Paginate ancestor statuses in public page (#7102)

This also limits the statuses returned by API, but pagination is not
implemented in Web API yet. I still expect it brings user experience
better than making a user wait to fetch all ancestor statuses and flooding
the column with them.

spec/models/concerns/status_threading_concern_spec.rb

@@ -14,34 +14,34 @@ describe StatusThreadingConcern do
     let!(:viewer) { Fabricate(:account, username: 'viewer') }
 
     it 'returns conversation history' do
-      expect(reply3.ancestors).to include(status, reply1, reply2)
+      expect(reply3.ancestors(4)).to include(status, reply1, reply2)
     end
 
     it 'does not return conversation history user is not allowed to see' do
       reply1.update(visibility: :private)
       status.update(visibility: :direct)
 
-      expect(reply3.ancestors(viewer)).to_not include(reply1, status)
+      expect(reply3.ancestors(4, viewer)).to_not include(reply1, status)
     end
 
     it 'does not return conversation history from blocked users' do
       viewer.block!(jeff)
-      expect(reply3.ancestors(viewer)).to_not include(reply1)
+      expect(reply3.ancestors(4, viewer)).to_not include(reply1)
     end
 
     it 'does not return conversation history from muted users' do
       viewer.mute!(jeff)
-      expect(reply3.ancestors(viewer)).to_not include(reply1)
+      expect(reply3.ancestors(4, viewer)).to_not include(reply1)
     end
 
     it 'does not return conversation history from silenced and not followed users' do
       jeff.update(silenced: true)
-      expect(reply3.ancestors(viewer)).to_not include(reply1)
+      expect(reply3.ancestors(4, viewer)).to_not include(reply1)
     end
 
     it 'does not return conversation history from blocked domains' do
       viewer.block_domain!('example.com')
-      expect(reply3.ancestors(viewer)).to_not include(reply2)
+      expect(reply3.ancestors(4, viewer)).to_not include(reply2)
     end
 
     it 'ignores deleted records' do
@@ -49,10 +49,32 @@ describe StatusThreadingConcern do
       second_status = Fabricate(:status, thread: first_status, account: alice)
 
       # Create cache and delete cached record
-      second_status.ancestors
+      second_status.ancestors(4)
       first_status.destroy
 
-      expect(second_status.ancestors).to eq([])
+      expect(second_status.ancestors(4)).to eq([])
+    end
+
+    it 'can return more records than previously requested' do
+      first_status  = Fabricate(:status, account: bob)
+      second_status = Fabricate(:status, thread: first_status, account: alice)
+      third_status = Fabricate(:status, thread: second_status, account: alice)
+
+      # Create cache
+      second_status.ancestors(1)
+
+      expect(third_status.ancestors(2)).to eq([first_status, second_status])
+    end
+
+    it 'can return fewer records than previously requested' do
+      first_status  = Fabricate(:status, account: bob)
+      second_status = Fabricate(:status, thread: first_status, account: alice)
+      third_status = Fabricate(:status, thread: second_status, account: alice)
+
+      # Create cache
+      second_status.ancestors(2)
+
+      expect(third_status.ancestors(1)).to eq([second_status])
     end
   end
 

spec/views/stream_entries/show.html.haml_spec.rb

@@ -48,7 +48,7 @@ describe 'stream_entries/show.html.haml', without_verify_partial_doubles: true d
     assign(:stream_entry, reply.stream_entry)
     assign(:account, alice)
     assign(:type, reply.stream_entry.activity_type.downcase)
-    assign(:ancestors, reply.stream_entry.activity.ancestors(bob) )
+    assign(:ancestors, reply.stream_entry.activity.ancestors(1, bob) )
     assign(:descendants, reply.stream_entry.activity.descendants(bob))
 
     render