# -*- coding: utf-8 -*-
from __future__ import unicode_literals

import datetime
from collections import Counter

from django.forms import (
    BaseForm, CharField, DateField, FileField, Form, IntegerField,
    SplitDateTimeField, ValidationError, formsets,
)
from django.forms.formsets import BaseFormSet, formset_factory
from django.forms.utils import ErrorList
from django.test import SimpleTestCase, mock
from django.utils.encoding import force_text


class Choice(Form):
    choice = CharField()
    votes = IntegerField()


# FormSet allows us to use multiple instance of the same form on 1 page. For now,
# the best way to create a FormSet is by using the formset_factory function.
ChoiceFormSet = formset_factory(Choice)


class FavoriteDrinkForm(Form):
    name = CharField()


class BaseFavoriteDrinksFormSet(BaseFormSet):
    def clean(self):
        seen_drinks = []

        for drink in self.cleaned_data:
            if drink['name'] in seen_drinks:
                raise ValidationError('You may only specify a drink once.')

            seen_drinks.append(drink['name'])


class EmptyFsetWontValidate(BaseFormSet):
    def clean(self):
        raise ValidationError("Clean method called")


# Let's define a FormSet that takes a list of favorite drinks, but raises an
# error if there are any duplicates. Used in ``test_clean_hook``,
# ``test_regression_6926`` & ``test_regression_12878``.
FavoriteDrinksFormSet = formset_factory(FavoriteDrinkForm, formset=BaseFavoriteDrinksFormSet, extra=3)


# Used in ``test_formset_splitdatetimefield``.
class SplitDateTimeForm(Form):
    when = SplitDateTimeField(initial=datetime.datetime.now)


SplitDateTimeFormSet = formset_factory(SplitDateTimeForm)


class CustomKwargForm(Form):
    def __init__(self, *args, **kwargs):
        self.custom_kwarg = kwargs.pop('custom_kwarg')
        super(CustomKwargForm, self).__init__(*args, **kwargs)


class FormsFormsetTestCase(SimpleTestCase):

    def make_choiceformset(
            self, formset_data=None, formset_class=ChoiceFormSet,
            total_forms=None, initial_forms=0, max_num_forms=0, min_num_forms=0, **kwargs):
        """
        Make a ChoiceFormset from the given formset_data.
        The data should be given as a list of (choice, votes) tuples.
        """
        kwargs.setdefault('prefix', 'choices')
        kwargs.setdefault('auto_id', False)

        if formset_data is None:
            return formset_class(**kwargs)

        if total_forms is None:
            total_forms = len(formset_data)

        def prefixed(*args):
            args = (kwargs['prefix'],) + args
            return '-'.join(args)

        data = {
            prefixed('TOTAL_FORMS'): str(total_forms),
            prefixed('INITIAL_FORMS'): str(initial_forms),
            prefixed('MAX_NUM_FORMS'): str(max_num_forms),
            prefixed('MIN_NUM_FORMS'): str(min_num_forms),
        }
        for i, (choice, votes) in enumerate(formset_data):
            data[prefixed(str(i), 'choice')] = choice
            data[prefixed(str(i), 'votes')] = votes

        return formset_class(data, **kwargs)

    def test_basic_formset(self):
        # A FormSet constructor takes the same arguments as Form. Let's create a FormSet
        # for adding data. By default, it displays 1 blank form. It can display more,
        # but we'll look at how to do so later.
        formset = self.make_choiceformset()
        self.assertHTMLEqual(
            str(formset),
            """<input type="hidden" name="choices-TOTAL_FORMS" value="1" />
<input type="hidden" name="choices-INITIAL_FORMS" value="0" />
<input type="hidden" name="choices-MIN_NUM_FORMS" value="0" />
<input type="hidden" name="choices-MAX_NUM_FORMS" value="1000" />
<tr><th>Choice:</th><td><input type="text" name="choices-0-choice" /></td></tr>
<tr><th>Votes:</th><td><input type="number" name="choices-0-votes" /></td></tr>"""
        )

        # We treat FormSet pretty much like we would treat a normal Form. FormSet has an
        # is_valid method, and a cleaned_data or errors attribute depending on whether all
        # the forms passed validation. However, unlike a Form instance, cleaned_data and
        # errors will be a list of dicts rather than just a single dict.

        formset = self.make_choiceformset([('Calexico', '100')])
        self.assertTrue(formset.is_valid())
        self.assertEqual([form.cleaned_data for form in formset.forms], [{'votes': 100, 'choice': 'Calexico'}])

        # If a FormSet was not passed any data, its is_valid and has_changed
        # methods should return False.
        formset = self.make_choiceformset()
        self.assertFalse(formset.is_valid())
        self.assertFalse(formset.has_changed())

    def test_form_kwargs_formset(self):
        """
        Custom kwargs set on the formset instance are passed to the
        underlying forms.
        """
        FormSet = formset_factory(CustomKwargForm, extra=2)
        formset = FormSet(form_kwargs={'custom_kwarg': 1})
        for form in formset:
            self.assertTrue(hasattr(form, 'custom_kwarg'))
            self.assertEqual(form.custom_kwarg, 1)

    def test_form_kwargs_formset_dynamic(self):
        """
        Form kwargs can be passed dynamically in a formset.
        """
        class DynamicBaseFormSet(BaseFormSet):
            def get_form_kwargs(self, index):
                return {'custom_kwarg': index}

        DynamicFormSet = formset_factory(CustomKwargForm, formset=DynamicBaseFormSet, extra=2)
        formset = DynamicFormSet(form_kwargs={'custom_kwarg': 'ignored'})
        for i, form in enumerate(formset):
            self.assertTrue(hasattr(form, 'custom_kwarg'))
            self.assertEqual(form.custom_kwarg, i)

    def test_form_kwargs_empty_form(self):
        FormSet = formset_factory(CustomKwargForm)
        formset = FormSet(form_kwargs={'custom_kwarg': 1})
        self.assertTrue(hasattr(formset.empty_form, 'custom_kwarg'))
        self.assertEqual(formset.empty_form.custom_kwarg, 1)

    def test_formset_validation(self):
        # FormSet instances can also have an error attribute if validation failed for
        # any of the forms.
        formset = self.make_choiceformset([('Calexico', '')])
        self.assertFalse(formset.is_valid())
        self.assertEqual(formset.errors, [{'votes': ['This field is required.']}])

    def test_formset_validation_count(self):
        """
        A formset's ManagementForm is validated once per FormSet.is_valid()
        call and each form of the formset is cleaned once.
        """
        def make_method_counter(func):
            """Add a counter to func for the number of times it's called."""
            counter = Counter()
            counter.call_count = 0

            def mocked_func(*args, **kwargs):
                counter.call_count += 1
                return func(*args, **kwargs)

            return mocked_func, counter

        mocked_is_valid, is_valid_counter = make_method_counter(formsets.ManagementForm.is_valid)
        mocked_full_clean, full_clean_counter = make_method_counter(BaseForm.full_clean)
        formset = self.make_choiceformset([('Calexico', '100'), ('Any1', '42'), ('Any2', '101')])

        with mock.patch('django.forms.formsets.ManagementForm.is_valid', mocked_is_valid), \
                mock.patch('django.forms.forms.BaseForm.full_clean', mocked_full_clean):
            self.assertTrue(formset.is_valid())
        self.assertEqual(is_valid_counter.call_count, 1)
        self.assertEqual(full_clean_counter.call_count, 4)

    def test_formset_has_changed(self):
        # FormSet instances has_changed method will be True if any data is
        # passed to his forms, even if the formset didn't validate
        blank_formset = self.make_choiceformset([('', '')])
        self.assertFalse(blank_formset.has_changed())

        # invalid formset test
        invalid_formset = self.make_choiceformset([('Calexico', '')])
        self.assertFalse(invalid_formset.is_valid())
        self.assertTrue(invalid_formset.has_changed())

        # valid formset test
        valid_formset = self.make_choiceformset([('Calexico', '100')])
        self.assertTrue(valid_formset.is_valid())
        self.assertTrue(valid_formset.has_changed())

    def test_formset_initial_data(self):
        # We can also prefill a FormSet with existing data by providing an ``initial``
        # argument to the constructor. ``initial`` should be a list of dicts. By default,
        # an extra blank form is included.

        initial = [{'choice': 'Calexico', 'votes': 100}]
        formset = self.make_choiceformset(initial=initial)
        form_output = []

        for form in formset.forms:
            form_output.append(form.as_ul())

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico" /></li>
<li>Votes: <input type="number" name="choices-0-votes" value="100" /></li>
<li>Choice: <input type="text" name="choices-1-choice" /></li>
<li>Votes: <input type="number" name="choices-1-votes" /></li>"""
        )

        # Let's simulate what would happen if we submitted this form.
        formset = self.make_choiceformset([('Calexico', '100'), ('', '')], initial_forms=1)
        self.assertTrue(formset.is_valid())
        self.assertEqual([form.cleaned_data for form in formset.forms], [{'votes': 100, 'choice': 'Calexico'}, {}])

    def test_second_form_partially_filled(self):
        # But the second form was blank! Shouldn't we get some errors? No. If we display
        # a form as blank, it's ok for it to be submitted as blank. If we fill out even
        # one of the fields of a blank form though, it will be validated. We may want to
        # required that at least x number of forms are completed, but we'll show how to
        # handle that later.
        formset = self.make_choiceformset([('Calexico', '100'), ('The Decemberists', '')], initial_forms=1)
        self.assertFalse(formset.is_valid())
        self.assertEqual(formset.errors, [{}, {'votes': ['This field is required.']}])

    def test_delete_prefilled_data(self):
        # If we delete data that was pre-filled, we should get an error. Simply removing
        # data from form fields isn't the proper way to delete it. We'll see how to
        # handle that case later.
        formset = self.make_choiceformset([('', ''), ('', '')], initial_forms=1)
        self.assertFalse(formset.is_valid())
        self.assertEqual(
            formset.errors,
            [{'votes': ['This field is required.'], 'choice': ['This field is required.']}, {}]
        )

    def test_displaying_more_than_one_blank_form(self):
        # Displaying more than 1 blank form ###########################################
        # We can also display more than 1 empty form at a time. To do so, pass a
        # extra argument to formset_factory.
        ChoiceFormSet = formset_factory(Choice, extra=3)

        formset = ChoiceFormSet(auto_id=False, prefix='choices')
        form_output = []

        for form in formset.forms:
            form_output.append(form.as_ul())

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<li>Choice: <input type="text" name="choices-0-choice" /></li>
<li>Votes: <input type="number" name="choices-0-votes" /></li>
<li>Choice: <input type="text" name="choices-1-choice" /></li>
<li>Votes: <input type="number" name="choices-1-votes" /></li>
<li>Choice: <input type="text" name="choices-2-choice" /></li>
<li>Votes: <input type="number" name="choices-2-votes" /></li>"""
        )

        # Since we displayed every form as blank, we will also accept them back as blank.
        # This may seem a little strange, but later we will show how to require a minimum
        # number of forms to be completed.

        data = {
            'choices-TOTAL_FORMS': '3',  # the number of forms rendered
            'choices-INITIAL_FORMS': '0',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms
            'choices-0-choice': '',
            'choices-0-votes': '',
            'choices-1-choice': '',
            'choices-1-votes': '',
            'choices-2-choice': '',
            'choices-2-votes': '',
        }

        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertTrue(formset.is_valid())
        self.assertEqual([form.cleaned_data for form in formset.forms], [{}, {}, {}])

    def test_min_num_displaying_more_than_one_blank_form(self):
        # We can also display more than 1 empty form passing min_num argument
        # to formset_factory. It will (essentially) increment the extra argument
        ChoiceFormSet = formset_factory(Choice, extra=1, min_num=1)

        formset = ChoiceFormSet(auto_id=False, prefix='choices')
        form_output = []

        for form in formset.forms:
            form_output.append(form.as_ul())

        # Min_num forms are required; extra forms can be empty.
        self.assertFalse(formset.forms[0].empty_permitted)
        self.assertTrue(formset.forms[1].empty_permitted)

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<li>Choice: <input type="text" name="choices-0-choice" /></li>
<li>Votes: <input type="number" name="choices-0-votes" /></li>
<li>Choice: <input type="text" name="choices-1-choice" /></li>
<li>Votes: <input type="number" name="choices-1-votes" /></li>"""
        )

    def test_min_num_displaying_more_than_one_blank_form_with_zero_extra(self):
        # We can also display more than 1 empty form passing min_num argument
        ChoiceFormSet = formset_factory(Choice, extra=0, min_num=3)

        formset = ChoiceFormSet(auto_id=False, prefix='choices')
        form_output = []

        for form in formset.forms:
            form_output.append(form.as_ul())

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<li>Choice: <input type="text" name="choices-0-choice" /></li>
<li>Votes: <input type="number" name="choices-0-votes" /></li>
<li>Choice: <input type="text" name="choices-1-choice" /></li>
<li>Votes: <input type="number" name="choices-1-votes" /></li>
<li>Choice: <input type="text" name="choices-2-choice" /></li>
<li>Votes: <input type="number" name="choices-2-votes" /></li>"""
        )

    def test_single_form_completed(self):
        # We can just fill out one of the forms.

        data = {
            'choices-TOTAL_FORMS': '3',  # the number of forms rendered
            'choices-INITIAL_FORMS': '0',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms
            'choices-0-choice': 'Calexico',
            'choices-0-votes': '100',
            'choices-1-choice': '',
            'choices-1-votes': '',
            'choices-2-choice': '',
            'choices-2-votes': '',
        }

        ChoiceFormSet = formset_factory(Choice, extra=3)
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertTrue(formset.is_valid())
        self.assertEqual([form.cleaned_data for form in formset.forms], [{'votes': 100, 'choice': 'Calexico'}, {}, {}])

    def test_formset_validate_max_flag(self):
        # If validate_max is set and max_num is less than TOTAL_FORMS in the
        # data, then throw an exception. MAX_NUM_FORMS in the data is
        # irrelevant here (it's output as a hint for the client but its
        # value in the returned data is not checked)

        data = {
            'choices-TOTAL_FORMS': '2',  # the number of forms rendered
            'choices-INITIAL_FORMS': '0',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '2',  # max number of forms - should be ignored
            'choices-0-choice': 'Zero',
            'choices-0-votes': '0',
            'choices-1-choice': 'One',
            'choices-1-votes': '1',
        }

        ChoiceFormSet = formset_factory(Choice, extra=1, max_num=1, validate_max=True)
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertFalse(formset.is_valid())
        self.assertEqual(formset.non_form_errors(), ['Please submit 1 or fewer forms.'])

    def test_formset_validate_min_flag(self):
        # If validate_min is set and min_num is more than TOTAL_FORMS in the
        # data, then throw an exception. MIN_NUM_FORMS in the data is
        # irrelevant here (it's output as a hint for the client but its
        # value in the returned data is not checked)

        data = {
            'choices-TOTAL_FORMS': '2',  # the number of forms rendered
            'choices-INITIAL_FORMS': '0',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms - should be ignored
            'choices-0-choice': 'Zero',
            'choices-0-votes': '0',
            'choices-1-choice': 'One',
            'choices-1-votes': '1',
        }

        ChoiceFormSet = formset_factory(Choice, extra=1, min_num=3, validate_min=True)
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertFalse(formset.is_valid())
        self.assertEqual(formset.non_form_errors(), ['Please submit 3 or more forms.'])

    def test_formset_validate_min_unchanged_forms(self):
        """
        min_num validation doesn't consider unchanged forms with initial data
        as "empty".
        """
        initial = [
            {'choice': 'Zero', 'votes': 0},
            {'choice': 'One', 'votes': 0},
        ]
        data = {
            'choices-TOTAL_FORMS': '2',
            'choices-INITIAL_FORMS': '2',
            'choices-MIN_NUM_FORMS': '0',
            'choices-MAX_NUM_FORMS': '2',
            'choices-0-choice': 'Zero',
            'choices-0-votes': '0',
            'choices-1-choice': 'One',
            'choices-1-votes': '1',  # changed from initial
        }
        ChoiceFormSet = formset_factory(Choice, min_num=2, validate_min=True)
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices', initial=initial)
        self.assertFalse(formset.forms[0].has_changed())
        self.assertTrue(formset.forms[1].has_changed())
        self.assertTrue(formset.is_valid())

    def test_formset_validate_min_excludes_empty_forms(self):
        data = {
            'choices-TOTAL_FORMS': '2',
            'choices-INITIAL_FORMS': '0',
        }
        ChoiceFormSet = formset_factory(Choice, extra=2, min_num=1, validate_min=True, can_delete=True)
        formset = ChoiceFormSet(data, prefix='choices')
        self.assertFalse(formset.has_changed())
        self.assertFalse(formset.is_valid())
        self.assertEqual(formset.non_form_errors(), ['Please submit 1 or more forms.'])

    def test_second_form_partially_filled_2(self):
        # And once again, if we try to partially complete a form, validation will fail.

        data = {
            'choices-TOTAL_FORMS': '3',  # the number of forms rendered
            'choices-INITIAL_FORMS': '0',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms
            'choices-0-choice': 'Calexico',
            'choices-0-votes': '100',
            'choices-1-choice': 'The Decemberists',
            'choices-1-votes': '',  # missing value
            'choices-2-choice': '',
            'choices-2-votes': '',
        }

        ChoiceFormSet = formset_factory(Choice, extra=3)
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertFalse(formset.is_valid())
        self.assertEqual(formset.errors, [{}, {'votes': ['This field is required.']}, {}])

    def test_more_initial_data(self):
        # The extra argument also works when the formset is pre-filled with initial
        # data.
        initial = [{'choice': 'Calexico', 'votes': 100}]
        ChoiceFormSet = formset_factory(Choice, extra=3)
        formset = ChoiceFormSet(initial=initial, auto_id=False, prefix='choices')
        form_output = []

        for form in formset.forms:
            form_output.append(form.as_ul())

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico" /></li>
<li>Votes: <input type="number" name="choices-0-votes" value="100" /></li>
<li>Choice: <input type="text" name="choices-1-choice" /></li>
<li>Votes: <input type="number" name="choices-1-votes" /></li>
<li>Choice: <input type="text" name="choices-2-choice" /></li>
<li>Votes: <input type="number" name="choices-2-votes" /></li>
<li>Choice: <input type="text" name="choices-3-choice" /></li>
<li>Votes: <input type="number" name="choices-3-votes" /></li>"""
        )

        # Make sure retrieving an empty form works, and it shows up in the form list

        self.assertTrue(formset.empty_form.empty_permitted)
        self.assertHTMLEqual(
            formset.empty_form.as_ul(),
            """<li>Choice: <input type="text" name="choices-__prefix__-choice" /></li>
<li>Votes: <input type="number" name="choices-__prefix__-votes" /></li>"""
        )

    def test_formset_with_deletion(self):
        # FormSets with deletion ######################################################
        # We can easily add deletion ability to a FormSet with an argument to
        # formset_factory. This will add a boolean field to each form instance. When
        # that boolean field is True, the form will be in formset.deleted_forms

        ChoiceFormSet = formset_factory(Choice, can_delete=True)

        initial = [{'choice': 'Calexico', 'votes': 100}, {'choice': 'Fergie', 'votes': 900}]
        formset = ChoiceFormSet(initial=initial, auto_id=False, prefix='choices')
        form_output = []

        for form in formset.forms:
            form_output.append(form.as_ul())

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico" /></li>
<li>Votes: <input type="number" name="choices-0-votes" value="100" /></li>
<li>Delete: <input type="checkbox" name="choices-0-DELETE" /></li>
<li>Choice: <input type="text" name="choices-1-choice" value="Fergie" /></li>
<li>Votes: <input type="number" name="choices-1-votes" value="900" /></li>
<li>Delete: <input type="checkbox" name="choices-1-DELETE" /></li>
<li>Choice: <input type="text" name="choices-2-choice" /></li>
<li>Votes: <input type="number" name="choices-2-votes" /></li>
<li>Delete: <input type="checkbox" name="choices-2-DELETE" /></li>"""
        )

        # To delete something, we just need to set that form's special delete field to
        # 'on'. Let's go ahead and delete Fergie.

        data = {
            'choices-TOTAL_FORMS': '3',  # the number of forms rendered
            'choices-INITIAL_FORMS': '2',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms
            'choices-0-choice': 'Calexico',
            'choices-0-votes': '100',
            'choices-0-DELETE': '',
            'choices-1-choice': 'Fergie',
            'choices-1-votes': '900',
            'choices-1-DELETE': 'on',
            'choices-2-choice': '',
            'choices-2-votes': '',
            'choices-2-DELETE': '',
        }

        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertTrue(formset.is_valid())
        self.assertEqual(
            [form.cleaned_data for form in formset.forms],
            [
                {'votes': 100, 'DELETE': False, 'choice': 'Calexico'},
                {'votes': 900, 'DELETE': True, 'choice': 'Fergie'},
                {},
            ]
        )
        self.assertEqual(
            [form.cleaned_data for form in formset.deleted_forms],
            [{'votes': 900, 'DELETE': True, 'choice': 'Fergie'}]
        )

        # If we fill a form with something and then we check the can_delete checkbox for
        # that form, that form's errors should not make the entire formset invalid since
        # it's going to be deleted.

        class CheckForm(Form):
            field = IntegerField(min_value=100)

        data = {
            'check-TOTAL_FORMS': '3',  # the number of forms rendered
            'check-INITIAL_FORMS': '2',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'check-MAX_NUM_FORMS': '0',  # max number of forms
            'check-0-field': '200',
            'check-0-DELETE': '',
            'check-1-field': '50',
            'check-1-DELETE': 'on',
            'check-2-field': '',
            'check-2-DELETE': '',
        }
        CheckFormSet = formset_factory(CheckForm, can_delete=True)
        formset = CheckFormSet(data, prefix='check')
        self.assertTrue(formset.is_valid())

        # If we remove the deletion flag now we will have our validation back.
        data['check-1-DELETE'] = ''
        formset = CheckFormSet(data, prefix='check')
        self.assertFalse(formset.is_valid())

        # Should be able to get deleted_forms from a valid formset even if a
        # deleted form would have been invalid.

        class Person(Form):
            name = CharField()

        PeopleForm = formset_factory(
            form=Person,
            can_delete=True)

        p = PeopleForm(
            {'form-0-name': '', 'form-0-DELETE': 'on',  # no name!
             'form-TOTAL_FORMS': 1, 'form-INITIAL_FORMS': 1,
             'form-MIN_NUM_FORMS': 0, 'form-MAX_NUM_FORMS': 1})

        self.assertTrue(p.is_valid())
        self.assertEqual(len(p.deleted_forms), 1)

    def test_formsets_with_ordering(self):
        # FormSets with ordering ######################################################
        # We can also add ordering ability to a FormSet with an argument to
        # formset_factory. This will add an integer field to each form instance. When
        # form validation succeeds, [form.cleaned_data for form in formset.forms] will have the data in the correct
        # order specified by the ordering fields. If a number is duplicated in the set
        # of ordering fields, for instance form 0 and form 3 are both marked as 1, then
        # the form index used as a secondary ordering criteria. In order to put
        # something at the front of the list, you'd need to set it's order to 0.

        ChoiceFormSet = formset_factory(Choice, can_order=True)

        initial = [{'choice': 'Calexico', 'votes': 100}, {'choice': 'Fergie', 'votes': 900}]
        formset = ChoiceFormSet(initial=initial, auto_id=False, prefix='choices')
        form_output = []

        for form in formset.forms:
            form_output.append(form.as_ul())

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico" /></li>
<li>Votes: <input type="number" name="choices-0-votes" value="100" /></li>
<li>Order: <input type="number" name="choices-0-ORDER" value="1" /></li>
<li>Choice: <input type="text" name="choices-1-choice" value="Fergie" /></li>
<li>Votes: <input type="number" name="choices-1-votes" value="900" /></li>
<li>Order: <input type="number" name="choices-1-ORDER" value="2" /></li>
<li>Choice: <input type="text" name="choices-2-choice" /></li>
<li>Votes: <input type="number" name="choices-2-votes" /></li>
<li>Order: <input type="number" name="choices-2-ORDER" /></li>"""
        )

        data = {
            'choices-TOTAL_FORMS': '3',  # the number of forms rendered
            'choices-INITIAL_FORMS': '2',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms
            'choices-0-choice': 'Calexico',
            'choices-0-votes': '100',
            'choices-0-ORDER': '1',
            'choices-1-choice': 'Fergie',
            'choices-1-votes': '900',
            'choices-1-ORDER': '2',
            'choices-2-choice': 'The Decemberists',
            'choices-2-votes': '500',
            'choices-2-ORDER': '0',
        }

        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertTrue(formset.is_valid())
        form_output = []

        for form in formset.ordered_forms:
            form_output.append(form.cleaned_data)

        self.assertEqual(form_output, [
            {'votes': 500, 'ORDER': 0, 'choice': 'The Decemberists'},
            {'votes': 100, 'ORDER': 1, 'choice': 'Calexico'},
            {'votes': 900, 'ORDER': 2, 'choice': 'Fergie'},
        ])

    def test_empty_ordered_fields(self):
        # Ordering fields are allowed to be left blank, and if they *are* left blank,
        # they will be sorted below everything else.

        data = {
            'choices-TOTAL_FORMS': '4',  # the number of forms rendered
            'choices-INITIAL_FORMS': '3',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms
            'choices-0-choice': 'Calexico',
            'choices-0-votes': '100',
            'choices-0-ORDER': '1',
            'choices-1-choice': 'Fergie',
            'choices-1-votes': '900',
            'choices-1-ORDER': '2',
            'choices-2-choice': 'The Decemberists',
            'choices-2-votes': '500',
            'choices-2-ORDER': '',
            'choices-3-choice': 'Basia Bulat',
            'choices-3-votes': '50',
            'choices-3-ORDER': '',
        }

        ChoiceFormSet = formset_factory(Choice, can_order=True)
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertTrue(formset.is_valid())
        form_output = []

        for form in formset.ordered_forms:
            form_output.append(form.cleaned_data)

        self.assertEqual(form_output, [
            {'votes': 100, 'ORDER': 1, 'choice': 'Calexico'},
            {'votes': 900, 'ORDER': 2, 'choice': 'Fergie'},
            {'votes': 500, 'ORDER': None, 'choice': 'The Decemberists'},
            {'votes': 50, 'ORDER': None, 'choice': 'Basia Bulat'},
        ])

    def test_ordering_blank_fieldsets(self):
        # Ordering should work with blank fieldsets.

        data = {
            'choices-TOTAL_FORMS': '3',  # the number of forms rendered
            'choices-INITIAL_FORMS': '0',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms
        }

        ChoiceFormSet = formset_factory(Choice, can_order=True)
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertTrue(formset.is_valid())
        form_output = []

        for form in formset.ordered_forms:
            form_output.append(form.cleaned_data)

        self.assertEqual(form_output, [])

    def test_formset_with_ordering_and_deletion(self):
        # FormSets with ordering + deletion ###########################################
        # Let's try throwing ordering and deletion into the same form.

        ChoiceFormSet = formset_factory(Choice, can_order=True, can_delete=True)

        initial = [
            {'choice': 'Calexico', 'votes': 100},
            {'choice': 'Fergie', 'votes': 900},
            {'choice': 'The Decemberists', 'votes': 500},
        ]
        formset = ChoiceFormSet(initial=initial, auto_id=False, prefix='choices')
        form_output = []

        for form in formset.forms:
            form_output.append(form.as_ul())

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico" /></li>
<li>Votes: <input type="number" name="choices-0-votes" value="100" /></li>
<li>Order: <input type="number" name="choices-0-ORDER" value="1" /></li>
<li>Delete: <input type="checkbox" name="choices-0-DELETE" /></li>
<li>Choice: <input type="text" name="choices-1-choice" value="Fergie" /></li>
<li>Votes: <input type="number" name="choices-1-votes" value="900" /></li>
<li>Order: <input type="number" name="choices-1-ORDER" value="2" /></li>
<li>Delete: <input type="checkbox" name="choices-1-DELETE" /></li>
<li>Choice: <input type="text" name="choices-2-choice" value="The Decemberists" /></li>
<li>Votes: <input type="number" name="choices-2-votes" value="500" /></li>
<li>Order: <input type="number" name="choices-2-ORDER" value="3" /></li>
<li>Delete: <input type="checkbox" name="choices-2-DELETE" /></li>
<li>Choice: <input type="text" name="choices-3-choice" /></li>
<li>Votes: <input type="number" name="choices-3-votes" /></li>
<li>Order: <input type="number" name="choices-3-ORDER" /></li>
<li>Delete: <input type="checkbox" name="choices-3-DELETE" /></li>"""
        )

        # Let's delete Fergie, and put The Decemberists ahead of Calexico.

        data = {
            'choices-TOTAL_FORMS': '4',  # the number of forms rendered
            'choices-INITIAL_FORMS': '3',  # the number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms
            'choices-0-choice': 'Calexico',
            'choices-0-votes': '100',
            'choices-0-ORDER': '1',
            'choices-0-DELETE': '',
            'choices-1-choice': 'Fergie',
            'choices-1-votes': '900',
            'choices-1-ORDER': '2',
            'choices-1-DELETE': 'on',
            'choices-2-choice': 'The Decemberists',
            'choices-2-votes': '500',
            'choices-2-ORDER': '0',
            'choices-2-DELETE': '',
            'choices-3-choice': '',
            'choices-3-votes': '',
            'choices-3-ORDER': '',
            'choices-3-DELETE': '',
        }

        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertTrue(formset.is_valid())
        form_output = []

        for form in formset.ordered_forms:
            form_output.append(form.cleaned_data)

        self.assertEqual(form_output, [
            {'votes': 500, 'DELETE': False, 'ORDER': 0, 'choice': 'The Decemberists'},
            {'votes': 100, 'DELETE': False, 'ORDER': 1, 'choice': 'Calexico'},
        ])
        self.assertEqual(
            [form.cleaned_data for form in formset.deleted_forms],
            [{'votes': 900, 'DELETE': True, 'ORDER': 2, 'choice': 'Fergie'}]
        )

    def test_invalid_deleted_form_with_ordering(self):
        # Should be able to get ordered forms from a valid formset even if a
        # deleted form would have been invalid.

        class Person(Form):
            name = CharField()

        PeopleForm = formset_factory(form=Person, can_delete=True, can_order=True)

        p = PeopleForm({
            'form-0-name': '',
            'form-0-DELETE': 'on',  # no name!
            'form-TOTAL_FORMS': 1,
            'form-INITIAL_FORMS': 1,
            'form-MIN_NUM_FORMS': 0,
            'form-MAX_NUM_FORMS': 1
        })

        self.assertTrue(p.is_valid())
        self.assertEqual(p.ordered_forms, [])

    def test_clean_hook(self):
        # FormSet clean hook ##########################################################
        # FormSets have a hook for doing extra validation that shouldn't be tied to any
        # particular form. It follows the same pattern as the clean hook on Forms.

        # We start out with a some duplicate data.

        data = {
            'drinks-TOTAL_FORMS': '2',  # the number of forms rendered
            'drinks-INITIAL_FORMS': '0',  # the number of forms with initial data
            'drinks-MIN_NUM_FORMS': '0',  # min number of forms
            'drinks-MAX_NUM_FORMS': '0',  # max number of forms
            'drinks-0-name': 'Gin and Tonic',
            'drinks-1-name': 'Gin and Tonic',
        }

        formset = FavoriteDrinksFormSet(data, prefix='drinks')
        self.assertFalse(formset.is_valid())

        # Any errors raised by formset.clean() are available via the
        # formset.non_form_errors() method.

        for error in formset.non_form_errors():
            self.assertEqual(str(error), 'You may only specify a drink once.')

        # Make sure we didn't break the valid case.

        data = {
            'drinks-TOTAL_FORMS': '2',  # the number of forms rendered
            'drinks-INITIAL_FORMS': '0',  # the number of forms with initial data
            'drinks-MIN_NUM_FORMS': '0',  # min number of forms
            'drinks-MAX_NUM_FORMS': '0',  # max number of forms
            'drinks-0-name': 'Gin and Tonic',
            'drinks-1-name': 'Bloody Mary',
        }

        formset = FavoriteDrinksFormSet(data, prefix='drinks')
        self.assertTrue(formset.is_valid())
        self.assertEqual(formset.non_form_errors(), [])

    def test_limiting_max_forms(self):
        # Limiting the maximum number of forms ########################################
        # Base case for max_num.

        # When not passed, max_num will take a high default value, leaving the
        # number of forms only controlled by the value of the extra parameter.

        LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=3)
        formset = LimitedFavoriteDrinkFormSet()
        form_output = []

        for form in formset.forms:
            form_output.append(str(form))

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<tr><th><label for="id_form-0-name">Name:</label></th>
<td><input type="text" name="form-0-name" id="id_form-0-name" /></td></tr>
<tr><th><label for="id_form-1-name">Name:</label></th>
<td><input type="text" name="form-1-name" id="id_form-1-name" /></td></tr>
<tr><th><label for="id_form-2-name">Name:</label></th>
<td><input type="text" name="form-2-name" id="id_form-2-name" /></td></tr>"""
        )

        # If max_num is 0 then no form is rendered at all.
        LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=3, max_num=0)
        formset = LimitedFavoriteDrinkFormSet()
        form_output = []

        for form in formset.forms:
            form_output.append(str(form))

        self.assertEqual('\n'.join(form_output), "")

        LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=5, max_num=2)
        formset = LimitedFavoriteDrinkFormSet()
        form_output = []

        for form in formset.forms:
            form_output.append(str(form))

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<tr><th><label for="id_form-0-name">Name:</label></th><td>
<input type="text" name="form-0-name" id="id_form-0-name" /></td></tr>
<tr><th><label for="id_form-1-name">Name:</label></th>
<td><input type="text" name="form-1-name" id="id_form-1-name" /></td></tr>"""
        )

        # max_num has no effect when extra is less than max_num.
        LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=1, max_num=2)
        formset = LimitedFavoriteDrinkFormSet()
        form_output = []

        for form in formset.forms:
            form_output.append(str(form))

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<tr><th><label for="id_form-0-name">Name:</label></th>
<td><input type="text" name="form-0-name" id="id_form-0-name" /></td></tr>"""
        )

    def test_max_num_with_initial_data(self):
        # max_num with initial data

        # When not passed, max_num will take a high default value, leaving the
        # number of forms only controlled by the value of the initial and extra
        # parameters.

        initial = [
            {'name': 'Fernet and Coke'},
        ]
        LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=1)
        formset = LimitedFavoriteDrinkFormSet(initial=initial)
        form_output = []

        for form in formset.forms:
            form_output.append(str(form))

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<tr><th><label for="id_form-0-name">Name:</label></th>
<td><input type="text" name="form-0-name" value="Fernet and Coke" id="id_form-0-name" /></td></tr>
<tr><th><label for="id_form-1-name">Name:</label></th>
<td><input type="text" name="form-1-name" id="id_form-1-name" /></td></tr>"""
        )

    def test_max_num_zero(self):
        # If max_num is 0 then no form is rendered at all, regardless of extra,
        # unless initial data is present. (This changed in the patch for bug
        # 20084 -- previously max_num=0 trumped initial data)

        LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=1, max_num=0)
        formset = LimitedFavoriteDrinkFormSet()
        form_output = []

        for form in formset.forms:
            form_output.append(str(form))

        self.assertEqual('\n'.join(form_output), "")

        # test that initial trumps max_num

        initial = [
            {'name': 'Fernet and Coke'},
            {'name': 'Bloody Mary'},
        ]
        LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=1, max_num=0)
        formset = LimitedFavoriteDrinkFormSet(initial=initial)
        form_output = []

        for form in formset.forms:
            form_output.append(str(form))
        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<tr><th><label for="id_form-0-name">Name:</label></th>
<td><input id="id_form-0-name" name="form-0-name" type="text" value="Fernet and Coke" /></td></tr>
<tr><th><label for="id_form-1-name">Name:</label></th>
<td><input id="id_form-1-name" name="form-1-name" type="text" value="Bloody Mary" /></td></tr>"""
        )

    def test_more_initial_than_max_num(self):
        # More initial forms than max_num now results in all initial forms
        # being displayed (but no extra forms).  This behavior was changed
        # from max_num taking precedence in the patch for #20084

        initial = [
            {'name': 'Gin Tonic'},
            {'name': 'Bloody Mary'},
            {'name': 'Jack and Coke'},
        ]
        LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=1, max_num=2)
        formset = LimitedFavoriteDrinkFormSet(initial=initial)
        form_output = []

        for form in formset.forms:
            form_output.append(str(form))
        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<tr><th><label for="id_form-0-name">Name:</label></th>
<td><input id="id_form-0-name" name="form-0-name" type="text" value="Gin Tonic" /></td></tr>
<tr><th><label for="id_form-1-name">Name:</label></th>
<td><input id="id_form-1-name" name="form-1-name" type="text" value="Bloody Mary" /></td></tr>
<tr><th><label for="id_form-2-name">Name:</label></th>
<td><input id="id_form-2-name" name="form-2-name" type="text" value="Jack and Coke" /></td></tr>"""
        )

        # One form from initial and extra=3 with max_num=2 should result in the one
        # initial form and one extra.
        initial = [
            {'name': 'Gin Tonic'},
        ]
        LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=3, max_num=2)
        formset = LimitedFavoriteDrinkFormSet(initial=initial)
        form_output = []

        for form in formset.forms:
            form_output.append(str(form))

        self.assertHTMLEqual(
            '\n'.join(form_output),
            """<tr><th><label for="id_form-0-name">Name:</label></th>
<td><input type="text" name="form-0-name" value="Gin Tonic" id="id_form-0-name" /></td></tr>
<tr><th><label for="id_form-1-name">Name:</label></th>
<td><input type="text" name="form-1-name" id="id_form-1-name" /></td></tr>"""
        )

    def test_regression_6926(self):
        # Regression test for #6926 ##################################################
        # Make sure the management form has the correct prefix.

        formset = FavoriteDrinksFormSet()
        self.assertEqual(formset.management_form.prefix, 'form')

        data = {
            'form-TOTAL_FORMS': '2',
            'form-INITIAL_FORMS': '0',
            'form-MIN_NUM_FORMS': '0',
            'form-MAX_NUM_FORMS': '0',
        }
        formset = FavoriteDrinksFormSet(data=data)
        self.assertEqual(formset.management_form.prefix, 'form')

        formset = FavoriteDrinksFormSet(initial={})
        self.assertEqual(formset.management_form.prefix, 'form')

    def test_regression_12878(self):
        # Regression test for #12878 #################################################

        data = {
            'drinks-TOTAL_FORMS': '2',  # the number of forms rendered
            'drinks-INITIAL_FORMS': '0',  # the number of forms with initial data
            'drinks-MIN_NUM_FORMS': '0',  # min number of forms
            'drinks-MAX_NUM_FORMS': '0',  # max number of forms
            'drinks-0-name': 'Gin and Tonic',
            'drinks-1-name': 'Gin and Tonic',
        }

        formset = FavoriteDrinksFormSet(data, prefix='drinks')
        self.assertFalse(formset.is_valid())
        self.assertEqual(formset.non_form_errors(), ['You may only specify a drink once.'])

    def test_formset_iteration(self):
        # Regression tests for #16455 -- formset instances are iterable
        ChoiceFormset = formset_factory(Choice, extra=3)
        formset = ChoiceFormset()

        # confirm iterated formset yields formset.forms
        forms = list(formset)
        self.assertEqual(forms, formset.forms)
        self.assertEqual(len(formset), len(forms))

        # confirm indexing of formset
        self.assertEqual(formset[0], forms[0])
        with self.assertRaises(IndexError):
            formset[3]

        # Formsets can override the default iteration order
        class BaseReverseFormSet(BaseFormSet):
            def __iter__(self):
                return reversed(self.forms)

            def __getitem__(self, idx):
                return super(BaseReverseFormSet, self).__getitem__(len(self) - idx - 1)

        ReverseChoiceFormset = formset_factory(Choice, BaseReverseFormSet, extra=3)
        reverse_formset = ReverseChoiceFormset()

        # confirm that __iter__ modifies rendering order
        # compare forms from "reverse" formset with forms from original formset
        self.assertEqual(str(reverse_formset[0]), str(forms[-1]))
        self.assertEqual(str(reverse_formset[1]), str(forms[-2]))
        self.assertEqual(len(reverse_formset), len(forms))

    def test_formset_nonzero(self):
        """
        Formsets with no forms should still evaluate as true.
        Regression test for #15722
        """
        ChoiceFormset = formset_factory(Choice, extra=0)
        formset = ChoiceFormset()
        self.assertEqual(len(formset.forms), 0)
        self.assertTrue(formset)

    def test_formset_splitdatetimefield(self):
        """
        Formset should also work with SplitDateTimeField(initial=datetime.datetime.now).
        Regression test for #18709.
        """
        data = {
            'form-TOTAL_FORMS': '1',
            'form-INITIAL_FORMS': '0',
            'form-0-when_0': '1904-06-16',
            'form-0-when_1': '15:51:33',
        }
        formset = SplitDateTimeFormSet(data)
        self.assertTrue(formset.is_valid())

    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)

    def test_formset_calls_forms_is_valid(self):
        # Regression tests for #18574 -- make sure formsets call
        # is_valid() on each form.

        class AnotherChoice(Choice):
            def is_valid(self):
                self.is_valid_called = True
                return super(AnotherChoice, self).is_valid()

        AnotherChoiceFormSet = formset_factory(AnotherChoice)
        data = {
            'choices-TOTAL_FORMS': '1',  # number of forms rendered
            'choices-INITIAL_FORMS': '0',  # number of forms with initial data
            'choices-MIN_NUM_FORMS': '0',  # min number of forms
            'choices-MAX_NUM_FORMS': '0',  # max number of forms
            'choices-0-choice': 'Calexico',
            'choices-0-votes': '100',
        }
        formset = AnotherChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertTrue(formset.is_valid())
        self.assertTrue(all(form.is_valid_called for form in formset.forms))

    def test_hard_limit_on_instantiated_forms(self):
        """A formset has a hard limit on the number of forms instantiated."""
        # reduce the default limit of 1000 temporarily for testing
        _old_DEFAULT_MAX_NUM = formsets.DEFAULT_MAX_NUM
        try:
            formsets.DEFAULT_MAX_NUM = 2
            ChoiceFormSet = formset_factory(Choice, max_num=1)
            # someone fiddles with the mgmt form data...
            formset = ChoiceFormSet(
                {
                    'choices-TOTAL_FORMS': '4',
                    'choices-INITIAL_FORMS': '0',
                    'choices-MIN_NUM_FORMS': '0',  # min number of forms
                    'choices-MAX_NUM_FORMS': '4',
                    'choices-0-choice': 'Zero',
                    'choices-0-votes': '0',
                    'choices-1-choice': 'One',
                    'choices-1-votes': '1',
                    'choices-2-choice': 'Two',
                    'choices-2-votes': '2',
                    'choices-3-choice': 'Three',
                    'choices-3-votes': '3',
                },
                prefix='choices',
            )
            # But we still only instantiate 3 forms
            self.assertEqual(len(formset.forms), 3)
            # and the formset isn't valid
            self.assertFalse(formset.is_valid())
        finally:
            formsets.DEFAULT_MAX_NUM = _old_DEFAULT_MAX_NUM

    def test_increase_hard_limit(self):
        """Can increase the built-in forms limit via a higher max_num."""
        # reduce the default limit of 1000 temporarily for testing
        _old_DEFAULT_MAX_NUM = formsets.DEFAULT_MAX_NUM
        try:
            formsets.DEFAULT_MAX_NUM = 3
            # for this form, we want a limit of 4
            ChoiceFormSet = formset_factory(Choice, max_num=4)
            formset = ChoiceFormSet(
                {
                    'choices-TOTAL_FORMS': '4',
                    'choices-INITIAL_FORMS': '0',
                    'choices-MIN_NUM_FORMS': '0',  # min number of forms
                    'choices-MAX_NUM_FORMS': '4',
                    'choices-0-choice': 'Zero',
                    'choices-0-votes': '0',
                    'choices-1-choice': 'One',
                    'choices-1-votes': '1',
                    'choices-2-choice': 'Two',
                    'choices-2-votes': '2',
                    'choices-3-choice': 'Three',
                    'choices-3-votes': '3',
                },
                prefix='choices',
            )
            # Four forms are instantiated and no exception is raised
            self.assertEqual(len(formset.forms), 4)
        finally:
            formsets.DEFAULT_MAX_NUM = _old_DEFAULT_MAX_NUM

    def test_non_form_errors_run_full_clean(self):
        # Regression test for #11160
        # If non_form_errors() is called without calling is_valid() first,
        # it should ensure that full_clean() is called.
        class BaseCustomFormSet(BaseFormSet):
            def clean(self):
                raise ValidationError("This is a non-form error")

        ChoiceFormSet = formset_factory(Choice, formset=BaseCustomFormSet)
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertIsInstance(formset.non_form_errors(), ErrorList)
        self.assertEqual(list(formset.non_form_errors()), ['This is a non-form error'])

    def test_validate_max_ignores_forms_marked_for_deletion(self):
        class CheckForm(Form):
            field = IntegerField()

        data = {
            'check-TOTAL_FORMS': '2',
            'check-INITIAL_FORMS': '0',
            'check-MAX_NUM_FORMS': '1',
            'check-0-field': '200',
            'check-0-DELETE': '',
            'check-1-field': '50',
            'check-1-DELETE': 'on',
        }
        CheckFormSet = formset_factory(CheckForm, max_num=1, validate_max=True,
                                       can_delete=True)
        formset = CheckFormSet(data, prefix='check')
        self.assertTrue(formset.is_valid())

    def test_formset_total_error_count(self):
        """A valid formset should have 0 total errors."""
        data = [  # formset_data, expected error count
            ([('Calexico', '100')], 0),
            ([('Calexico', '')], 1),
            ([('', 'invalid')], 2),
            ([('Calexico', '100'), ('Calexico', '')], 1),
            ([('Calexico', ''), ('Calexico', '')], 2),
        ]

        for formset_data, expected_error_count in data:
            formset = self.make_choiceformset(formset_data)
            self.assertEqual(formset.total_error_count(), expected_error_count)

    def test_formset_total_error_count_with_non_form_errors(self):
        data = {
            'choices-TOTAL_FORMS': '2',  # the number of forms rendered
            'choices-INITIAL_FORMS': '0',  # the number of forms with initial data
            'choices-MAX_NUM_FORMS': '2',  # max number of forms - should be ignored
            'choices-0-choice': 'Zero',
            'choices-0-votes': '0',
            'choices-1-choice': 'One',
            'choices-1-votes': '1',
        }

        ChoiceFormSet = formset_factory(Choice, extra=1, max_num=1, validate_max=True)
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertEqual(formset.total_error_count(), 1)

        data['choices-1-votes'] = ''
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertEqual(formset.total_error_count(), 2)

    def test_html_safe(self):
        formset = self.make_choiceformset()
        self.assertTrue(hasattr(formset, '__html__'))
        self.assertEqual(force_text(formset), formset.__html__())


data = {
    'choices-TOTAL_FORMS': '1',  # the number of forms rendered
    'choices-INITIAL_FORMS': '0',  # the number of forms with initial data
    'choices-MIN_NUM_FORMS': '0',  # min number of forms
    'choices-MAX_NUM_FORMS': '0',  # max number of forms
    'choices-0-choice': 'Calexico',
    'choices-0-votes': '100',
}


class FormsetAsFooTests(SimpleTestCase):
    def test_as_table(self):
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertHTMLEqual(
            formset.as_table(),
            """<input type="hidden" name="choices-TOTAL_FORMS" value="1" />
<input type="hidden" name="choices-INITIAL_FORMS" value="0" />
<input type="hidden" name="choices-MIN_NUM_FORMS" value="0" />
<input type="hidden" name="choices-MAX_NUM_FORMS" value="0" />
<tr><th>Choice:</th><td><input type="text" name="choices-0-choice" value="Calexico" /></td></tr>
<tr><th>Votes:</th><td><input type="number" name="choices-0-votes" value="100" /></td></tr>"""
        )

    def test_as_p(self):
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertHTMLEqual(
            formset.as_p(),
            """<input type="hidden" name="choices-TOTAL_FORMS" value="1" />
<input type="hidden" name="choices-INITIAL_FORMS" value="0" />
<input type="hidden" name="choices-MIN_NUM_FORMS" value="0" />
<input type="hidden" name="choices-MAX_NUM_FORMS" value="0" />
<p>Choice: <input type="text" name="choices-0-choice" value="Calexico" /></p>
<p>Votes: <input type="number" name="choices-0-votes" value="100" /></p>"""
        )

    def test_as_ul(self):
        formset = ChoiceFormSet(data, auto_id=False, prefix='choices')
        self.assertHTMLEqual(
            formset.as_ul(),
            """<input type="hidden" name="choices-TOTAL_FORMS" value="1" />
<input type="hidden" name="choices-INITIAL_FORMS" value="0" />
<input type="hidden" name="choices-MIN_NUM_FORMS" value="0" />
<input type="hidden" name="choices-MAX_NUM_FORMS" value="0" />
<li>Choice: <input type="text" name="choices-0-choice" value="Calexico" /></li>
<li>Votes: <input type="number" name="choices-0-votes" value="100" /></li>"""
        )


# Regression test for #11418 #################################################
class ArticleForm(Form):
    title = CharField()
    pub_date = DateField()


ArticleFormSet = formset_factory(ArticleForm)


class TestIsBoundBehavior(SimpleTestCase):
    def test_no_data_raises_validation_error(self):
        with self.assertRaises(ValidationError):
            ArticleFormSet({}).is_valid()

    def test_with_management_data_attrs_work_fine(self):
        data = {
            'form-TOTAL_FORMS': '1',
            'form-INITIAL_FORMS': '0',
        }
        formset = ArticleFormSet(data)
        self.assertEqual(0, formset.initial_form_count())
        self.assertEqual(1, formset.total_form_count())
        self.assertTrue(formset.is_bound)
        self.assertTrue(formset.forms[0].is_bound)
        self.assertTrue(formset.is_valid())
        self.assertTrue(formset.forms[0].is_valid())
        self.assertEqual([{}], formset.cleaned_data)

    def test_form_errors_are_caught_by_formset(self):
        data = {
            'form-TOTAL_FORMS': '2',
            'form-INITIAL_FORMS': '0',
            'form-0-title': 'Test',
            'form-0-pub_date': '1904-06-16',
            'form-1-title': 'Test',
            'form-1-pub_date': '',  # <-- this date is missing but required
        }
        formset = ArticleFormSet(data)
        self.assertFalse(formset.is_valid())
        self.assertEqual([{}, {'pub_date': ['This field is required.']}], formset.errors)

    def test_empty_forms_are_unbound(self):
        data = {
            'form-TOTAL_FORMS': '1',
            'form-INITIAL_FORMS': '0',
            'form-0-title': 'Test',
            'form-0-pub_date': '1904-06-16',
        }
        unbound_formset = ArticleFormSet()
        bound_formset = ArticleFormSet(data)

        empty_forms = [
            unbound_formset.empty_form,
            bound_formset.empty_form
        ]

        # Empty forms should be unbound
        self.assertFalse(empty_forms[0].is_bound)
        self.assertFalse(empty_forms[1].is_bound)

        # The empty forms should be equal.
        self.assertHTMLEqual(empty_forms[0].as_p(), empty_forms[1].as_p())


class TestEmptyFormSet(SimpleTestCase):
    def test_empty_formset_is_valid(self):
        """An empty formset still calls clean()"""
        EmptyFsetWontValidateFormset = formset_factory(FavoriteDrinkForm, extra=0, formset=EmptyFsetWontValidate)
        formset = EmptyFsetWontValidateFormset(
            data={'form-INITIAL_FORMS': '0', 'form-TOTAL_FORMS': '0'},
            prefix="form",
        )
        formset2 = EmptyFsetWontValidateFormset(
            data={'form-INITIAL_FORMS': '0', 'form-TOTAL_FORMS': '1', 'form-0-name': 'bah'},
            prefix="form",
        )
        self.assertFalse(formset.is_valid())
        self.assertFalse(formset2.is_valid())

    def test_empty_formset_media(self):
        """Make sure media is available on empty formset, refs #19545"""
        class MediaForm(Form):
            class Media:
                js = ('some-file.js',)
        self.assertIn('some-file.js', str(formset_factory(MediaForm, extra=0)().media))

    def test_empty_formset_is_multipart(self):
        """Make sure `is_multipart()` works with empty formset, refs #19545"""
        class FileForm(Form):
            file = FileField()
        self.assertTrue(formset_factory(FileForm, extra=0)().is_multipart())
