Add generators.

This seemed like the easiest place to start.

Rakefile

@@ -3,7 +3,6 @@ require "bundler/gem_tasks"
 require 'rake/testtask'
 
 Rake::TestTask.new do |t|
-  t.libs << "lib"
   t.test_files = FileList['test/*_test.rb']
   t.ruby_opts = ['-r./test/test_helper.rb']
   t.verbose = true

lib/generators/serializer/USAGE

@@ -0,0 +1,6 @@
+Description:
+    Generates a serializer for the given resource with tests.
+
+Example:
+    `rails generate serializer Account name created_at`
+

lib/generators/serializer/serializer_generator.rb

@@ -0,0 +1,37 @@
+module Rails
+  module Generators
+    class SerializerGenerator < NamedBase
+      source_root File.expand_path("../templates", __FILE__)
+      check_class_collision :suffix => "Serializer"
+
+      argument :attributes, :type => :array, :default => [], :banner => "field:type field:type"
+
+      class_option :parent, :type => :string, :desc => "The parent class for the generated serializer"
+
+      def create_serializer_file
+        template 'serializer.rb', File.join('app/serializers', class_path, "#{file_name}_serializer.rb")
+      end
+
+      private
+
+      def attributes_names
+        [:id] + attributes.select { |attr| !attr.reference? }.map { |a| a.name.to_sym }
+      end
+
+      def association_names
+        attributes.select { |attr| attr.reference? }.map { |a| a.name.to_sym }
+      end
+
+      def parent_class_name
+        if options[:parent]
+          options[:parent]
+        elsif defined?(::ApplicationSerializer)
+          "ApplicationSerializer"
+        else
+          "ActiveModel::Serializer"
+        end
+      end
+    end
+  end
+end
+

lib/generators/serializer/templates/serializer.rb

@@ -0,0 +1,8 @@
+<% module_namespacing  do -%>
+class <%= class_name %>Serializer < <%= parent_class_name %>
+  attributes <%= attributes_names.map(&:inspect).join(", ") %>
+end
+<% association_names.each  do |attribute| -%>
+  has_one :<%= attribute %>
+<% end  -%>
+<% end  -%>

test/generators_test.rb

@@ -0,0 +1,59 @@
+class Foo < Rails::Application
+  if Rails.version.to_s.start_with? '4'
+    config.eager_load = false
+    config.secret_key_base = 'abc123'
+  end
+end
+
+Rails.application.load_generators
+
+require 'generators/serializer/serializer_generator'
+
+class SerializerGeneratorTest < Rails::Generators::TestCase
+  destination File.expand_path("../tmp", __FILE__)
+  setup :prepare_destination
+
+  tests Rails::Generators::SerializerGenerator
+  arguments %w(account name:string description:text business:references)
+
+  def test_generates_a_serializer
+    run_generator
+    assert_file "app/serializers/account_serializer.rb", /class AccountSerializer < ActiveModel::Serializer/
+  end
+
+  def test_generates_a_namespaced_serializer
+    run_generator ["admin/account"]
+    assert_file "app/serializers/admin/account_serializer.rb", /class Admin::AccountSerializer < ActiveModel::Serializer/
+  end
+
+  def test_uses_application_serializer_if_one_exists
+    Object.const_set(:ApplicationSerializer, Class.new)
+    run_generator
+    assert_file "app/serializers/account_serializer.rb", /class AccountSerializer < ApplicationSerializer/
+  ensure
+    Object.send :remove_const, :ApplicationSerializer
+  end
+
+  def test_uses_given_parent
+    Object.const_set(:ApplicationSerializer, Class.new)
+    run_generator ["Account", "--parent=MySerializer"]
+    assert_file "app/serializers/account_serializer.rb", /class AccountSerializer < MySerializer/
+  ensure
+    Object.send :remove_const, :ApplicationSerializer
+  end
+
+  def test_generates_attributes_and_associations
+    run_generator
+    assert_file "app/serializers/account_serializer.rb" do |serializer|
+      assert_match(/^  attributes :id, :name, :description$/, serializer)
+      assert_match(/^  has_one :business$/, serializer)
+    end
+  end
+
+  def test_with_no_attributes_does_not_add_extra_space
+    run_generator ["account"]
+    assert_file "app/serializers/account_serializer.rb" do |content|
+      assert_no_match /\n\nend/, content
+    end
+  end
+end

test/test_helper.rb

@@ -5,3 +5,4 @@ require "active_support/json"
 
 require 'rails'
 
+require 'minitest/autorun'