[CMake] CTEST_CUSTOM_PRE_TEST and child process disassociation

[Eric BOIX]

	Dear cmake users,

Consider a package that offers some client/server functionalities. In such
a context some regression tests (as defined with ADD_TEST(...) ) concern
the server and some others tests concern the client. Typically, I thus need
to launch a server at the beginning of ctest, then to run each individual
client test, and then to cleanly kill the server (oh well, in theory :).

For this, I use CTEST_CUSTOM_PRE_TEST which I configured to be a shell script
(I know this is not portable but, for the time being, I don't know any
better way). This typical CUSTOM_PRE_TEST is of the form:
   #!/bin/bash
   the_server_to_test > log &
   echo Done

The problem is that ctest seems to wait for the disassociation of the
child process (in this case the server I wish to test) before proceeding with
each atomic test. This can be easily checked by configuring
CTEST_CUSTOM_PRE_TEST with the following simple script:
   #!/bin/bash
   sleep 30 >log &
for which ctest will wait for 30 seconds i.e. the end of the child process
before proceeding with the test suite per se. In despair, and just to
make sure, I also tried
   sleep 30 < /dev/null >log 2>&1 &
and in drunken despair I even tried
   nohup sleep 30 < /dev/null >log 2>&1 &
but ctest behavior seems to always be the same...

Interestingly enough when I launch those shell scripts manually from 
the command line (as opposed to launching them from within ctest) I then
get my hands back on the invoking shell while the server (on in the
above examples the sleep command) keeps on running...

My questions is thus: when using CTEST_CUSTOM_PRE_TEST how can one force
ctest not to wait for child process disassociation ?

	Yours,
	Eric Boix.