'Test connectivity (or lack thereof) between hosts in VLANTopo'

@unittest.skipIf(('-quick' in sys.argv), 'long    test')
def testVLANTopo(self):

    p = pexpect.spawn('python    -m    mininet.examples.vlanhost')
    p.expect(self.prompt)
    p.sendline('pingall    1')
    p.expect('(\\d+)%    dropped', timeout=30)
    percent = (int(p.match.group(1)) if p.match else (-1))
    p.expect(self.prompt)
    p.sendline('exit')
    p.wait()
    self.assertEqual(percent, 80)
