fix splay tree bench test

Fixed an issue where the delete operation attempted to remove nodes
outside the valid range. The index range is now progressively
narrowed during the operation.

test/bench/tree_editing_bench_test.go

@@ -21,7 +21,6 @@ package bench
 import (
 	"fmt"
 	"math/rand"
-	"strconv"
 	"testing"
 	"time"
 
@@ -34,17 +33,6 @@ import (
 	"github.com/yorkie-team/yorkie/test/helper"
 )
 
-func randomArray(n, min, max int) []int {
-	arr := make([]int, n)
-	rand.Seed(time.Now().UnixNano())
-
-	for i := 0; i < n; i++ {
-		arr[i] = rand.Intn(max-min+1) + min
-	}
-
-	return arr
-}
-
 type stringValue struct {
 	content string
 	removed bool
@@ -67,39 +55,43 @@ func (v *stringValue) String() string {
 	return v.content
 }
 
+func buildSplayTree(size int) *splay.Tree[*stringValue] {
+	tree := splay.NewTree[*stringValue](nil)
+	for i := 0; i < size; i++ {
+		tree.Insert(newSplayNode("a"))
+	}
+	return tree
+}
+
 func BenchmarkSplayTree(b *testing.B) {
 	operationCount := []int{10000, 20000, 30000}
+	rand.Seed(time.Now().UnixNano())
 
-	for _, n := range operationCount {
+	for _, size := range operationCount {
 		b.ResetTimer()
-		arr := randomArray(n, 1, n)
 
-		b.Run(fmt.Sprintf("Insert %d", n), func(b *testing.B) {
+		b.Run(fmt.Sprintf("Insert %d", size), func(b *testing.B) {
 			tree := splay.NewTree[*stringValue](nil)
-			for _, i := range arr {
-				tree.Insert(newSplayNode(strconv.FormatInt(int64(i), 10)))
+			for i := 0; i < size; i++ {
+				tree.Insert(newSplayNode("a"))
 			}
 		})
-		b.Run(fmt.Sprintf("Random read %d", n), func(b *testing.B) {
+		b.Run(fmt.Sprintf("Random read %d", size), func(b *testing.B) {
 			b.StopTimer()
-			tree := splay.NewTree[*stringValue](nil)
-			for _, i := range arr {
-				tree.Insert(newSplayNode(strconv.FormatInt(int64(i), 10)))
-			}
+			tree := buildSplayTree(size)
 			b.StartTimer()
-			for _, i := range randomArray(n, 0, n-1) {
-				tree.Find(i)
+
+			for i := 0; i < size; i++ {
+				tree.Find(rand.Intn(size - i))
 			}
 		})
-		b.Run(fmt.Sprintf("Delete %d", n), func(b *testing.B) {
+		b.Run(fmt.Sprintf("Delete %d", size), func(b *testing.B) {
 			b.StopTimer()
-			tree := splay.NewTree[*stringValue](nil)
-			for _, i := range arr {
-				tree.Insert(newSplayNode(strconv.FormatInt(int64(i), 10)))
-			}
+			tree := buildSplayTree(size)
 			b.StartTimer()
-			for _, i := range randomArray(n, 1, n) {
-				node, _, _ := tree.Find(i)
+
+			for i := 0; i < size; i++ {
+				node, _, _ := tree.Find(rand.Intn(size))
 				if node != nil {
 					tree.Delete(node)
 				}