We should have some way of ensuring that all parts of the API configuration possibilities are tested.  A simple manual approach would be to systematically list all API options and identifying which ones are tested (or not), and then working to keep it up to date.

A more advanced method could enforce that the coverage is up to date.  So if add a new API option is added without a corresponding Python test, that gets flagged during PR testing.  This could be aided by either tagging test functions with some annotation:

# @wttest.tests("wiredtiger_open", "cache_size")

or better, for the Python testing itself to "track" which API configuration strings have been used and compare it against the list in dist/api_data.py .