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, 2 insertions, 2 deletions

diff --git a/integration_test/stats_test.go b/integration_test/stats_test.go
index e0be126..8816e8c 100644
--- a/integration_test/stats_test.go
+++ b/integration_test/stats_test.go
@@ -16,8 +16,8 @@ func (s *EventStatsTestSuite) TestCalculate() {
 	// Setup a test with fixed latency in proposing and network,
 	// and make sure the calculated statistics is expected.
 	var (
-		networkLatency   = &FixedLatencyModel{Latency: 100}
-		proposingLatency = &FixedLatencyModel{Latency: 300}
+		networkLatency   = &test.FixedLatencyModel{Latency: 100}
+		proposingLatency = &test.FixedLatencyModel{Latency: 300}
 		req              = s.Require()
 	)