Fixing import errors

tests/app/settings.py

@@ -20,6 +20,7 @@ INSTALLED_APPS = [
     'django.contrib.admin',
     'django.contrib.auth',
     'django.contrib.contenttypes',
+    'django.contrib.messages',
     'django.contrib.sessions',
     'django.contrib.staticfiles',
 ]

tests/app/urls.py

@@ -3,15 +3,16 @@ from __future__ import unicode_literals
 import re
 
 from django.conf import settings
-from django.conf.urls import include, url
+from django.conf.urls import include
+from django.urls import path, re_path
 from django.views.static import serve
 from wagtail.admin import urls as wagtailadmin_urls
 from wagtail.core import urls as wagtail_urls
 
 urlpatterns = [
-    url(r'^admin/', include(wagtailadmin_urls)),
-    url(r'', include(wagtail_urls)),
+    path('admin/', include(wagtailadmin_urls)),
+    path('', include(wagtail_urls)),
     #  For media serving
-    url(r'^%s(?P<path>.*)$' % re.escape(
+    re_path(r'^%s(?P<path>.*)$' % re.escape(
         settings.MEDIA_URL.lstrip('/')), serve, kwargs={'document_root': settings.MEDIA_ROOT})
 ]

wagtailvideos/forms.py

@@ -3,7 +3,7 @@ from django.forms.models import modelform_factory
 from django.utils.translation import ugettext as _
 from enumchoicefield.forms import EnumField
 from wagtail.admin import widgets
-from wagtail.admin.forms import (
+from wagtail.admin.forms.collections import (
     BaseCollectionMemberForm, collection_member_permission_formset_factory)
 
 from wagtailvideos.fields import WagtailVideoField

wagtailvideos/models.py

@@ -18,7 +18,7 @@ from django.dispatch.dispatcher import receiver
 from django.forms.utils import flatatt
 from django.urls import reverse
 from django.utils.encoding import python_2_unicode_compatible
-from django.utils.text import mark_safe
+from django.utils.html import mark_safe
 from django.utils.translation import ugettext_lazy as _
 from enumchoicefield import ChoiceEnum, EnumChoiceField
 from taggit.managers import TaggableManager

wagtailvideos/views/chooser.py

@@ -2,7 +2,7 @@ import json
 
 from django.shortcuts import get_object_or_404, render
 from django.urls import reverse
-from wagtail.admin.forms import SearchForm
+from wagtail.admin.forms.search import SearchForm
 from wagtail.admin.modal_workflow import render_modal_workflow
 from wagtail.admin.utils import PermissionPolicyChecker, popular_tags_for_model
 from wagtail.core.models import Collection

wagtailvideos/views/videos.py

@@ -4,7 +4,7 @@ from django.urls import reverse
 from django.utils.translation import ugettext as _
 from django.views.decorators.vary import vary_on_headers
 from wagtail.admin import messages
-from wagtail.admin.forms import SearchForm
+from wagtail.admin.forms.search import SearchForm
 from wagtail.admin.utils import PermissionPolicyChecker, popular_tags_for_model
 from wagtail.core.models import Collection
 from wagtail.search.backends import get_search_backends