Support refering to factory based on class name

Allows for build/creating based on RSpec's described_class, useful since
we've deprecated other syntaxes from FG.

Closes thoughtbot#386

lib/factory_girl.rb

@@ -38,6 +38,7 @@
 require 'factory_girl/reload'
 require 'factory_girl/decorator'
 require 'factory_girl/decorator/attribute_hash'
+require 'factory_girl/decorator/class_key_hash'
 require 'factory_girl/decorator/disallows_duplicates_registry'
 require 'factory_girl/decorator/invocation_tracker'
 require 'factory_girl/decorator/invocation_ignorer'

lib/factory_girl/decorator/class_key_hash.rb

@@ -0,0 +1,27 @@
+module FactoryGirl
+  class Decorator
+    class ClassKeyHash < Decorator
+      def [](key)
+        @component[symbolized_key key]
+      end
+
+      def []=(key, value)
+        @component[symbolized_key key] = value
+      end
+
+      def key?(key)
+        @component.key? symbolized_key(key)
+      end
+
+      private
+
+      def symbolized_key(key)
+        if key.respond_to?(:to_sym)
+          key.to_sym
+        else
+          key.to_s.underscore.to_sym
+        end
+      end
+    end
+  end
+end

lib/factory_girl/registry.rb

@@ -6,7 +6,7 @@ class Registry
 
     def initialize(name)
       @name  = name
-      @items = {}
+      @items = Decorator::ClassKeyHash.new({})
     end
 
     def clear
@@ -19,7 +19,7 @@ def each(&block)
 
     def find(name)
       if registered?(name)
-        @items[name.to_sym]
+        @items[name]
       else
         raise ArgumentError, "#{@name} not registered: #{name}"
       end
@@ -28,11 +28,11 @@ def find(name)
     alias :[] :find
 
     def register(name, item)
-      @items[name.to_sym] = item
+      @items[name] = item
     end
 
     def registered?(name)
-      @items.key?(name.to_sym)
+      @items.key?(name)
     end
   end
 end

spec/acceptance/keyed_by_class_spec.rb

@@ -0,0 +1,22 @@
+require 'spec_helper'
+
+describe 'finding factories keyed by class instead of symbol' do
+  before do
+    define_model("User") do
+      attr_accessor :name, :email
+    end
+
+    FactoryGirl.define do
+      factory :user do
+        name 'John Doe'
+        sequence(:email) {|n| "person#{n}@example.com" }
+      end
+    end
+  end
+
+  it 'allows interaction based on class name' do
+    user = FactoryGirl.create User, email: 'person@example.com'
+    user.email.should == 'person@example.com'
+    user.name.should == 'John Doe'
+  end
+end

spec/factory_girl/registry_spec.rb

@@ -57,4 +57,12 @@
     subject.clear
     subject.count.should be_zero
   end
+
+  it "registers classes" do
+    define_class("User")
+    subject.register(User, registered_object)
+    subject.to_a.should == [registered_object]
+    subject.find(:user).should == registered_object
+    subject.find(User).should == registered_object
+  end
 end