[nspcc-dev#266] nns: Return empty Array from resolve instead of Null

In case if no records of the specified type found.

Signed-off-by: Anna Shaleva <[email protected]>

nns/nns_contract.go

@@ -443,7 +443,8 @@ func DeleteRecords(name string, typ RecordType) {
 // Resolve resolves given name (not more then three redirects are allowed).
 func Resolve(name string, typ RecordType) []string {
 	ctx := storage.GetReadOnlyContext()
-	return resolve(ctx, nil, name, typ, 2)
+	res := []string{}
+	return resolve(ctx, res, name, typ, 2)
 }
 
 // GetAllRecords returns an Iterator with RecordState items for the given name.

tests/container_test.go

@@ -153,7 +153,7 @@ func TestContainerPut(t *testing.T) {
 		})
 
 		c.Invoke(t, stackitem.Null{}, "delete", cnt.id[:], cnt.sig, cnt.token)
-		cNNS.Invoke(t, stackitem.Null{}, "resolve", "mycnt.neofs", int64(nns.TXT))
+		cNNS.Invoke(t, stackitem.NewArray([]stackitem.Item{}), "resolve", "mycnt.neofs", int64(nns.TXT))
 
 		t.Run("register in advance", func(t *testing.T) {
 			cnt.value[len(cnt.value)-1] = 10

tests/nns_test.go

@@ -380,4 +380,6 @@ func TestNNSResolve(t *testing.T) {
 	c.Invoke(t, records, "resolve", "test.com", int64(nns.TXT))
 	c.Invoke(t, records, "resolve", "test.com.", int64(nns.TXT))
 	c.InvokeFail(t, "invalid domain name format", "resolve", "test.com..", int64(nns.TXT))
+	// Empty result.
+	c.Invoke(t, stackitem.NewArray([]stackitem.Item{}), "resolve", "test.com", int64(nns.CNAME))
 }