All JSON value types as dict values.

Verify multiple subinterpreters can use simplejson concurrently.

Nested dicts exercise recursive encoding within the dict loop.

Dict keys that aren't already strings go through encoder_stringify_key and the non-cached branch of the key_memo logic. Both paths mus

Fast path with non-string keys that get stringified.

Slow path with non-string keys + sort_keys.

Verify Scanner heap type instances decode correctly.

Heap types must be GC-tracked so they can be collected.

A single encoder/decoder instance used by many threads.

Single-key dict.

Fast path: skipkeys drops unencodable keys.

skipkeys on the PyDict_Next fast path must not leak skipped keys.

Slow path: skipkeys + sort_keys drops unencodable keys.

Verify types are heap types inside subinterpreters.

Verify destroying one subinterpreter doesn't affect another.

The indexed fast path for exact tuples must not leak.

Slow path: tuple subclass uses iterator.