How to run WAF compiled C++ program from within test script?

Dear WAF build system experts,

Let's suppose that you use the WAF build system to build a library fooLib and a program fooProg. Then, you want to check the program fooProg by a Python script fooProgTest that checks the output of fooProg.

Here is an minimum example for fooLib and fooProg:

$ cat fooLib/fooLib.cpp 
int foo()
{
    return 42;
}

$ cat fooProg/fooProg.cpp 
#include <iostream>

extern int foo();

int main()
{
    std::cout << foo() << std::endl;
    return 0;
}

In this example, it is my goal to to have a Python script that checks that fooProg outputs 42. Here comes my not so clean solution:

import os
from waflib.Tools import waf_unit_test


def options(opt):
    opt.load("compiler_cxx waf_unit_test python")


def configure(cnf):
    cnf.load("compiler_cxx waf_unit_test python")

def build(bld):
    bld.add_post_fun(waf_unit_test.summary)
    bld.options.clear_failed_tests= True

    bld(features= "cxx cxxshlib",
        target= "fooLib",
        source= "fooLib/fooLib.cpp")

    bld(features= "cxx cxxprogram",
        target= "fooProg/fooProg",
        source= "fooProg/fooProg.cpp",
        use= "fooLib")

    testEnv= os.environ.copy()
    testEnv["FOO_EXE"]= bld.path.find_or_declare("fooProg/fooProg").abspath()
    bld(features= "test_scripts",
        test_scripts_source= "fooProgTest/fooProgTest.py",
        test_scripts_template= "${PYTHON} ${SRC[0].abspath()}",
        test_scripts_paths= {
            "LD_LIBRARY_PATH": bld.bldnode.abspath()
        },
        test_scripts_env= testEnv
       ) 

cat fooProgTest/fooProgTest.py 
#!/usr/bin/env python

import os
import subprocess

assert subprocess.check_output("{}".format(
        os.environ["FOO_EXE"])).startswith("42")

My questions are below:

• Does anyone of you know how to avoid setting LD_LIBRARY_PATH manually?
• How to avoid setting the path of fooProg via the environment variable "FOO_EXE"?

Thank you very much!