Batched remove status service (#3735)

* Make Pubsubhubbub::DistributionWorker handle both single stream entry
arguments, as well as arrays of stream entries

* Add BatchedRemoveStatusService, make SuspendAccountService use it

* Improve method names

* Add test

* Add more tests

* Use PuSH payloads of 100 to have a clear mapping of
1000 input statuses -> 10 PuSH payloads

It was nice while it lasted

spec/services/batched_remove_status_service_spec.rb

@@ -0,0 +1,61 @@
+require 'rails_helper'
+
+RSpec.describe BatchedRemoveStatusService do
+  subject { BatchedRemoveStatusService.new }
+
+  let!(:alice)  { Fabricate(:account) }
+  let!(:bob)    { Fabricate(:account, username: 'bob', domain: 'example.com', salmon_url: 'http://example.com/salmon') }
+  let!(:jeff)   { Fabricate(:account) }
+
+  let(:status1) { PostStatusService.new.call(alice, 'Hello @bob@example.com') }
+  let(:status2) { PostStatusService.new.call(alice, 'Another status') }
+
+  before do
+    allow(Redis.current).to receive_messages(publish: nil)
+
+    stub_request(:post, 'http://example.com/push').to_return(status: 200, body: '', headers: {})
+    stub_request(:post, 'http://example.com/salmon').to_return(status: 200, body: '', headers: {})
+
+    Fabricate(:subscription, account: alice, callback_url: 'http://example.com/push', confirmed: true, expires_at: 30.days.from_now)
+    jeff.follow!(alice)
+
+    status1
+    status2
+
+    subject.call([status1, status2])
+  end
+
+  it 'removes statuses from author\'s home feed' do
+    expect(Feed.new(:home, alice).get(10)).to_not include([status1.id, status2.id])
+  end
+
+  it 'removes statuses from local follower\'s home feed' do
+    expect(Feed.new(:home, jeff).get(10)).to_not include([status1.id, status2.id])
+  end
+
+  it 'notifies streaming API of followers' do
+    expect(Redis.current).to have_received(:publish).with("timeline:#{jeff.id}", any_args).at_least(:once)
+  end
+
+  it 'notifies streaming API of author' do
+    expect(Redis.current).to have_received(:publish).with("timeline:#{alice.id}", any_args).at_least(:once)
+  end
+
+  it 'notifies streaming API of public timeline' do
+    expect(Redis.current).to have_received(:publish).with('timeline:public', any_args).at_least(:once)
+  end
+
+  it 'sends PuSH update to PuSH subscribers with two payloads united' do
+    expect(a_request(:post, 'http://example.com/push').with { |req|
+      matches = req.body.scan(TagManager::VERBS[:delete])
+      matches.size == 2
+    }).to have_been_made
+  end
+
+  it 'sends Salmon slap to previously mentioned users' do
+    expect(a_request(:post, "http://example.com/salmon").with { |req|
+      xml = OStatus2::Salmon.new.unpack(req.body)
+      xml.match(TagManager::VERBS[:delete])
+    }).to have_been_made.once
+  end
+end