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, 21 insertions, 0 deletions

diff --git a/core/test/governance.go b/core/test/governance.go
index a4e86d1..58ab582 100644
--- a/core/test/governance.go
+++ b/core/test/governance.go
@@ -18,12 +18,20 @@
 package test
 
 import (
+	"fmt"
+
 	"github.com/dexon-foundation/dexon-consensus-core/core/types"
 	"github.com/dexon-foundation/dexon-consensus-core/crypto"
 	"github.com/dexon-foundation/dexon-consensus-core/crypto/eth"
 	"github.com/shopspring/decimal"
 )
 
+var (
+	// ErrPrivateKeyNotExists means caller request private key for an
+	// unknown validator ID.
+	ErrPrivateKeyNotExists = fmt.Errorf("private key not exists")
+)
+
 // Governance is an implementation of Goverance for testing purpose.
 type Governance struct {
 	BlockProposingInterval int
@@ -79,3 +87,16 @@ func (g *Governance) GetConfigurationChangeEvent(
 	epoch int) []types.ConfigurationChangeEvent {
 	return nil
 }
+
+// GetPrivateKey return the private key for that validator, this function
+// is a test utility and not a general core.Governance interface.
+func (g *Governance) GetPrivateKey(
+	vID types.ValidatorID) (key crypto.PrivateKey, err error) {
+
+	key, exists := g.PrivateKeys[vID]
+	if !exists {
+		err = ErrPrivateKeyNotExists
+		return
+	}
+	return
+}