Refactor iban country code validation.

iban/iban.go

@@ -89,8 +89,8 @@ func Validate(value string) error {
 		return err
 	}
 
-	code, err := validateCountryCode(value)
-	if err != nil {
+	code := extractCountryCode(value)
+	if err := validateCountryCode(code); err != nil {
 		return err
 	}
 
@@ -99,15 +99,15 @@ func Validate(value string) error {
 		return ErrCountryCodeNotPresent
 	}
 
-	if err = validateBbanLength(value, structure); err != nil {
+	if err := validateBbanLength(value, structure); err != nil {
 		return err
 	}
 
-	if err = validateBbanStructure(value, structure); err != nil {
+	if err := validateBbanStructure(value, structure); err != nil {
 		return err
 	}
 
-	if err = validateCheckDigit(value, code); err != nil {
+	if err := validateCheckDigit(value, code); err != nil {
 		return err
 	}
 

iban/iban_test.go

@@ -295,9 +295,9 @@ func TestValidateDigit(t *testing.T) {
 func TestValidateCountryCode(t *testing.T) {
 	for _, cs := range validCases {
 		t.Run(cs.iban, func(t *testing.T) {
-			code, err := validateCountryCode(cs.iban)
+			code := extractCountryCode(cs.iban)
+			err := validateCountryCode(code)
 			require.NoError(t, err)
-			require.Equal(t, cs.countryCode, code)
 		})
 	}
 }
@@ -396,3 +396,12 @@ func TestMustParseInvalid(t *testing.T) {
 		})
 	}
 }
+
+func BenchmarkValidate(b *testing.B) {
+	b.ReportAllocs()
+	b.SetBytes(2)
+
+	for i := 0; i < b.N; i++ {
+		_ = Validate("AL47212110090000000235698741")
+	}
+}

iban/validate.go

@@ -33,20 +33,7 @@ func validateMinLength(value string) error {
 	return nil
 }
 
-func validateCountryCode(value string) (string, error) {
-	code := extractCountryCode(value)
-	if err := validateCountryCodeFormat(code); err != nil {
-		return "", err
-	}
-
-	if !country.Exists(code) {
-		return "", ErrCountryCodeNotPresent
-	}
-
-	return code, nil
-}
-
-func validateCountryCodeFormat(code string) error {
+func validateCountryCode(code string) error {
 	for _, r := range code {
 		if unicode.IsLower(r) {
 			return ErrCountryCodeNotUpper