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, 24 insertions, 5 deletions

diff --git a/core/test/interface.go b/core/test/interface.go
index 6c7b22e..0e963fd 100644
--- a/core/test/interface.go
+++ b/core/test/interface.go
@@ -1,13 +1,13 @@
 // 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
+// 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
+// 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.
 //
@@ -17,7 +17,10 @@
 
 package test
 
-import "github.com/dexon-foundation/dexon-consensus-core/blockdb"
+import (
+	"github.com/dexon-foundation/dexon-consensus-core/blockdb"
+	"github.com/dexon-foundation/dexon-consensus-core/core/types"
+)
 
 // Revealer defines the interface to reveal a group
 // of pre-generated blocks.
@@ -27,3 +30,19 @@ type Revealer interface {
 	// Reset the revealing.
 	Reset()
 }
+
+// Stopper defines an interface for Scheduler to tell when to stop execution.
+type Stopper interface {
+	// ShouldStop is provided with the ID of the handler just finishes an event.
+	// It's thread-safe to access internal/shared state of the handler at this
+	// moment.
+	// The Stopper should check state of that handler and return 'true'
+	// if the execution could be stopped.
+	ShouldStop(vID types.ValidatorID) bool
+}
+
+// EventHandler defines an interface to handle a Scheduler event.
+type EventHandler interface {
+	// Handle the event belongs to this handler, and return derivated events.
+	Handle(*Event) []*Event
+}