Reapply plugin load path changes from [5720]

Closes #6842
Closes #6851


git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5738 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

3 files changed, 58 insertions, 10 deletions

diff --git a/railties/CHANGELOG b/railties/CHANGELOG
index 0b34532801..ce2f2b0611 100644
--- a/railties/CHANGELOG
+++ b/railties/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Make config.plugins affect the load path and the dependencies system.  Allows you to control plugin loading order, and keep disabled plugins off the load path. [James Adam]
+
 * Don't generate a components directory in new Rails apps.  [Jeremy Kemper]
 
 * Fixed script/process/spawner to work properly with Mongrel including in -r (daemonize mode) [DHH]
diff --git a/railties/lib/initializer.rb b/railties/lib/initializer.rb
index 908dde71c2..5b529ffc3d 100644
--- a/railties/lib/initializer.rb
+++ b/railties/lib/initializer.rb
@@ -48,7 +48,7 @@ module Rails
     # instance.
     def initialize(configuration)
       @configuration = configuration
-      @loaded_plugins = Set.new
+      @loaded_plugins = []
     end
 
     # Sequentially step through all of the available initialization routines,
@@ -176,9 +176,22 @@ module Rails
     # * evaluate <tt>init.rb</tt> if present
     #
     # After all plugins are loaded, duplicates are removed from the load path.
-    # Plugins are loaded in alphabetical order.
+    # If an array of plugin names is specified in config.plugins, the plugins
+    # will be loaded in that order. Otherwise, plugins are loaded in alphabetical
+    # order.
     def load_plugins
-      find_plugins(configuration.plugin_paths).sort.each { |path| load_plugin path }
+      if configuration.plugins.nil?
+        # a nil value implies we don't care about plugins; load 'em all in a reliable order
+        find_plugins(configuration.plugin_paths).sort.each { |path| load_plugin path }
+      elsif !configuration.plugins.empty?
+        # we've specified a config.plugins array, so respect that order
+        plugin_paths = find_plugins(configuration.plugin_paths)
+        configuration.plugins.each do |name|
+          path = plugin_paths.find { |p| File.basename(p) == name }
+          raise(LoadError, "Cannot find the plugin '#{name}'!") if path.nil?
+          load_plugin path
+        end
+      end 
       $LOAD_PATH.uniq!
     end
 
@@ -345,7 +358,7 @@ module Rails
       end
 
       def plugin_enabled?(path)
-        configuration.plugins.empty? || configuration.plugins.include?(File.basename(path))
+        configuration.plugins.nil? || configuration.plugins.include?(File.basename(path))
       end
 
       # Load the plugin at <tt>path</tt> unless already loaded.
@@ -374,6 +387,7 @@ module Rails
         if has_lib
           application_lib_index = $LOAD_PATH.index(File.join(RAILS_ROOT, "lib")) || 0
           $LOAD_PATH.insert(application_lib_index + 1, lib_path)
+          Dependencies.load_paths << lib_path
         end
 
         # Allow plugins to reference the current configuration object
@@ -470,7 +484,9 @@ module Rails
     # any method of +nil+. Set to +false+ for the standard Ruby behavior.
     attr_accessor :whiny_nils
 
-    # The list of plugins to load. If this is set to <tt>[]</tt>, all plugins will be loaded.
+    # The list of plugins to load. If this is set to <tt>nil</tt>, all plugins will
+    # be loaded. If this is set to <tt>[]</tt>, no plugins will be loaded. Otherwise,
+    # plugins will be loaded in the order specified.
     attr_accessor :plugins
 
     # The path to the root of the plugins directory. By default, it is in
@@ -592,7 +608,6 @@ module Rails
           vendor
         ).map { |dir| "#{root_path}/#{dir}" }.select { |dir| File.directory?(dir) }
 
-        paths.concat Dir["#{root_path}/vendor/plugins/*/lib/"]
         paths.concat builtin_directories
       end
 
@@ -642,7 +657,7 @@ module Rails
       end
 
       def default_plugins
-        []
+        nil
       end
 
       def default_plugin_paths
diff --git a/railties/test/plugin_test.rb b/railties/test/plugin_test.rb
index 5ab1e15414..f46f1db615 100644
--- a/railties/test/plugin_test.rb
+++ b/railties/test/plugin_test.rb
@@ -43,7 +43,7 @@ class PluginTest < Test::Unit::TestCase
 
   def test_load_plugin
     stubby = "#{File.dirname(__FILE__)}/fixtures/plugins/default/stubby"
-    expected = Set.new(['stubby'])
+    expected = ['stubby']
 
     assert @init.send(:load_plugin, stubby)
     assert_equal expected, @init.loaded_plugins
@@ -66,10 +66,41 @@ class PluginTest < Test::Unit::TestCase
   def test_load_plugins_from_two_sources
     assert_loaded_plugins %w(a stubby acts_as_chunky_bacon), ['default', 'alternate']
   end
+ 
+  def test_load_all_plugins_when_config_plugins_is_nil
+    @init.configuration.plugins = nil
+    assert_loaded_plugins %w(a stubby acts_as_chunky_bacon), ['default', 'alternate']
+  end
+
+  def test_load_no_plugins_when_config_plugins_is_empty_array
+    @init.configuration.plugins = []
+    assert_loaded_plugins [], ['default', 'alternate']   
+  end
+ 
+  def test_load_only_selected_plugins
+    plugins = %w(stubby a)
+    @init.configuration.plugins = plugins
+    assert_loaded_plugins plugins, ['default', 'alternate']
+  end
+ 
+  def test_load_plugins_in_order
+    plugins = %w(stubby acts_as_chunky_bacon a)
+    @init.configuration.plugins = plugins
+    assert_plugin_load_order plugins, ['default', 'alternate']
+  end
 
+  def test_raise_error_when_plugin_not_found
+    @init.configuration.plugins = %w(this_plugin_does_not_exist)
+    assert_raise(LoadError) { load_plugins(['default', 'alternate']) }
+  end
+  
   protected
-    def assert_loaded_plugins(plugins, path)
-      assert_equal Set.new(plugins), load_plugins(path)
+    def assert_loaded_plugins(plugins, paths)
+      assert_equal plugins.sort, load_plugins(paths).sort
+    end
+    
+    def assert_plugin_load_order(plugins, paths)
+      assert_equal plugins, load_plugins(paths)
     end
 
     def load_plugins(*paths)