add an input helper to run without the need of a config and only from…

… the plugin object

Fixes #40

lib/logstash/devutils/rspec/logstash_helpers.rb

@@ -86,6 +86,19 @@ def output_func(event)
     result
   end # def input
 
+  def plugin_input(plugin, &block)
+    queue = Queue.new
+
+    input_thread = Thread.new do
+      plugin.run(queue)
+    end
+    result = block.call(queue)
+
+    plugin.do_stop
+    input_thread.join
+    result
+  end
+
   def agent(&block)
 
     it("agent(#{caller[0].gsub(/ .*/, "")}) runs") do