Scope

Test that the CTR hooks set with `mongocrypt_setopt_aes_256_ctr` may be set without setting other hooks.

Background

Supporting CTR mode on macOS 10.14 and earlier was deliberately not done:. This is the only crypto primitive with such a restriction.

Native CTR-mode AES encryption is deliberately not supported on macOS <= 10.14 See: MONGOCRYPT-440

PYTHON-4181 proposes changing the Python bindings to prefer libmongocrypt with native crypto support.

For the Python bindings to support macOS <= 10.14, the CTR crypto hooks are conditionally set for macOS <= 10.14. See: https://github.com/mongodb/libmongocrypt/pull/756#issuecomment-1967497615

Setting the CTR hooks (without other hooks) does not appear to be explicitly tested.

This ticket proposes adding tests to ensure this behavior continues to be supported.