Only include two-letter province texts

address.go

@@ -1,6 +1,8 @@
 package fatturapa
 
 import (
+	"regexp"
+
 	"github.com/invopop/gobl/l10n"
 	"github.com/invopop/gobl/org"
 )
@@ -9,6 +11,10 @@ const (
 	foreignCAP = "00000"
 )
 
+var (
+	provinceRegexp = regexp.MustCompile(`^[A-Z]{2}$`)
+)
+
 // address from IndirizzoType
 type address struct {
 	Indirizzo    string // Street
@@ -24,7 +30,7 @@ func newAddress(addr *org.Address) *address {
 		Indirizzo:    addressStreet(addr),
 		NumeroCivico: addr.Number,
 		Comune:       addr.Locality,
-		Provincia:    addr.Region,
+		Provincia:    addressRegion(addr),
 		Nazione:      addr.Country.String(),
 	}
 	if addr.Country == l10n.IT {
@@ -35,6 +41,19 @@ func newAddress(addr *org.Address) *address {
 	return ad
 }
 
+// addressRegion will simply check if the region is using the
+// standard two digital capital letter code for the Italian province,
+// or return an empty string to avoid FatturaPA validation issues.
+// The province is optional, so it's not a problem if it's not set.
+func addressRegion(address *org.Address) string {
+	if address.Country == l10n.IT {
+		if provinceRegexp.MatchString(address.Region) {
+			return address.Region
+		}
+	}
+	return ""
+}
+
 func addressStreet(address *org.Address) string {
 	if address.PostOfficeBox != "" {
 		return address.PostOfficeBox

address_test.go

@@ -0,0 +1,53 @@
+package fatturapa
+
+import (
+	"testing"
+
+	"github.com/invopop/gobl/l10n"
+	"github.com/invopop/gobl/org"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAddressRegion(t *testing.T) {
+	t.Run("should return the region two letter code", func(t *testing.T) {
+		addr := &org.Address{
+			Number:   "1",
+			Street:   "Via Roma",
+			Locality: "Roma",
+			Region:   "RM",
+			Code:     "00100",
+			Country:  l10n.IT,
+		}
+
+		out := newAddress(addr)
+		assert.Equal(t, "RM", out.Provincia)
+	})
+
+	t.Run("should ignore text name", func(t *testing.T) {
+		addr := &org.Address{
+			Number:   "1",
+			Street:   "Via Roma",
+			Locality: "Roma",
+			Region:   "Rome",
+			Code:     "00100",
+			Country:  l10n.IT,
+		}
+
+		out := newAddress(addr)
+		assert.Empty(t, out.Provincia)
+	})
+
+	t.Run("should ignore foreign addresses", func(t *testing.T) {
+		addr := &org.Address{
+			Number:   "2",
+			Street:   "Rome Street",
+			Locality: "London",
+			Region:   "RM",
+			Code:     "00100",
+			Country:  l10n.GB,
+		}
+
+		out := newAddress(addr)
+		assert.Empty(t, out.Provincia)
+	})
+}