Test MemoryError on locale encoding C functions

Fix also two typos.

Author: vstinner

Lib/test/test_codecs.py

@@ -4203,7 +4203,7 @@ def check_decode_strings(self, errors):
                     errmsg = f"decode error: pos={error_pos}"
                     self.assertEqual(str(cm.exception), errmsg)
                 else:
-                    if errors == ("strict", "surrogateescape"):
+                    if errors in ("strict", "surrogateescape"):
                         decoded = self.decode_locale_surrogateescape(encoded)
                         self.assertEqual(decoded, expected)
 
@@ -4233,6 +4233,24 @@ def test_decode_unsupported_error_handler(self):
             self.decode_locale(b'', 'backslashreplace')
         self.assertEqual(str(cm.exception), 'unsupported error handler')
 
+    def test_memory_error(self):
+        # Make sure that MemoryError is handled properly
+        with self.assertRaises(MemoryError):
+            with support.inject_memory_error_cm():
+                self.decode_locale(b'short ascii string', 0, 'strict')
+
+        with self.assertRaises(MemoryError):
+            with support.inject_memory_error_cm():
+                self.decode_locale_surrogateescape(b'short ascii string')
+
+        with self.assertRaises(MemoryError):
+            with support.inject_memory_error_cm():
+                self.encode_locale('short string', 0, 'strict')
+
+        with self.assertRaises(MemoryError):
+            with support.inject_memory_error_cm():
+                self.encode_locale_surrogateescape('short string')
+
 
 class Rot13Test(unittest.TestCase):
     """Test the educational ROT-13 codec."""

Modules/_testlimitedcapi/codec.c

@@ -31,7 +31,7 @@ decode_locale(PyObject *Py_UNUSED(module), PyObject *arg)
     size_t size = size_canary;
     wchar_t *wstr = Py_DecodeLocale(str, &size);
 
-    if (str == NULL) {
+    if (wstr == NULL) {
         if (size == (size_t)-1) {
             PyErr_NoMemory();
         }