Re-add lib/paperclip_processors for custom processors.

Also, add integration tests for custom processor definition and unit
test for Paperclip.load_processor (thoughtbot/paperclip#1535).

features/basic_integration.feature

@@ -24,6 +24,21 @@ Feature: Rails integration
     And I should see an image with a path of "/paperclip/custom/attachments/original/5k.png"
     And the file at "/paperclip/custom/attachments/original/5k.png" should be the same as "spec/support/fixtures/5k.png"
 
+  Scenario: Add custom processors
+    Given I add a "test" processor in "lib/paperclip"
+    And I add a "cool" processor in "lib/paperclip_processors"
+    And I attach :attachment with:
+      """
+      styles: { original: {} }, processors: [:test, :cool]
+      """
+    And I start the rails application
+    When I go to the new user page
+    And I fill in "Name" with "something"
+    And I attach the file "spec/support/fixtures/5k.png" to "Attachment"
+    And I press "Submit"
+    Then I should see "Name: something"
+    And I should see an image with a path of "/paperclip/custom/attachments/original/5k.png"
+
   Scenario: Filesystem integration test
     Given I attach :attachment with:
       """

features/step_definitions/rails_steps.rb

@@ -196,6 +196,35 @@ Given /^I am using Rails newer than ([\d\.]+)$/ do |version|
   end
 end
 
+Given(/^I add a "(.*?)" processor in "(.*?)"$/) do |processor, directory|
+  filename = "#{directory}/#{processor}.rb"
+  in_current_dir do
+    FileUtils.mkdir_p directory
+    File.open(filename, "w") do |f|
+      f.write(<<-CLASS)
+        module Paperclip
+          class #{processor.capitalize} < Processor
+            def make
+              basename = File.basename(file.path, File.extname(file.path))
+              dst_format = options[:format] ? ".\#{options[:format]}" : ''
+
+              dst = Tempfile.new([basename, dst_format])
+              dst.binmode
+
+              convert(':src :dst',
+                src: File.expand_path(file.path),
+                dst: File.expand_path(dst.path)
+              )
+
+              dst
+            end
+          end
+        end
+      CLASS
+    end
+  end
+end
+
 def transform_file(filename)
   if File.exist?(filename)
     content = File.read(filename)

lib/paperclip.rb

@@ -33,6 +33,7 @@ require 'paperclip/geometry_parser_factory'
 require 'paperclip/geometry_detector_factory'
 require 'paperclip/geometry'
 require 'paperclip/processor'
+require 'paperclip/processor_helpers'
 require 'paperclip/tempfile'
 require 'paperclip/thumbnail'
 require 'paperclip/interpolations/plural_cache'

lib/paperclip/processor.rb

@@ -45,41 +45,4 @@ module Paperclip
       Paperclip.run('identify', arguments, local_options)
     end
   end
-
-  module ProcessorHelpers
-    def processor(name) #:nodoc:
-      @known_processors ||= {}
-      if @known_processors[name.to_s]
-        @known_processors[name.to_s]
-      else
-        name = name.to_s.camelize
-        load_processor(name) unless Paperclip.const_defined?(name)
-        processor = Paperclip.const_get(name)
-        @known_processors[name.to_s] = processor
-      end
-    end
-
-    def load_processor(name)
-      if defined?(Rails.root) && Rails.root
-        require File.expand_path(Rails.root.join("lib", "paperclip", "#{name.underscore}.rb"))
-      end
-    end
-
-    def clear_processors!
-      @known_processors.try(:clear)
-    end
-
-    # You can add your own processor via the Paperclip configuration. Normally
-    # Paperclip will load all processors from the
-    # Rails.root/lib/paperclip_processors directory, but here you can add any
-    # existing class using this mechanism.
-    #
-    #   Paperclip.configure do |c|
-    #     c.register_processor :watermarker, WatermarkingProcessor.new
-    #   end
-    def register_processor(name, processor)
-      @known_processors ||= {}
-      @known_processors[name.to_s] = processor
-    end
-  end
 end

lib/paperclip/processor_helpers.rb

+module Paperclip
+  module ProcessorHelpers
+    class NoSuchProcessor < StandardError; end
+
+    def processor(name) #:nodoc:
+      @known_processors ||= {}
+      if @known_processors[name.to_s]
+        @known_processors[name.to_s]
+      else
+        name = name.to_s.camelize
+        load_processor(name) unless Paperclip.const_defined?(name)
+        processor = Paperclip.const_get(name)
+        @known_processors[name.to_s] = processor
+      end
+    end
+
+    def load_processor(name)
+      if defined?(Rails.root) && Rails.root
+        filename = "#{name.to_s.underscore}.rb"
+        directories = %w(lib/paperclip lib/paperclip_processors)
+
+        required = directories.map do |directory|
+          pathname = File.expand_path(Rails.root.join(directory, filename))
+          file_exists = File.exist?(pathname)
+          require pathname if file_exists
+          file_exists
+        end
+
+        raise LoadError, "Could not find the '#{name}' processor in any of these paths: #{directories.join(', ')}" unless required.any?
+      end
+    end
+
+    def clear_processors!
+      @known_processors.try(:clear)
+    end
+
+    # You can add your own processor via the Paperclip configuration. Normally
+    # Paperclip will load all processors from the
+    # Rails.root/lib/paperclip_processors directory, but here you can add any
+    # existing class using this mechanism.
+    #
+    #   Paperclip.configure do |c|
+    #     c.register_processor :watermarker, WatermarkingProcessor.new
+    #   end
+    def register_processor(name, processor)
+      @known_processors ||= {}
+      @known_processors[name.to_s] = processor
+    end
+  end
+end

spec/paperclip/processor_helpers_spec.rb

+require 'spec_helper'
+
+describe Paperclip::ProcessorHelpers do
+  describe '.load_processor' do
+    context 'when the file exists in lib/paperclip' do
+      it 'loads it correctly' do
+        pathname = Pathname.new('my_app')
+        main_path = 'main_path'
+        alternate_path = 'alternate_path'
+
+        Rails.stubs(:root).returns(pathname)
+        File.expects(:expand_path).with(pathname.join('lib/paperclip', 'custom.rb')).returns(main_path)
+        File.expects(:expand_path).with(pathname.join('lib/paperclip_processors', 'custom.rb')).returns(alternate_path)
+        File.expects(:exist?).with(main_path).returns(true)
+        File.expects(:exist?).with(alternate_path).returns(false)
+
+        Paperclip.expects(:require).with(main_path)
+
+        Paperclip.load_processor(:custom)
+      end
+    end
+
+    context 'when the file exists in lib/paperclip_processors' do
+      it 'loads it correctly' do
+        pathname = Pathname.new('my_app')
+        main_path = 'main_path'
+        alternate_path = 'alternate_path'
+
+        Rails.stubs(:root).returns(pathname)
+        File.expects(:expand_path).with(pathname.join('lib/paperclip', 'custom.rb')).returns(main_path)
+        File.expects(:expand_path).with(pathname.join('lib/paperclip_processors', 'custom.rb')).returns(alternate_path)
+        File.expects(:exist?).with(main_path).returns(false)
+        File.expects(:exist?).with(alternate_path).returns(true)
+
+        Paperclip.expects(:require).with(alternate_path)
+
+        Paperclip.load_processor(:custom)
+      end
+    end
+
+    context 'when the file does not exist in lib/paperclip_processors' do
+      it 'raises an error' do
+        pathname = Pathname.new('my_app')
+        main_path = 'main_path'
+        alternate_path = 'alternate_path'
+
+        Rails.stubs(:root).returns(pathname)
+        File.stubs(:expand_path).with(pathname.join('lib/paperclip', 'custom.rb')).returns(main_path)
+        File.stubs(:expand_path).with(pathname.join('lib/paperclip_processors', 'custom.rb')).returns(alternate_path)
+        File.stubs(:exist?).with(main_path).returns(false)
+        File.stubs(:exist?).with(alternate_path).returns(false)
+
+        assert_raises(LoadError) { Paperclip.processor(:custom) }
+      end
+    end
+  end
+end