Fixed tests

pkg/engine/engine_test.go

@@ -5,6 +5,7 @@ import (
 	"crypto/ecdh"
 	"crypto/rand"
 	"encoding/hex"
+	"fmt"
 	"strings"
 	"testing"
 )
@@ -792,7 +793,8 @@ func TestRandomMessageSizes(t *testing.T) {
 	sizes := []int{0, 1, 15, 16, 17, 31, 32, 33, 63, 64, 65, 127, 128, 256, 512, 1000, 4096}
 
 	for _, size := range sizes {
-		t.Run(string(rune(size)), func(t *testing.T) {
+		size := size // capture range variable
+		t.Run(fmt.Sprintf("%d_bytes", size), func(t *testing.T) {
 			plaintext := make([]byte, size)
 			if size > 0 {
 				rand.Read(plaintext)