Fix linter reported issues

Signed-off-by: Chun-Hung Tseng <[email protected]>

node_test.go

@@ -129,7 +129,7 @@ func TestNodeStepUnblock(t *testing.T) {
 // TestNodePropose ensures that node.Propose sends the given proposal to the underlying raft.
 func TestNodePropose(t *testing.T) {
 	var msgs []raftpb.Message
-	appendStep := func(r *raft, m raftpb.Message) error {
+	appendStep := func(_ *raft, m raftpb.Message) error {
 		t.Log(DescribeMessage(m, nil))
 		if m.Type == raftpb.MsgAppResp {
 			return nil // injected by (*raft).advance
@@ -240,7 +240,7 @@ func TestNodeReadIndexToOldLeader(t *testing.T) {
 // to the underlying raft.
 func TestNodeProposeConfig(t *testing.T) {
 	var msgs []raftpb.Message
-	appendStep := func(r *raft, m raftpb.Message) error {
+	appendStep := func(_ *raft, m raftpb.Message) error {
 		if m.Type == raftpb.MsgAppResp {
 			return nil // injected by (*raft).advance
 		}
@@ -386,7 +386,7 @@ func TestBlockProposal(t *testing.T) {
 func TestNodeProposeWaitDropped(t *testing.T) {
 	var msgs []raftpb.Message
 	droppingMsg := []byte("test_dropping")
-	dropStep := func(r *raft, m raftpb.Message) error {
+	dropStep := func(_ *raft, m raftpb.Message) error {
 		if m.Type == raftpb.MsgProp && strings.Contains(m.String(), string(droppingMsg)) {
 			t.Logf("dropping message: %v", m.String())
 			return ErrProposalDropped

raft.go

@@ -2015,7 +2015,7 @@ func (r *raft) switchToConfig(cfg tracker.Config, trk tracker.ProgressMap) pb.Co
 		// Otherwise, still probe the newly added replicas; there's no reason to
 		// let them wait out a heartbeat interval (or the next incoming
 		// proposal).
-		r.trk.Visit(func(id uint64, pr *tracker.Progress) {
+		r.trk.Visit(func(id uint64, _ *tracker.Progress) {
 			if id == r.id {
 				return
 			}

raft_paper_test.go

@@ -76,7 +76,7 @@ func testUpdateTermFromMessage(t *testing.T, state StateType) {
 // Reference: section 5.1
 func TestRejectStaleTermMessage(t *testing.T) {
 	called := false
-	fakeStep := func(r *raft, m pb.Message) error {
+	fakeStep := func(_ *raft, _ pb.Message) error {
 		called = true
 		return nil
 	}

raft_test.go

@@ -1073,7 +1073,7 @@ func TestPastElectionTimeout(t *testing.T) {
 // from old term and does not pass it to the actual stepX function.
 func TestStepIgnoreOldTermMsg(t *testing.T) {
 	called := false
-	fakeStep := func(r *raft, m pb.Message) error {
+	fakeStep := func(_ *raft, _ pb.Message) error {
 		called = true
 		return nil
 	}

rawnode_test.go

@@ -509,7 +509,7 @@ func TestRawNodeProposeAddDuplicateNode(t *testing.T) {
 // to the underlying raft. It also ensures that ReadState can be read out.
 func TestRawNodeReadIndex(t *testing.T) {
 	var msgs []pb.Message
-	appendStep := func(r *raft, m pb.Message) error {
+	appendStep := func(_ *raft, m pb.Message) error {
 		msgs = append(msgs, m)
 		return nil
 	}