ActivityPub delivery (#4566)

* Deliver ActivityPub Like

* Deliver ActivityPub Undo-Like

* Deliver ActivityPub Create/Announce activities

* Deliver ActivityPub creates from mentions

* Deliver ActivityPub Block/Undo-Block

* Deliver ActivityPub Accept/Reject-Follow

* Deliver ActivityPub Undo-Follow

* Deliver ActivityPub Follow

* Deliver ActivityPub Delete activities

Incidentally fix #889

* Adjust BatchedRemoveStatusService for ActivityPub

* Add tests for ActivityPub workers

* Add tests for FollowService

* Add tests for FavouriteService, UnfollowService and PostStatusService

* Add tests for ReblogService, BlockService, UnblockService, ProcessMentionsService

* Add tests for AuthorizeFollowService, RejectFollowService, RemoveStatusService

* Add tests for BatchedRemoveStatusService

* Deliver updates to a local account to ActivityPub followers

* Minor adjustments

spec/services/reject_follow_service_spec.rb

@@ -22,7 +22,7 @@ RSpec.describe RejectFollowService do
     end
   end
 
-  describe 'remote' do
+  describe 'remote OStatus' do
     let(:bob) { Fabricate(:user, email: 'bob@example.com', account: Fabricate(:account, username: 'bob', domain: 'example.com', salmon_url: 'http://salmon.example.com')).account }
 
     before do
@@ -46,4 +46,26 @@ RSpec.describe RejectFollowService do
       }).to have_been_made.once
     end
   end
+
+  describe 'remote ActivityPub' do
+    let(:bob) { Fabricate(:user, email: 'bob@example.com', account: Fabricate(:account, username: 'bob', domain: 'example.com', protocol: :activitypub, inbox_url: 'http://example.com/inbox')).account }
+
+    before do
+      FollowRequest.create(account: bob, target_account: sender)
+      stub_request(:post, bob.inbox_url).to_return(status: 200)
+      subject.call(bob, sender)
+    end
+
+    it 'removes follow request' do
+      expect(bob.requested?(sender)).to be false
+    end
+
+    it 'does not create follow relation' do
+      expect(bob.following?(sender)).to be false
+    end
+
+    it 'sends a reject activity' do
+      expect(a_request(:post, bob.inbox_url)).to have_been_made.once
+    end
+  end
 end