Split model_fields tests into different files.

tests/model_fields/test_genericipaddressfield.py

@@ -0,0 +1,35 @@
+from django.core.exceptions import ValidationError
+from django.db import models
+from django.test import TestCase
+
+from .models import GenericIPAddress
+
+
+class GenericIPAddressFieldTests(TestCase):
+
+    def test_genericipaddressfield_formfield_protocol(self):
+        """
+        GenericIPAddressField with a specified protocol does not generate a
+        formfield without a protocol.
+        """
+        model_field = models.GenericIPAddressField(protocol='IPv4')
+        form_field = model_field.formfield()
+        with self.assertRaises(ValidationError):
+            form_field.clean('::1')
+        model_field = models.GenericIPAddressField(protocol='IPv6')
+        form_field = model_field.formfield()
+        with self.assertRaises(ValidationError):
+            form_field.clean('127.0.0.1')
+
+    def test_null_value(self):
+        """
+        Null values should be resolved to None.
+        """
+        GenericIPAddress.objects.create()
+        o = GenericIPAddress.objects.get()
+        self.assertIsNone(o.ip)
+
+    def test_save_load(self):
+        instance = GenericIPAddress.objects.create(ip='::1')
+        loaded = GenericIPAddress.objects.get()
+        self.assertEqual(loaded.ip, instance.ip)