Python headers are being reorganized to clarify what's public, specific to CPython or "internal". See issues bpo-35134 (Add a new Include/cpython/ subdirectory) and bpo-35081 (Move internal headers to Include/internal/).

Problem: the _testcapi module designed to only test the *public* API. Functions tested by _testcapi cannot be made internal.

I propose to add a new _testinternalcapi module reserved to test internal APIs.

Attached PR implements this idea: it makes _Py_GetConfigsAsDict() private and moves _testcapi.get_configs() to _testinternalcapi.get_configs().