Fixing MX tax identity code validation with strange characters

CHANGELOG.md

@@ -6,12 +6,19 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/) and this p
 
 ## [Unreleased]
 
+### Added
+
+- `bill`: normalize line discounts and charges to remove empty rows.
+
+### Fixed
+
+- `tax`: identity code handling will skip default validation for specific countries that use special characters.
+
 ## [v0.204.0]
 
 ### Added
 
 - `br-nfse-v1`: added initial Brazil NFS-e addon
-- `bill`: normalize line discounts and charges to remove empty rows.
 
 ### Changed
 

regimes/mx/examples/out/retentions.json

@@ -4,7 +4,7 @@
 		"uuid": "8a51fd30-2a27-11ee-be56-0242ac120002",
 		"dig": {
 			"alg": "sha256",
-			"val": "df116edc1be8cffa73ea841b6fc36bb367ac300466c9f1e57f024cbefa410e45"
+			"val": "bf9567fd923b6a5962e91b333a730ef03759c3e82d42827de31796249266f11e"
 		}
 	},
 	"doc": {
@@ -39,7 +39,7 @@
 			"name": "UNIVERSIDAD ROBOTICA ESPAÑOLA",
 			"tax_id": {
 				"country": "MX",
-				"code": "URE180429TM6"
+				"code": "K\u0026A010301I16"
 			},
 			"addresses": [
 				{

regimes/mx/examples/retentions.yaml

@@ -19,7 +19,7 @@ customer:
     mx-cfdi-use: "G01"
   tax_id:
     country: "MX"
-    code: "URE180429TM6"
+    code: "K&A010301I16"
     zone: "86991"
 lines:
   - quantity: "1"

regimes/mx/tax_identity.go

@@ -75,14 +75,10 @@ func NormalizeTaxCode(code cbc.Code) cbc.Code {
 // defined by the Mexican SAT.
 func ValidateTaxCode(value interface{}) error {
 	code, ok := value.(cbc.Code)
-	if !ok {
+	if !ok || code == "" {
 		return nil
 	}
-	if code == "" {
-		return nil
-	}
-	typ := DetermineTaxCodeType(code)
-	if typ.IsEmpty() {
+	if typ := DetermineTaxCodeType(code); typ.IsEmpty() {
 		return tax.ErrIdentityCodeInvalid
 	}
 	return nil

tax/identity.go

@@ -55,6 +55,10 @@ var (
 
 	// IdentityCodeBadCharsRegexp is used to remove any characters that are not valid in a tax code.
 	IdentityCodeBadCharsRegexp = regexp.MustCompile(`[^A-Z0-9]+`)
+
+	// IdentityCodeValidationIgnore is a list of countries that should not have their tax identity
+	// codes validated due to local rules.
+	IdentityCodeValidationIgnore = []l10n.TaxCountryCode{"MX"}
 )
 
 // RequireIdentityCode is an additional check to use alongside
@@ -108,13 +112,12 @@ func (id *Identity) Calculate() error {
 // on the tax identity. Identities are an exception to the normal
 // normalization rules as they cannot be normalized using addons.
 func (id *Identity) Normalize() {
-	r := id.Regime()
-	if r == nil {
+	if r := id.Regime(); r != nil {
+		r.NormalizeObject(id)
+	} else {
 		// Fallback to common normalization
 		NormalizeIdentity(id)
-		return
 	}
-	r.NormalizeObject(id)
 }
 
 // Validate checks to ensure the tax ID contains all the required
@@ -123,7 +126,12 @@ func (id *Identity) Normalize() {
 func (id *Identity) Validate() error {
 	err := validation.ValidateStruct(id,
 		validation.Field(&id.Country, validation.Required),
-		validation.Field(&id.Code, validation.Match(IdentityCodePatternRegexp)),
+		validation.Field(&id.Code,
+			validation.Skip.When(
+				id.Country.In(IdentityCodeValidationIgnore...),
+			),
+			validation.Match(IdentityCodePatternRegexp),
+		),
 		validation.Field(&id.Zone, validation.Empty),
 		validation.Field(&id.Type),
 	)
@@ -142,10 +150,14 @@ func (v validateTaxID) Validate(value interface{}) error {
 	if id == nil || !ok {
 		return nil
 	}
-	rules := []*validation.FieldRules{
-		validation.Field(&id.Code,
-			validation.When(v.requireCode, validation.Required),
-		),
+	rules := []*validation.FieldRules{}
+	if v.requireCode {
+		rules = append(rules,
+			validation.Field(&id.Code,
+				validation.Required,
+				validation.Skip,
+			),
+		)
 	}
 	return validation.ValidateStruct(id, rules...)
 }

tax/identity_test.go

@@ -50,6 +50,22 @@ func TestTaxIdentity(t *testing.T) {
 	assert.NotPanics(t, func() {
 		tID.Normalize()
 	})
+
+	t.Run("mexican case with custom validation", func(t *testing.T) {
+		tID := &tax.Identity{
+			Country: "MX",
+			Code:    "K&A010301I16",
+		}
+		assert.NoError(t, tID.Validate())
+	})
+
+	t.Run("invalid non-exception case", func(t *testing.T) {
+		tID := &tax.Identity{
+			Country: "ZW", // update when ZW regime is added
+			Code:    "AB&DE",
+		}
+		assert.ErrorContains(t, tID.Validate(), "code: must be in a valid format")
+	})
 }
 
 func TestParseIdentity(t *testing.T) {
@@ -77,12 +93,22 @@ func TestValidationRules(t *testing.T) {
 }
 
 func TestNormalizeIdentity(t *testing.T) {
-	tID := &tax.Identity{
-		Country: "AU",
-		Code:    "  x315-7928 m  ",
-	}
-	tax.NormalizeIdentity(tID)
-	assert.Equal(t, tID.Code.String(), "X3157928M")
+	t.Run("regular case", func(t *testing.T) {
+		tID := &tax.Identity{
+			Country: "AU",
+			Code:    "  x315-7928 m  ",
+		}
+		tax.NormalizeIdentity(tID)
+		assert.Equal(t, tID.Code.String(), "X3157928M")
+	})
+	t.Run("with alt country", func(t *testing.T) {
+		tID := &tax.Identity{
+			Country: "EL",
+			Code:    "GR925667500",
+		}
+		tax.NormalizeIdentity(tID, "GR")
+		assert.Equal(t, tID.Code.String(), "925667500")
+	})
 }
 
 func TestIdentityNormalize(t *testing.T) {