Mark simplejson as completed (#9211)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

stubs/simplejson/@tests/stubtest_allowlist.txt

@@ -1,14 +1,13 @@
-simplejson.JSONDecodeError.__init__
-simplejson.JSONDecoder.__init__
-simplejson.JSONDecoder.decode
-simplejson.JSONDecoder.raw_decode
-simplejson.JSONEncoder.__init__
-simplejson.decoder.JSONDecoder.__init__
-simplejson.decoder.JSONDecoder.decode
-simplejson.decoder.JSONDecoder.raw_decode
-simplejson.dump
-simplejson.dumps
-simplejson.encoder.JSONEncoder.__init__
-simplejson.load
-simplejson.loads
+# Speedups (C vs Python inconsistency):
+simplejson.scanner.make_scanner
 simplejson.scanner.JSONDecodeError.__init__
+simplejson.JSONDecodeError.__init__
+
+# Tests are not included:
+simplejson.tests.*
+
+# Internal and compat tools:
+simplejson.compat
+simplejson.ordered_dict
+simplejson.tool
+simplejson.OrderedDict

stubs/simplejson/@tests/test_cases/check_simplejson.py

@@ -0,0 +1,16 @@
+from __future__ import annotations
+
+from typing_extensions import assert_type
+
+from simplejson import JSONEncoder, dumps
+
+
+class CustomEncoder(JSONEncoder):  # eventhough it does not have `extra_kw` arg.
+    ...
+
+
+# We are only testing `dumps` here, because they are all the same:
+dumps([], extra_kw=True)  # type: ignore
+
+# Ok:
+assert_type(dumps([], cls=CustomEncoder, extra_kw=True), str)