Force apt-get to prompt yes/no

There's just no way to do this with the current implementation of apt-get, you would need to open a feature request and appeal to the maintainer. The current behavior of apt-get is that when the list of packages you implicitly declared to be installed is equal to the amount of packages that will get installed, and no other packages are affected with upgrades or breaks, apt-get presumes the user already is sure of what is going to be done, if you are not sure or want to analyze what will be done without actually installing the package, you can use Costas recommendation of -s, --simulate, --just-print, --dry-run, --recon, --no-act.

There are other tools like apt-listbugs that would analyze the versions of packages to be installed before you actually install them (in this case for bugs) and warn you.

The command assume yes just in case of installing one package (which initiated from command line) AND all dependencies in the system already i.e nothing to install except one asked package.

In other word "if nothing to see (no extra packages) then no prompt (nothing to ask for)".

For testing purposes you can use a key -s, --simulate, --just-print, --dry-run, --recon, --no-act