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]>

contracts/nns/contract.go

@@ -629,7 +629,7 @@ func Resolve(name string, typ recordtype.Type) []string {
 	}
 
 	ctx := storage.GetReadOnlyContext()
-	return resolve(ctx, nil, name, typ, 2)
+	return resolve(ctx, []string{}, name, typ, 2)
 }
 
 // GetAllRecords returns an Iterator with RecordState items for the given name.

tests/container_test.go

@@ -221,7 +221,7 @@ func TestContainerPut(t *testing.T) {
 				})
 
 				c.Invoke(t, stackitem.Null{}, "delete", cnt.id[:], cnt.sig, cnt.token)
-				cNNS.Invoke(t, stackitem.Null{}, "resolve", "mycnt."+containerDomain, int64(recordtype.TXT))
+				cNNS.Invoke(t, stackitem.NewArray([]stackitem.Item{}), "resolve", "mycnt."+containerDomain, int64(recordtype.TXT))
 
 				t.Run("register in advance", func(t *testing.T) {
 					cnt.value[len(cnt.value)-1]++

tests/nns_test.go

@@ -416,6 +416,9 @@ func TestNNSResolve(t *testing.T) {
 	c.Invoke(t, records, "resolve", "test.com.", int64(recordtype.TXT))
 	c.InvokeFail(t, "invalid domain fragment", "resolve", "test.com..", int64(recordtype.TXT))
 
+	// Empty result.
+	c.Invoke(t, stackitem.NewArray([]stackitem.Item{}), "resolve", "test.com", int64(recordtype.AAAA))
+
 	// Check CNAME is properly resolved and is not included into the result list.
 	c.Invoke(t, stackitem.NewArray([]stackitem.Item{stackitem.Make("1.2.3.4"), stackitem.Make("5.6.7.8")}), "resolve", "test.com", int64(recordtype.A))
 	// And this time it should be properly included without resolution.