def test_launchWorkerProcesses(self):
        """
        Given a C{spawnProcess} function, C{launchWorkerProcess} launches a
        python process with an existing path as its argument.
        """
        protocols = [ProcessProtocol() for i in range(4)]
        arguments = []
        environment = {}

        def fakeSpawnProcess(processProtocol, executable, args=(), env={},
                             path=None, uid=None, gid=None, usePTY=0,
                             childFDs=None):
            arguments.append(executable)
            arguments.extend(args)
            environment.update(env)

        self.runner.launchWorkerProcesses(
            fakeSpawnProcess, protocols, ["foo"])
        self.assertEqual(arguments[0], arguments[1])
        self.assertTrue(os.path.exists(arguments[2]))
        self.assertEqual("foo", arguments[3])
        self.assertEqual(os.pathsep.join(sys.path),
                         environment["TRIAL_PYTHONPATH"])

        Given a C{spawnProcess} function, C{launchWorkerProcess} launches a
        python process with an existing path as its argument.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/_dist/test/test_disttrial.py