Adding info to the readme on how to specify the type, adding an additional

test to cover a computed property without a type

README.md

@@ -232,6 +232,20 @@ class PostSerializer < ActiveModel::Serializer
 end
 ```
 
+The type of a computed attribute (like :full_name above) is not easily
+calculated without some sophisticated static code analysis. To specify the
+type of a computed attribute:
+
+```ruby
+class PersonSerializer < ActiveModel::Serializer
+  attributes :first_name, :last_name, {:full_name => :string}
+
+  def full_name
+    "#{object.first_name} #{object.last_name}"
+  end
+end
+```
+
 If you would like the key in the outputted JSON to be different from its name
 in ActiveRecord, you can use the `:key` option to customize it:
 

test/serializer_test.rb

@@ -491,16 +491,17 @@ class SerializerTest < ActiveModel::TestCase
 
       # Computed attributes (not real columns or associations).
       def can_edit; end
+      def can_view; end
       def drafts; end
 
-      attributes :name, :age, :can_edit => :boolean
+      attributes :name, :age, {:can_edit => :boolean}, :can_view
       has_many :posts, :serializer => Class.new
       has_many :drafts, :serializer => Class.new
       has_one :parent, :serializer => Class.new
     end
 
     assert_equal serializer.schema, {
-      :attributes => { :name => :string, :age => :integer, :can_edit => :boolean },
+      :attributes => { :name => :string, :age => :integer, :can_edit => :boolean, :can_view => nil },
       :associations => {
         :posts => { :has_many => :posts },
         :drafts => nil,