Allow child factories to be defined by nesting

GETTING_STARTED.md

@@ -133,7 +133,21 @@ The behavior of the association method varies depending on the build strategy us
 Inheritance
 -----------
 
-You can easily create multiple factories for the same class without repeating common attributes by using inheritance:
+You can easily create multiple factories for the same class without repeating common attributes by nesting factories:
+
+    factory :post do
+      title 'A title'
+
+      factory :approved_post do
+        approved true
+      end
+    end
+
+    approved_post = FactoryGirl.create(:approved_post)
+    approved_post.title # => 'A title'
+    approved_post.approved # => true
+
+You can also assign the parent explicitly:
 
     factory :post do
       title 'A title'
@@ -143,9 +157,11 @@ You can easily create multiple factories for the same class without repeating co
       approved true
     end
 
-    FactoryGirl.create(:approved_post).title     # => 'A title'
+    approved_post = FactoryGirl.create(:approved_post)
+    approved_post.title # => 'A title'
+    approved_post.approved # => true
 
-As mentioned above, it's good practice to define a basic factory for each class with only the attributes required to create it. Then, create more-specific factories that inherit from this basic parent. Factory definitions are still code, so keep them DRY.
+As mentioned above, it's good practice to define a basic factory for each class with only the attributes required to create it. Then, create more specific factories that inherit from this basic parent. Factory definitions are still code, so keep them DRY.
 
 Sequences
 ---------

lib/factory_girl/definition_proxy.rb

@@ -4,8 +4,11 @@ module FactoryGirl
       undef_method(method) unless method =~ /(^__|^nil\?$|^send$|^object_id$|^extend$|^instance_eval$)/
     end
 
+    attr_reader :child_factories
+
     def initialize(factory)
       @factory = factory
+      @child_factories = []
     end
 
     # Adds an attribute that should be assigned on generated instances for this
@@ -143,5 +146,9 @@ module FactoryGirl
     def to_create(&block)
       @factory.to_create(&block)
     end
+
+    def factory(name, options = {}, &block)
+      @child_factories << [name, options, block]
+    end
   end
 end

lib/factory_girl/syntax/default.rb

@@ -20,6 +20,10 @@ module FactoryGirl
             factory.inherit_from(FactoryGirl.factory_by_name(parent))
           end
           FactoryGirl.register_factory(factory)
+
+          proxy.child_factories.each do |(child_name, child_options, child_block)|
+            factory(child_name, child_options.merge(:parent => name), &child_block)
+          end
         end
 
         def sequence(name, start_value = 1, &block)

spec/acceptance/parent_spec.rb

@@ -7,33 +7,29 @@ describe "an instance generated by a factory that inherits from another factory"
 
     FactoryGirl.define do
       factory :user do
-        name { "John" }
-        email { "john@example.com" }
-      end
+        name  "John"
+        email "john@example.com"
 
-      factory :admin, :parent => :user do
-        admin { true }
-        email { "admin@example.com" }
+        factory :admin do
+          admin true
+          email "admin@example.com"
+        end
       end
     end
   end
 
-  subject { FactoryGirl.create(:admin) }
-
-  it "uses the parent build class" do
-    subject.should be_kind_of(User)
+  describe "the parent class" do
+    subject     { FactoryGirl.create(:user) }
+    it          { should_not be_admin }
+    its(:email) { should == "john@example.com" }
   end
 
-  it "inherits attributes" do
-    subject.name.should == 'John'
-  end
-
-  it "has its own attributes" do
-    subject.should be_admin
-  end
-
-  it "overrides attributes" do
-    subject.email.should == 'admin@example.com'
+  describe "the child class" do
+    subject     { FactoryGirl.create(:admin) }
+    it          { should be_kind_of(User) }
+    it          { should be_admin }
+    its(:name)  { should == "John" }
+    its(:email) { should == "admin@example.com" }
   end
 end
 

spec/factory_girl/definition_proxy_spec.rb

@@ -37,6 +37,16 @@ describe FactoryGirl::DefinitionProxy do
     }.should raise_error(FactoryGirl::AttributeDefinitionError)
   end
 
+  describe "child factories" do
+    its(:child_factories) { should == [] }
+
+    it "should be able to add child factories" do
+      block = lambda {}
+      subject.factory(:admin, { :aliases => [:great] }, &block)
+      subject.child_factories.should == [[:admin, { :aliases => [:great] }, block]]
+    end
+  end
+
   describe "adding an attribute using a in-line sequence" do
     it "should create the sequence" do
       mock(FactoryGirl::Sequence).new(:name, 1)