Test for setting allow_none=True for nullable CharFields

rest_framework/tests/test_serializer.py

@@ -1504,6 +1504,7 @@ class AttributeMappingOnAutogeneratedFieldsTests(TestCase):
             image_field = models.ImageField(max_length=1024, blank=True)
             slug_field = models.SlugField(max_length=1024, blank=True)
             url_field = models.URLField(max_length=1024, blank=True)
+            nullable_char_field = models.CharField(max_length=1024, blank=True, null=True)
 
         class AMOAFSerializer(serializers.ModelSerializer):
             class Meta:
@@ -1536,6 +1537,10 @@ class AttributeMappingOnAutogeneratedFieldsTests(TestCase):
             'url_field': [
                 ('max_length', 1024),
             ],
+            'nullable_char_field': [
+                ('max_length', 1024),
+                ('allow_none', True),
+            ],
         }
 
     def field_test(self, field):
@@ -1572,6 +1577,9 @@ class AttributeMappingOnAutogeneratedFieldsTests(TestCase):
     def test_url_field(self):
         self.field_test('url_field')
 
+    def test_nullable_char_field(self):
+        self.field_test('nullable_char_field')
+
 
 class DefaultValuesOnAutogeneratedFieldsTests(TestCase):