Add option to share bookmarks publicly (#503)

* Make shared view public, add user profile fallback

* Allow unauthenticated access to shared bookmarks API

* Link shared bookmarks in unauthenticated layout

* Add public sharing setting

* Only show shared bookmarks link if there are publicly shared bookmarks

* Disable public sharing if sharing is disabled

* Show specific helper text when public sharing is enabled

* Fix tests

* Add more tests

* Improve setting description

bookmarks/tests/test_anonymous_view.py

@@ -0,0 +1,26 @@
+from django.test import TestCase
+from django.urls import reverse
+
+from bookmarks.tests.helpers import BookmarkFactoryMixin
+
+
+class AnonymousViewTestCase(TestCase, BookmarkFactoryMixin):
+    def assertSharedBookmarksLinkCount(self, response, count):
+        url = reverse('bookmarks:shared')
+        self.assertContains(response, f'<a href="{url}" class="btn btn-link">Shared bookmarks</a>',
+                            count=count)
+
+    def test_publicly_shared_bookmarks_link(self):
+        # should not render link if no public shares exist
+        user = self.setup_user(enable_sharing=True)
+        self.setup_bookmark(user=user, shared=True)
+
+        response = self.client.get(reverse('login'))
+        self.assertSharedBookmarksLinkCount(response, 0)
+
+        # should render link if public shares exist
+        user.profile.enable_public_sharing = True
+        user.profile.save()
+
+        response = self.client.get(reverse('login'))
+        self.assertSharedBookmarksLinkCount(response, 1)