Improve French NIF validation

DimitriPapadopoulos · arthurdejong · commit eeaf6650c1e7 · 2021-07-18T22:07:13.000+02:00
Closes arthurdejong#266
diff --git a/stdnum/fr/nif.py b/stdnum/fr/nif.py
@@ -1,7 +1,7 @@
 # nif.py - functions for handling French tax identification numbers
 # coding: utf-8
 #
-# Copyright (C) 2016 Dimitri Papadopoulos
+# Copyright (C) 2016-2021 Dimitri Papadopoulos
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -20,10 +20,10 @@
 
 """NIF (Numéro d'Immatriculation Fiscale, French tax identification number).
 
-The NIF (Numéro d'Immatriculation Fiscale, Numéro d'Identité Fiscale or
-Numéro d'Identification Fiscale) also known as numéro fiscal de référence or
-SPI (Simplification des Procédures d'Identification) is a 13-digit number
-issued by the French tax authorities to people for tax reporting purposes.
+The NIF (Numéro d'Immatriculation Fiscale or Numéro d'Identification Fiscale)
+also known as numéro fiscal de référence or SPI (Simplification des
+Procédures d'Identification) is a 13-digit number issued by the French tax
+authorities to people for tax reporting purposes.
 
 More information:
 
@@ -36,6 +36,10 @@
 Traceback (most recent call last):
     ...
 InvalidLength: ...
+>>> validate('9701987765432')
+Traceback (most recent call last):
+    ...
+InvalidComponent: ...
 >>> format('0701987765432')
 '07 01 987 765 432'
 """
@@ -55,6 +59,8 @@ def validate(number):
     number = compact(number)
     if not isdigits(number):
         raise InvalidFormat()
+    if number[0] not in ('0', '1', '2', '3'):
+        raise InvalidComponent()
     if len(number) != 13:
         raise InvalidLength()
     return number
