From f5d4db10855978ee054687ba2e04882f65e76630 Mon Sep 17 00:00:00 2001
From: Joshua Clayton <jclayton@thoughtbot.com>
Date: Fri, 16 Mar 2012 13:04:31 -0400
Subject: [PATCH] Ensure attributes set on instance are calculated uniquely

This fixes a bug where assignment occurs multiple times; in the case of
nested attributes, assignment mutates the instance, meaning that it
occurring multiple times will cause issues.

Closes #314
---
 lib/factory_girl/attribute_assigner.rb    |  2 +-
 spec/acceptance/nested_attributes_spec.rb | 32 +++++++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 spec/acceptance/nested_attributes_spec.rb

diff --git a/lib/factory_girl/attribute_assigner.rb b/lib/factory_girl/attribute_assigner.rb
index 5bdf873..4eae168 100644
--- a/lib/factory_girl/attribute_assigner.rb
+++ b/lib/factory_girl/attribute_assigner.rb
@@ -37,7 +37,7 @@ module FactoryGirl
     end
 
     def attributes_to_set_on_instance
-      attribute_names_to_assign - @attribute_names_assigned
+      (attribute_names_to_assign - @attribute_names_assigned).uniq
     end
 
     def attributes_to_set_on_hash
diff --git a/spec/acceptance/nested_attributes_spec.rb b/spec/acceptance/nested_attributes_spec.rb
new file mode 100644
index 0000000..f1cd350
--- /dev/null
+++ b/spec/acceptance/nested_attributes_spec.rb
@@ -0,0 +1,32 @@
+require "spec_helper"
+
+describe "association assignment from nested attributes" do
+  before do
+    define_model("Post", :title => :string) do
+      has_many :comments
+      accepts_nested_attributes_for :comments
+    end
+
+    define_model("Comment", :post_id => :integer, :body => :text) do
+      belongs_to :post
+    end
+
+    FactoryGirl.define do
+      factory :post do
+        comments_attributes { [FactoryGirl.attributes_for(:comment), FactoryGirl.attributes_for(:comment)] }
+      end
+
+      factory :comment do
+        sequence(:body) {|n| "Body #{n}" }
+      end
+    end
+  end
+
+  it "assigns the correct amount of comments" do
+    FactoryGirl.create(:post).comments.count.should == 2
+  end
+
+  it "assigns the correct amount of comments when overridden" do
+    FactoryGirl.create(:post, :comments_attributes => [FactoryGirl.attributes_for(:comment)]).comments.count.should == 1
+  end
+end