When stowing, you still need to specify what to stow or unstow. With the `--dir` and `--target` options, all you're doing is to tell `stow` where packages are to be found and where they are to be linked to, but you don't tell it what to do.
In your case, either of these would work:
stow --target="$HOME/.dotfiles/test" --dir="$HOME/.dotfiles/.common-dotfiles" .
stow --target="$HOME/.dotfiles/test" --dir="$HOME/.dotfiles" .common-dotfiles
(I would personally prefer the second option as it refers to `.common-dotfiles` as the package to stow from `"$HOME/.dotfiles"`, while the first variation refers to `"$HOME/.dotfiles/.common-dotfiles"` as the directory containing packages.)
You can also explicitly tell `stow` that you want to stow a particular package with `--stow` (or `-S`):
stow --target="$HOME/.dotfiles/test" --dir="$HOME/.dotfiles" --stow .common-dotfiles