def test_startService(self):
        """
        L{ProcessMonitor.startService} starts all monitored processes.
        """
        self.pm.addProcess("foo", ["foo"])
        # Schedule the process to start
        self.pm.startService()
        # advance the reactor to start the process
        self.reactor.advance(0)
        self.assertIn("foo", self.pm.protocols)

        L{ProcessMonitor.startService} starts all monitored processes.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/runner/test/test_procmon.py