How to abort a test?

Hi!

(x-posting to gdb-patches@ and/or dejagnu@, depending on the point of view)

I am trying to make some improvements in the gdb testsuite, especially when testing with
gdbserver on a remote target board.  I'd like to add a check so that if the gdbserver
specified by the user does not exist on the remote board, the test will error out and
abort.  There is no point in testing anything else after that, we know it will fail
(and take a long of time before doing so, because gdb needs to timeout first).

When raising an exception, such as:

  error "The specified gdbserver path does not exist."

I can make it propagate up to where runtest catches it:

  runtest.exp:1474:    if { [catch "uplevel #0 source $test_file_name"] == 1 } {

The test will be aborted, runtest will output a detailed error, but the test will still
pass.  Intuitively, I would think that a test that throws an error should automatically
be failed or unresolved, since something unexpected happened.

The only option I see right now would be to fix the whole return chain and add proper
error handling everywhere, to exit early when an error happens.  However, that means
changing tens (hundreds?) of callsites through the testsuite, which is why I'm
looking for alternative solutions first.

My situation is actually very similar to this unanswered stackoverflow question, so
bonus points for us if we can answer it at the same time :)

  http://stackoverflow.com/questions/16131622/abort-a-test-in-a-dejagnu-testsuite

It's the first hit when you Google "dejagnu abort test", so I'm sure it would help
more people.

Thanks for your help,

Simon