test.py

import subprocess



server_args = ['whatsappServer', '8875']
client1_args = ['whatsappClient', 'client1', '127.0.0.1', '8875']
client2_args = ['whatsappClient', 'client2', '127.0.0.1', '8875']


def main():
    server = subprocess.Popen(server_args,
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            universal_newlines=True,
            bufsize=0)

    c1 = subprocess.Popen(client1_args,
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            universal_newlines=True,
            bufsize=0)


    c2 = subprocess.Popen(client2_args,
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            universal_newlines=True,
            bufsize=0)

    c1.stdin.write('send client2 hello')
    print(server.stdout.readline())
    print(server.stdout.readline())
    print(server.stdout.readline())

    server.stdin.close()
    c1.stdin.close()
    c2.stdin.close()
    server.stdout.close()
    c1.stdout.close()
    c2.stdout.close()
    

if __name__ == '__main__':
    main()