func (s *FilterSuite) assertAgentTerminates(c *gc.C, f filter.Filter) {
s.assertFilterDies(c, f)
c.Assert(f.Wait(), gc.Equals, worker.ErrTerminateAgent)
}
// Ensure we get a signal on f.Dead()
func (s *FilterSuite) assertFilterDies(c *gc.C, f filter.Filter) {
deadC := s.notifyAsserterC(c, f.Dead())
deadC.AssertClosed()
}