test: add transport layer (#97)

The purpose of transport layer is to abstract the way to send messages and setup connections between peers in a p2p network. The peer discovery is simulated by a hosted server: every peer sends its address to a known server. Once collecting enough peers, respond the whole peers lists to all peers.

Changes:
- Add test.Trasnport interface
- Add test.Transport implementation by golang channel.
- Add test.transport implementation by TCP connection.
- Move LatencyModel to core/test package
- Add Marshaller interface

1 files changed, 64 insertions, 0 deletions

diff --git a/core/test/interface.go b/core/test/interface.go
index 0e963fd..9932262 100644
--- a/core/test/interface.go
+++ b/core/test/interface.go
@@ -46,3 +46,67 @@ type EventHandler interface {
 	// Handle the event belongs to this handler, and return derivated events.
 	Handle(*Event) []*Event
 }
+
+// TransportPeerType defines the type of peer, either 'peer' or 'server'.
+type TransportPeerType string
+
+const (
+	// TransportPeerServer is the type of peer server.
+	TransportPeerServer TransportPeerType = "server"
+	// TransportPeer is the type of peer.
+	TransportPeer TransportPeerType = "peer"
+)
+
+// TransportEnvelope define the payload format of a message when transporting.
+type TransportEnvelope struct {
+	// PeerType defines the type of source peer, could be either "peer" or
+	// "server".
+	PeerType TransportPeerType
+	// From defines the validatorID of the source peer.
+	From types.ValidatorID
+	// Msg is the actual payload of this message.
+	Msg interface{}
+}
+
+// TransportServer defines the peer server in the network.
+type TransportServer interface {
+	Transport
+	// Host the server, consider it's a setup procedure. The
+	// returned channel could be used after 'WaitForPeers' returns.
+	Host() (chan *TransportEnvelope, error)
+	// WaitForPeers waits for all peers to join the network.
+	WaitForPeers(numPeers int) error
+}
+
+// TransportClient defines those peers in the network.
+type TransportClient interface {
+	Transport
+	// Report a message to the peer server.
+	Report(msg interface{}) error
+	// Join the network, should block until joined.
+	Join(serverEndpoint interface{}) (<-chan *TransportEnvelope, error)
+}
+
+// Transport defines the interface for basic transportation capabilities.
+type Transport interface {
+	// Broadcast a message to all peers in network.
+	Broadcast(msg interface{}) error
+	// Send one message to a peer.
+	Send(endpoint types.ValidatorID, msg interface{}) error
+	// Close would cleanup allocated resources.
+	Close() error
+
+	// Peers return IDs of all connected validators in p2p favor.
+	// This method should be accessed after ether 'Join' or 'WaitForPeers'
+	// returned.
+	Peers() map[types.ValidatorID]struct{}
+}
+
+// Marshaller defines an interface to convert between interface{} and []byte.
+type Marshaller interface {
+	// Unmarshal converts a []byte back to interface{} based on the type
+	// of message.
+	Unmarshal(msgType string, payload []byte) (msg interface{}, err error)
+	// Marshal converts a message to byte string
+	Marshal(msg interface{}) (msgType string, payload []byte, err error)
+}