Order TwitterStreamAgents in setup_workers

Enforcing the order ensures the config hash stays identical when the
Agent configuration does not change.

 #1191

app/models/agents/twitter_stream_agent.rb

@@ -125,7 +125,7 @@ module Agents
     end
 
     def self.setup_worker
-      Agents::TwitterStreamAgent.active.group_by { |agent| agent.twitter_oauth_token }.map do |oauth_token, agents|
+      Agents::TwitterStreamAgent.active.order(:id).group_by { |agent| agent.twitter_oauth_token }.map do |oauth_token, agents|
         if Agents::TwitterStreamAgent.dependencies_missing?
           STDERR.puts Agents::TwitterStreamAgent.twitter_dependencies_missing
           STDERR.flush

spec/models/agents/twitter_stream_agent_spec.rb

@@ -134,12 +134,13 @@ describe Agents::TwitterStreamAgent do
     end
 
     it "returns now workers if no agent is active" do
-      mock(Agents::TwitterStreamAgent).active { [] }
+      @agent.destroy
+      expect(Agents::TwitterStreamAgent.active).to be_empty
       expect(Agents::TwitterStreamAgent.setup_worker).to eq([])
     end
 
     it "returns a worker for an active agent" do
-      mock(Agents::TwitterStreamAgent).active { [@agent] }
+      expect(Agents::TwitterStreamAgent.active).to eq([@agent])
       workers = Agents::TwitterStreamAgent.setup_worker
       expect(workers).to be_a(Array)
       expect(workers.length).to eq(1)
@@ -151,9 +152,9 @@ describe Agents::TwitterStreamAgent do
 
     it "correctly maps keywords to agents" do
       agent2 = @agent.dup
-      agent2.id = 123455
       agent2.options[:filters] = ['agent2']
-      mock(Agents::TwitterStreamAgent).active { [@agent, agent2] }
+      agent2.save!
+      expect(Agents::TwitterStreamAgent.active.order(:id).pluck(:id)).to eq([@agent.id, agent2.id])
 
       workers = Agents::TwitterStreamAgent.setup_worker
       filter_to_agent_map = workers.first.config[:filter_to_agent_map]