add test

Author: kaisecheng

qa/integration/services/monitoring_api.rb

@@ -31,6 +31,12 @@ def pipeline_stats(pipeline_id)
     stats_response.fetch("pipelines").fetch(pipeline_id)
   end
 
+  def pipelines_stats
+    resp = Manticore.get("http://localhost:#{@port}/_node/stats/pipelines").body
+    stats_response = JSON.parse(resp)
+    stats_response.fetch("pipelines")
+  end
+
   def event_stats
     resp = Manticore.get("http://localhost:#{@port}/_node/stats").body
     stats_response = JSON.parse(resp)

x-pack/qa/integration/monitoring/direct_shipping_spec.rb

@@ -31,6 +31,12 @@
 
   include_examples "record monitoring data to es"
 
+  it "gives pipelines stats" do
+    api = MonitoringAPI.new
+    stats = api.pipelines_stats
+    expect(stats.keys).not_to be_nil
+  end
+
   after :all do
     @logstash_service.stop unless @logstash_service.nil?
     @elasticsearch_service.stop unless @elasticsearch_service.nil?