This test does not test the output as well as I would like, but I think
I am limited by htmldocck. I would really just like to strip all the
HTML tags from the output for the sake of the different `@has` checks,
but that doesn't seem to be currently possible.

The output is not quite as nice as it used to be, but it does work.

For example, this code:

    $arg:expr

used to be pretty-printed as:

    $ arg : expr

but is now pretty-printed as:

    $arg : expr