Setup library is linked against the driver library, because it needs some driver internal features and because it needs some C/C functionality(which it also gets by linking against driver lib). That is all needed for the "Connection test" feature, and is a bit of overkill for it. Also some translation units from driver are redundant in the setup lib.
Test feature can use ODBC API. As a side effect, DSN info will be carried over in the string, and not in DSN struct