Added roundchange tests and updated docs and comments

consensus/istanbul/backend/backend.go

@@ -338,6 +338,7 @@ func (sb *backend) IsQIBFTConsensus() bool {
 	return false
 }
 
+// StartQBFTConsensus stops existing legacy ibft consensus and starts the new qibft consensus
 func (sb *backend) StartQIBFTConsensus() error {
 	sb.logger.Trace("Starting QIBFT Consensus")
 	if err := sb.Stop(); err != nil {

consensus/qibft/core/roundchange_test.go

@@ -90,3 +90,67 @@ func TestRoundChangeSet(t *testing.T) {
 		t.Errorf("the change messages mismatch: have %v, want nil", rc.roundChanges[view.Round.Uint64()])
 	}
 }
+
+func TestGetMinRoundChange(t *testing.T) {
+	rcs := getRoundChangeSetForPositveTests()
+	minRC := rcs.getMinRoundChange(big.NewInt(1))
+	if minRC.Uint64() != 2 {
+		t.Errorf("min Round Change mismatch: have %v, want 2", minRC.Uint64())
+	}
+}
+
+func TestClearLowerThan(t *testing.T) {
+	rcs := getRoundChangeSetForPositveTests()
+	rcs.ClearLowerThan(big.NewInt(3))
+	if len(rcs.roundChanges) > 0 {
+		t.Errorf("Number of Round Change messages mismatch: have %v, want 0", len(rcs.roundChanges))
+	}
+
+	rcs = getRoundChangeSetForPositveTests()
+	rcs.ClearLowerThan(big.NewInt(2))
+	rcMsgs := rcs.roundChanges[2]
+	if len(rcMsgs.messages) != 3 {
+		t.Errorf("Number of Round Change messages mismatch: have %v, want 3", len(rcs.roundChanges))
+	}
+}
+
+func getRoundChangeSetForPositveTests() *roundChangeSet {
+	vset := validator.NewSet(generateValidators(4), istanbul.RoundRobin)
+
+	view := &View{
+		Sequence: big.NewInt(1),
+		Round:    big.NewInt(2),
+	}
+	proposal := makeBlock(1)
+
+	rcs := newRoundChangeSet(vset)
+
+	encodedRCMsg1, _ := Encode(&RoundChangeMessage{
+		View:             view,
+		PreparedRound:    big.NewInt(1),
+		PreparedBlock:    proposal,
+		PreparedMessages: nil,
+	})
+
+	msg1 := &message{
+		Code:    msgRoundChange,
+		Msg:     encodedRCMsg1,
+		Address: vset.GetByIndex(0).Address(),
+	}
+	msg2 := &message{
+		Code:    msgRoundChange,
+		Msg:     encodedRCMsg1,
+		Address: vset.GetByIndex(1).Address(),
+	}
+	msg3 := &message{
+		Code:    msgRoundChange,
+		Msg:     encodedRCMsg1,
+		Address: vset.GetByIndex(2).Address(),
+	}
+
+	rcs.Add(view.Round, msg1, big.NewInt(1), proposal, nil)
+	rcs.Add(view.Round, msg2, big.NewInt(1), proposal, nil)
+	rcs.Add(view.Round, msg3, big.NewInt(1), proposal, nil)
+
+	return rcs
+}

consensus/qibft/core/types.go

@@ -181,6 +181,7 @@ func Encode(val interface{}) ([]byte, error) {
 	return rlp.EncodeToBytes(val)
 }
 
+// Request is used to construct a Preprepare message
 type Request struct {
 	Proposal        istanbul.Proposal
 	RCMessages      *messageSet
@@ -235,6 +236,7 @@ func (v *View) Cmp(y *View) int {
 	return 0
 }
 
+// Preprepare represents the message sent, when msgPreprepare is broadcasted
 type Preprepare struct {
 	View             *View
 	Proposal         istanbul.Proposal
@@ -264,6 +266,7 @@ func (b *Preprepare) DecodeRLP(s *rlp.Stream) error {
 	return nil
 }
 
+// Subject represents the message sent when msgPrepare and msgCommit is broadcasted
 type Subject struct {
 	View   *View
 	Digest istanbul.Proposal
@@ -292,6 +295,7 @@ func (b *Subject) String() string {
 	return fmt.Sprintf("{View: %v, Proposal: %v}", b.View, b.Digest.String())
 }
 
+// RoundChangeMessage represents the message sent when msgRoundChange is broadcasted
 type RoundChangeMessage struct {
 	View             *View
 	PreparedRound    *big.Int

docs/Consensus/ibft/ibft-parameters.md

@@ -66,4 +66,10 @@ nodes. This was introduced to enable existing network the ability to upgrade at
 it is incompatible with the existing formula. For new networks, it is recommended to set this value to `0` to use the 
 updated formula immediately.
 
+To update this value, the same process can be followed as other hard-forks.
+
+### qibftBlock
+
+The `qibftBlock` sets the block number from which to use `qibft` consensus. This was introduced to enable existing ibft networks the ability to start using qibft consensus at a point in the future. For new networks, it is recommended to set this value to `0` to use the updated formula immediately.
+
 To update this value, the same process can be followed as other hard-forks.