Refactor Plugin Loader. Add plugin lib paths early, and add lots of tests. Closes #9795 [lazyatom]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8115 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

5 files changed, 409 insertions, 129 deletions

diff --git a/railties/test/initializer_test.rb b/railties/test/initializer_test.rb
index 5707a63258..156f670e87 100644
--- a/railties/test/initializer_test.rb
+++ b/railties/test/initializer_test.rb
@@ -135,3 +135,84 @@ uses_mocha 'framework paths' do
       end
   end
 end
+
+uses_mocha "Initializer plugin loading tests" do
+  require File.dirname(__FILE__) + '/plugin_test_helper'
+
+  class InitializerPluginLoadingTests < Test::Unit::TestCase
+    def setup
+      @configuration     = Rails::Configuration.new
+      @configuration.plugin_paths << plugin_fixture_root_path
+      @initializer       = Rails::Initializer.new(@configuration)
+      @valid_plugin_path = plugin_fixture_path('default/stubby')
+      @empty_plugin_path = plugin_fixture_path('default/empty')
+    end
+
+    def test_no_plugins_are_loaded_if_the_configuration_has_an_empty_plugin_list
+      only_load_the_following_plugins! []
+      @initializer.load_plugins
+      assert_equal [], @initializer.loaded_plugins
+    end
+
+    def test_only_the_specified_plugins_are_located_in_the_order_listed
+      plugin_names = [:plugin_with_no_lib_dir, :acts_as_chunky_bacon]
+      only_load_the_following_plugins! plugin_names
+      load_plugins!
+      assert_plugins plugin_names, @initializer.loaded_plugins
+    end
+
+    def test_all_plugins_are_loaded_when_registered_plugin_list_is_untouched
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      load_plugins!
+      assert_plugins [:a, :acts_as_chunky_bacon, :plugin_with_no_lib_dir, :stubby], @initializer.loaded_plugins, failure_tip
+    end
+
+    def test_all_plugins_loaded_when_all_is_used
+      plugin_names = [:stubby, :acts_as_chunky_bacon, :all]
+      only_load_the_following_plugins! plugin_names
+      load_plugins!
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins [:stubby, :acts_as_chunky_bacon, :a, :plugin_with_no_lib_dir], @initializer.loaded_plugins, failure_tip
+    end
+
+    def test_all_plugins_loaded_after_all
+      plugin_names = [:stubby, :all, :acts_as_chunky_bacon]
+      only_load_the_following_plugins! plugin_names
+      load_plugins!
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins [:stubby, :a, :plugin_with_no_lib_dir, :acts_as_chunky_bacon], @initializer.loaded_plugins, failure_tip
+    end
+
+    def test_plugin_names_may_be_strings
+      plugin_names = ['stubby', 'acts_as_chunky_bacon', :a, :plugin_with_no_lib_dir]
+      only_load_the_following_plugins! plugin_names
+      load_plugins!
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins plugin_names, @initializer.loaded_plugins, failure_tip
+    end
+
+    def test_registering_a_plugin_name_that_does_not_exist_raises_a_load_error
+      only_load_the_following_plugins! [:stubby, :acts_as_a_non_existant_plugin]
+      assert_raises(LoadError) do
+        load_plugins!
+      end
+    end
+    
+    def test_should_ensure_all_loaded_plugins_load_paths_are_added_to_the_load_path
+      only_load_the_following_plugins! [:stubby, :acts_as_chunky_bacon]
+
+      @initializer.add_plugin_load_paths
+      
+      assert $LOAD_PATH.include?(File.join(plugin_fixture_path('default/stubby'), 'lib'))
+      assert $LOAD_PATH.include?(File.join(plugin_fixture_path('default/acts/acts_as_chunky_bacon'), 'lib'))
+    end
+    
+    private
+    
+      def load_plugins!
+        @initializer.add_plugin_load_paths
+        @initializer.load_plugins
+      end
+  end
+  
+end  
diff --git a/railties/test/plugin_loader_test.rb b/railties/test/plugin_loader_test.rb
index 3c2c37e794..fe77de4474 100644
--- a/railties/test/plugin_loader_test.rb
+++ b/railties/test/plugin_loader_test.rb
@@ -1,90 +1,140 @@
 require File.dirname(__FILE__) + '/plugin_test_helper'
 
-class TestPluginLoader < Test::Unit::TestCase
-  def setup
-    @initializer       = Rails::Initializer.new(Rails::Configuration.new)
-    @valid_plugin_path = plugin_fixture_path('default/stubby')
-    @empty_plugin_path = plugin_fixture_path('default/empty')
-  end
-  
-  def test_determining_if_the_plugin_order_has_been_explicitly_set
-    loader = loader_for(@valid_plugin_path)
-    assert !loader.send(:explicit_plugin_loading_order?)
-    only_load_the_following_plugins! %w(stubby acts_as_chunky_bacon)
-    assert loader.send(:explicit_plugin_loading_order?)
-  end
-  
-  def test_enabled_if_not_named_explicitly
-    stubby_loader = loader_for(@valid_plugin_path)
-    acts_as_loader = loader_for('acts_as/acts_as_chunky_bacon')
+uses_mocha "Plugin Loader Tests" do
+
+  class TestPluginLoader < Test::Unit::TestCase
+    ORIGINAL_LOAD_PATH = $LOAD_PATH.dup
     
-    only_load_the_following_plugins! ['stubby', :all]
-    assert stubby_loader.send(:enabled?)
-    assert acts_as_loader.send(:enabled?)
+    def setup
+      reset_load_path!
+      
+      @configuration     = Rails::Configuration.new
+      @configuration.plugin_paths << plugin_fixture_root_path
+      @initializer       = Rails::Initializer.new(@configuration)
+      @valid_plugin_path = plugin_fixture_path('default/stubby')
+      @empty_plugin_path = plugin_fixture_path('default/empty')
+      
+      @loader = Rails::Plugin::Loader.new(@initializer)
+    end
+
+    def test_should_locate_plugins_by_asking_each_locator_specifed_in_configuration_for_its_plugins_result
+      locator_1 = stub(:plugins => [:a, :b, :c])
+      locator_2 = stub(:plugins => [:d, :e, :f])
+      locator_class_1 = stub(:new => locator_1)
+      locator_class_2 = stub(:new => locator_2)
+      @configuration.plugin_locators = [locator_class_1, locator_class_2]
+      assert_equal [:a, :b, :c, :d, :e, :f], @loader.send(:locate_plugins)
+    end
     
-    assert stubby_loader.send(:explicitly_enabled?)
-    assert !acts_as_loader.send(:explicitly_enabled?)
-  end
-  
-  def test_determining_whether_a_given_plugin_is_loaded
-    plugin_loader = loader_for(@valid_plugin_path)
-    assert !plugin_loader.loaded?
-    assert_nothing_raised do
-      plugin_loader.send(:register_plugin_as_loaded)
-    end
-    assert plugin_loader.loaded?
-  end
-  
-  def test_if_a_path_is_a_plugin_path
-    # This is a plugin path, with a lib dir
-    assert loader_for(@valid_plugin_path).plugin_path?
-    # This just has an init.rb and no lib dir
-    assert loader_for(plugin_fixture_path('default/plugin_with_no_lib_dir')).plugin_path?
-    # This would be a plugin path, but the directory is empty
-    assert !loader_for(plugin_fixture_path('default/empty')).plugin_path?
-    # This is a non sense path
-    assert !loader_for(plugin_fixture_path('default/this_directory_does_not_exist')).plugin_path?
-  end
-  
-  def test_if_you_try_to_load_a_non_plugin_path_you_get_a_load_error
-    # This path is fine so nothing is raised
-    assert_nothing_raised do
-      loader_for(@valid_plugin_path).send(:report_nonexistant_or_empty_plugin!)
+    def test_should_memoize_the_result_of_locate_plugins_as_all_plugins
+      plugin_list = [:a, :b, :c]
+      @loader.expects(:locate_plugins).once.returns(plugin_list)
+      assert_equal plugin_list, @loader.all_plugins
+      assert_equal plugin_list, @loader.all_plugins # ensuring that locate_plugins isn't called again
     end
     
-    # This is an empty path so it raises
-    assert_raises(LoadError) do
-      loader_for(@empty_plugin_path).send(:report_nonexistant_or_empty_plugin!)
+    def test_should_return_empty_array_if_configuration_plugins_is_empty
+      @configuration.plugins = []
+      assert_equal [], @loader.plugins
     end
     
-    assert_raises(LoadError) do
-      loader_for('this_is_not_a_plugin_directory').send(:report_nonexistant_or_empty_plugin!)
+    def test_should_find_all_availble_plugins_and_return_as_all_plugins
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins [:a, :acts_as_chunky_bacon, :plugin_with_no_lib_dir, :stubby], @loader.all_plugins, failure_tip      
     end
-  end
-  
-  def test_loading_a_plugin_gives_the_init_file_access_to_all_it_needs
-    failure_tip = "Perhaps someone has written another test that loads this same plugin and therefore makes the StubbyMixin constant defined already."
-    assert !defined?(StubbyMixin), failure_tip
-    assert !added_to_load_path?(@valid_plugin_path)
-    # The init.rb of this plugin raises if it doesn't have access to all the things it needs
-    assert_nothing_raised do
-      loader_for(@valid_plugin_path).load
-    end
-    assert added_to_load_path?(@valid_plugin_path)
-    assert defined?(StubbyMixin)
-  end
-  
-  private
-    def loader_for(path, initializer = @initializer)
-      Rails::Plugin::Loader.new(initializer, path)
+
+    def test_should_return_all_plugins_as_plugins_when_registered_plugin_list_is_untouched
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins [:a, :acts_as_chunky_bacon, :plugin_with_no_lib_dir, :stubby], @loader.plugins, failure_tip
+    end
+    
+    def test_should_return_all_plugins_as_plugins_when_registered_plugin_list_is_nil
+      @configuration.plugins = nil
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins [:a, :acts_as_chunky_bacon, :plugin_with_no_lib_dir, :stubby], @loader.plugins, failure_tip
+    end
+
+    def test_should_return_specific_plugins_named_in_config_plugins_array_if_set
+      plugin_names = [:acts_as_chunky_bacon, :stubby]
+      only_load_the_following_plugins! plugin_names
+      assert_plugins plugin_names, @loader.plugins
+    end
+    
+    def test_should_respect_the_order_of_plugins_given_in_configuration
+      plugin_names = [:stubby, :acts_as_chunky_bacon]
+      only_load_the_following_plugins! plugin_names
+      assert_plugins plugin_names, @loader.plugins      
+    end
+    
+    def test_should_load_all_plugins_in_natural_order_when_all_is_used
+      only_load_the_following_plugins! [:all]
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins [:a, :acts_as_chunky_bacon, :plugin_with_no_lib_dir, :stubby], @loader.plugins, failure_tip
     end
     
-    def plugin_fixture_path(path)
-      File.join(plugin_fixture_root_path, path)
+    def test_should_load_specified_plugins_in_order_and_then_all_remaining_plugins_when_all_is_used
+      only_load_the_following_plugins! [:stubby, :acts_as_chunky_bacon, :all]
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins [:stubby, :acts_as_chunky_bacon, :a, :plugin_with_no_lib_dir], @loader.plugins, failure_tip
     end
     
-    def added_to_load_path?(path)
-      $LOAD_PATH.grep(/#{path}/).size == 1
+    def test_should_be_able_to_specify_loading_of_plugins_loaded_after_all
+      only_load_the_following_plugins!  [:stubby, :all, :acts_as_chunky_bacon]
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins [:stubby, :a, :plugin_with_no_lib_dir, :acts_as_chunky_bacon], @loader.plugins, failure_tip
+    end
+
+    def test_should_accept_plugin_names_given_as_strings
+      only_load_the_following_plugins! ['stubby', 'acts_as_chunky_bacon', :a, :plugin_with_no_lib_dir]
+      failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
+      assert_plugins [:stubby, :acts_as_chunky_bacon, :a, :plugin_with_no_lib_dir], @loader.plugins, failure_tip
+    end
+    
+    def test_should_add_plugin_load_paths_to_global_LOAD_PATH_array
+      only_load_the_following_plugins! [:stubby, :acts_as_chunky_bacon]
+      stubbed_application_lib_index_in_LOAD_PATHS = 5
+      @loader.stubs(:application_lib_index).returns(stubbed_application_lib_index_in_LOAD_PATHS)
+      
+      @loader.add_plugin_load_paths
+      
+      assert $LOAD_PATH.index(File.join(plugin_fixture_path('default/stubby'), 'lib')) >= stubbed_application_lib_index_in_LOAD_PATHS
+      assert $LOAD_PATH.index(File.join(plugin_fixture_path('default/acts/acts_as_chunky_bacon'), 'lib')) >= stubbed_application_lib_index_in_LOAD_PATHS    
+    end   
+    
+    def test_should_add_plugin_load_paths_to_Dependencies_load_paths
+      only_load_the_following_plugins! [:stubby, :acts_as_chunky_bacon]
+
+      @loader.add_plugin_load_paths
+      
+      assert Dependencies.load_paths.include?(File.join(plugin_fixture_path('default/stubby'), 'lib'))
+      assert Dependencies.load_paths.include?(File.join(plugin_fixture_path('default/acts/acts_as_chunky_bacon'), 'lib'))    
     end
     
+    def test_should_add_plugin_load_paths_to_Dependencies_load_once_paths
+      only_load_the_following_plugins! [:stubby, :acts_as_chunky_bacon]
+
+      @loader.add_plugin_load_paths
+      
+      assert Dependencies.load_once_paths.include?(File.join(plugin_fixture_path('default/stubby'), 'lib'))
+      assert Dependencies.load_once_paths.include?(File.join(plugin_fixture_path('default/acts/acts_as_chunky_bacon'), 'lib'))    
+    end
+    
+    def test_should_add_all_load_paths_from_a_plugin_to_LOAD_PATH_array
+      plugin_load_paths = ["a", "b"]
+      plugin = stub(:load_paths => plugin_load_paths)
+      @loader.stubs(:plugins).returns([plugin])
+      
+      @loader.add_plugin_load_paths
+      
+      plugin_load_paths.each { |path| assert $LOAD_PATH.include?(path) }
+    end
+    
+    private
+    
+      def reset_load_path!
+        $LOAD_PATH.clear
+        ORIGINAL_LOAD_PATH.each { |path| $LOAD_PATH << path }        
+      end
+  end
+    
 end
\ No newline at end of file
diff --git a/railties/test/plugin_locator_test.rb b/railties/test/plugin_locator_test.rb
index 3ac4493d47..ccd270dd10 100644
--- a/railties/test/plugin_locator_test.rb
+++ b/railties/test/plugin_locator_test.rb
@@ -1,61 +1,69 @@
 require File.dirname(__FILE__) + '/plugin_test_helper'
 
-class TestPluginFileSystemLocator < Test::Unit::TestCase
-  def setup
-    configuration = Rails::Configuration.new
-    # We need to add our testing plugin directory to the plugin paths so
-    # the locator knows where to look for our plugins
-    configuration.plugin_paths << plugin_fixture_root_path
-    @initializer = Rails::Initializer.new(configuration)
-    @locator     = new_locator
-  end
+uses_mocha "Plugin Locator Tests" do
+
+  class PluginLocatorTest < Test::Unit::TestCase
   
-  def test_no_plugins_are_loaded_if_the_configuration_has_an_empty_plugin_list
-    only_load_the_following_plugins! []
-    assert_equal [], @locator.plugins
-  end
+    def test_should_require_subclasses_to_implement_the_plugins_method
+      assert_raises(RuntimeError) do
+        Rails::Plugin::Locator.new(nil).plugins
+      end
+    end
   
-  def test_only_the_specified_plugins_are_located_in_the_order_listed
-    plugin_names = [:stubby, :acts_as_chunky_bacon]
-    only_load_the_following_plugins! plugin_names
-    assert_equal plugin_names, @locator.plugin_names
-  end
+    def test_should_iterator_over_plugins_returned_by_plugins_when_calling_each
+      locator = Rails::Plugin::Locator.new(nil)
+      locator.stubs(:plugins).returns([:a, :b, :c])
+      plugin_consumer = mock
+      plugin_consumer.expects(:consume).with(:a)
+      plugin_consumer.expects(:consume).with(:b)
+      plugin_consumer.expects(:consume).with(:c)
+    
+      locator.each do |plugin|
+        plugin_consumer.consume(plugin)
+      end
+    end
   
-  def test_all_plugins_are_loaded_when_registered_plugin_list_is_untouched
-    failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
-    assert_equal [:a, :acts_as_chunky_bacon, :plugin_with_no_lib_dir, :stubby], @locator.plugin_names, failure_tip
   end
+
+
+  class PluginFileSystemLocatorTest < Test::Unit::TestCase
+    def setup
+      @configuration = Rails::Configuration.new
+      # We need to add our testing plugin directory to the plugin paths so
+      # the locator knows where to look for our plugins
+      @configuration.plugin_paths << plugin_fixture_root_path
+      @initializer       = Rails::Initializer.new(@configuration)
+      @locator           = Rails::Plugin::FileSystemLocator.new(@initializer)
+      @valid_plugin_path = plugin_fixture_path('default/stubby')
+      @empty_plugin_path = plugin_fixture_path('default/empty')
+    end
+
+    def test_should_return_rails_plugin_instances_when_calling_create_plugin_with_a_valid_plugin_directory
+      assert_kind_of Rails::Plugin, @locator.send(:create_plugin, @valid_plugin_path)  
+    end
   
-  def test_all_plugins_loaded_when_all_is_used
-    plugin_names = [:stubby, :acts_as_chunky_bacon, :all]
-    only_load_the_following_plugins! plugin_names
-    failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
-    assert_equal [:stubby, :acts_as_chunky_bacon, :a, :plugin_with_no_lib_dir], @locator.plugin_names, failure_tip
-  end
+    def test_should_return_nil_when_calling_create_plugin_with_an_invalid_plugin_directory
+      assert_nil @locator.send(:create_plugin, @empty_plugin_path)  
+    end
   
-  def test_all_plugins_loaded_after_all
-    plugin_names = [:stubby, :all, :acts_as_chunky_bacon]
-    only_load_the_following_plugins! plugin_names
-    failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
-    assert_equal [:stubby, :a, :plugin_with_no_lib_dir, :acts_as_chunky_bacon], @locator.plugin_names, failure_tip
-  end
+    def test_should_return_all_plugins_found_under_the_set_plugin_paths
+      assert_equal ["a", "acts_as_chunky_bacon", "plugin_with_no_lib_dir", "stubby"], @locator.plugins.map(&:name)
+    end
   
-  def test_plugin_names_may_be_strings
-    plugin_names = ['stubby', 'acts_as_chunky_bacon', :a, :plugin_with_no_lib_dir]
-    only_load_the_following_plugins! plugin_names
-    failure_tip = "It's likely someone has added a new plugin fixture without updating this list"
-    assert_equal [:stubby, :acts_as_chunky_bacon, :a, :plugin_with_no_lib_dir], @locator.plugin_names, failure_tip
-  end
+    def test_should_find_plugins_only_under_the_plugin_paths_set_in_configuration
+      @configuration.plugin_paths = [File.join(plugin_fixture_root_path, "default")]
+      assert_equal ["acts_as_chunky_bacon", "plugin_with_no_lib_dir", "stubby"], @locator.plugins.map(&:name)
+    
+      @configuration.plugin_paths = [File.join(plugin_fixture_root_path, "alternate")]
+      assert_equal ["a"], @locator.plugins.map(&:name)
+    end
   
-  def test_registering_a_plugin_name_that_does_not_exist_raises_a_load_error
-    only_load_the_following_plugins! [:stubby, :acts_as_a_non_existant_plugin]
-    assert_raises(LoadError) do
-      @initializer.load_plugins
+    def test_should_not_raise_any_error_and_return_no_plugins_if_the_plugin_path_value_does_not_exist
+      @configuration.plugin_paths = ["some_missing_directory"]
+      assert_nothing_raised do
+        assert @locator.plugins.empty?
+      end
     end
   end
-  
-  private
-    def new_locator(initializer = @initializer)
-      Rails::Plugin::FileSystemLocator.new(initializer)
-    end   
-end
\ No newline at end of file
+
+end # uses_mocha
\ No newline at end of file
diff --git a/railties/test/plugin_test.rb b/railties/test/plugin_test.rb
new file mode 100644
index 0000000000..a791e42ae8
--- /dev/null
+++ b/railties/test/plugin_test.rb
@@ -0,0 +1,130 @@
+require File.dirname(__FILE__) + '/plugin_test_helper'
+
+uses_mocha "Plugin Tests" do
+
+  class PluginTest < Test::Unit::TestCase
+
+    def setup
+      @initializer       = Rails::Initializer.new(Rails::Configuration.new)
+      @valid_plugin_path = plugin_fixture_path('default/stubby')
+      @empty_plugin_path = plugin_fixture_path('default/empty')    
+    end
+
+    def test_should_determine_plugin_name_from_the_directory_of_the_plugin
+      assert_equal 'stubby', plugin_for(@valid_plugin_path).name
+      assert_equal 'empty', plugin_for(@empty_plugin_path).name
+    end
+
+    def test_should_not_be_loaded_when_created
+      assert !plugin_for(@valid_plugin_path).loaded?
+    end
+
+    def test_should_be_marked_as_loaded_when_load_is_called
+      plugin = plugin_for(@valid_plugin_path)
+      assert !plugin.loaded?
+      plugin.stubs(:evaluate_init_rb)
+      assert_nothing_raised do
+        plugin.send(:load, anything)
+      end
+      assert plugin.loaded?
+    end
+  
+    def test_should_determine_validity_of_given_path
+      # This is a plugin path, with a lib dir
+      assert plugin_for(@valid_plugin_path).valid?
+      # This just has an init.rb and no lib dir
+      assert plugin_for(plugin_fixture_path('default/plugin_with_no_lib_dir')).valid?
+      # This would be a plugin path, but the directory is empty
+      assert !plugin_for(plugin_fixture_path('default/empty')).valid?
+      # This is a non sense path
+      assert !plugin_for(plugin_fixture_path('default/this_directory_does_not_exist')).valid?
+    end
+  
+    def test_should_return_empty_array_for_load_paths_when_plugin_has_no_lib_directory
+      assert_equal [], plugin_for(plugin_fixture_path('default/plugin_with_no_lib_dir')).load_paths
+    end
+  
+    def test_should_return_array_with_lib_path_for_load_paths_when_plugin_has_a_lib_directory
+      expected_lib_dir = File.join(plugin_fixture_path('default/stubby'), 'lib')
+      assert_equal [expected_lib_dir], plugin_for(plugin_fixture_path('default/stubby')).load_paths
+    end
+  
+    def test_should_raise_a_load_error_when_trying_to_determine_the_load_paths_from_an_invalid_plugin
+      assert_nothing_raised do
+        plugin_for(@valid_plugin_path).load_paths
+      end
+    
+      assert_raises(LoadError) do
+        plugin_for(@empty_plugin_path).load_paths
+      end
+    
+      assert_raises(LoadError) do
+        plugin_for('this_is_not_a_plugin_directory').load_paths
+      end
+    end
+  
+    def test_should_raise_a_load_error_when_trying_to_load_an_invalid_plugin
+      # This path is fine so nothing is raised
+      assert_nothing_raised do
+        plugin = plugin_for(@valid_plugin_path)
+        plugin.stubs(:evaluate_init_rb)
+        plugin.send(:load, @initializer)
+      end
+    
+      # This is an empty path so it raises
+      assert_raises(LoadError) do
+        plugin = plugin_for(@empty_plugin_path)
+        plugin.stubs(:evaluate_init_rb)      
+        plugin.send(:load, @initializer)
+      end
+    
+      assert_raises(LoadError) do
+        plugin = plugin_for('this_is_not_a_plugin_directory')
+        plugin.stubs(:evaluate_init_rb)
+        plugin.send(:load, @initializer)
+      end
+    end
+    
+    def test_should_raise_a_load_error_when_trying_to_access_load_paths_of_an_invalid_plugin
+      # This path is fine so nothing is raised
+      assert_nothing_raised do
+        plugin_for(@valid_plugin_path).load_paths
+      end
+    
+      # This is an empty path so it raises
+      assert_raises(LoadError) do
+        plugin_for(@empty_plugin_path).load_paths
+      end
+    
+      assert_raises(LoadError) do
+        plugin_for('this_is_not_a_plugin_directory').load_paths
+      end
+    end    
+  
+    def test_loading_a_plugin_gives_the_init_file_access_to_all_it_needs
+      failure_tip = "Perhaps someone has written another test that loads this same plugin and therefore makes the StubbyMixin constant defined already."
+      assert !defined?(StubbyMixin), failure_tip
+      plugin = plugin_for(@valid_plugin_path)
+      plugin.load_paths.each { |path| $LOAD_PATH.unshift(path) }
+      # The init.rb of this plugin raises if it doesn't have access to all the things it needs
+      assert_nothing_raised do
+        plugin.load(@initializer)
+      end
+      assert defined?(StubbyMixin)
+    end
+    
+    def test_should_sort_naturally_by_name
+      a = plugin_for("path/a")
+      b = plugin_for("path/b")
+      z = plugin_for("path/z")
+      assert_equal [a, b, z], [b, z, a].sort
+    end
+  
+    private
+  
+      def plugin_for(path)
+        Rails::Plugin.new(path)
+      end
+  end
+
+end # uses_mocha
\ No newline at end of file
diff --git a/railties/test/plugin_test_helper.rb b/railties/test/plugin_test_helper.rb
index 0b065a5444..f8c094d19f 100644
--- a/railties/test/plugin_test_helper.rb
+++ b/railties/test/plugin_test_helper.rb
@@ -4,15 +4,26 @@ $:.unshift File.dirname(__FILE__) + "/../../activesupport/lib"
 require 'test/unit'
 require 'active_support'
 require 'initializer'
+require File.join(File.dirname(__FILE__), 'abstract_unit')
 
 # We need to set RAILS_ROOT if it isn't already set
 RAILS_ROOT = '.' unless defined?(RAILS_ROOT)
+
 class Test::Unit::TestCase
-  def plugin_fixture_root_path
-    File.join(File.dirname(__FILE__), 'fixtures', 'plugins')
-  end
+  private  
+    def plugin_fixture_root_path
+      File.join(File.dirname(__FILE__), 'fixtures', 'plugins')
+    end
+  
+    def only_load_the_following_plugins!(plugins)
+      @initializer.configuration.plugins = plugins
+    end
   
-  def only_load_the_following_plugins!(plugins)
-    @initializer.configuration.plugins = plugins
-  end
+    def plugin_fixture_path(path)
+      File.join(plugin_fixture_root_path, path)
+    end
+    
+    def assert_plugins(list_of_names, array_of_plugins, message=nil)
+      assert_equal list_of_names.map(&:to_s), array_of_plugins.map(&:name), message
+    end    
 end
\ No newline at end of file