Add tests for the checksum filter.

spec/filters/checksum.rb

@@ -0,0 +1,41 @@
+require "test_utils"
+require "logstash/filters/checksum"
+require 'openssl'
+
+describe LogStash::Filters::Checksum do
+  extend LogStash::RSpec
+  
+  LogStash::Filters::Checksum::ALGORITHMS.each do |alg|
+    describe "#{alg} checksum with single field" do
+      config <<-CONFIG
+        filter {
+          checksum {
+            algorithm => "#{alg}"
+            keys => ["test"]
+          }
+        }
+        CONFIG
+
+      sample "test" => "foo bar" do
+        insist { !subject["logstash_checksum"].nil? }
+        insist { subject["logstash_checksum"] } == OpenSSL::Digest.hexdigest(alg, "|test|foo bar|")
+      end
+    end
+    
+    describe "#{alg} checksum with multiple keys" do
+      config <<-CONFIG
+        filter {
+          checksum {
+            algorithm => "#{alg}"
+            keys => ["test1", "test2"]
+          }
+        }
+        CONFIG
+
+      sample "test1" => "foo", "test2" => "bar" do
+        insist { !subject["logstash_checksum"].nil? }
+        insist { subject["logstash_checksum"] } == OpenSSL::Digest.hexdigest(alg, "|test1|foo|test2|bar|")
+      end
+    end
+  end
+end