test: add test.Scheduler (#58)

When simulating execution of core.Consensus by passing packets through golang-channel or real-socket, we need to utilize time.Sleep and time.Now to simulate the required network/proposing latency. It's problematic when we try to test a simulation with long network latency.

Instead, Scheduler would try to execute the event with minimum timestamp, thus time.Sleep is replaced with Scheduler.nextTick, and time.Now is replaced with Event.Time.

Changes:
- Add test.Scheduler.
- Add test.Stopper interface to provide encapsulate different stop conditions for scheduler.
- Add a reference implementation for test.Stopper, it will stop scheduler when all validators confirmed X blocks proposed from themselves.
- Add a test scenario on core.Consensus that all validators are not byzantine.

1 files changed, 44 insertions, 0 deletions

diff --git a/integration_test/latency.go b/integration_test/latency.go
new file mode 100644
index 0000000..383d069
--- /dev/null
+++ b/integration_test/latency.go
@@ -0,0 +1,44 @@
+// Copyright 2018 The dexon-consensus-core Authors
+// This file is part of the dexon-consensus-core library.
+//
+// The dexon-consensus-core library is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Lesser General Public License as
+// published by the Free Software Foundation, either version 3 of the License,
+// or (at your option) any later version.
+//
+// The dexon-consensus-core library is distributed in the hope that it will be
+// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
+// General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the dexon-consensus-core library. If not, see
+// <http://www.gnu.org/licenses/>.
+
+package integration
+
+import (
+	"math/rand"
+	"time"
+)
+
+// LatencyModel defines an interface to randomly decide latency
+// for one operation.
+type LatencyModel interface {
+	Delay() time.Duration
+}
+
+// normalLatencyModel would return latencies in normal distribution.
+type normalLatencyModel struct {
+	Sigma float64
+	Mean  float64
+}
+
+// Delay implements LatencyModel interface.
+func (m *normalLatencyModel) Delay() time.Duration {
+	delay := rand.NormFloat64()*m.Sigma + m.Mean
+	if delay < 0 {
+		delay = m.Sigma / 2
+	}
+	return time.Duration(delay) * time.Millisecond
+}