def test_twistdPathInsert(self):
        """
        The twistd script adds the current working directory to sys.path so
        that it's able to import modules from it.
        """
        script = self.bin.child("twistd")
        if not script.exists():
            raise SkipTest(
                "Script tests do not apply to installed configuration.")
        cwd = getcwd()
        self.addCleanup(chdir, cwd)
        testDir = FilePath(self.mktemp())
        testDir.makedirs()
        chdir(testDir.path)
        testDir.child("bar.tac").setContent(
            "import sys\n"
            "print sys.path\n")
        output = outputFromPythonScript(script, '-ny', 'bar.tac')
        self.assertIn(repr(testDir.path), output)

        The twistd script adds the current working directory to sys.path so
        that it's able to import modules from it.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/scripts/test/test_scripts.py