def test_freshPyReplacesStalePyc(self):
        """
        Verify that if a stale .pyc file on the PYTHONPATH is replaced by a
        fresh .py file, the plugins in the new .py are picked up rather than
        the stale .pyc, even if the .pyc is still around.
        """
        mypath = self.appPackage.child("stale.py")
        mypath.setContent(pluginFileContents('one'))
        # Make it super stale
        x = time.time() - 1000
        os.utime(mypath.path, (x, x))
        pyc = mypath.sibling('stale.pyc')
        # compile it
        if _PY3:
            # On python 3, don't use the __pycache__ directory; the intention
            # of scanning for .pyc files is for configurations where you want
            # to intentionally include them, which means we _don't_ scan for
            # them inside cache directories.
            extra = dict(legacy=True)
        else:
            # On python 2 this option doesn't exist.
            extra = dict()
        compileall.compile_dir(self.appPackage.path, quiet=1, **extra)
        os.utime(pyc.path, (x, x))
        # Eliminate the other option.
        mypath.remove()
        # Make sure it's the .pyc path getting cached.
        self.resetEnvironment()
        # Sanity check.
        self.assertIn('one', self.getAllPlugins())
        self.failIfIn('two', self.getAllPlugins())
        self.resetEnvironment()
        mypath.setContent(pluginFileContents('two'))
        self.failIfIn('one', self.getAllPlugins())
        self.assertIn('two', self.getAllPlugins())

        Verify that if a stale .pyc file on the PYTHONPATH is replaced by a
        fresh .py file, the plugins in the new .py are picked up rather than
        the stale .pyc, even if the .pyc is still around.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_plugin.py