puyopuyotetr.is/spec/services/fan_out_on_write_service_spec.rb

require 'rails_helper'

RSpec.describe FanOutOnWriteService do
  let(:author)   { Fabricate(:account, username: 'tom') }
  let(:status)   { Fabricate(:status, text: 'Hello @alice #test', account: author) }
  let(:alice)    { Fabricate(:user, account: Fabricate(:account, username: 'alice')).account }
  let(:follower) { Fabricate(:account, username: 'bob') }

  subject { FanOutOnWriteService.new }

  before do
    alice
    follower.follow!(author)

    ProcessMentionsService.new.call(status)
    ProcessHashtagsService.new.call(status)

    subject.call(status)
  end

  it 'delivers status to home timeline' do
    expect(Feed.new(:home, author).get(1).map(&:id)).to include status.id
  end

  it 'delivers status to local followers' do
    expect(Feed.new(:home, follower).get(1).map(&:id)).to include status.id
  end

  it 'delivers status to mentioned users' do
    expect(Feed.new(:mentions, alice).get(1).map(&:id)).to include status.id
  end

  it 'delivers status to hashtag' do
    expect(Tag.find_by!(name: 'test').statuses.pluck(:id)).to include status.id
  end

  it 'delivers status to public timeline' do
    expect(Status.as_public_timeline(alice).map(&:id)).to include status.id
  end
end