect_constructor(self):
         args = ("bad.py", 1, 2)
diff --git a/extra_tests/snippets/builtin_exceptions.py b/extra_tests/snippets/builtin_exceptions.py
@@ -85,6 +85,13 @@ def __init__(self, value):
 assert exc.offset is None
 assert exc.text is None
 
+err = SyntaxError("bad bad", ("bad.py", 1, 2, "abcdefg"))
+err.msg = "changed"
+assert err.msg == "changed"
+assert str(err) == "changed (bad.py, line 1)"
+del err.msg
+assert err.msg is None
+
 # Regression to:
 # https://github.com/RustPython/RustPython/issues/2779
 
