Implement region argument for serializerfields

The region argument was implemented for the database field and form
field, but not the Django REST framework serializers.
Align the serializer with the other fields.

Add a bunch of tests for that field.

phonenumber_field/serializerfields.py

@@ -1,16 +1,22 @@
+from django.conf import settings
 from django.utils.translation import gettext_lazy as _
 from rest_framework import serializers
 from rest_framework.exceptions import ValidationError
 
-from phonenumber_field.phonenumber import to_python
+from phonenumber_field.phonenumber import to_python, validate_region
 
 
 class PhoneNumberField(serializers.CharField):
     default_error_messages = {"invalid": _("Enter a valid phone number.")}
 
+    def __init__(self, *args, region=None, **kwargs):
+        super().__init__(*args, **kwargs)
+        validate_region(region)
+        self.region = region or getattr(settings, "PHONENUMBER_DEFAULT_REGION", None)
+
     def to_internal_value(self, data):
         str_value = super().to_internal_value(data)
-        phone_number = to_python(str_value)
+        phone_number = to_python(str_value, region=self.region)
         if phone_number and not phone_number.is_valid():
             raise ValidationError(self.error_messages["invalid"])
         return phone_number

tests/test_serializers.py

@@ -1,6 +1,7 @@
-from django.test import SimpleTestCase
+from django.test import SimpleTestCase, override_settings
 from rest_framework import serializers
 
+from phonenumber_field.phonenumber import PhoneNumber
 from phonenumber_field.serializerfields import PhoneNumberField
 
 from .models import OptionalPhoneNumber
@@ -25,3 +26,74 @@ class PhoneNumberSerializer(serializers.Serializer):
 
         s = PhoneNumberSerializer(data={"phone": 1})
         self.assertIs(s.is_valid(), False)
+
+    def test_empty_required(self):
+        class PhoneNumberSerializer(serializers.Serializer):
+            phone = PhoneNumberField()
+
+        serializer = PhoneNumberSerializer(data={"phone": ""})
+        self.assertIs(serializer.is_valid(), False)
+        self.assertEqual(serializer.validated_data, {})
+
+    def test_empty_optional(self):
+        class PhoneNumberSerializer(serializers.Serializer):
+            phone = PhoneNumberField(allow_blank=True)
+
+        serializer = PhoneNumberSerializer(data={"phone": ""})
+        self.assertIs(serializer.is_valid(), True)
+        self.assertEqual(serializer.validated_data, {"phone": ""})
+
+    def test_e164_phone_number(self):
+        class PhoneNumberSerializer(serializers.Serializer):
+            phone = PhoneNumberField()
+
+        serializer = PhoneNumberSerializer(data={"phone": "+33612345678"})
+        self.assertIs(serializer.is_valid(), True)
+        self.assertEqual(serializer.validated_data, {"phone": "+33612345678"})
+        self.assertIsInstance(serializer.validated_data["phone"], PhoneNumber)
+
+    def test_region(self):
+        class PhoneNumberSerializer(serializers.Serializer):
+            phone = PhoneNumberField(region="FR")
+
+        serializer = PhoneNumberSerializer(data={"phone": "0612345678"})
+        self.assertIs(serializer.is_valid(), True)
+        self.assertEqual(serializer.validated_data, {"phone": "+33612345678"})
+        self.assertIsInstance(serializer.validated_data["phone"], PhoneNumber)
+
+    def test_region_invalid(self):
+        class PhoneNumberSerializer(serializers.Serializer):
+            phone = PhoneNumberField(region="GB")
+
+        serializer = PhoneNumberSerializer(data={"phone": "0612345678"})
+        self.assertIs(serializer.is_valid(), False)
+        self.assertEqual(serializer.validated_data, {})
+        self.assertEqual(serializer.errors, {"phone": ["Enter a valid phone number."]})
+
+    @override_settings(PHONENUMBER_DEFAULT_REGION="FR")
+    def test_region_from_settings(self):
+        class PhoneNumberSerializer(serializers.Serializer):
+            phone = PhoneNumberField()
+
+        serializer = PhoneNumberSerializer(data={"phone": "0612345678"})
+        self.assertIs(serializer.is_valid(), True)
+        self.assertEqual(serializer.validated_data, {"phone": "+33612345678"})
+        self.assertIsInstance(serializer.validated_data["phone"], PhoneNumber)
+
+    @override_settings(PHONENUMBER_DEFAULT_REGION="GB")
+    def test_region_kwarg_precedes_setting(self):
+        class PhoneNumberSerializer(serializers.Serializer):
+            phone = PhoneNumberField(region="FR")
+
+        serializer = PhoneNumberSerializer(data={"phone": "0612345678"})
+        self.assertIs(serializer.is_valid(), True)
+        self.assertEqual(serializer.validated_data, {"phone": "+33612345678"})
+        self.assertIsInstance(serializer.validated_data["phone"], PhoneNumber)
+
+    def test_invalid_region(self):
+        with self.assertRaisesMessage(
+            ValueError, "“INVALID” is not a valid region code. Choices are"
+        ):
+
+            class PhoneNumberSerializer(serializers.Serializer):
+                phone = PhoneNumberField(region="INVALID")