For the test_app_server to run properly on Haiku, you need to prepare a few things.

There is a pseudo target "install-test-apps" which needs to be built like this:

$ TARGET_PLATFORM=libbe_test jam install-test-apps

This will build "test_registrar", "test_app_server",
the needed libs and some test apps and install everything into "generated/tests/libbe_test/(your architecture)/apps".

You can use the "run.sh" script installed in the "generated/tests/libbe_test/(your architecture)/apps" folder to run the servers,
as well as open the test app folder in Tracker (via the -o option),
or launch specific test app(s) by specifying their name in the command line,
for example "run WindowInvalidation".

NOTE: it is currently necessary to prefix the starting of test_app_server with
	LD_PRELOAD="lib/libbe_test.so"
This is a bug that should be fixed (go for it :-),
but supplying the library manually is a workaround for using test_app_server for now.

Have fun!