metainfo: Omit empty Metainfo.InfoBytes

metainfo/metainfo.go

@@ -9,7 +9,7 @@ import (
 )
 
 type MetaInfo struct {
-	InfoBytes    bencode.Bytes `bencode:"info"`
+	InfoBytes    bencode.Bytes `bencode:"info,omitempty"`
 	Announce     string        `bencode:"announce,omitempty"`
 	AnnounceList AnnounceList  `bencode:"announce-list,omitempty"`
 	Nodes        []Node        `bencode:"nodes,omitempty"`

metainfo/nodes_test.go

@@ -1,6 +1,7 @@
 package metainfo
 
 import (
+	"bytes"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -61,3 +62,13 @@ func TestUnmarshalBadMetainfoNodes(t *testing.T) {
 	err := bencode.Unmarshal([]byte("d5:nodesl1:ai42eee"), &mi)
 	require.Error(t, err)
 }
+
+func TestMetainfoEmptyInfoBytes(t *testing.T) {
+	var buf bytes.Buffer
+	require.NoError(t, (&MetaInfo{
+		// Include a non-empty field that comes after "info".
+		UrlList: []string{"hello"},
+	}).Write(&buf))
+	var mi MetaInfo
+	require.NoError(t, bencode.Unmarshal(buf.Bytes(), &mi))
+}