func (s *PresenceSuite) TestWatchPeriod(c *C) {
presence.FakePeriod(1)
presence.RealTimeSlot()
w := presence.NewWatcher(s.presence)
p := presence.NewPinger(s.presence, "a")
defer w.Stop()
defer p.Stop()
ch := make(chan presence.Change)
w.Watch("a", ch)
assertChange(c, ch, presence.Change{"a", false})
// A single ping.
c.Assert(p.Start(), IsNil)
c.Assert(p.Stop(), IsNil)
// Wait for next periodic refresh.
time.Sleep(1 * time.Second)
assertChange(c, ch, presence.Change{"a", true})
}
func (s *PresenceSuite) TestPingerPeriodAndResilience(c *C) {
// This test verifies both the periodic pinging,
// and also a great property of the design: deaths
// also expire, which means erroneous scenarios are
// automatically recovered from.
const period = 1
presence.FakePeriod(period)
presence.RealTimeSlot()
w := presence.NewWatcher(s.presence)
p1 := presence.NewPinger(s.presence, "a")
p2 := presence.NewPinger(s.presence, "a")
defer w.Stop()
defer p1.Stop()
defer p2.Stop()
// Start p1 and let it go on.
c.Assert(p1.Start(), IsNil)
w.Sync()
assertAlive(c, w, "a", true)
// Start and kill p2, which will temporarily
// invalidate p1 and set the key as dead.
c.Assert(p2.Start(), IsNil)
c.Assert(p2.Kill(), IsNil)
w.Sync()
assertAlive(c, w, "a", false)
// Wait for two periods, and check again. Since
// p1 is still alive, p2's death will expire and
// the key will come back.
time.Sleep(period * 2 * time.Second)
w.Sync()
assertAlive(c, w, "a", true)
}