From 6802dc2a8a282ba2e7c0370ff3dc17302a32be91 Mon Sep 17 00:00:00 2001
From: TAGOMORI Satoshi <tagomoris@gmail.com>
Date: Wed, 10 Feb 2016 00:40:24 +0900
Subject: [PATCH] Fix to do `require` for required files straightforward, per
 files

* Currently, all required files are loaded by `lib/fluent/load.rb` even for tests
  * This file creates the implicit order of files to be loaded
  * There's no explicit dependency definition, and there are many circular dependencies
  * This situation is totally broken
* Without this change, we can't run tests by `bundle exec rake test TEST=test/file.rb`
  * Running whole tests consumes long time, and it's not acceptable

This change is to make straightforward dependency from all files to others.
We can load any file in fluentd source code, make clean dependencies, and
also can run each files itself to test it.
---
 lib/fluent/agent.rb                           |  9 ++--
 lib/fluent/buffer.rb                          |  6 +++
 lib/fluent/command/bundler_injection.rb       |  3 ++
 lib/fluent/command/cat.rb                     |  2 +-
 lib/fluent/command/debug.rb                   |  5 ++-
 lib/fluent/command/fluentd.rb                 |  3 +-
 lib/fluent/config.rb                          |  9 ++--
 lib/fluent/config/basic_parser.rb             |  7 ++-
 lib/fluent/config/configure_proxy.rb          |  2 +
 lib/fluent/config/dsl.rb                      |  3 ++
 lib/fluent/config/element.rb                  |  5 ++-
 lib/fluent/config/literal_parser.rb           | 13 +++---
 lib/fluent/config/parser.rb                   |  8 ++--
 lib/fluent/config/section.rb                  |  6 +--
 lib/fluent/config/types.rb                    |  7 ++-
 lib/fluent/config/v1_parser.rb                | 14 +++---
 lib/fluent/configurable.rb                    | 12 ++---
 lib/fluent/engine.rb                          | 19 +++++---
 lib/fluent/event.rb                           |  2 +
 lib/fluent/event_router.rb                    |  6 ++-
 lib/fluent/filter.rb                          |  6 +++
 lib/fluent/formatter.rb                       |  6 ++-
 lib/fluent/input.rb                           |  5 +++
 lib/fluent/label.rb                           |  4 +-
 lib/fluent/log.rb                             |  5 ++-
 lib/fluent/mixin.rb                           |  6 ++-
 lib/fluent/output.rb                          | 10 ++++-
 lib/fluent/parser.rb                          | 14 +++++-
 lib/fluent/plugin.rb                          |  6 +++
 lib/fluent/plugin/buf_file.rb                 |  7 +++
 lib/fluent/plugin/buf_memory.rb               |  6 +++
 lib/fluent/plugin/exec_util.rb                |  9 +++-
 lib/fluent/plugin/filter_grep.rb              |  3 ++
 .../plugin/filter_record_transformer.rb       | 12 ++---
 lib/fluent/plugin/filter_stdout.rb            |  3 ++
 lib/fluent/plugin/in_debug_agent.rb           |  2 +
 lib/fluent/plugin/in_dummy.rb                 |  5 +++
 lib/fluent/plugin/in_exec.rb                  |  8 +++-
 lib/fluent/plugin/in_forward.rb               |  7 +++
 lib/fluent/plugin/in_gc_stat.rb               |  4 ++
 lib/fluent/plugin/in_http.rb                  | 11 ++++-
 lib/fluent/plugin/in_monitor_agent.rb         | 17 ++++---
 lib/fluent/plugin/in_object_space.rb          |  5 +++
 lib/fluent/plugin/in_stream.rb                |  9 ++++
 lib/fluent/plugin/in_syslog.rb                |  8 +++-
 lib/fluent/plugin/in_tail.rb                  |  6 +++
 lib/fluent/plugin/in_tcp.rb                   |  2 +
 lib/fluent/plugin/out_copy.rb                 |  4 ++
 lib/fluent/plugin/out_exec.rb                 |  5 ++-
 lib/fluent/plugin/out_exec_filter.rb          |  7 +++
 lib/fluent/plugin/out_file.rb                 |  6 +++
 lib/fluent/plugin/out_forward.rb              | 12 +++--
 lib/fluent/plugin/out_null.rb                 |  2 +
 lib/fluent/plugin/out_relabel.rb              |  2 +
 lib/fluent/plugin/out_roundrobin.rb           |  3 ++
 lib/fluent/plugin/out_stdout.rb               |  2 +
 lib/fluent/plugin/out_stream.rb               | 12 ++---
 lib/fluent/plugin/socket_util.rb              |  6 ++-
 lib/fluent/process.rb                         |  6 +++
 lib/fluent/registry.rb                        |  6 ++-
 lib/fluent/root_agent.rb                      | 13 +++---
 lib/fluent/rpc.rb                             |  4 +-
 lib/fluent/supervisor.rb                      | 44 ++++---------------
 lib/fluent/system_config.rb                   | 12 +++--
 lib/fluent/test.rb                            |  2 +-
 lib/fluent/test/base.rb                       |  4 ++
 lib/fluent/test/filter_test.rb                |  3 ++
 lib/fluent/test/formatter_test.rb             |  5 ++-
 lib/fluent/test/input_test.rb                 |  5 +++
 lib/fluent/test/output_test.rb                |  4 ++
 lib/fluent/test/parser_test.rb                |  5 ++-
 lib/fluent/timezone.rb                        |  2 +
 test/plugin/test_in_forward.rb                |  4 ++
 test/test_event_router.rb                     |  1 +
 test/test_plugin_classes.rb                   |  3 ++
 test/test_process.rb                          |  1 +
 test/test_root_agent.rb                       |  1 +
 77 files changed, 371 insertions(+), 142 deletions(-)

diff --git a/lib/fluent/agent.rb b/lib/fluent/agent.rb
index 1c766fe197..9543b4a277 100644
--- a/lib/fluent/agent.rb
+++ b/lib/fluent/agent.rb
@@ -13,10 +13,13 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 #
-module Fluent
-  require 'fluent/configurable'
-  require 'fluent/engine'
 
+require 'fluent/configurable'
+require 'fluent/engine'
+require 'fluent/plugin'
+require 'fluent/output'
+
+module Fluent
   #
   # Agent is a resource unit who manages emittable plugins
   #
diff --git a/lib/fluent/buffer.rb b/lib/fluent/buffer.rb
index 2187d835f1..d7327ddcbd 100644
--- a/lib/fluent/buffer.rb
+++ b/lib/fluent/buffer.rb
@@ -13,6 +13,12 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 #
+
+require 'monitor'
+require 'fileutils'
+
+require 'fluent/configurable'
+
 module Fluent
   class BufferError < StandardError
   end
diff --git a/lib/fluent/command/bundler_injection.rb b/lib/fluent/command/bundler_injection.rb
index 8e244f7ce5..5b90e0684b 100644
--- a/lib/fluent/command/bundler_injection.rb
+++ b/lib/fluent/command/bundler_injection.rb
@@ -14,6 +14,9 @@
 #    limitations under the License.
 #
 
+require 'rbconfig'
+require 'rubygems'
+
 if ENV['BUNDLE_BIN_PATH']
   puts 'error: You seem to use `bundle exec` already.'
   exit 1
diff --git a/lib/fluent/command/cat.rb b/lib/fluent/command/cat.rb
index 8ec8a5e2c1..172a066c86 100644
--- a/lib/fluent/command/cat.rb
+++ b/lib/fluent/command/cat.rb
@@ -66,7 +66,7 @@
   message_key = s
 }
 
-(class<<self;self;end).module_eval do
+(class << self; self; end).module_eval do
   define_method(:usage) do |msg|
     puts op.to_s
     puts "error: #{msg}" if msg
diff --git a/lib/fluent/command/debug.rb b/lib/fluent/command/debug.rb
index 22a21d18a5..1210695337 100644
--- a/lib/fluent/command/debug.rb
+++ b/lib/fluent/command/debug.rb
@@ -34,7 +34,7 @@
   unix = b
 }
 
-(class<<self;self;end).module_eval do
+(class << self; self; end).module_eval do
   define_method(:usage) do |msg|
     puts op.to_s
     puts "error: #{msg}" if msg
@@ -60,7 +60,8 @@
   uri = "druby://#{host}:#{port}"
 end
 
-require 'fluent/load'
+require 'fluent/log'
+require 'fluent/engine'
 
 $log = Fluent::Log.new(STDERR, Fluent::Log::LEVEL_TRACE)
 Fluent::Engine.init
diff --git a/lib/fluent/command/fluentd.rb b/lib/fluent/command/fluentd.rb
index 39fd24bc41..8e4a65c1e5 100644
--- a/lib/fluent/command/fluentd.rb
+++ b/lib/fluent/command/fluentd.rb
@@ -15,6 +15,7 @@
 #
 
 require 'optparse'
+
 require 'fluent/supervisor'
 
 op = OptionParser.new
@@ -119,7 +120,7 @@
   opts[:gem_install_path] = s
 }
 
-(class<<self;self;end).module_eval do
+(class << self; self; end).module_eval do
   define_method(:usage) do |msg|
     puts op.to_s
     puts "error: #{msg}" if msg
diff --git a/lib/fluent/config.rb b/lib/fluent/config.rb
index 5ff253a714..66cc47a69c 100644
--- a/lib/fluent/config.rb
+++ b/lib/fluent/config.rb
@@ -14,10 +14,11 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'fluent/config/error'
-  require 'fluent/config/element'
+require 'fluent/config/error'
+require 'fluent/config/element'
+require 'fluent/configurable'
 
+module Fluent
   module Config
     def self.parse(str, fname, basepath = Dir.pwd, v1_config = false)
       if fname =~ /\.rb$/
@@ -39,8 +40,6 @@ def self.new(name = '')
     end
   end
 
-  require 'fluent/configurable'
-
   module PluginId
     def configure(conf)
       @id = conf['@id'] || conf['id']
diff --git a/lib/fluent/config/basic_parser.rb b/lib/fluent/config/basic_parser.rb
index 7d695807fb..2a92f6b9b7 100644
--- a/lib/fluent/config/basic_parser.rb
+++ b/lib/fluent/config/basic_parser.rb
@@ -14,12 +14,11 @@
 #    limitations under the License.
 #
 
+require 'stringio'
+require 'fluent/config/error'
+
 module Fluent
   module Config
-
-    require 'stringio'
-    require 'fluent/config/error'
-
     class BasicParser
       def initialize(strscan)
         @ss = strscan
diff --git a/lib/fluent/config/configure_proxy.rb b/lib/fluent/config/configure_proxy.rb
index 5083da0b4a..af9be8d135 100644
--- a/lib/fluent/config/configure_proxy.rb
+++ b/lib/fluent/config/configure_proxy.rb
@@ -14,6 +14,8 @@
 #    limitations under the License.
 #
 
+require 'fluent/configurable'
+
 module Fluent
   module Config
     class ConfigureProxy
diff --git a/lib/fluent/config/dsl.rb b/lib/fluent/config/dsl.rb
index 8282007c48..538b13d5d6 100644
--- a/lib/fluent/config/dsl.rb
+++ b/lib/fluent/config/dsl.rb
@@ -14,7 +14,10 @@
 #    limitations under the License.
 #
 
+require 'json'
+
 require 'fluent/config'
+require 'fluent/config/element'
 
 module Fluent
   module Config
diff --git a/lib/fluent/config/element.rb b/lib/fluent/config/element.rb
index ba1f124621..5d47824646 100644
--- a/lib/fluent/config/element.rb
+++ b/lib/fluent/config/element.rb
@@ -14,9 +14,10 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'fluent/config/error'
+require 'fluent/config/error'
+require 'fluent/config/literal_parser'
 
+module Fluent
   module Config
     class Element < Hash
       def initialize(name, arg, attrs, elements, unused = nil)
diff --git a/lib/fluent/config/literal_parser.rb b/lib/fluent/config/literal_parser.rb
index b65479e098..403b7a12ee 100644
--- a/lib/fluent/config/literal_parser.rb
+++ b/lib/fluent/config/literal_parser.rb
@@ -14,13 +14,16 @@
 #    limitations under the License.
 #
 
-module Fluent
-  module Config
+require 'stringio'
+
+require 'json'
+require 'yajl'
+require 'irb/ruby-lex'  # RubyLex
 
-    require 'yajl'
-    require 'fluent/config/basic_parser'
-    require 'irb/ruby-lex'  # RubyLex
+require 'fluent/config/basic_parser'
 
+module Fluent
+  module Config
     class LiteralParser < BasicParser
       def self.unescape_char(c)
         case c
diff --git a/lib/fluent/config/parser.rb b/lib/fluent/config/parser.rb
index 6024f5d5b9..98e8cbfbec 100644
--- a/lib/fluent/config/parser.rb
+++ b/lib/fluent/config/parser.rb
@@ -14,11 +14,13 @@
 #    limitations under the License.
 #
 
+require 'uri'
+
+require 'fluent/config/error'
+require 'fluent/config/element'
+
 module Fluent
   module Config
-    require 'fluent/config/error'
-    require 'fluent/config/element'
-
     class Parser
       def self.parse(io, fname, basepath = Dir.pwd)
         attrs, elems = Parser.new(basepath, io.each_line, fname).parse!(true)
diff --git a/lib/fluent/config/section.rb b/lib/fluent/config/section.rb
index 8549e22fd3..0a0933201c 100644
--- a/lib/fluent/config/section.rb
+++ b/lib/fluent/config/section.rb
@@ -16,10 +16,10 @@
 
 require 'json'
 
-module Fluent
-  require 'fluent/config/error'
-  require 'fluent/config/v1_parser'
+require 'fluent/config/error'
+require 'fluent/config/v1_parser'
 
+module Fluent
   module Config
     class Section < BasicObject
       def self.name
diff --git a/lib/fluent/config/types.rb b/lib/fluent/config/types.rb
index 5442b66189..13af0b8264 100644
--- a/lib/fluent/config/types.rb
+++ b/lib/fluent/config/types.rb
@@ -14,9 +14,12 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'json'
+require 'json'
+
+require 'fluent/config/error'
+require 'fluent/configurable'
 
+module Fluent
   module Config
     def self.size_value(str)
       case str.to_s
diff --git a/lib/fluent/config/v1_parser.rb b/lib/fluent/config/v1_parser.rb
index 0303e9cd5f..4eceaedc3c 100644
--- a/lib/fluent/config/v1_parser.rb
+++ b/lib/fluent/config/v1_parser.rb
@@ -14,14 +14,16 @@
 #    limitations under the License.
 #
 
-module Fluent
-  module Config
+require 'strscan'
+require 'uri'
 
-    require 'strscan'
-    require 'fluent/config/error'
-    require 'fluent/config/literal_parser'
-    require 'fluent/config/element'
+require 'fluent/config/error'
+require 'fluent/config/basic_parser'
+require 'fluent/config/literal_parser'
+require 'fluent/config/element'
 
+module Fluent
+  module Config
     class V1Parser < LiteralParser
       ELEMENT_NAME = /[a-zA-Z0-9_]+/
 
diff --git a/lib/fluent/configurable.rb b/lib/fluent/configurable.rb
index 262e062690..16bc784d47 100644
--- a/lib/fluent/configurable.rb
+++ b/lib/fluent/configurable.rb
@@ -14,13 +14,13 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'fluent/config/configure_proxy'
-  require 'fluent/config/section'
-  require 'fluent/config/error'
-  require 'fluent/registry'
-  require 'fluent/plugin'
+require 'fluent/config/configure_proxy'
+require 'fluent/config/section'
+require 'fluent/config/error'
+require 'fluent/registry'
+require 'fluent/plugin'
 
+module Fluent
   module Configurable
     def self.included(mod)
       mod.extend(ClassMethods)
diff --git a/lib/fluent/engine.rb b/lib/fluent/engine.rb
index 2f942b3ef4..0e98c02494 100644
--- a/lib/fluent/engine.rb
+++ b/lib/fluent/engine.rb
@@ -14,12 +14,21 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'fluent/event_router'
-  require 'fluent/root_agent'
-  require 'fluent/time'
-  require 'fluent/system_config'
+require 'socket'
+require 'rubygems'
+
+require 'msgpack'
+require 'cool.io'
 
+require 'fluent/config'
+require 'fluent/event'
+require 'fluent/event_router'
+require 'fluent/root_agent'
+require 'fluent/time'
+require 'fluent/system_config'
+require 'fluent/plugin'
+
+module Fluent
   class EngineClass
     class DummyMessagePackFactory
       def packer(*args)
diff --git a/lib/fluent/event.rb b/lib/fluent/event.rb
index f07bfd1a1e..7152b2cd3a 100644
--- a/lib/fluent/event.rb
+++ b/lib/fluent/event.rb
@@ -14,6 +14,8 @@
 #    limitations under the License.
 #
 
+require 'fluent/engine'
+
 module Fluent
   class EventStream
     include Enumerable
diff --git a/lib/fluent/event_router.rb b/lib/fluent/event_router.rb
index 339e406292..7ff4828606 100644
--- a/lib/fluent/event_router.rb
+++ b/lib/fluent/event_router.rb
@@ -13,9 +13,11 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 #
-module Fluent
-  require 'fluent/match'
 
+require 'fluent/match'
+require 'fluent/event'
+
+module Fluent
   #
   # EventRouter is responsible to route events to a collector.
   #
diff --git a/lib/fluent/filter.rb b/lib/fluent/filter.rb
index b5da9c4982..86d6357f31 100644
--- a/lib/fluent/filter.rb
+++ b/lib/fluent/filter.rb
@@ -14,6 +14,12 @@
 #    limitations under the License.
 #
 
+require 'fluent/config'
+require 'fluent/configurable'
+require 'fluent/engine'
+require 'fluent/event'
+require 'fluent/log'
+
 module Fluent
   class Filter
     include Configurable
diff --git a/lib/fluent/formatter.rb b/lib/fluent/formatter.rb
index dbc4c86b4b..9bbaefd306 100644
--- a/lib/fluent/formatter.rb
+++ b/lib/fluent/formatter.rb
@@ -14,9 +14,11 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'fluent/registry'
+require 'fluent/configurable'
+require 'fluent/registry'
+require 'fluent/mixin'
 
+module Fluent
   class Formatter
     include Configurable
 
diff --git a/lib/fluent/input.rb b/lib/fluent/input.rb
index 10a6022bae..7de192019a 100644
--- a/lib/fluent/input.rb
+++ b/lib/fluent/input.rb
@@ -14,6 +14,11 @@
 #    limitations under the License.
 #
 
+require 'fluent/config'
+require 'fluent/configurable'
+require 'fluent/engine'
+require 'fluent/log'
+
 module Fluent
   class Input
     include Configurable
diff --git a/lib/fluent/label.rb b/lib/fluent/label.rb
index 2473832b27..d94f102089 100644
--- a/lib/fluent/label.rb
+++ b/lib/fluent/label.rb
@@ -14,9 +14,9 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'fluent/agent'
+require 'fluent/agent'
 
+module Fluent
   class Label < Agent
     def initialize(name, opts = {})
       super(opts)
diff --git a/lib/fluent/log.rb b/lib/fluent/log.rb
index 978da489d1..e0340497c0 100644
--- a/lib/fluent/log.rb
+++ b/lib/fluent/log.rb
@@ -65,6 +65,9 @@ def initialize(out=STDERR, level=LEVEL_TRACE, opts={})
       # TODO: This variable name is unclear so we should change to better name.
       @threads_exclude_events = []
 
+      # Fluent::Engine requires Fluent::Log, so we must take that object lazily
+      @engine = Fluent.const_get('Engine')
+
       if opts.has_key?(:suppress_repeated_stacktrace)
         @suppress_repeated_stacktrace = opts[:suppress_repeated_stacktrace]
       end
@@ -285,7 +288,7 @@ def event(level, args)
           record[key] = record[key].inspect unless record[key].respond_to?(:to_msgpack)
         }
         record['message'] = message.dup
-        Engine.push_log_event("#{@tag}.#{level}", time.to_i, record)
+        @engine.push_log_event("#{@tag}.#{level}", time.to_i, record)
       end
 
       return time, message
diff --git a/lib/fluent/mixin.rb b/lib/fluent/mixin.rb
index ff4b1680d1..a2e7ea3a63 100644
--- a/lib/fluent/mixin.rb
+++ b/lib/fluent/mixin.rb
@@ -14,10 +14,12 @@
 #    limitations under the License.
 #
 
+require 'fluent/timezone'
+require 'fluent/time'
+require 'fluent/config/error'
+
 module Fluent
   class TimeFormatter
-    require 'fluent/timezone'
-
     def initialize(format, localtime, timezone = nil)
       @tc1 = 0
       @tc1_str = nil
diff --git a/lib/fluent/output.rb b/lib/fluent/output.rb
index ebeea00c34..75cd27f9bf 100644
--- a/lib/fluent/output.rb
+++ b/lib/fluent/output.rb
@@ -14,6 +14,15 @@
 #    limitations under the License.
 #
 
+require 'thread'
+
+require 'fluent/config'
+require 'fluent/configurable'
+require 'fluent/engine'
+require 'fluent/log'
+require 'fluent/plugin'
+require 'fluent/timezone'
+
 module Fluent
   class OutputChain
     def initialize(array, tag, es, chain=NullOutputChain.instance)
@@ -93,7 +102,6 @@ def secondary_init(primary)
     end
   end
 
-
   class OutputThread
     def initialize(output)
       @output = output
diff --git a/lib/fluent/parser.rb b/lib/fluent/parser.rb
index ef14b46a09..dd933e358a 100644
--- a/lib/fluent/parser.rb
+++ b/lib/fluent/parser.rb
@@ -14,9 +14,19 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'fluent/registry'
+require 'time'
+require 'json'
+
+require 'yajl'
 
+require 'fluent/config/error'
+require 'fluent/config/element'
+require 'fluent/configurable'
+require 'fluent/engine'
+require 'fluent/registry'
+require 'fluent/time'
+
+module Fluent
   class ParserError < StandardError
   end
 
diff --git a/lib/fluent/plugin.rb b/lib/fluent/plugin.rb
index da26d4d67c..b4a4fbda41 100644
--- a/lib/fluent/plugin.rb
+++ b/lib/fluent/plugin.rb
@@ -14,6 +14,10 @@
 #    limitations under the License.
 #
 
+require 'rubygems'
+
+require 'fluent/config/error'
+
 module Fluent
   class PluginClass
     # This class is refactored using Fluent::Registry at v0.14
@@ -66,10 +70,12 @@ def new_buffer(type)
     end
 
     def new_parser(type)
+      require 'fluent/parser'
       TextParser.lookup(type)
     end
 
     def new_formatter(type)
+      require 'fluent/formatter'
       TextFormatter.lookup(type)
     end
 
diff --git a/lib/fluent/plugin/buf_file.rb b/lib/fluent/plugin/buf_file.rb
index c3285da110..02c018e976 100644
--- a/lib/fluent/plugin/buf_file.rb
+++ b/lib/fluent/plugin/buf_file.rb
@@ -14,6 +14,13 @@
 #    limitations under the License.
 #
 
+require 'fileutils'
+require 'uri'
+
+require 'fluent/env'
+require 'fluent/plugin'
+require 'fluent/buffer'
+
 module Fluent
   class FileBufferChunk < BufferChunk
     def initialize(key, path, unique_id, mode="a+", symlink_path = nil)
diff --git a/lib/fluent/plugin/buf_memory.rb b/lib/fluent/plugin/buf_memory.rb
index 7ed3a16d35..00b3b6f8a0 100644
--- a/lib/fluent/plugin/buf_memory.rb
+++ b/lib/fluent/plugin/buf_memory.rb
@@ -14,6 +14,12 @@
 #    limitations under the License.
 #
 
+require 'stringio'
+
+require 'fluent/engine'
+require 'fluent/plugin'
+require 'fluent/buffer'
+
 module Fluent
   class MemoryBufferChunk < BufferChunk
     def initialize(key, data='')
diff --git a/lib/fluent/plugin/exec_util.rb b/lib/fluent/plugin/exec_util.rb
index 9ed3d9edff..33548dd9ab 100644
--- a/lib/fluent/plugin/exec_util.rb
+++ b/lib/fluent/plugin/exec_util.rb
@@ -14,10 +14,15 @@
 #    limitations under the License.
 #
 
+require 'msgpack'
+require 'yajl'
+
+require 'fluent/engine'
+require 'fluent/plugin'
+require 'fluent/parser'
+
 module Fluent
   module ExecUtil
-    require 'fluent/parser'
-
     SUPPORTED_FORMAT = {
       'tsv' => :tsv,
       'json' => :json,
diff --git a/lib/fluent/plugin/filter_grep.rb b/lib/fluent/plugin/filter_grep.rb
index 95a21bcd3d..be8b61a2fa 100644
--- a/lib/fluent/plugin/filter_grep.rb
+++ b/lib/fluent/plugin/filter_grep.rb
@@ -14,6 +14,9 @@
 #    limitations under the License.
 #
 
+require 'fluent/filter'
+require 'fluent/config/error'
+
 module Fluent
   class GrepFilter < Filter
     Fluent::Plugin.register_filter('grep', self)
diff --git a/lib/fluent/plugin/filter_record_transformer.rb b/lib/fluent/plugin/filter_record_transformer.rb
index 3838c23700..36293d7e7d 100644
--- a/lib/fluent/plugin/filter_record_transformer.rb
+++ b/lib/fluent/plugin/filter_record_transformer.rb
@@ -14,17 +14,19 @@
 #    limitations under the License.
 #
 
+require 'socket'
+require 'json'
 require 'ostruct'
 
+require 'fluent/filter'
+require 'fluent/config/error'
+require 'fluent/event'
+require 'fluent/time'
+
 module Fluent
   class RecordTransformerFilter < Filter
     Fluent::Plugin.register_filter('record_transformer', self)
 
-    def initialize
-      require 'socket'
-      super
-    end
-
     desc 'A comma-delimited list of keys to delete.'
     config_param :remove_keys, :string, default: nil
     desc 'A comma-delimited list of keys to keep.'
diff --git a/lib/fluent/plugin/filter_stdout.rb b/lib/fluent/plugin/filter_stdout.rb
index 5ab0290a99..4fc14d4c43 100644
--- a/lib/fluent/plugin/filter_stdout.rb
+++ b/lib/fluent/plugin/filter_stdout.rb
@@ -14,6 +14,9 @@
 #    limitations under the License.
 #
 
+require 'fluent/filter'
+require 'fluent/plugin'
+
 module Fluent
   class StdoutFilter < Filter
     Plugin.register_filter('stdout', self)
diff --git a/lib/fluent/plugin/in_debug_agent.rb b/lib/fluent/plugin/in_debug_agent.rb
index 60a6ffea97..cfb196298b 100644
--- a/lib/fluent/plugin/in_debug_agent.rb
+++ b/lib/fluent/plugin/in_debug_agent.rb
@@ -14,6 +14,8 @@
 #    limitations under the License.
 #
 
+require 'fluent/input'
+
 module Fluent
   class DebugAgentInput < Input
     Plugin.register_input('debug_agent', self)
diff --git a/lib/fluent/plugin/in_dummy.rb b/lib/fluent/plugin/in_dummy.rb
index b436eb2210..365eb975f4 100644
--- a/lib/fluent/plugin/in_dummy.rb
+++ b/lib/fluent/plugin/in_dummy.rb
@@ -14,6 +14,11 @@
 #    limitations under the License.
 #
 
+require 'json'
+
+require 'fluent/input'
+require 'fluent/config/error'
+
 module Fluent
   class DummyInput < Input
     Fluent::Plugin.register_input('dummy', self)
diff --git a/lib/fluent/plugin/in_exec.rb b/lib/fluent/plugin/in_exec.rb
index b5ea3e3e97..b9274400ca 100644
--- a/lib/fluent/plugin/in_exec.rb
+++ b/lib/fluent/plugin/in_exec.rb
@@ -14,6 +14,13 @@
 #    limitations under the License.
 #
 
+require 'yajl'
+
+require 'fluent/input'
+require 'fluent/time'
+require 'fluent/timezone'
+require 'fluent/config/error'
+
 module Fluent
   class ExecInput < Input
     Plugin.register_input('exec', self)
@@ -21,7 +28,6 @@ class ExecInput < Input
     def initialize
       super
       require 'fluent/plugin/exec_util'
-      require 'fluent/timezone'
     end
 
     desc 'The command (program) to execute.'
diff --git a/lib/fluent/plugin/in_forward.rb b/lib/fluent/plugin/in_forward.rb
index c9d6d51a20..7a4c2189ea 100644
--- a/lib/fluent/plugin/in_forward.rb
+++ b/lib/fluent/plugin/in_forward.rb
@@ -14,6 +14,13 @@
 #    limitations under the License.
 #
 
+require 'fcntl'
+
+require 'cool.io'
+require 'yajl'
+
+require 'fluent/input'
+
 module Fluent
   class ForwardInput < Input
     Plugin.register_input('forward', self)
diff --git a/lib/fluent/plugin/in_gc_stat.rb b/lib/fluent/plugin/in_gc_stat.rb
index e0dbfdea41..22690f3e7e 100644
--- a/lib/fluent/plugin/in_gc_stat.rb
+++ b/lib/fluent/plugin/in_gc_stat.rb
@@ -14,6 +14,10 @@
 #    limitations under the License.
 #
 
+require 'cool.io'
+
+require 'fluent/input'
+
 module Fluent
   class GCStatInput < Input
     Plugin.register_input('gc_stat', self)
diff --git a/lib/fluent/plugin/in_http.rb b/lib/fluent/plugin/in_http.rb
index 255a5c5fe3..aee6c3a8fa 100644
--- a/lib/fluent/plugin/in_http.rb
+++ b/lib/fluent/plugin/in_http.rb
@@ -14,6 +14,16 @@
 #    limitations under the License.
 #
 
+require 'uri'
+require 'socket'
+require 'json'
+
+require 'cool.io'
+
+require 'fluent/input'
+require 'fluent/event'
+require 'fluent/process'
+
 module Fluent
   class HttpInput < Input
     Plugin.register_input('http', self)
@@ -24,7 +34,6 @@ class HttpInput < Input
 
     def initialize
       require 'webrick/httputils'
-      require 'uri'
       super
     end
 
diff --git a/lib/fluent/plugin/in_monitor_agent.rb b/lib/fluent/plugin/in_monitor_agent.rb
index 9ec0a5a1d7..e4389fc4ba 100644
--- a/lib/fluent/plugin/in_monitor_agent.rb
+++ b/lib/fluent/plugin/in_monitor_agent.rb
@@ -14,17 +14,20 @@
 #    limitations under the License.
 #
 
+require 'json'
+require 'webrick'
+require 'cgi'
+
+require 'cool.io'
+
+require 'fluent/input'
+require 'fluent/output'
+require 'fluent/filter'
+
 module Fluent
   class MonitorAgentInput < Input
     Plugin.register_input('monitor_agent', self)
 
-    require 'webrick'
-
-    def initialize
-      require 'cgi'
-      super
-    end
-
     config_param :bind, :string, default: '0.0.0.0'
     config_param :port, :integer, default: 24220
     config_param :tag, :string, default: nil
diff --git a/lib/fluent/plugin/in_object_space.rb b/lib/fluent/plugin/in_object_space.rb
index d29e90905d..e3c28399fb 100644
--- a/lib/fluent/plugin/in_object_space.rb
+++ b/lib/fluent/plugin/in_object_space.rb
@@ -14,6 +14,11 @@
 #    limitations under the License.
 #
 
+require 'cool.io'
+require 'yajl'
+
+require 'fluent/input'
+
 module Fluent
   class ObjectSpaceInput < Input
     Plugin.register_input('object_space', self)
diff --git a/lib/fluent/plugin/in_stream.rb b/lib/fluent/plugin/in_stream.rb
index d2f9c030aa..3f2d1fcba4 100644
--- a/lib/fluent/plugin/in_stream.rb
+++ b/lib/fluent/plugin/in_stream.rb
@@ -14,6 +14,15 @@
 #    limitations under the License.
 #
 
+require 'fileutils'
+require 'socket'
+
+require 'cool.io'
+require 'yajl'
+
+require 'fluent/input'
+require 'fluent/event'
+
 module Fluent
   # obsolete
   class StreamInput < Input
diff --git a/lib/fluent/plugin/in_syslog.rb b/lib/fluent/plugin/in_syslog.rb
index fc7d5e2b9d..0f4291fe65 100644
--- a/lib/fluent/plugin/in_syslog.rb
+++ b/lib/fluent/plugin/in_syslog.rb
@@ -14,6 +14,13 @@
 #    limitations under the License.
 #
 
+require 'cool.io'
+require 'yajl'
+
+require 'fluent/input'
+require 'fluent/config/error'
+require 'fluent/parser'
+
 module Fluent
   class SyslogInput < Input
     Plugin.register_input('syslog', self)
@@ -60,7 +67,6 @@ class SyslogInput < Input
 
     def initialize
       super
-      require 'cool.io'
       require 'fluent/plugin/socket_util'
     end
 
diff --git a/lib/fluent/plugin/in_tail.rb b/lib/fluent/plugin/in_tail.rb
index fc8c51ac47..b5fb28bf7d 100644
--- a/lib/fluent/plugin/in_tail.rb
+++ b/lib/fluent/plugin/in_tail.rb
@@ -14,6 +14,12 @@
 #    limitations under the License.
 #
 
+require 'cool.io'
+
+require 'fluent/input'
+require 'fluent/config/error'
+require 'fluent/event'
+
 module Fluent
   class NewTailInput < Input
     Plugin.register_input('tail', self)
diff --git a/lib/fluent/plugin/in_tcp.rb b/lib/fluent/plugin/in_tcp.rb
index df02c5ecbf..cfac648bf9 100644
--- a/lib/fluent/plugin/in_tcp.rb
+++ b/lib/fluent/plugin/in_tcp.rb
@@ -14,6 +14,8 @@
 #    limitations under the License.
 #
 
+require 'cool.io'
+
 require 'fluent/plugin/socket_util'
 
 module Fluent
diff --git a/lib/fluent/plugin/out_copy.rb b/lib/fluent/plugin/out_copy.rb
index de43630589..c26804b218 100644
--- a/lib/fluent/plugin/out_copy.rb
+++ b/lib/fluent/plugin/out_copy.rb
@@ -14,6 +14,10 @@
 #    limitations under the License.
 #
 
+require 'fluent/output'
+require 'fluent/config/error'
+require 'fluent/event'
+
 module Fluent
   class CopyOutput < MultiOutput
     Plugin.register_output('copy', self)
diff --git a/lib/fluent/plugin/out_exec.rb b/lib/fluent/plugin/out_exec.rb
index 2062afda51..653686bf3e 100644
--- a/lib/fluent/plugin/out_exec.rb
+++ b/lib/fluent/plugin/out_exec.rb
@@ -14,6 +14,10 @@
 #    limitations under the License.
 #
 
+require 'tempfile'
+
+require 'fluent/output'
+require 'fluent/config/error'
 require 'fluent/plugin/exec_util'
 
 module Fluent
@@ -22,7 +26,6 @@ class ExecOutput < TimeSlicedOutput
 
     def initialize
       super
-      require 'tempfile'
       @localtime = false
     end
 
diff --git a/lib/fluent/plugin/out_exec_filter.rb b/lib/fluent/plugin/out_exec_filter.rb
index 46021c37bc..4e549a84fe 100644
--- a/lib/fluent/plugin/out_exec_filter.rb
+++ b/lib/fluent/plugin/out_exec_filter.rb
@@ -14,7 +14,14 @@
 #    limitations under the License.
 #
 
+require 'yajl'
+
+require 'fluent/output'
+require 'fluent/env'
+require 'fluent/time'
+require 'fluent/timezone'
 require 'fluent/plugin/exec_util'
+require 'fluent/config/error'
 
 module Fluent
   class ExecFilterOutput < BufferedOutput
diff --git a/lib/fluent/plugin/out_file.rb b/lib/fluent/plugin/out_file.rb
index 08e355cd5c..d2d795acad 100644
--- a/lib/fluent/plugin/out_file.rb
+++ b/lib/fluent/plugin/out_file.rb
@@ -14,6 +14,12 @@
 #    limitations under the License.
 #
 
+require 'fileutils'
+require 'zlib'
+
+require 'fluent/output'
+require 'fluent/config/error'
+
 module Fluent
   class FileOutput < TimeSlicedOutput
     Plugin.register_output('file', self)
diff --git a/lib/fluent/plugin/out_forward.rb b/lib/fluent/plugin/out_forward.rb
index 3063b8caa6..57d747095a 100644
--- a/lib/fluent/plugin/out_forward.rb
+++ b/lib/fluent/plugin/out_forward.rb
@@ -14,6 +14,15 @@
 #    limitations under the License.
 #
 
+require 'base64'
+require 'socket'
+require 'fileutils'
+
+require 'cool.io'
+
+require 'fluent/output'
+require 'fluent/config/error'
+
 module Fluent
   class ForwardOutputError < StandardError
   end
@@ -29,9 +38,6 @@ class ForwardOutput < ObjectBufferedOutput
 
     def initialize
       super
-      require "base64"
-      require 'socket'
-      require 'fileutils'
       require 'fluent/plugin/socket_util'
       @nodes = []  #=> [Node]
     end
diff --git a/lib/fluent/plugin/out_null.rb b/lib/fluent/plugin/out_null.rb
index e60ab03af0..032f683a99 100644
--- a/lib/fluent/plugin/out_null.rb
+++ b/lib/fluent/plugin/out_null.rb
@@ -14,6 +14,8 @@
 #    limitations under the License.
 #
 
+require 'fluent/output'
+
 module Fluent
   class NullOutput < Output
     Plugin.register_output('null', self)
diff --git a/lib/fluent/plugin/out_relabel.rb b/lib/fluent/plugin/out_relabel.rb
index 82196b43f3..9622e66f29 100644
--- a/lib/fluent/plugin/out_relabel.rb
+++ b/lib/fluent/plugin/out_relabel.rb
@@ -14,6 +14,8 @@
 #    limitations under the License.
 #
 
+require 'fluent/output'
+
 module Fluent
   class RelabelOutput < Output
     Plugin.register_output('relabel', self)
diff --git a/lib/fluent/plugin/out_roundrobin.rb b/lib/fluent/plugin/out_roundrobin.rb
index 34212b4bc9..a17195ea21 100644
--- a/lib/fluent/plugin/out_roundrobin.rb
+++ b/lib/fluent/plugin/out_roundrobin.rb
@@ -14,6 +14,9 @@
 #    limitations under the License.
 #
 
+require 'fluent/output'
+require 'fluent/config/error'
+
 module Fluent
   class RoundRobinOutput < MultiOutput
     Plugin.register_output('roundrobin', self)
diff --git a/lib/fluent/plugin/out_stdout.rb b/lib/fluent/plugin/out_stdout.rb
index fbaa700622..47968d3481 100644
--- a/lib/fluent/plugin/out_stdout.rb
+++ b/lib/fluent/plugin/out_stdout.rb
@@ -14,6 +14,8 @@
 #    limitations under the License.
 #
 
+require 'fluent/output'
+
 module Fluent
   class StdoutOutput < Output
     Plugin.register_output('stdout', self)
diff --git a/lib/fluent/plugin/out_stream.rb b/lib/fluent/plugin/out_stream.rb
index 2ee222010b..d66d2d53d2 100644
--- a/lib/fluent/plugin/out_stream.rb
+++ b/lib/fluent/plugin/out_stream.rb
@@ -14,15 +14,15 @@
 #    limitations under the License.
 #
 
+require 'socket'
+require 'fileutils'
+
+require 'fluent/output'
+require 'fluent/event'
+
 module Fluent
   # obsolete
   class StreamOutput < BufferedOutput
-    def initialize
-      require 'socket'
-      require 'fileutils'
-      super
-    end
-
     config_param :send_timeout, :time, default: 60
 
     def configure(conf)
diff --git a/lib/fluent/plugin/socket_util.rb b/lib/fluent/plugin/socket_util.rb
index 7b9829e879..c5fb7ad98c 100644
--- a/lib/fluent/plugin/socket_util.rb
+++ b/lib/fluent/plugin/socket_util.rb
@@ -14,13 +14,15 @@
 #    limitations under the License.
 #
 
+require 'ipaddr'
+
 require 'cool.io'
 
+require 'fluent/plugin'
+
 module Fluent
   module SocketUtil
     def create_udp_socket(host)
-      require 'ipaddr'
-
       if IPAddr.new(IPSocket.getaddress(host)).ipv4?
         UDPSocket.new
       else
diff --git a/lib/fluent/process.rb b/lib/fluent/process.rb
index d2f87a0351..87151f8a48 100644
--- a/lib/fluent/process.rb
+++ b/lib/fluent/process.rb
@@ -14,6 +14,12 @@
 #    limitations under the License.
 #
 
+require 'thread'
+
+require 'fluent/config'
+require 'fluent/engine'
+require 'fluent/event'
+
 module Fluent
   class DetachProcessManager
     require 'singleton'
diff --git a/lib/fluent/registry.rb b/lib/fluent/registry.rb
index e5e1c87188..2500db891c 100644
--- a/lib/fluent/registry.rb
+++ b/lib/fluent/registry.rb
@@ -14,9 +14,11 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'fluent/config/error'
+require 'rubygems'
+
+require 'fluent/config/error'
 
+module Fluent
   class Registry
     def initialize(kind, search_prefix)
       @kind = kind
diff --git a/lib/fluent/root_agent.rb b/lib/fluent/root_agent.rb
index 147cea094b..35857652f8 100644
--- a/lib/fluent/root_agent.rb
+++ b/lib/fluent/root_agent.rb
@@ -13,14 +13,17 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 #
-module Fluent
 
-  require 'delegate'
+require 'delegate'
 
-  require 'fluent/agent'
-  require 'fluent/label'
-  require 'fluent/system_config'
+require 'fluent/config/error'
+require 'fluent/agent'
+require 'fluent/engine'
+require 'fluent/label'
+require 'fluent/plugin'
+require 'fluent/system_config'
 
+module Fluent
   #
   # Fluentd forms a tree structure to manage plugins:
   #
diff --git a/lib/fluent/rpc.rb b/lib/fluent/rpc.rb
index 2c7e70a16c..53b899ad81 100644
--- a/lib/fluent/rpc.rb
+++ b/lib/fluent/rpc.rb
@@ -14,10 +14,10 @@
 #    limitations under the License.
 #
 
+require 'webrick'
+
 module Fluent
   module RPC
-    require 'webrick'
-
     class Server
       def initialize(endpoint, log)
         bind, port = endpoint.split(':')
diff --git a/lib/fluent/supervisor.rb b/lib/fluent/supervisor.rb
index d09883bc23..65712fa669 100644
--- a/lib/fluent/supervisor.rb
+++ b/lib/fluent/supervisor.rb
@@ -14,10 +14,16 @@
 #    limitations under the License.
 #
 
-require 'fluent/load'
-require 'fluent/system_config'
 require 'etc'
 
+require 'fluent/config'
+require 'fluent/env'
+require 'fluent/engine'
+require 'fluent/log'
+require 'fluent/plugin'
+require 'fluent/rpc'
+require 'fluent/system_config'
+
 module Fluent
   class Supervisor
     def self.get_etc_passwd(user)
@@ -468,40 +474,6 @@ def read_config
       @conf = Fluent::Config.parse(@config_data, @config_fname, @config_basedir, @use_v1_config)
     end
 
-    class SystemConfig
-      include Configurable
-
-      config_param :log_level, default: nil do |level|
-        Log.str_to_level(level)
-      end
-      config_param :suppress_repeated_stacktrace, :bool, default: nil
-      config_param :emit_error_log_interval, :time, default: nil
-      config_param :suppress_config_dump, :bool, default: nil
-      config_param :without_source, :bool, default: nil
-      config_param :rpc_endpoint, :string, default: nil
-      config_param :enable_get_dump, :bool, default: nil
-      config_param :process_name, default: nil
-
-      def initialize(conf)
-        super()
-        configure(conf)
-      end
-
-      def apply(supervisor)
-        system = self
-        supervisor.instance_eval {
-          @log.level = @log_level = system.log_level unless system.log_level.nil?
-          @suppress_interval = system.emit_error_log_interval unless system.emit_error_log_interval.nil?
-          @suppress_config_dump = system.suppress_config_dump unless system.suppress_config_dump.nil?
-          @suppress_repeated_stacktrace = system.suppress_repeated_stacktrace unless system.suppress_repeated_stacktrace.nil?
-          @without_source = system.without_source unless system.without_source.nil?
-          @rpc_endpoint = system.rpc_endpoint unless system.rpc_endpoint.nil?
-          @enable_get_dump = system.enable_get_dump unless system.enable_get_dump.nil?
-          @process_name = system.process_name unless system.process_name.nil?
-        }
-      end
-    end
-
     def run_configure
       Fluent::Engine.run_configure(@conf)
     end
diff --git a/lib/fluent/system_config.rb b/lib/fluent/system_config.rb
index 4452e9dd86..e7d252c864 100644
--- a/lib/fluent/system_config.rb
+++ b/lib/fluent/system_config.rb
@@ -14,9 +14,10 @@
 #    limitations under the License.
 #
 
-module Fluent
-  require 'fluent/configurable'
+require 'fluent/configurable'
+require 'fluent/config/element'
 
+module Fluent
   module SystemConfigMixin
     def system_config
       @_system_config || Fluent::Engine.system_config
@@ -56,8 +57,13 @@ def self.create(conf)
       SystemConfig.new(systems.first)
     end
 
-    def initialize(conf={})
+    def self.blank_system_config
+      Fluent::Config::Element.new('<SYSTEM>', '', {}, [])
+    end
+
+    def initialize(conf=nil)
       super()
+      conf ||= SystemConfig.blank_system_config
       configure(conf)
     end
 
diff --git a/lib/fluent/test.rb b/lib/fluent/test.rb
index f552f7a20d..d34b4442f7 100644
--- a/lib/fluent/test.rb
+++ b/lib/fluent/test.rb
@@ -15,7 +15,7 @@
 #
 
 require 'test/unit'
-require 'fluent/load'
+require 'fluent/env' # for Fluent.windows?
 require 'fluent/test/base'
 require 'fluent/test/input_test'
 require 'fluent/test/output_test'
diff --git a/lib/fluent/test/base.rb b/lib/fluent/test/base.rb
index 8c40ac77ce..713a944ad3 100644
--- a/lib/fluent/test/base.rb
+++ b/lib/fluent/test/base.rb
@@ -14,6 +14,10 @@
 #    limitations under the License.
 #
 
+require 'fluent/engine'
+require 'fluent/system_config'
+require 'fluent/config'
+
 module Fluent
   module Test
     def self.setup
diff --git a/lib/fluent/test/filter_test.rb b/lib/fluent/test/filter_test.rb
index 2a55bee08a..88cca149d6 100644
--- a/lib/fluent/test/filter_test.rb
+++ b/lib/fluent/test/filter_test.rb
@@ -14,6 +14,9 @@
 #    limitations under the License.
 #
 
+require 'fluent/test/base'
+require 'fluent/event'
+
 module Fluent
   module Test
     class FilterTestDriver < TestDriver
diff --git a/lib/fluent/test/formatter_test.rb b/lib/fluent/test/formatter_test.rb
index f840cebf52..d7bd2a888c 100644
--- a/lib/fluent/test/formatter_test.rb
+++ b/lib/fluent/test/formatter_test.rb
@@ -14,10 +14,11 @@
 #    limitations under the License.
 #
 
+require 'fluent/formatter'
+require 'fluent/config'
+
 module Fluent
   module Test
-    require 'fluent/config'
-
     class FormatterTestDriver
       def initialize(klass_or_str, proc=nil, &block)
         if klass_or_str.is_a?(Class)
diff --git a/lib/fluent/test/input_test.rb b/lib/fluent/test/input_test.rb
index 341211cd5f..f0c0c90bff 100644
--- a/lib/fluent/test/input_test.rb
+++ b/lib/fluent/test/input_test.rb
@@ -14,6 +14,11 @@
 #    limitations under the License.
 #
 
+require 'fluent/buffer'
+require 'fluent/engine'
+require 'fluent/time'
+require 'fluent/test/base'
+
 module Fluent
   class FileBuffer < BasicBuffer
     def self.clear_buffer_paths
diff --git a/lib/fluent/test/output_test.rb b/lib/fluent/test/output_test.rb
index 83d749e94a..62b971a2f0 100644
--- a/lib/fluent/test/output_test.rb
+++ b/lib/fluent/test/output_test.rb
@@ -14,6 +14,10 @@
 #    limitations under the License.
 #
 
+require 'fluent/engine'
+require 'fluent/event'
+require 'fluent/test/input_test'
+
 module Fluent
   module Test
     class TestOutputChain
diff --git a/lib/fluent/test/parser_test.rb b/lib/fluent/test/parser_test.rb
index 7c6f6ddd6b..79706c192f 100644
--- a/lib/fluent/test/parser_test.rb
+++ b/lib/fluent/test/parser_test.rb
@@ -14,10 +14,11 @@
 #    limitations under the License.
 #
 
+require 'fluent/parser'
+require 'fluent/config'
+
 module Fluent
   module Test
-    require 'fluent/config'
-
     class ParserTestDriver
       def initialize(klass_or_str, format=nil, conf={}, &block)
         if klass_or_str.is_a?(Class)
diff --git a/lib/fluent/timezone.rb b/lib/fluent/timezone.rb
index 4320a728d0..f0383495be 100644
--- a/lib/fluent/timezone.rb
+++ b/lib/fluent/timezone.rb
@@ -16,6 +16,8 @@
 
 require 'tzinfo'
 
+require 'fluent/config/error'
+
 module Fluent
   class Timezone
     # [+-]HH:MM, [+-]HHMM, [+-]HH
diff --git a/test/plugin/test_in_forward.rb b/test/plugin/test_in_forward.rb
index b103d8d3e7..c68a73a374 100644
--- a/test/plugin/test_in_forward.rb
+++ b/test/plugin/test_in_forward.rb
@@ -1,7 +1,11 @@
 require_relative '../helper'
+
 require 'fluent/test'
 require 'base64'
 
+require 'fluent/env'
+require 'fluent/plugin/in_forward'
+
 class ForwardInputTest < Test::Unit::TestCase
   def setup
     Fluent::Test.setup
diff --git a/test/test_event_router.rb b/test/test_event_router.rb
index 3e2ff61f96..cc2bd88c45 100644
--- a/test/test_event_router.rb
+++ b/test/test_event_router.rb
@@ -1,3 +1,4 @@
+require_relative 'helper'
 require 'fluent/event_router'
 require_relative 'test_plugin_classes'
 
diff --git a/test/test_plugin_classes.rb b/test/test_plugin_classes.rb
index 77e8c39e30..70cc9416ac 100644
--- a/test/test_plugin_classes.rb
+++ b/test/test_plugin_classes.rb
@@ -1,4 +1,7 @@
 require_relative 'helper'
+require 'fluent/input'
+require 'fluent/output'
+require 'fluent/filter'
 
 module FluentTest
   class FluentTestInput < ::Fluent::Input
diff --git a/test/test_process.rb b/test/test_process.rb
index ae846c3529..7c8c2a072b 100644
--- a/test/test_process.rb
+++ b/test/test_process.rb
@@ -1,6 +1,7 @@
 require_relative 'helper'
 require 'fluent/test'
 require 'fluent/event'
+require 'fluent/process'
 require 'stringio'
 require 'msgpack'
 
diff --git a/test/test_root_agent.rb b/test/test_root_agent.rb
index 50ff51b55e..8357a683f7 100644
--- a/test/test_root_agent.rb
+++ b/test/test_root_agent.rb
@@ -1,3 +1,4 @@
+require_relative 'helper'
 require 'fluent/event_router'
 require 'fluent/system_config'
 require_relative 'test_plugin_classes'