'Asserts that a formset used to render the response has a specific error.
For field errors, specify the ``form_index`` and the ``field``.
For non-field errors, specify the ``form_index`` and the ``field`` as
None.
For non-form errors, specify ``form_index`` as None and the ``field``
as None.'

def assertFormsetError(self, response, formset, form_index, field, errors, msg_prefix=u''):

    if msg_prefix:
        msg_prefix += u':    '
    contexts = to_list(response.context)
    if (not contexts):
        self.fail((msg_prefix + u'Response    did    not    use    any    contexts    to    render    the    response'))
    errors = to_list(errors)
    found_formset = False
    for (i, context) in enumerate(contexts):
        if (formset not in context):
            continue
        found_formset = True
        for err in errors:
            if (field is not None):
                if (field in context[formset].forms[form_index].errors):
                    field_errors = context[formset].forms[form_index].errors[field]
                    self.assertTrue((err in field_errors), (msg_prefix + (u"The    field    '%s'    on    formset    '%s',    form    %d    in    context    %d    does    not    contain    the    error    '%s'    (actual    errors:    %s)" % (field, formset, form_index, i, err, repr(field_errors)))))
                elif (field in context[formset].forms[form_index].fields):
                    self.fail((msg_prefix + (u"The    field    '%s'    on    formset    '%s',    form    %d    in    context    %d    contains    no    errors" % (field, formset, form_index, i))))
                else:
                    self.fail((msg_prefix + (u"The    formset    '%s',    form    %d    in    context    %d    does    not    contain    the    field    '%s'" % (formset, form_index, i, field))))
            elif (form_index is not None):
                non_field_errors = context[formset].forms[form_index].non_field_errors()
                self.assertFalse((len(non_field_errors) == 0), (msg_prefix + (u"The    formset    '%s',    form    %d    in    context    %d    does    not    contain    any    non-field    errors." % (formset, form_index, i))))
                self.assertTrue((err in non_field_errors), (msg_prefix + (u"The    formset    '%s',    form    %d    in    context    %d    does    not    contain    the    non-field    error    '%s'    (actual    errors:    %s)" % (formset, form_index, i, err, repr(non_field_errors)))))
            else:
                non_form_errors = context[formset].non_form_errors()
                self.assertFalse((len(non_form_errors) == 0), (msg_prefix + (u"The    formset    '%s'    in    context    %d    does    not    contain    any    non-form    errors." % (formset, i))))
                self.assertTrue((err in non_form_errors), (msg_prefix + (u"The    formset    '%s'    in    context    %d    does    not    contain    the    non-form    error    '%s'    (actual    errors:    %s)" % (formset, i, err, repr(non_form_errors)))))
    if (not found_formset):
        self.fail((msg_prefix + (u"The    formset    '%s'    was    not    used    to    render    the    response" % formset)))
