tweak activemodel load order a bit

activemodel/Rakefile

@@ -1,11 +1,19 @@
 #!/usr/bin/env ruby
-$LOAD_PATH << File.join(File.dirname(__FILE__), 'vendor', 'rspec', 'lib')
 require 'rake'
-require 'spec/rake/spectask'
+require 'rake/testtask'
 require 'rake/rdoctask'
 
+task :default => :test
+
+Rake::TestTask.new do |t| 
+  t.libs << "test"
+  t.pattern = 'test/**/*_test.rb'
+  t.verbose = true
+  t.warning = true
+end
+
 # Generate the RDoc documentation
-Rake::RDocTask.new { |rdoc|
+Rake::RDocTask.new do |rdoc|
   rdoc.rdoc_dir = 'doc'
   rdoc.title    = "Active Model"
   rdoc.options << '--line-numbers' << '--inline-source' << '-A cattr_accessor=object'
@@ -13,4 +21,4 @@ Rake::RDocTask.new { |rdoc|
   rdoc.template = "#{ENV['template']}.rb" if ENV['template']
   rdoc.rdoc_files.include('README', 'CHANGES')
   rdoc.rdoc_files.include('lib/**/*.rb')
-}
+end

activemodel/lib/active_model.rb

@@ -1,17 +1,5 @@
-$LOAD_PATH << File.join(File.dirname(__FILE__), '..', '..', 'activesupport', 'lib')
-
-# premature optimization?
-require 'active_support/inflector'
-require 'active_support/core_ext/string/inflections'
-String.send :include, ActiveSupport::CoreExtensions::String::Inflections
-
-require 'active_model/base'
 require 'active_model/observing'
-require 'active_model/callbacks'
-require 'active_model/validations'
-
-ActiveModel::Base.class_eval do
-  include ActiveModel::Observing
-  include ActiveModel::Callbacks
-  include ActiveModel::Validations
-end
+# disabled until they're tested
+# require 'active_model/callbacks'
+# require 'active_model/validations'
+require 'active_model/base'

activemodel/lib/active_model/base.rb

@@ -1,4 +1,8 @@
 module ActiveModel
   class Base
+    include Observing
+    # disabled, until they're tested
+    # include Callbacks
+    # include Validations
   end
 end

activemodel/lib/active_model/callbacks.rb

@@ -1,3 +1,5 @@
+require 'active_model/observing'
+
 module ActiveModel
   module Callbacks
     

activemodel/lib/active_model/core.rb

@@ -0,0 +1,7 @@
+# This file is required by each major ActiveModel component for the core requirements.  This allows you to
+# load individual pieces of ActiveModel as needed.
+$LOAD_PATH << File.join(File.dirname(__FILE__), '..', '..', '..', 'activesupport', 'lib')
+
+# premature optimization?
+# So far, we only need the string inflections and not the rest of ActiveSupport.
+require 'active_support/inflector'

activemodel/lib/active_model/observing.rb

@@ -1,4 +1,6 @@
 require 'observer'
+require 'singleton'
+require 'active_model/core'
 
 module ActiveModel
   module Observing
@@ -73,7 +75,7 @@ module ActiveModel
     # Start observing the declared classes and their subclasses.
     def initialize
       self.observed_classes = self.class.models if self.class.models
-      observed_classes.each { |klass| add_observer! klass }
+      observed_classes.each { |klass| klass.add_observer(self) }
     end
 
     # Send observed_method(object) if the method exists.
@@ -85,16 +87,12 @@ module ActiveModel
     # Passes the new subclass.
     def observed_class_inherited(subclass) #:nodoc:
       self.class.observe(observed_classes + [subclass])
-      add_observer!(subclass)
+      subclass.add_observer(self)
     end
 
-    protected
-      def observed_classes
-        @observed_classes ||= [self.class.observed_class]
-      end
-
-      def add_observer!(klass)
-        klass.add_observer(self)
-      end
+  protected
+    def observed_classes
+      @observed_classes ||= [self.class.observed_class]
+    end
   end
 end

activemodel/lib/active_model/validations.rb

@@ -1,3 +1,5 @@
+require 'active_model/observing'
+
 module ActiveModel
   module Validations
     def self.included(base) # :nodoc: