Issue #22166: clear codec caches in test_codecs

Python/codecs.c

@@ -185,6 +185,32 @@ PyObject *_PyCodec_Lookup(const char *encoding)
     return NULL;
 }
 
+int _PyCodec_Forget(const char *encoding)
+{
+    PyInterpreterState *interp;
+    PyObject *v;
+    int result;
+
+    interp = PyThreadState_GET()->interp;
+    if (interp->codec_search_path == NULL) {
+        return -1;
+    }
+
+    /* Convert the encoding to a normalized Python string: all
+       characters are converted to lower case, spaces and hyphens are
+       replaced with underscores. */
+    v = normalizestring(encoding);
+    if (v == NULL) {
+        return -1;
+    }
+
+    /* Drop the named codec from the internal cache */
+    result = PyDict_DelItem(interp->codec_search_cache, v);
+    Py_DECREF(v);
+
+    return result;
+}
+
 /* Codec registry encoding check API. */
 
 int PyCodec_KnownEncoding(const char *encoding)