Well, installing the DDS alias is a form of namespace pollution that a normal user/enviornment may not want. It may even conflict. So in a 'follow' session I don't want to install DDS unless they already have DDS installed. Its possible that doing so without them noticing may even overwrite a different DDS that they have installed. OTOH, on a CPAN-Tester enviornment I believe that such an overwite would be immaterial. Its a test enviornment and such things can and will happen and as such shouldnt be of a signifigant impact, so I would want the tester to test the DDS extension too. If it got overwitten by another module afterwards, or overwrote an existing DDS it probably wouldnt matter. But in a non-tester scenario id wouldnt want to run the risk.

It seems to me that you have two separate issues:

1. Whether to test the DDS alias
2. Whether to install the DDS alias

If it were me I would always do (1) and only do (2) if the user asked for it, defaulting to "no" in non-interactive environments.