inputs/base: Copy the codec's charset when switching.

Includes tests

lib/logstash/inputs/base.rb

@@ -128,10 +128,10 @@ def fix_streaming_codecs
     case @codec
       when LogStash::Codecs::Plain
         @logger.info("Automatically switching from #{@codec.class.config_name} to line codec", :plugin => self.class.config_name)
-        @codec = LogStash::Codecs::Line.new
+        @codec = LogStash::Codecs::Line.new("charset" => @codec.charset)
       when LogStash::Codecs::JSON
         @logger.info("Automatically switching from #{@codec.class.config_name} to json_lines codec", :plugin => self.class.config_name)
-        @codec = LogStash::Codecs::JSONLines.new
+        @codec = LogStash::Codecs::JSONLines.new("charset" => @codec.charset)
     end
   end
 end # class LogStash::Inputs::Base

spec/inputs/base.rb

@@ -0,0 +1,13 @@
+# encoding: utf-8
+require "test_utils"
+
+describe "LogStash::Inputs::Base#fix_streaming_codecs" do
+  it "should carry the charset setting along when switching" do
+    require "logstash/inputs/tcp"
+    require "logstash/codecs/plain"
+    plain = LogStash::Codecs::Plain.new("charset" => "CP1252")
+    tcp = LogStash::Inputs::Tcp.new("codec" => plain, "port" => 3333)
+    tcp.instance_eval { fix_streaming_codecs }
+    insist { tcp.codec.charset } == "CP1252"
+  end
+end