func (m *Messenger) Recv(from *upid.UPID, msg proto.Message) {
	m.messageQueue <- &message{from, msg}
}
Recv receives a upid and a message, it will dispatch the message to its handler
with the upid. This is for testing.
package mock
import (
	"reflect"
	"github.com/gogo/protobuf/proto"
	"github.com/mesos/mesos-go/api/v0/messenger"
	"github.com/mesos/mesos-go/api/v0/upid"
	"github.com/stretchr/testify/mock"
	"golang.org/x/net/context"
)
type message struct {
	from *upid.UPID
	msg  proto.Message
}
type Messenger struct {
	mock.Mock
	messageQueue chan *message
	handlers     map[string]messenger.MessageHandler
	stop         chan struct{}
}
func NewMessenger() *Messenger {
	return &Messenger{
		messageQueue: make(chan *message, 1),
		handlers:     make(map[string]messenger.MessageHandler),
		stop:         make(chan struct{}),
	}
}
func (m *Messenger) Install(handler messenger.MessageHandler, msg proto.Message) error {
	m.handlers[reflect.TypeOf(msg).Elem().Name()] = handler
	return m.Called().Error(0)
}
func (m *Messenger) Send(ctx context.Context, upid *upid.UPID, msg proto.Message) error {
	return m.Called().Error(0)
}
func (m *Messenger) Route(ctx context.Context, upid *upid.UPID, msg proto.Message) error {
	return m.Called().Error(0)
}
func (m *Messenger) Start() error {
	go m.recvLoop()
	return m.Called().Error(0)
}
func (m *Messenger) Stop() error {
	select {
	case <-m.stop:
	default:
		close(m.stop)
	}
	return m.Called().Error(0)
}
func (m *Messenger) UPID() upid.UPID {
	return m.Called().Get(0).(upid.UPID)
}
func (m *Messenger) recvLoop() {
	for {
		select {
		case <-m.stop:
			return
		case msg := <-m.messageQueue:
			name := reflect.TypeOf(msg.msg).Elem().Name()
			m.handlers[name](msg.from, msg.msg)
		}
	}
}