raft: do not use underscore in var name

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

raft/raft_test.go

@@ -2304,10 +2304,10 @@ func TestReadOnlyOptionLease(t *testing.T) {
 // when it commits at least one log entry at it term.
 func TestReadOnlyForNewLeader(t *testing.T) {
 	nodeConfigs := []struct {
-		id            uint64
-		committed     uint64
-		applied       uint64
-		compact_index uint64
+		id           uint64
+		committed    uint64
+		applied      uint64
+		compactIndex uint64
 	}{
 		{1, 1, 1, 0},
 		{2, 2, 2, 2},
@@ -2318,8 +2318,8 @@ func TestReadOnlyForNewLeader(t *testing.T) {
 		storage := NewMemoryStorage()
 		storage.Append([]pb.Entry{{Index: 1, Term: 1}, {Index: 2, Term: 1}})
 		storage.SetHardState(pb.HardState{Term: 1, Commit: c.committed})
-		if c.compact_index != 0 {
-			storage.Compact(c.compact_index)
+		if c.compactIndex != 0 {
+			storage.Compact(c.compactIndex)
 		}
 		cfg := newTestConfig(c.id, []uint64{1, 2, 3}, 10, 1, storage)
 		cfg.Applied = c.applied