cabin mocking version 2

cabin_helper.rb

class LogTracker
  def filter(&block)
    cache.detect(&block)
  end

  def cache()
    @cache ||= []
  end

  def <<(hash)
    cache.push(hash)
  end
end

module Cabin
  def self.build(level, subscriber)
    instance = Cabin::Channel.new
    instance.level = level
    instance.subscribe(subscriber)
    instance
  end
end

riemann_spec.rb

    context "when using a Json string, tags might be an ArrayList" do
      let(:tcp) { double('tcpsocket') }
      # LogTracker and Cabin.build defined in logstash-devutils
      let(:mocklog) { LogTracker.new }
      let(:tracker) { Cabin.build(:debug, mocklog) }

      it "logs an error unless the ArrayList implements compact" do
        allow(Cabin::Channel).to receive(:get).and_return(tracker)
        #stub out riemann server
        allow(TCPSocket).to receive(:new).and_return(tcp)
        allow(UDPSocket).to receive(:new).and_return(tcp)
        allow(tcp).to receive(:<<)
        # small risk here, this is the riemann response in binary
        # it is the TCP OK response to a send, it is unlikely to change.
        allow(tcp).to receive(:read).with(4).and_return("\x00\x00\x00\x02")
        allow(tcp).to receive(:read).with(2).and_return("\x10\x01")

        json_string = '{"tags":["good_enough", "smart_enough", "doggone_it", "people_like_me", null], "message":"hello", "node_info":{"name":"node1", "status":"up"}, "@version":"1", "@timestamp":"2015-06-03T23:34:54.076Z", "host":"vagrant-ubuntu-trusty-64"}'
        event = LogStash::Event.new(LogStash::Json.load(json_string))
        output = LogStash::Plugin.lookup("output", "riemann").new
        expect {output.register}.not_to raise_error
        output.receive(event)
        expected = mocklog.filter {|h| !!(h[:error].inspect =~ %r|undefined method .compact. for ..Java..JavaUtil..ArrayList|)}
        expect(expected).to be nil
      end
    end
  end

z-console-output.txt

GOOD OUTCOME ------------------------------
guy at Elastics-MacBook-Pro in ~/elastic/logstash-output-riemann on master*
$ be rspec ./spec/outputs/riemann_spec.rb:113
Using Accessor#strict_set for specs
Run options:
  include {:locations=>{"./spec/outputs/riemann_spec.rb"=>[113]}}
  exclude {:redis=>true, :socket=>true, :performance=>true, :couchdb=>true, :elasticsearch=>true, :elasticsearch_secure=>true, :export_cypher=>true, :integration=>true, :windows=>true}

outputs/riemann
  build_riemann_formatted_event
    when using a Json string, tags might be an ArrayList
      logs an error unless the ArrayList implements compact

Finished in 0.528 seconds (files took 0.618 seconds to load)
1 example, 0 failures

Randomized with seed 29023

BAD OUTCOME -------------------------------
guy at Elastics-MacBook-Pro in ~/elastic/logstash-output-riemann on master*
$ be rspec ./spec/outputs/riemann_spec.rb:113
Using Accessor#strict_set for specs
Run options:
  include {:locations=>{"./spec/outputs/riemann_spec.rb"=>[113]}}
  exclude {:redis=>true, :socket=>true, :performance=>true, :couchdb=>true, :elasticsearch=>true, :elasticsearch_secure=>true, :export_cypher=>true, :integration=>true, :windows=>true}

outputs/riemann
  build_riemann_formatted_event
    when using a Json string, tags might be an ArrayList
      logs an error unless the ArrayList implements compact (FAILED - 1)

Failures:

  1) outputs/riemann build_riemann_formatted_event when using a Json string, tags might be an ArrayList logs an error unless the ArrayList implements compact
     Failure/Error: expect(expected).to be nil

       expected nil
            got #<Hash:5590> => {:timestamp=>"2015-08-19T09:43:58.871000+0100", :message=>"Unhandled exception", :error=>#<NoMethodError: undefined method `compact' for #<Java::JavaUtil::ArrayList:0x366c4480>>, :level=>:debug, :file=>"logstash/outputs/riemann.rb", :line=>"163", :method=>"send_to_riemann"}
     # ./spec/outputs/riemann_spec.rb:136:in `(root)'

Finished in 0.486 seconds (files took 0.559 seconds to load)
1 example, 1 failure

Failed examples:

rspec ./spec/outputs/riemann_spec.rb:119 # outputs/riemann build_riemann_formatted_event when using a Json string, tags might be an ArrayList logs an error unless the ArrayList implements compact

Randomized with seed 46154