Dj1.11 - Fix rendering of group permission checkboxes

The format_permissions tag used to lay out the permission checkboxes
worked by iterating over the BoundField, which gave a sequence of
CheckboxChoiceInput objects. This class has been dropped in 1.11 and
superseded by BoundWidget, which has a different way of accessing the
checkbox value. Add separate code paths for the two cases.

wagtail/wagtailusers/templatetags/wagtailusers_tags.py

@@ -2,6 +2,7 @@ from __future__ import absolute_import, unicode_literals
 
 import itertools
 
+import django
 from django import template
 from wagtail.wagtailcore import hooks
 
@@ -29,8 +30,9 @@ def format_permissions(permission_bound_field):
             (any_non_add_change_delete_permission, checkbox),
         ]
 
-        (where 'checkbox' is an instance of django.forms.widgets.CheckboxChoiceInput, renderable
-        as HTML using checkbox.tag() )
+        (where 'checkbox' is an object with a tag() method that renders the checkbox as HTML;
+        this is an instance of django.forms.widgets.CheckboxChoiceInput on Django <1.11,
+        and a BoundWidget on Django >=1.11)
 
         - and returns a table template formatted with this list.
 
@@ -41,10 +43,20 @@ def format_permissions(permission_bound_field):
 
     # iterate over permission_bound_field to build a lookup of individual renderable
     # checkbox objects
-    checkboxes_by_id = {
-        int(checkbox.choice_value): checkbox
-        for checkbox in permission_bound_field
-    }
+    if django.VERSION < (1, 11):
+        # On Django <1.11, iterating over the BoundField returns a sequence of CheckboxChoiceInput objects,
+        # whose ID is available as .choice_value
+        checkboxes_by_id = {
+            int(checkbox.choice_value): checkbox
+            for checkbox in permission_bound_field
+        }
+    else:
+        # On Django >=1.11, iterating over the BoundField returns a sequence of BoundWidget objects,
+        # whose ID is available as .data['value']
+        checkboxes_by_id = {
+            int(checkbox.data['value']): checkbox
+            for checkbox in permission_bound_field
+        }
 
     object_perms = []
     other_perms = []

wagtail/wagtailusers/tests.py

@@ -756,16 +756,11 @@ class TestGroupEditView(TestCase, WagtailTestUtils):
         # the checkbox for self.existing_permission should be ticked
         response = self.get()
 
-        # Use BeautifulSoup to search for a checkbox element with name="permissions", checked="checked",
-        # value=<existing_permission.id>. Can't use assertContains here because the id attribute is unpredictable
-        soup = BeautifulSoup(response.content, 'html5lib')
-
-        self.assertTrue(
-            soup.find(
-                'input',
-                {'name': 'permissions', 'type': 'checkbox', 'checked': 'checked', 'value': self.existing_permission.id}
-            )
-        )
+        # use allow_extra_attrs because the input will also have an id (with an unpredictable value)
+        self.assertTagInHTML(
+            '<input name="permissions" type="checkbox" checked value="%s">' % self.existing_permission.id,
+            str(response.content),
+            allow_extra_attrs=True)
 
     def test_group_edit_loads_with_page_permissions_shown(self):
         # The test group has one page permission to begin with