Allow as_json(true) to be given.

lib/active_model/serializer.rb

@@ -201,6 +201,9 @@ module ActiveModel
       # methods, provided by default by ActiveRecord. You can implement these
       # methods on your custom models if you want the serializer's schema method
       # to work.
+      #
+      # TODO: This is currently coupled to Active Record. We need to
+      # figure out a way to decouple those two.
       def schema
         klass = model_class
         columns = klass.columns_hash
@@ -241,7 +244,6 @@ module ActiveModel
 
       def inherited(klass) #:nodoc:
         return if klass.anonymous?
-
         name = klass.name.demodulize.underscore.sub(/_serializer$/, '')
 
         klass.class_eval do
@@ -260,8 +262,9 @@ module ActiveModel
 
     # Returns a json representation of the serializable
     # object including the root.
-    def as_json(*)
-      if root = @options[:root] || _root
+    def as_json(options=nil)
+      options ||= {}
+      if root = options.fetch(:root, @options.fetch(:root, _root))
         @hash = hash = {}
         hash.merge!(root => serializable_hash)
         hash

test/serializer_test.rb

@@ -703,7 +703,19 @@ class SerializerTest < ActiveModel::TestCase
     author = author_class.new(:id => 5, :name => "Tom Dale")
     post.author = author
 
-    hash = serializer_class.new(post, nil, :root => :blog_post)
+    assert_equal({
+      :blog_post => {
+        :title => "New Post",
+        :body => "It's a new post!",
+        :author => { :id => 5, :name => "Tom Dale" }
+      }
+    }, serializer_class.new(post, nil, :root => :blog_post).as_json)
+
+    assert_equal({
+      :title => "New Post",
+      :body => "It's a new post!",
+      :author => { :id => 5, :name => "Tom Dale" }
+    }, serializer_class.new(post, nil, :root => false).as_json)
 
     assert_equal({
       :blog_post => {
@@ -711,7 +723,13 @@ class SerializerTest < ActiveModel::TestCase
         :body => "It's a new post!",
         :author => { :id => 5, :name => "Tom Dale" }
       }
-    }, hash.as_json)
+    }, serializer_class.new(post, nil).as_json(:root => :blog_post))
+
+    assert_equal({
+      :title => "New Post",
+      :body => "It's a new post!",
+      :author => { :id => 5, :name => "Tom Dale" }
+    }, serializer_class.new(post, nil).as_json(:root => false))
   end
 
   def test_serializer_has_access_to_root_object