Add a way to build new objects

Concept: allow formal_wearing objects to set up new objects as targets for saving data.

lib/formal_wear/class_methods.rb

@@ -1,9 +1,18 @@
 module FormalWear
   module ClassMethods
+    def build(name, block)
+      create_accessors([name])
+      define_build_method(name, block)
+    end
+
     def create_accessors(keys)
       keys.each { |k| self.send(:attr_accessor, k) unless method_defined?(k) }
     end
 
+    def define_build_method(name, block)
+      define_method(:"build_#{name}") { block.call }
+    end
+
     def validate_attrs!(attrs)
       attrs.each do |a, opts|
         opts.assert_valid_keys(*ALLOWED_KEYS)

lib/formal_wear/instance_methods.rb

@@ -6,6 +6,7 @@ module InstanceMethods
     def initialize(options = {})
       set_sources(options)
       update_sources
+      build_objects
     end
 
     def required_attributes
@@ -80,6 +81,10 @@ def saving(&block)
       after_save
     end
 
+    def build_objects
+      self.methods.select { |m| m.match(/build_/) }.each { |m| self.send(:"#{m.to_s.sub(/\Abuild_/, '')}=", self.send(m)) }
+    end
+
     def sanitize_and_fill_attributes(fields)
       fields.deep_dup.each do |field, options|
         fill_attributes!(field, options)
@@ -155,7 +160,7 @@ def set_source_reader(alt, obj)
     def update_sources
       required_fields.each do |field, options|
         send(:"#{field}=", options[:source].call(self)) if options[:source] rescue nil
-      end
+      end if required_fields
     end
   end
 end

spec/bare_object_spec.rb

@@ -1,12 +1,49 @@
 require 'spec_helper'
 require_relative './support/bare_object'
+require_relative './support/new_object'
+require 'pry'
 
 describe BareObject do
   let(:obj) { BareObject }
 
   context 'including FormalWear' do
     before { obj.send(:include, FormalWear) }
 
+    context 'when build is invoked' do
+      before do
+        obj.class_eval do
+          build :new_obj, -> { NewObject.new }
+        end
+      end
+
+      it 'creates a reader called new_obj' do
+        obj.method_defined?(:new_obj).should be_true
+      end
+
+      it 'creates a method called build_new_obj' do
+        obj.method_defined?(:build_new_obj).should be_true
+      end
+
+      context 'and BareObject is instantiated' do
+        let!(:new_object) { NewObject.new }
+        subject { BareObject.new(ExternalObjectOne.new('Formal', 'Wear')) }
+
+        it 'invokes build_new_obj' do
+          BareObject.any_instance.expects(:build_new_obj).returns(true)
+          subject
+        end
+
+        it 'creates a NewObj' do
+          NewObject.expects(:new).returns(new_object)
+          subject
+        end
+
+        it 'stores NewObj in @new_obj' do
+          subject.new_obj.should be_a(NewObject)
+        end
+      end
+    end
+
     context 'when required_attr is invoked' do
       before do
         obj.class_eval do

spec/support/new_object.rb

@@ -0,0 +1,2 @@
+class NewObject
+end