How do you run dmd-testsuite?

[Johan Engelen via digitalmars-d-ldc]

Hi all,
  As you know, I dislike the dmd-testsuite: I cannot run a single 
test easily, I cannot even run it on Windows, it is inflexible, 
and it is out-of-tree so not tied with fixes/features we make.
Still, it is what we have so I have to live with it.

How do you guys run just a single test of the testsuite?

-Johan