alias_method_chain preserves the original method's visibility. Closes #7854.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6441 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

3 files changed, 61 insertions, 2 deletions

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index deddebd458..63ca49bec4 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* alias_method_chain preserves the original method's visibility.  #7854 [Jonathan Viney]
+
 * Update Dependencies to ignore constants inherited from ancestors. Closes #6951. [Nicholas Seckar]
 
 * Array#to_query preserves its ordering.  #7756 [Greg Spurrier]
diff --git a/activesupport/lib/active_support/core_ext/module/aliasing.rb b/activesupport/lib/active_support/core_ext/module/aliasing.rb
index 81e81696d8..b36874520b 100644
--- a/activesupport/lib/active_support/core_ext/module/aliasing.rb
+++ b/activesupport/lib/active_support/core_ext/module/aliasing.rb
@@ -25,8 +25,20 @@ class Module
     # e.g. target?_without_feature is not a valid method name.
     aliased_target, punctuation = target.to_s.sub(/([?!=])$/, ''), $1
     yield(aliased_target, punctuation) if block_given?
-    alias_method "#{aliased_target}_without_#{feature}#{punctuation}", target
-    alias_method target, "#{aliased_target}_with_#{feature}#{punctuation}"
+    
+    with_method, without_method = "#{aliased_target}_with_#{feature}#{punctuation}", "#{aliased_target}_without_#{feature}#{punctuation}"
+    
+    alias_method without_method, target
+    alias_method target, with_method
+    
+    case
+      when public_method_defined?(without_method)
+        public target
+      when protected_method_defined?(without_method)
+        protected target
+      when private_method_defined?(without_method)
+        private target
+    end
   end
 
   # Allows you to make aliases for attributes, which includes 
diff --git a/activesupport/test/core_ext/module_test.rb b/activesupport/test/core_ext/module_test.rb
index 884b44030c..73ab371da5 100644
--- a/activesupport/test/core_ext/module_test.rb
+++ b/activesupport/test/core_ext/module_test.rb
@@ -129,6 +129,10 @@ module BarMethods
   def quux_with_baz=(v)
     send(:quux_without_baz=, v) << '_with_baz'
   end
+  
+  def duck_with_orange
+    duck_without_orange << '_with_orange'
+  end
 end
 
 class MethodAliasingTest < Test::Unit::TestCase
@@ -226,4 +230,45 @@ class MethodAliasingTest < Test::Unit::TestCase
     end
     assert block_called
   end
+  
+  def test_alias_method_chain_preserves_private_method_status
+    FooClassWithBarMethod.send(:define_method, 'duck', Proc.new { 'duck' })
+    FooClassWithBarMethod.send(:include, BarMethodAliaser)
+    FooClassWithBarMethod.send(:private, :duck)
+    
+    FooClassWithBarMethod.alias_method_chain :duck, :orange
+    
+    assert_raises NoMethodError do
+      @instance.duck
+    end
+    
+    assert_equal 'duck_with_orange', @instance.send(:duck)
+    assert FooClassWithBarMethod.private_method_defined?(:duck)
+  end
+  
+  def test_alias_method_chain_preserves_protected_method_status
+    FooClassWithBarMethod.send(:define_method, 'duck', Proc.new { 'duck' })
+    FooClassWithBarMethod.send(:include, BarMethodAliaser)
+    FooClassWithBarMethod.send(:protected, :duck)
+    
+    FooClassWithBarMethod.alias_method_chain :duck, :orange
+    
+    assert_raises NoMethodError do
+      @instance.duck
+    end
+    
+    assert_equal 'duck_with_orange', @instance.send(:duck)
+    assert FooClassWithBarMethod.protected_method_defined?(:duck)
+  end
+  
+  def test_alias_method_chain_preserves_public_method_status
+    FooClassWithBarMethod.send(:define_method, 'duck', Proc.new { 'duck' })
+    FooClassWithBarMethod.send(:include, BarMethodAliaser)
+    FooClassWithBarMethod.send(:public, :duck)
+    
+    FooClassWithBarMethod.alias_method_chain :duck, :orange
+    
+    assert_equal 'duck_with_orange', @instance.duck
+    assert FooClassWithBarMethod.public_method_defined?(:duck)
+  end
 end