add some test

vendor/github.com/33cn/chain33/common/skiplist/queue.go

@@ -71,6 +71,11 @@ func (cache *Queue) CreateSkipValue(item Scorer) *SkipValue {
 	return skvalue
 }
 
+//MaxSize 最大的cache数量
+func (cache *Queue) MaxSize() int64 {
+	return cache.maxsize
+}
+
 //Exist 是否存在
 func (cache *Queue) Exist(hash string) bool {
 	_, exists := cache.txMap[hash]

vendor/github.com/33cn/chain33/common/skiplist/skiplist.go

@@ -234,6 +234,9 @@ func (sl *SkipList) Insert(value *SkipValue) int {
 
 // Delete 删除节点
 func (sl *SkipList) Delete(value *SkipValue) int {
+	if value == nil {
+		return 0
+	}
 	var update [maxLevel]*skipListNode
 	x := sl.header
 	for i := sl.level - 1; i >= 0; i-- {