新增，随机生成指定长度的数字

str/pad.go

@@ -1,6 +1,12 @@
 package str
 
-import "strings"
+import (
+	"math/rand"
+	"strings"
+	"time"
+
+	"github.com/farseer-go/fs/parse"
+)
 
 // PadLeft 为str向左填充paddingChar，直到长度=totalWidth
 func PadLeft(str string, totalWidth int, paddingChar string) string {
@@ -17,3 +23,9 @@ func PadRight(str string, totalWidth int, paddingChar string) string {
 	}
 	return str + strings.Repeat(paddingChar, totalWidth-Length(str))
 }
+
+// RandString 随机字符串
+func RandInt64(max int) string {
+	val := parse.ToString(rand.New(rand.NewSource(time.Now().UnixNano())).Intn(max))
+	return PadLeft(val, len(parse.ToString(max)), "0")
+}

test/str_pad_test.go

@@ -1,9 +1,10 @@
 package test
 
 import (
+	"testing"
+
 	"github.com/farseer-go/utils/str"
 	"github.com/stretchr/testify/assert"
-	"testing"
 )
 
 func TestPadRight(t *testing.T) {
@@ -15,3 +16,7 @@ func TestPadLeft(t *testing.T) {
 	assert.Equal(t, str.PadLeft("1", 5, "0"), "00001")
 	assert.Equal(t, str.PadLeft("哈哈", 5, "哼"), "哼哼哼哈哈")
 }
+
+func TestRandInt64(t *testing.T) {
+	assert.Equal(t, len(str.RandInt64(999999999)), 9)
+}