Fixed #16479 - Forms generated from formsets use ErrorList instead of supplied error_class

Patch with tests from charettes, updated.

django/forms/formsets.py

@@ -123,7 +123,11 @@ class BaseFormSet(object):
         """
         Instantiates and returns the i-th form instance in a formset.
         """
-        defaults = {'auto_id': self.auto_id, 'prefix': self.add_prefix(i)}
+        defaults = {
+            'auto_id': self.auto_id,
+            'prefix': self.add_prefix(i),
+            'error_class': self.error_class,
+            }
         if self.is_bound:
             defaults['data'] = self.data
             defaults['files'] = self.files

tests/regressiontests/forms/tests/formsets.py

@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 
 from django.forms import Form, CharField, IntegerField, ValidationError, DateField
 from django.forms.formsets import formset_factory, BaseFormSet
+from django.forms.util import ErrorList
 from django.test import TestCase
 
 
@@ -847,6 +848,15 @@ class FormsFormsetTestCase(TestCase):
         self.assertTrue(formset)
 
 
+    def test_formset_error_class(self):
+        # Regression tests for #16479 -- formsets form use ErrorList instead of supplied error_class
+        class CustomErrorList(ErrorList):
+            pass
+
+        formset = FavoriteDrinksFormSet(error_class=CustomErrorList)
+        self.assertEqual(formset.forms[0].error_class, CustomErrorList)
+
+
 data = {
     'choices-TOTAL_FORMS': '1', # the number of forms rendered
     'choices-INITIAL_FORMS': '0', # the number of forms with initial data