def test_timeoutEventuallyForcesConnectionClosed(self):
        """
        When a L{H2Connection} has timed the connection out, and the transport
        doesn't get torn down within 15 seconds, it gets forcibly closed.
        """
        reactor, conn, transport = self.prepareAbortTest()

        # Advance the clock to see that we abort the connection.
        reactor.advance(14)
        self.assertTrue(transport.disconnecting)
        self.assertFalse(transport.disconnected)
        reactor.advance(1)
        self.assertTrue(transport.disconnecting)
        self.assertTrue(transport.disconnected)

        When a L{H2Connection} has timed the connection out, and the transport
        doesn't get torn down within 15 seconds, it gets forcibly closed.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_http2.py