added gem plugin installation to acceptance test

examples/test.pp

@@ -0,0 +1,10 @@
+# This file is use for the beaker tests.
+
+# basic installation
+include '::fluentd'
+
+# install a gem plugin
+::fluentd::plugin { 'fluent-plugin-elasticsearch':
+  type    => 'gem',
+  require => Class['::fluentd']
+}

spec/acceptance/fluentd_spec.rb

@@ -2,17 +2,19 @@ require 'spec_helper_acceptance'
 
 RSpec.describe 'fluentd' do
   it 'runs successfully' do
-    manifest = File.read(File.expand_path('../../examples/init.pp', File.dirname(__FILE__)))
+    manifest = File.read(File.expand_path('../../examples/test.pp', File.dirname(__FILE__)))
 
     # Run it twice and test for idempotency
     apply_manifest(manifest, catch_failures: true)
     expect(apply_manifest(manifest, catch_failures: true).exit_code).to be_zero
   end
 
+  # test package
   describe package('td-agent') do
     it { is_expected.to be_installed }
   end
 
+  # test service
   describe service('td-agent') do
     it { is_expected.to be_running }
     # @todo
@@ -34,4 +36,10 @@ RSpec.describe 'fluentd' do
       it { is_expected.to be_enabled }
     end
   end
+
+  # test gem installed plugin
+  describe command('/opt/td-agent/embedded/bin/gem list') do
+    its(:stdout) { should contain('fluent-plugin-elasticsearch') }
+  end
+
 end