This is mostly pertaining to this test file: https://github.com/rstudio/websocket/blob/380d4db886c2a377a6a9878ef90338b1ccc692ec/src/tests/main.c#L4 which includes the engine header, but doesn't use any of its API, and so doesn't need it. [This API was deprecated in OpenSSL 3.](https://docs.openssl.org/3.0/man7/migration_guide/#engines-and-method-apis)
This is mostly pertaining to this test file:
websocket/src/tests/main.c
Line 4 in 380d4db
which includes the engine header, but doesn't use any of its API, and so doesn't need it. This API was deprecated in OpenSSL 3.