From af16f6896104d1ffdee8a179e0ad6a6bbcc46f30 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 11 Aug 2017 14:34:49 -0500
Subject: [PATCH 1/8] Make debugging easier

---
 Gemfile      | 1 +
 Gemfile.lock | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/Gemfile b/Gemfile
index 08ce6864c..32d7ff145 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,4 +8,5 @@ gem "rubocop", ">= 0.49", require: false
 
 group :test do
   gem "minitest", "~> 5.0"
+  gem "byebug"
 end
diff --git a/Gemfile.lock b/Gemfile.lock
index 4b8a5ac12..32e6f8e5f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -48,6 +48,7 @@ GEM
     arel (7.1.4)
     ast (2.3.0)
     builder (3.2.3)
+    byebug (9.0.6)
     concurrent-ruby (1.0.5)
     erubis (2.7.0)
     globalid (0.3.7)
@@ -128,6 +129,7 @@ PLATFORMS
 
 DEPENDENCIES
   bundler (~> 1.12)
+  byebug
   minitest (~> 5.0)
   rails
   rake (>= 11.1)

From 9251b0bf748fce9e4468aed90af62a4b0b324c05 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 11 Aug 2017 15:26:27 -0500
Subject: [PATCH 2/8] Move to a single singleton

---
 lib/install/angular.rb                        |  4 +-
 lib/install/elm.rb                            | 13 ++-
 lib/install/react.rb                          |  4 +-
 lib/install/template.rb                       |  2 +-
 lib/install/vue.rb                            |  8 +-
 lib/tasks/webpacker/clobber.rake              |  5 +-
 lib/tasks/webpacker/compile.rake              | 12 ++-
 lib/tasks/webpacker/verify_install.rake       |  2 +-
 lib/webpacker.rb                              | 28 +++---
 lib/webpacker/commands.rb                     | 22 +++++
 lib/webpacker/compiler.rb                     | 65 +++++++-------
 lib/webpacker/configuration.rb                | 87 ++++++++-----------
 lib/webpacker/env.rb                          | 26 ------
 lib/webpacker/file_loader.rb                  | 29 -------
 lib/webpacker/helper.rb                       |  4 +-
 lib/webpacker/instance.rb                     | 41 +++++++++
 lib/webpacker/logger.rb                       | 17 ----
 lib/webpacker/manifest.rb                     | 64 ++++++++------
 test/compiler_test.rb                         | 20 ++---
 test/configuration_test.rb                    | 41 ++++-----
 test/env_test.rb                              | 16 ----
 test/helper_test.rb                           | 26 +++---
 test/manifest_test.rb                         | 26 ++----
 ...acker_test.rb => webpacker_test_helper.rb} |  7 ++
 24 files changed, 262 insertions(+), 307 deletions(-)
 create mode 100644 lib/webpacker/commands.rb
 delete mode 100644 lib/webpacker/env.rb
 delete mode 100644 lib/webpacker/file_loader.rb
 create mode 100644 lib/webpacker/instance.rb
 delete mode 100644 lib/webpacker/logger.rb
 delete mode 100644 test/env_test.rb
 rename test/{webpacker_test.rb => webpacker_test_helper.rb} (53%)

diff --git a/lib/install/angular.rb b/lib/install/angular.rb
index 09112d028..10f1df401 100644
--- a/lib/install/angular.rb
+++ b/lib/install/angular.rb
@@ -3,8 +3,8 @@
 puts "Copying angular loader to config/webpack/loaders"
 copy_file "#{__dir__}/config/loaders/installers/angular.js", "config/webpack/loaders/angular.js"
 
-puts "Copying angular example entry file to #{Webpacker::Configuration.entry_path}"
-copy_file "#{__dir__}/examples/angular/hello_angular.js", "#{Webpacker::Configuration.entry_path}/hello_angular.js"
+puts "Copying angular example entry file to #{Webpacker::Configuration.source_entry_path}"
+copy_file "#{__dir__}/examples/angular/hello_angular.js", "#{Webpacker::Configuration.source_entry_path}/hello_angular.js"
 
 puts "Copying hello_angular app to #{Webpacker::Configuration.source_path}"
 directory "#{__dir__}/examples/angular/hello_angular", "#{Webpacker::Configuration.source_path}/hello_angular"
diff --git a/lib/install/elm.rb b/lib/install/elm.rb
index 033254436..d002e2bf9 100644
--- a/lib/install/elm.rb
+++ b/lib/install/elm.rb
@@ -4,12 +4,12 @@
 copy_file "#{__dir__}/config/loaders/installers/elm.js",
           "config/webpack/loaders/elm.js"
 
-puts "Copying elm example entry file to #{Webpacker::Configuration.entry_path}"
-copy_file "#{__dir__}/examples/elm/Main.elm", "#{Webpacker::Configuration.entry_path}/Main.elm"
+puts "Copying elm example entry file to #{Webpacker::Configuration.source_entry_path}"
+copy_file "#{__dir__}/examples/elm/Main.elm", "#{Webpacker::Configuration.source_entry_path}/Main.elm"
 
-puts "Copying elm app file to #{Webpacker::Configuration.entry_path}"
+puts "Copying elm app file to #{Webpacker::Configuration.source_entry_path}"
 copy_file "#{__dir__}/examples/elm/hello_elm.js",
-          "#{Webpacker::Configuration.entry_path}/hello_elm.js"
+          "#{Webpacker::Configuration.source_entry_path}/hello_elm.js"
 
 puts "Installing all elm dependencies"
 run "yarn add elm elm-webpack-loader"
@@ -17,11 +17,10 @@
 run "yarn run elm package install -- --yes"
 
 puts "Updating Webpack paths to include Elm file extension"
-insert_into_file Webpacker::Configuration.file_path, "    - .elm\n", after: /extensions:\n/
+insert_into_file Webpacker::Configuration.config_path, "    - .elm\n", after: /extensions:\n/
 
 puts "Updating elm source location"
-source_path = File.join(Webpacker::Configuration.source, Webpacker::Configuration.fetch(:source_entry_path))
-gsub_file "elm-package.json", /\"\.\"\n/, %("#{source_path}"\n)
+gsub_file "elm-package.json", /\"\.\"\n/, %("#{Webpacker::Configuration.source_entry_path}"\n)
 
 puts "Updating .gitignore to include elm-stuff folder"
 insert_into_file ".gitignore", "/elm-stuff\n", before: "/node_modules\n"
diff --git a/lib/install/react.rb b/lib/install/react.rb
index 9e16414de..fc837cbf7 100644
--- a/lib/install/react.rb
+++ b/lib/install/react.rb
@@ -22,8 +22,8 @@
 puts "Copying react loader to config/webpack/loaders"
 copy_file "#{__dir__}/config/loaders/installers/react.js", "config/webpack/loaders/react.js"
 
-puts "Copying react example entry file to #{Webpacker::Configuration.entry_path}"
-copy_file "#{__dir__}/examples/react/hello_react.jsx", "#{Webpacker::Configuration.entry_path}/hello_react.jsx"
+puts "Copying react example entry file to #{Webpacker::Configuration.source_entry_path}"
+copy_file "#{__dir__}/examples/react/hello_react.jsx", "#{Webpacker::Configuration.source_entry_path}/hello_react.jsx"
 
 puts "Installing all react dependencies"
 run "yarn add react react-dom babel-preset-react prop-types"
diff --git a/lib/install/template.rb b/lib/install/template.rb
index 9960facfc..888958a8e 100644
--- a/lib/install/template.rb
+++ b/lib/install/template.rb
@@ -12,7 +12,7 @@
 copy_file "#{__dir__}/config/.babelrc", ".babelrc"
 
 puts "Creating javascript app source directory"
-directory "#{__dir__}/javascript", "#{Webpacker::Configuration.source}"
+directory "#{__dir__}/javascript", "app/javascript"
 
 puts "Copying binstubs"
 directory "#{__dir__}/bin", "bin"
diff --git a/lib/install/vue.rb b/lib/install/vue.rb
index 24f3c7ef7..9a9f8009d 100644
--- a/lib/install/vue.rb
+++ b/lib/install/vue.rb
@@ -3,11 +3,11 @@
 puts "Copying vue loader to config/webpack/loaders"
 copy_file "#{__dir__}/config/loaders/installers/vue.js", "config/webpack/loaders/vue.js"
 
-puts "Copying the example entry file to #{Webpacker::Configuration.entry_path}"
-copy_file "#{__dir__}/examples/vue/hello_vue.js", "#{Webpacker::Configuration.entry_path}/hello_vue.js"
+puts "Copying the example entry file to #{Webpacker::Configuration.source_entry_path}"
+copy_file "#{__dir__}/examples/vue/hello_vue.js", "#{Webpacker::Configuration.source_entry_path}/hello_vue.js"
 
-puts "Copying vue app file to #{Webpacker::Configuration.entry_path}"
-copy_file "#{__dir__}/examples/vue/app.vue", "#{Webpacker::Configuration.entry_path}/app.vue"
+puts "Copying vue app file to #{Webpacker::Configuration.source_entry_path}"
+copy_file "#{__dir__}/examples/vue/app.vue", "#{Webpacker::Configuration.source_entry_path}/app.vue"
 
 puts "Installing all vue dependencies"
 run "yarn add vue vue-loader vue-template-compiler"
diff --git a/lib/tasks/webpacker/clobber.rake b/lib/tasks/webpacker/clobber.rake
index ec5d3962e..748ccd178 100644
--- a/lib/tasks/webpacker/clobber.rake
+++ b/lib/tasks/webpacker/clobber.rake
@@ -3,9 +3,8 @@ require "webpacker/configuration"
 namespace :webpacker do
   desc "Remove the webpack compiled output directory"
   task clobber: ["webpacker:verify_install", :environment] do
-    output_path = Webpacker::Configuration.output_path
-    FileUtils.rm_r(output_path) if File.exist?(output_path)
-    $stdout.puts "Removed webpack output path directory #{output_path}"
+    Webpacker.clobber
+    $stdout.puts "Removed webpack output path directory #{Webpacker.config.public_output_path}"
   end
 end
 
diff --git a/lib/tasks/webpacker/compile.rake b/lib/tasks/webpacker/compile.rake
index bb3f35c9c..877b89b81 100644
--- a/lib/tasks/webpacker/compile.rake
+++ b/lib/tasks/webpacker/compile.rake
@@ -1,10 +1,18 @@
 $stdout.sync = true
 
+def ensure_log_goes_to_stdout
+  old_logger = Webpacker.logger
+  Webpacker.logger = ActiveSupport::Logger.new(STDOUT)
+  yield
+ensure
+  Webpacker.logger = old_logger
+end
+
 namespace :webpacker do
   desc "Compile javascript packs using webpack for production with digests"
   task compile: ["webpacker:verify_install", :environment] do
-    Webpacker.ensure_log_goes_to_stdout do
-      if Webpacker::Compiler.compile
+    ensure_log_goes_to_stdout do
+      if Webpacker.compile
         # Successful compilation!
       else
         # Failed compilation
diff --git a/lib/tasks/webpacker/verify_install.rake b/lib/tasks/webpacker/verify_install.rake
index ca20906d6..73f2adca8 100644
--- a/lib/tasks/webpacker/verify_install.rake
+++ b/lib/tasks/webpacker/verify_install.rake
@@ -3,7 +3,7 @@ require "webpacker/configuration"
 namespace :webpacker do
   desc "Verifies if webpacker is installed"
   task verify_install: [:check_node, :check_yarn, :check_binstubs] do
-    if File.exist?(Webpacker::Configuration.file_path)
+    if Webpacker.config.config_path.exist?
       $stdout.puts "Webpacker is installed 🎉 🍰"
       $stdout.puts "Using #{Webpacker::Configuration.file_path} file for setting up webpack paths"
     else
diff --git a/lib/webpacker.rb b/lib/webpacker.rb
index 958eff25d..893a73728 100644
--- a/lib/webpacker.rb
+++ b/lib/webpacker.rb
@@ -1,25 +1,27 @@
+require "active_support/core_ext/module/attribute_accessors"
+require "active_support/logger"
+require "active_support/tagged_logging"
+
 module Webpacker
   extend self
-
-  def bootstrap
-    Webpacker::Env.load
-    Webpacker::Configuration.load
-    Webpacker::Manifest.load
+  
+  def instance=(instance)
+    @instance = instance
   end
 
-  def compile
-    Webpacker::Compiler.compile
-    Webpacker::Manifest.load
+  def instance
+    @instance ||= Webpacker::Instance.new
   end
 
-  def env
-    Webpacker::Env.current
-  end
+  delegate :logger, :logger=, :env, to: :instance
+  delegate :config, :compiler, :manifest, :commands, to: :instance
+  delegate :bootstrap, :clobber, :compile, to: :commands
 end
 
-require "webpacker/logger"
-require "webpacker/env"
+require "webpacker/instance"
 require "webpacker/configuration"
 require "webpacker/manifest"
 require "webpacker/compiler"
+require "webpacker/commands"
+
 require "webpacker/railtie" if defined?(Rails)
diff --git a/lib/webpacker/commands.rb b/lib/webpacker/commands.rb
new file mode 100644
index 000000000..69617ef77
--- /dev/null
+++ b/lib/webpacker/commands.rb
@@ -0,0 +1,22 @@
+class Webpacker::Commands
+  delegate :config, :compiler, :manifest, to: :@webpacker
+
+  def initialize(webpacker)
+    @webpacker = webpacker
+  end
+
+  def clobber
+    config.public_output_path.rmtree if config.public_output_path.exist?
+    config.cache_path.rmtree if config.cache_path.exist?
+  end
+
+  def bootstrap
+    config.refresh
+    manifest.refresh
+  end
+
+  def compile
+    compiler.compile
+    manifest.refresh
+  end
+end
diff --git a/lib/webpacker/compiler.rb b/lib/webpacker/compiler.rb
index d85775e61..949f16b9e 100644
--- a/lib/webpacker/compiler.rb
+++ b/lib/webpacker/compiler.rb
@@ -1,20 +1,19 @@
 require "open3"
-require "webpacker/env"
-require "webpacker/configuration"
-
-module Webpacker::Compiler
-  extend self
-
-  delegate :cache_path, :output_path, :source, to: Webpacker::Configuration
-  delegate :logger, to: Webpacker
 
+class Webpacker::Compiler
   # Additional paths that test compiler needs to watch
   # Webpacker::Compiler.watched_paths << 'bower_components'
   mattr_accessor(:watched_paths) { [] }
 
+  delegate :config, :logger, :env, to: :@webpacker
+
+  def initialize(webpacker)
+    @webpacker = webpacker
+  end
+
   def compile
     if stale?
-      cache_source_timestamp
+      record_compilation_timestamp
       run_webpack
     else
       logger.debug "No compiling needed as everything is fresh"
@@ -23,11 +22,7 @@ def compile
 
   # Returns true if all the compiled packs are up to date with the underlying asset files.
   def fresh?
-    if cached_timestamp_path.exist? && output_path.exist?
-      cached_timestamp_path.read == current_source_timestamp
-    else
-      false
-    end
+    source_last_changed_at == source_compiled_from_last_change_at
   end
 
   # Returns true if the compiled packs are out of date with the underlying asset files.
@@ -35,26 +30,19 @@ def stale?
     !fresh?
   end
 
-  # FIXME: Deprecate properly
-  alias_method :compile?, :fresh?
-
-  def default_watched_paths
-    ["#{source}/**/*", "yarn.lock", "package.json", "config/webpack/**/*"].freeze
-  end
-
   private
-    def current_source_timestamp
-      files = Dir[*default_watched_paths, *watched_paths].reject { |f| File.directory?(f) }
-      files.map { |f| File.mtime(f).utc.to_i }.max.to_s
+    def source_compiled_from_last_change_at
+      compilation_timestamp_path.read if compilation_timestamp_path.exist? && config.public_manifest_path.exist?
     end
 
-    def cache_source_timestamp
-      cache_path.mkpath
-      cached_timestamp_path.write(current_source_timestamp)
+    def source_last_changed_at
+      files = Dir[*default_watched_paths, *watched_paths].reject { |f| File.directory?(f) }
+      files.map { |f| File.mtime(f).utc.to_i }.max.to_s
     end
 
-    def cached_timestamp_path
-      cache_path.join(".compiler-timestamp")
+    def record_compilation_timestamp
+      config.cache_path.mkpath
+      compilation_timestamp_path.write(source_last_changed_at)
     end
 
     def run_webpack
@@ -63,15 +51,24 @@ def run_webpack
       sterr, stdout, status = Open3.capture3(webpack_env, "#{RbConfig.ruby} ./bin/webpack")
 
       if status.success?
-        logger.info "Compiled all packs in #{Webpacker::Configuration.entry_path}"
-        true
+        logger.info "Compiled all packs in #{config.source_entry_path}"
       else
-        logger.error "Compilation Failed:\n#{sterr}\n#{stdout}"
-        false
+        logger.error "Compilation failed:\n#{sterr}\n#{stdout}"
       end
+
+      status.success?
+    end
+
+
+    def default_watched_paths
+      ["#{config.source_path}/**/*", "yarn.lock", "package.json", "config/webpack/**/*"].freeze
+    end
+
+    def compilation_timestamp_path
+      config.cache_path.join(".compiled-from-last-change-at")
     end
 
     def webpack_env
-      { "NODE_ENV" => Webpacker.env, "ASSET_HOST" => ActionController::Base.helpers.compute_asset_host }
+      { "NODE_ENV" => env, "ASSET_HOST" => ActionController::Base.helpers.compute_asset_host }
     end
 end
diff --git a/lib/webpacker/configuration.rb b/lib/webpacker/configuration.rb
index c04ce8bdd..b3eb77ee4 100644
--- a/lib/webpacker/configuration.rb
+++ b/lib/webpacker/configuration.rb
@@ -1,67 +1,52 @@
-# Loads webpacker configuration from config/webpacker.yml
+class Webpacker::Configuration
+  delegate :root_path, :config_path, :env, to: :@webpacker
 
-require "webpacker/file_loader"
-
-class Webpacker::Configuration < Webpacker::FileLoader
-  class << self
-    def entry_path
-      source_path.join(fetch(:source_entry_path))
-    end
-
-    def output_path
-      public_path.join(fetch(:public_output_path))
-    end
-
-    def manifest_path
-      output_path.join("manifest.json")
-    end
+  def initialize(webpacker)
+    @webpacker = webpacker
+  end
 
-    def source_path
-      Rails.root.join(source)
-    end
+  def refresh
+    @data = load
+  end
 
-    def public_path
-      Rails.root.join("public")
-    end
+  def source_path
+    root_path.join(data[:source_path])
+  end
 
-    def file_path(root: Rails.root)
-      root.join("config/webpacker.yml")
-    end
+  def source_entry_path
+    source_path.join(data[:source_entry_path])
+  end
 
-    def default_file_path
-      file_path(root: Pathname.new(__dir__).join("../install"))
-    end
+  def public_path
+    root_path.join("public")
+  end
 
-    def cache_path
-      Rails.root.join(fetch(:cache_path))
-    end
+  def public_output_path
+    public_path.join(data[:public_output_path])
+  end
 
-    def source
-      fetch(:source_path)
-    end
+  def public_manifest_path
+    public_output_path.join("manifest.json")
+  end
 
-    def compile?
-      fetch(:compile)
-    end
+  def cache_path
+    root_path.join(data[:cache_path])
+  end
 
-    def fetch(key)
-      data.fetch(key, defaults[key])
-    end
+  def compile?
+    data[:compile]
+  end
 
+  private
     def data
-      load if Webpacker.env.development?
-      ensure_loaded_instance(self)
-      instance.data
+      if env.development?
+        refresh
+      else
+        @data ||= load
+      end
     end
 
-    def defaults
-      @defaults ||= HashWithIndifferentAccess.new(YAML.load(default_file_path.read)[Webpacker.env])
-    end
-  end
-
-  private
     def load
-      return super unless File.exist?(@path)
-      HashWithIndifferentAccess.new(YAML.load(File.read(@path))[Webpacker.env])
+      YAML.load(config_path.read)[env].deep_symbolize_keys
     end
 end
diff --git a/lib/webpacker/env.rb b/lib/webpacker/env.rb
deleted file mode 100644
index 32cc2220e..000000000
--- a/lib/webpacker/env.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-# Singleton registry for determining NODE_ENV from config/webpacker.yml
-require "webpacker/file_loader"
-
-class Webpacker::Env < Webpacker::FileLoader
-  DEFAULT = "production"
-
-  class << self
-    def current
-      ensure_loaded_instance(self)
-      instance.data.inquiry
-    end
-
-    def file_path
-      Rails.root.join("config", "webpacker.yml")
-    end
-  end
-
-  private
-    def load
-      ENV["NODE_ENV"].presence_in(available_environments) || Rails.env.presence_in(available_environments) || DEFAULT
-    end
-
-    def available_environments
-      File.exist?(@path) ? YAML.load(File.read(@path)).keys : [].freeze
-    end
-end
diff --git a/lib/webpacker/file_loader.rb b/lib/webpacker/file_loader.rb
deleted file mode 100644
index 42eca50a0..000000000
--- a/lib/webpacker/file_loader.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-# Provides a base singleton-configuration pattern for loading a file, given a path
-class Webpacker::FileLoader
-  class NotFoundError < StandardError; end
-  class FileLoaderError < StandardError; end
-
-  class_attribute :instance
-  attr_accessor :data
-
-  class << self
-    def load(path = file_path)
-      self.instance = new(path)
-    end
-
-    protected
-      def ensure_loaded_instance(klass)
-        raise Webpacker::FileLoader::FileLoaderError.new("#{klass.name}#load must be called first") unless instance
-      end
-  end
-
-  private
-    def initialize(path)
-      @path = path
-      @data = load
-    end
-
-    def load
-      {}.freeze
-    end
-end
diff --git a/lib/webpacker/helper.rb b/lib/webpacker/helper.rb
index 0034ed099..191ad4adc 100644
--- a/lib/webpacker/helper.rb
+++ b/lib/webpacker/helper.rb
@@ -9,7 +9,7 @@ module Webpacker::Helper
   # In production mode:
   #   <%= asset_pack_path 'calendar.css' %> # => "/packs/calendar-1016838bab065ae1e122.css"
   def asset_pack_path(name, **options)
-    asset_path(Webpacker::Manifest.lookup(name), **options)
+    asset_path(Webpacker.manifest.lookup(name), **options)
   end
   # Creates a script tag that references the named pack file, as compiled by Webpack per the entries list
   # in config/webpack/shared.js. By default, this list is auto-generated to match everything in
@@ -47,7 +47,7 @@ def stylesheet_pack_tag(*names, **options)
 
   private
     def sources_from_pack_manifest(names, type:)
-      names.map { |name| Webpacker::Manifest.lookup(pack_name_with_extension(name, type: type)) }
+      names.map { |name| Webpacker.manifest.lookup(pack_name_with_extension(name, type: type)) }
     end
 
     def pack_name_with_extension(name, type:)
diff --git a/lib/webpacker/instance.rb b/lib/webpacker/instance.rb
new file mode 100644
index 000000000..d87d4ea72
--- /dev/null
+++ b/lib/webpacker/instance.rb
@@ -0,0 +1,41 @@
+class Webpacker::Instance
+  cattr_accessor(:logger) { ActiveSupport::TaggedLogging.new(ActiveSupport::Logger.new(STDOUT)) }
+
+  attr_reader :root_path, :config_path
+
+  def initialize(root_path: Rails.root, config_path: Rails.root.join("config/webpacker.yml"))
+    @root_path, @config_path = root_path, config_path
+  end
+
+  def env
+    (ENV["NODE_ENV"].presence_in(available_environments) || 
+      Rails.env.presence_in(available_environments) ||
+        "production".freeze).inquiry
+  end
+
+  def config
+    @config ||= Webpacker::Configuration.new self
+  end
+
+  def compiler
+    @compiler ||= Webpacker::Compiler.new self
+  end
+
+  def manifest
+    @manifest ||= Webpacker::Manifest.new self
+  end
+
+  def commands
+    @commands ||= Webpacker::Commands.new self
+  end
+
+
+  private
+    def available_environments
+      if config_path.exist?
+        YAML.load(config_path.read).keys
+      else
+        [].freeze
+      end
+    end  
+end
\ No newline at end of file
diff --git a/lib/webpacker/logger.rb b/lib/webpacker/logger.rb
deleted file mode 100644
index 61648afe4..000000000
--- a/lib/webpacker/logger.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require "active_support/core_ext/module/attribute_accessors"
-require "active_support/logger"
-require "active_support/tagged_logging"
-
-module Webpacker::Logger
-  mattr_accessor(:logger) { ActiveSupport::TaggedLogging.new(ActiveSupport::Logger.new(STDOUT)) }
-
-  def ensure_log_goes_to_stdout
-    old_logger = logger
-    self.logger = ActiveSupport::Logger.new(STDOUT)
-    yield
-  ensure
-    self.logger = old_logger
-  end
-end
-
-Webpacker.extend Webpacker::Logger
diff --git a/lib/webpacker/manifest.rb b/lib/webpacker/manifest.rb
index 015b65f7f..8063fe4d0 100644
--- a/lib/webpacker/manifest.rb
+++ b/lib/webpacker/manifest.rb
@@ -1,5 +1,3 @@
-require "webpacker/file_loader"
-
 # Singleton registry for accessing the packs path using a generated manifest.
 # This allows javascript_pack_tag, stylesheet_pack_tag, asset_pack_path to take a reference to,
 # say, "calendar.js" or "calendar.css" and turn it into "/packs/calendar.js" or
@@ -11,40 +9,52 @@
 #
 # When the configuration is set to on-demand compilation, with the `compile: true` option in
 # the webpacker.yml file, any lookups will be preceeded by a compilation if one is needed.
-class Webpacker::Manifest < Webpacker::FileLoader
-  class << self
-    def file_path
-      Webpacker::Configuration.manifest_path
+class Webpacker::Manifest
+  class MissingEntryError < StandardError; end
+
+  delegate :config, :compiler, :env, to: :@webpacker
+
+  def initialize(webpacker)
+    @webpacker = webpacker
+  end
+
+  def refresh
+    @data = load
+  end
+
+  def lookup(name)
+    compile
+    find name
+  end
+
+  private
+    def compile
+      Webpacker.logger.tagged("Webpacker") { compiler.compile } if config.compile?
     end
 
-    def lookup(name)
-      if Webpacker::Configuration.compile?
-        compile_and_find!(name)
-      else
-        find!(name)
-      end
+    def find(name)
+      data[name.to_s] || handle_missing_entry(name)
     end
 
-    def lookup_path(name)
-      Rails.root.join(File.join(Webpacker::Configuration.public_path, lookup(name)))
+    def handle_missing_entry(name)
+      raise Webpacker::Manifest::MissingEntryError, 
+        "Can't find #{name} in #{config.public_manifest_path}. Is webpack still compiling?"
     end
 
-    private
-      def find!(name)
-        ensure_loaded_instance(self)
-        instance.data[name.to_s] ||
-          raise(Webpacker::FileLoader::NotFoundError.new("Can't find #{name} in #{file_path}. Is webpack still compiling?"))
-      end
 
-      def compile_and_find!(name)
-        Webpacker.logger.tagged("Webpacker") { Webpacker.compile }
-        find!(name)
+    def data
+      if env.development?
+        refresh
+      else
+        @data ||= load
       end
-  end
+    end
 
-  private
     def load
-      return super unless File.exist?(@path)
-      JSON.parse(File.read(@path))
+      if config.public_manifest_path.exist?
+        JSON.parse config.public_manifest_path.read
+      else
+        {}
+      end
     end
 end
diff --git a/test/compiler_test.rb b/test/compiler_test.rb
index 3059ae6ac..e356b7594 100644
--- a/test/compiler_test.rb
+++ b/test/compiler_test.rb
@@ -1,22 +1,12 @@
-require "webpacker_test"
+require "webpacker_test_helper"
 
 class CompilerTest < Minitest::Test
-  def test_default_watched_paths
-    assert_equal Webpacker::Compiler.default_watched_paths, ["app/javascript/**/*", "yarn.lock", "package.json", "config/webpack/**/*"]
-  end
-
-  def test_empty_watched_paths
-    assert_equal Webpacker::Compiler.watched_paths, []
-  end
-
-  def test_watched_paths
-    Webpacker::Compiler.stub :watched_paths, ["Gemfile"] do
-      assert_equal Webpacker::Compiler.watched_paths, ["Gemfile"]
-    end
+  def setup
+    Webpacker.compiler.send(:compilation_timestamp_path).delete
   end
 
   def test_freshness
-    assert Webpacker::Compiler.stale?
-    assert !Webpacker::Compiler.fresh?
+    assert Webpacker.compiler.stale?
+    assert !Webpacker.compiler.fresh?
   end
 end
diff --git a/test/configuration_test.rb b/test/configuration_test.rb
index dc1d96f6c..4fdfa4d55 100644
--- a/test/configuration_test.rb
+++ b/test/configuration_test.rb
@@ -1,41 +1,32 @@
-require "webpacker_test"
+require "webpacker_test_helper"
 
 class ConfigurationTest < Minitest::Test
-  def test_entry_path
-    entry_path = File.join(File.dirname(__FILE__), "test_app/app/javascript", "packs").to_s
-    assert_equal Webpacker::Configuration.entry_path.to_s, entry_path
-  end
-
-  def test_file_path
-    file_path = File.join(File.dirname(__FILE__), "test_app/config", "webpacker.yml").to_s
-    assert_equal Webpacker::Configuration.file_path.to_s, file_path
-  end
-
-  def test_manifest_path
-    manifest_path = File.join(File.dirname(__FILE__), "test_app/public/packs", "manifest.json").to_s
-    assert_equal Webpacker::Configuration.manifest_path.to_s, manifest_path
+  def test_source_path
+    source_path = File.expand_path File.join(File.dirname(__FILE__), "test_app/app/javascript").to_s
+    assert_equal source_path, Webpacker.config.source_path.to_s
   end
 
-  def test_output_path
-    output_path = File.join(File.dirname(__FILE__), "test_app/public/packs").to_s
-    assert_equal Webpacker::Configuration.output_path.to_s, output_path
+  def test_source_entry_path
+    source_entry_path = File.expand_path File.join(File.dirname(__FILE__), "test_app/app/javascript", "packs").to_s
+    assert_equal Webpacker.config.source_entry_path.to_s, source_entry_path
   end
 
-  def test_source
-    assert_equal Webpacker::Configuration.source.to_s, "app/javascript"
+  def test_public_output_path
+    public_output_path = File.expand_path File.join(File.dirname(__FILE__), "test_app/public/packs").to_s
+    assert_equal Webpacker.config.public_output_path.to_s, public_output_path
   end
 
-  def test_source_path
-    source_path = File.join(File.dirname(__FILE__), "test_app/app/javascript").to_s
-    assert_equal Webpacker::Configuration.source_path.to_s, source_path
+  def test_public_manifest_path
+    public_manifest_path = File.expand_path File.join(File.dirname(__FILE__), "test_app/public/packs", "manifest.json").to_s
+    assert_equal Webpacker.config.public_manifest_path.to_s, public_manifest_path
   end
 
   def test_cache_path
-    cache_path = File.join(File.dirname(__FILE__), "test_app/tmp/cache/webpacker").to_s
-    assert_equal Webpacker::Configuration.cache_path.to_s, cache_path
+    cache_path = File.expand_path File.join(File.dirname(__FILE__), "test_app/tmp/cache/webpacker").to_s
+    assert_equal Webpacker.config.cache_path.to_s, cache_path
   end
 
   def test_compile?
-    refute Webpacker::Configuration.compile?
+    assert Webpacker.config.compile?
   end
 end
diff --git a/test/env_test.rb b/test/env_test.rb
deleted file mode 100644
index cab5acce9..000000000
--- a/test/env_test.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-require "webpacker_test"
-
-class EnvTest < Minitest::Test
-  def test_current_env
-    assert_equal Webpacker::Env.current, "production"
-    assert_equal Webpacker.env, "production"
-
-    assert Webpacker::Env.current.production?
-    assert Webpacker.env.production?
-  end
-
-  def test_file_path
-    correct_path = File.join(File.dirname(__FILE__), "test_app/config", "webpacker.yml").to_s
-    assert_equal Webpacker::Env.file_path.to_s, correct_path
-  end
-end
diff --git a/test/helper_test.rb b/test/helper_test.rb
index 527968b24..82c52c452 100644
--- a/test/helper_test.rb
+++ b/test/helper_test.rb
@@ -1,4 +1,4 @@
-require "webpacker_test"
+require "webpacker_test_helper"
 
 class HelperTest < ActionView::TestCase
   def setup
@@ -12,24 +12,28 @@ def test_asset_pack_path
   end
 
   def test_javascript_pack_tag
-    script = %(<script src="/packs/bootstrap-300631c4f0e0f9c865bc.js"></script>)
-    assert_equal @view.javascript_pack_tag("bootstrap.js"), script
+    assert_equal \
+      %(<script src="/packs/bootstrap-300631c4f0e0f9c865bc.js"></script>), 
+      @view.javascript_pack_tag("bootstrap.js")
   end
 
   def test_javascript_pack_tag_splat
-    script = %(<script src="/packs/bootstrap-300631c4f0e0f9c865bc.js" defer="defer"></script>\n) +
-      %(<script src="/packs/application-k344a6d59eef8632c9d1.js" defer="defer"></script>)
-    assert_equal @view.javascript_pack_tag("bootstrap.js", "application.js", defer: true), script
+    assert_equal \
+    %(<script src="/packs/bootstrap-300631c4f0e0f9c865bc.js" defer="defer"></script>\n) +
+        %(<script src="/packs/application-k344a6d59eef8632c9d1.js" defer="defer"></script>),
+      @view.javascript_pack_tag("bootstrap.js", "application.js", defer: true)
   end
 
   def test_stylesheet_pack_tag
-    style = %(<link rel="stylesheet" media="screen" href="/packs/bootstrap-c38deda30895059837cf.css" />)
-    assert_equal @view.stylesheet_pack_tag("bootstrap.css"), style
+    assert_equal \
+      %(<link rel="stylesheet" media="screen" href="/packs/bootstrap-c38deda30895059837cf.css" />), 
+      @view.stylesheet_pack_tag("bootstrap.css")
   end
 
   def test_stylesheet_pack_tag_splat
-    style = %(<link rel="stylesheet" media="all" href="/packs/bootstrap-c38deda30895059837cf.css" />\n) +
-      %(<link rel="stylesheet" media="all" href="/packs/application-dd6b1cd38bfa093df600.css" />)
-    assert_equal @view.stylesheet_pack_tag("bootstrap.css", "application.css", media: "all"), style
+    assert_equal \
+      %(<link rel="stylesheet" media="all" href="/packs/bootstrap-c38deda30895059837cf.css" />\n) +
+        %(<link rel="stylesheet" media="all" href="/packs/application-dd6b1cd38bfa093df600.css" />),
+      @view.stylesheet_pack_tag("bootstrap.css", "application.css", media: "all")
   end
 end
diff --git a/test/manifest_test.rb b/test/manifest_test.rb
index 528064800..c62a8df3a 100644
--- a/test/manifest_test.rb
+++ b/test/manifest_test.rb
@@ -1,32 +1,20 @@
-require "webpacker_test"
+require "webpacker_test_helper"
 
 class ManifestTest < Minitest::Test
-  def test_file_path
-    file_path = File.join(File.dirname(__FILE__), "test_app/public/packs", "manifest.json").to_s
-    assert_equal Webpacker::Manifest.file_path.to_s, file_path
-  end
-
   def test_lookup_exception
-    manifest_path = File.join(File.dirname(__FILE__), "test_app/public/packs", "manifest.json").to_s
+    manifest_path = File.expand_path File.join(File.dirname(__FILE__), "test_app/public/packs", "manifest.json").to_s
     asset_file = "calendar.js"
 
-    Webpacker::Configuration.stub :compile?, false do
-      error = assert_raises Webpacker::FileLoader::NotFoundError do
-        Webpacker::Manifest.lookup(asset_file)
+    Webpacker.config.stub :compile?, false do
+      error = assert_raises Webpacker::Manifest::MissingEntryError do
+        Webpacker.manifest.lookup(asset_file)
       end
 
-      assert_equal error.message, "Can't find #{asset_file} in #{manifest_path}. Is webpack still compiling?"
+      assert_equal "Can't find #{asset_file} in #{manifest_path}. Is webpack still compiling?", error.message
     end
   end
 
   def test_lookup_success
-    asset_file = "bootstrap.js"
-    assert_equal Webpacker::Manifest.lookup(asset_file), "/packs/bootstrap-300631c4f0e0f9c865bc.js"
-  end
-
-  def test_lookup_path
-    file_path = File.join(File.dirname(__FILE__), "test_app/public/packs", "bootstrap-300631c4f0e0f9c865bc.js").to_s
-    asset_file = "bootstrap.js"
-    assert_equal Webpacker::Manifest.lookup_path(asset_file).to_s, file_path
+    assert_equal Webpacker.manifest.lookup("bootstrap.js"), "/packs/bootstrap-300631c4f0e0f9c865bc.js"
   end
 end
diff --git a/test/webpacker_test.rb b/test/webpacker_test_helper.rb
similarity index 53%
rename from test/webpacker_test.rb
rename to test/webpacker_test_helper.rb
index f05871147..07dc2596a 100644
--- a/test/webpacker_test.rb
+++ b/test/webpacker_test_helper.rb
@@ -3,8 +3,14 @@
 require "minitest/autorun"
 require "rails"
 require "rails/test_help"
+require "byebug"
+
 require "webpacker"
 
+Webpacker.instance = Webpacker::Instance.new \
+  root_path: Pathname.new(File.expand_path("../test_app", __FILE__)),
+  config_path: Pathname.new(File.expand_path("../../lib/install/config/webpacker.yml", __FILE__))
+
 module TestApp
   class Application < ::Rails::Application
     config.root = File.join(File.dirname(__FILE__), "test_app")
@@ -12,4 +18,5 @@ class Application < ::Rails::Application
   end
 end
 
+Rails.backtrace_cleaner.remove_silencers!
 TestApp::Application.initialize!

From ab6ed5401999aa73f2ef6357b37df110595770e9 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 11 Aug 2017 15:26:35 -0500
Subject: [PATCH 3/8] Missing space

---
 lib/tasks/webpacker/yarn_install.rake | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/tasks/webpacker/yarn_install.rake b/lib/tasks/webpacker/yarn_install.rake
index 40d632d07..c60978f68 100644
--- a/lib/tasks/webpacker/yarn_install.rake
+++ b/lib/tasks/webpacker/yarn_install.rake
@@ -1,5 +1,5 @@
 namespace :webpacker do
-  desc "Support for older Rails versions.Install all JavaScript dependencies as specified via Yarn"
+  desc "Support for older Rails versions. Install all JavaScript dependencies as specified via Yarn"
   task :yarn_install, [:arg1, :arg2] do |task, args|
     system "yarn #{args[:arg1]} #{args[:arg2]}"
   end

From 01653cc6468343118aa66b1bf5f92569be6025df Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 11 Aug 2017 15:27:16 -0500
Subject: [PATCH 4/8] Correct reference

---
 lib/tasks/webpacker/verify_install.rake | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/tasks/webpacker/verify_install.rake b/lib/tasks/webpacker/verify_install.rake
index 73f2adca8..902b2af39 100644
--- a/lib/tasks/webpacker/verify_install.rake
+++ b/lib/tasks/webpacker/verify_install.rake
@@ -5,7 +5,7 @@ namespace :webpacker do
   task verify_install: [:check_node, :check_yarn, :check_binstubs] do
     if Webpacker.config.config_path.exist?
       $stdout.puts "Webpacker is installed 🎉 🍰"
-      $stdout.puts "Using #{Webpacker::Configuration.file_path} file for setting up webpack paths"
+      $stdout.puts "Using #{Webpacker.config.config_path} file for setting up webpack paths"
     else
       $stderr.puts "Configuration config/webpacker.yml file not found. \n"\
            "Make sure webpacker:install is run successfully before " \

From 67a97a1b5569b71b0f5e7c1ccc5709c065207ff6 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 11 Aug 2017 15:32:48 -0500
Subject: [PATCH 5/8] Ignore the temporary

---
 .gitignore | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.gitignore b/.gitignore
index 207100846..f53d152a2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,5 @@
 /pkg
 /test/test_app/log
 node_modules
+.byebug_history
+/test/test_app/tmp

From 1c68f2d845082e236774af3cf36664fb7f9b13c4 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 11 Aug 2017 15:38:00 -0500
Subject: [PATCH 6/8] Update references in the installers

---
 lib/install/angular.rb |  8 ++++----
 lib/install/elm.rb     | 12 ++++++------
 lib/install/react.rb   |  4 ++--
 lib/install/vue.rb     |  8 ++++----
 4 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/lib/install/angular.rb b/lib/install/angular.rb
index 10f1df401..2b5073f54 100644
--- a/lib/install/angular.rb
+++ b/lib/install/angular.rb
@@ -3,11 +3,11 @@
 puts "Copying angular loader to config/webpack/loaders"
 copy_file "#{__dir__}/config/loaders/installers/angular.js", "config/webpack/loaders/angular.js"
 
-puts "Copying angular example entry file to #{Webpacker::Configuration.source_entry_path}"
-copy_file "#{__dir__}/examples/angular/hello_angular.js", "#{Webpacker::Configuration.source_entry_path}/hello_angular.js"
+puts "Copying angular example entry file to #{Webpacker.config.source_entry_path}"
+copy_file "#{__dir__}/examples/angular/hello_angular.js", "#{Webpacker.config.source_entry_path}/hello_angular.js"
 
-puts "Copying hello_angular app to #{Webpacker::Configuration.source_path}"
-directory "#{__dir__}/examples/angular/hello_angular", "#{Webpacker::Configuration.source_path}/hello_angular"
+puts "Copying hello_angular app to #{Webpacker.config.source_path}"
+directory "#{__dir__}/examples/angular/hello_angular", "#{Webpacker.config.source_path}/hello_angular"
 
 puts "Copying tsconfig.json to the Rails root directory for typescript"
 copy_file "#{__dir__}/examples/angular/tsconfig.json", "tsconfig.json"
diff --git a/lib/install/elm.rb b/lib/install/elm.rb
index d002e2bf9..a815498bc 100644
--- a/lib/install/elm.rb
+++ b/lib/install/elm.rb
@@ -4,12 +4,12 @@
 copy_file "#{__dir__}/config/loaders/installers/elm.js",
           "config/webpack/loaders/elm.js"
 
-puts "Copying elm example entry file to #{Webpacker::Configuration.source_entry_path}"
-copy_file "#{__dir__}/examples/elm/Main.elm", "#{Webpacker::Configuration.source_entry_path}/Main.elm"
+puts "Copying elm example entry file to #{Webpacker.config.source_entry_path}"
+copy_file "#{__dir__}/examples/elm/Main.elm", "#{Webpacker.config.source_entry_path}/Main.elm"
 
-puts "Copying elm app file to #{Webpacker::Configuration.source_entry_path}"
+puts "Copying elm app file to #{Webpacker.config.source_entry_path}"
 copy_file "#{__dir__}/examples/elm/hello_elm.js",
-          "#{Webpacker::Configuration.source_entry_path}/hello_elm.js"
+          "#{Webpacker.config.source_entry_path}/hello_elm.js"
 
 puts "Installing all elm dependencies"
 run "yarn add elm elm-webpack-loader"
@@ -17,10 +17,10 @@
 run "yarn run elm package install -- --yes"
 
 puts "Updating Webpack paths to include Elm file extension"
-insert_into_file Webpacker::Configuration.config_path, "    - .elm\n", after: /extensions:\n/
+insert_into_file Webpacker.config.config_path, "    - .elm\n", after: /extensions:\n/
 
 puts "Updating elm source location"
-gsub_file "elm-package.json", /\"\.\"\n/, %("#{Webpacker::Configuration.source_entry_path}"\n)
+gsub_file "elm-package.json", /\"\.\"\n/, %("#{Webpacker.config.source_entry_path}"\n)
 
 puts "Updating .gitignore to include elm-stuff folder"
 insert_into_file ".gitignore", "/elm-stuff\n", before: "/node_modules\n"
diff --git a/lib/install/react.rb b/lib/install/react.rb
index fc837cbf7..1eb4d8a25 100644
--- a/lib/install/react.rb
+++ b/lib/install/react.rb
@@ -22,8 +22,8 @@
 puts "Copying react loader to config/webpack/loaders"
 copy_file "#{__dir__}/config/loaders/installers/react.js", "config/webpack/loaders/react.js"
 
-puts "Copying react example entry file to #{Webpacker::Configuration.source_entry_path}"
-copy_file "#{__dir__}/examples/react/hello_react.jsx", "#{Webpacker::Configuration.source_entry_path}/hello_react.jsx"
+puts "Copying react example entry file to #{Webpacker.config.source_entry_path}"
+copy_file "#{__dir__}/examples/react/hello_react.jsx", "#{Webpacker.config.source_entry_path}/hello_react.jsx"
 
 puts "Installing all react dependencies"
 run "yarn add react react-dom babel-preset-react prop-types"
diff --git a/lib/install/vue.rb b/lib/install/vue.rb
index 9a9f8009d..20f0424df 100644
--- a/lib/install/vue.rb
+++ b/lib/install/vue.rb
@@ -3,11 +3,11 @@
 puts "Copying vue loader to config/webpack/loaders"
 copy_file "#{__dir__}/config/loaders/installers/vue.js", "config/webpack/loaders/vue.js"
 
-puts "Copying the example entry file to #{Webpacker::Configuration.source_entry_path}"
-copy_file "#{__dir__}/examples/vue/hello_vue.js", "#{Webpacker::Configuration.source_entry_path}/hello_vue.js"
+puts "Copying the example entry file to #{Webpacker.config.source_entry_path}"
+copy_file "#{__dir__}/examples/vue/hello_vue.js", "#{Webpacker.config.source_entry_path}/hello_vue.js"
 
-puts "Copying vue app file to #{Webpacker::Configuration.source_entry_path}"
-copy_file "#{__dir__}/examples/vue/app.vue", "#{Webpacker::Configuration.source_entry_path}/app.vue"
+puts "Copying vue app file to #{Webpacker.config.source_entry_path}"
+copy_file "#{__dir__}/examples/vue/app.vue", "#{Webpacker.config.source_entry_path}/app.vue"
 
 puts "Installing all vue dependencies"
 run "yarn add vue vue-loader vue-template-compiler"

From 18ff191746209c45ea3440c41a7dc650a0587ea8 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 11 Aug 2017 15:44:46 -0500
Subject: [PATCH 7/8] Bring back the defaults after all

Need a better system for ensuring that the config is kept updated with
new keys before we nix it.
---
 lib/webpacker/configuration.rb | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/lib/webpacker/configuration.rb b/lib/webpacker/configuration.rb
index b3eb77ee4..f78504db8 100644
--- a/lib/webpacker/configuration.rb
+++ b/lib/webpacker/configuration.rb
@@ -10,11 +10,11 @@ def refresh
   end
 
   def source_path
-    root_path.join(data[:source_path])
+    root_path.join(fetch(:source_path))
   end
 
   def source_entry_path
-    source_path.join(data[:source_entry_path])
+    source_path.join(fetch(:source_entry_path))
   end
 
   def public_path
@@ -22,7 +22,7 @@ def public_path
   end
 
   def public_output_path
-    public_path.join(data[:public_output_path])
+    public_path.join(fetch(:public_output_path))
   end
 
   def public_manifest_path
@@ -30,14 +30,18 @@ def public_manifest_path
   end
 
   def cache_path
-    root_path.join(data[:cache_path])
+    root_path.join(fetch(:cache_path))
   end
 
   def compile?
-    data[:compile]
+    fetch(:compile)
   end
 
   private
+    def fetch(key)
+      data.fetch(key, defaults[key])
+    end
+
     def data
       if env.development?
         refresh
@@ -49,4 +53,9 @@ def data
     def load
       YAML.load(config_path.read)[env].deep_symbolize_keys
     end
+
+    def defaults
+      @defaults ||= \
+        YAML.load(File.read(File.expand_path("../../install/config/webpacker.yml", __FILE__)))[env].deep_symbolize_keys
+    end
 end

From ead55077d347b837471353dccd2cde1dc7bfa745 Mon Sep 17 00:00:00 2001
From: Gaurav Tiwari <gaurav@gauravtiwari.co.uk>
Date: Fri, 11 Aug 2017 22:25:16 +0100
Subject: [PATCH 8/8] Add back source_dir

---
 lib/install/template.rb        | 2 +-
 lib/webpacker/configuration.rb | 6 +++++-
 test/configuration_test.rb     | 4 ++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/lib/install/template.rb b/lib/install/template.rb
index 888958a8e..963c880ac 100644
--- a/lib/install/template.rb
+++ b/lib/install/template.rb
@@ -12,7 +12,7 @@
 copy_file "#{__dir__}/config/.babelrc", ".babelrc"
 
 puts "Creating javascript app source directory"
-directory "#{__dir__}/javascript", "app/javascript"
+directory "#{__dir__}/javascript", Webpacker.config.source_dir
 
 puts "Copying binstubs"
 directory "#{__dir__}/bin", "bin"
diff --git a/lib/webpacker/configuration.rb b/lib/webpacker/configuration.rb
index f78504db8..bf6e67f52 100644
--- a/lib/webpacker/configuration.rb
+++ b/lib/webpacker/configuration.rb
@@ -10,7 +10,7 @@ def refresh
   end
 
   def source_path
-    root_path.join(fetch(:source_path))
+    root_path.join(source_dir)
   end
 
   def source_entry_path
@@ -37,6 +37,10 @@ def compile?
     fetch(:compile)
   end
 
+  def source_dir
+    fetch(:source_path)
+  end
+
   private
     def fetch(key)
       data.fetch(key, defaults[key])
diff --git a/test/configuration_test.rb b/test/configuration_test.rb
index 4fdfa4d55..5f47dc3e0 100644
--- a/test/configuration_test.rb
+++ b/test/configuration_test.rb
@@ -1,6 +1,10 @@
 require "webpacker_test_helper"
 
 class ConfigurationTest < Minitest::Test
+  def test_source
+    assert_equal "app/javascript", Webpacker.config.source_dir
+  end
+
   def test_source_path
     source_path = File.expand_path File.join(File.dirname(__FILE__), "test_app/app/javascript").to_s
     assert_equal source_path, Webpacker.config.source_path.to_s