- add tests for drop filter

- promote drop filter to milestone 3

lib/logstash/filters/drop.rb

@@ -17,7 +17,7 @@ require "logstash/namespace"
 # "debug". This will cause all events matching to be dropped.
 class LogStash::Filters::Drop < LogStash::Filters::Base
   config_name "drop"
-  milestone 1
+  milestone 3
 
   public
   def register

spec/filters/drop.rb

@@ -0,0 +1,19 @@
+require "test_utils"
+require "logstash/filters/drop"
+
+describe LogStash::Filters::Drop do
+  extend LogStash::RSpec
+
+  describe "drop the event" do
+    config <<-CONFIG
+      filter {
+        drop { }
+      }
+    CONFIG
+
+    sample "hello" do
+      insist { subject }.nil?
+    end
+  end
+
+end