Add tests for ActiveSupport::Rescuable. Use ActiveSupport::Rescuable in ActionController::Base.

5 files changed, 136 insertions, 119 deletions

diff --git a/actionpack/lib/action_controller/rescue.rb b/actionpack/lib/action_controller/rescue.rb
index 0e0fe15fdb..ec8e9b92d5 100644
--- a/actionpack/lib/action_controller/rescue.rb
+++ b/actionpack/lib/action_controller/rescue.rb
@@ -41,10 +41,9 @@ module ActionController #:nodoc:
       base.rescue_templates = Hash.new(DEFAULT_RESCUE_TEMPLATE)
       base.rescue_templates.update DEFAULT_RESCUE_TEMPLATES
 
-      base.class_inheritable_array :rescue_handlers
-      base.rescue_handlers = []
-
       base.extend(ClassMethods)
+      base.send :include, ActiveSupport::Rescuable
+
       base.class_eval do
         alias_method_chain :perform_action, :rescue
       end
@@ -54,65 +53,12 @@ module ActionController #:nodoc:
       def process_with_exception(request, response, exception) #:nodoc:
         new.process(request, response, :rescue_action, exception)
       end
-
-      # Rescue exceptions raised in controller actions.
-      #
-      # <tt>rescue_from</tt> receives a series of exception classes or class
-      # names, and a trailing <tt>:with</tt> option with the name of a method
-      # or a Proc object to be called to handle them. Alternatively a block can
-      # be given.
-      #
-      # Handlers that take one argument will be called with the exception, so
-      # that the exception can be inspected when dealing with it.
-      #
-      # Handlers are inherited. They are searched from right to left, from
-      # bottom to top, and up the hierarchy. The handler of the first class for
-      # which <tt>exception.is_a?(klass)</tt> holds true is the one invoked, if
-      # any.
-      #
-      #   class ApplicationController < ActionController::Base
-      #     rescue_from User::NotAuthorized, :with => :deny_access # self defined exception
-      #     rescue_from ActiveRecord::RecordInvalid, :with => :show_errors
-      #
-      #     rescue_from 'MyAppError::Base' do |exception|
-      #       render :xml => exception, :status => 500
-      #     end
-      #
-      #     protected
-      #       def deny_access
-      #         ...
-      #       end
-      #
-      #       def show_errors(exception)
-      #         exception.record.new_record? ? ...
-      #       end
-      #   end
-      def rescue_from(*klasses, &block)
-        options = klasses.extract_options!
-        unless options.has_key?(:with)
-          block_given? ? options[:with] = block : raise(ArgumentError, "Need a handler. Supply an options hash that has a :with key as the last argument.")
-        end
-
-        klasses.each do |klass|
-          key = if klass.is_a?(Class) && klass <= Exception
-            klass.name
-          elsif klass.is_a?(String)
-            klass
-          else
-            raise(ArgumentError, "#{klass} is neither an Exception nor a String")
-          end
-
-          # Order is important, we put the pair at the end. When dealing with an
-          # exception we will follow the documented order going from right to left.
-          rescue_handlers << [key, options[:with]]
-        end
-      end
     end
 
     protected
       # Exception handler called when the performance of an action raises an exception.
       def rescue_action(exception)
-        rescue_action_with_handler(exception) || rescue_action_without_handler(exception)
+        rescue_with_handler(exception) || rescue_action_without_handler(exception)
       end
 
       # Overwrite to implement custom logging of errors. By default logs as fatal.
@@ -168,18 +114,6 @@ module ActionController #:nodoc:
         render_for_file(rescues_path("layout"), response_code_for_rescue(exception))
       end
 
-      # Tries to rescue the exception by looking up and calling a registered handler.
-      def rescue_action_with_handler(exception)
-        if handler = handler_for_rescue(exception)
-          if handler.arity != 0
-            handler.call(exception)
-          else
-            handler.call
-          end
-          true # don't rely on the return value of the handler
-        end
-      end
-
       def rescue_action_without_handler(exception)
         log_error(exception) if logger
         erase_results if performed?
@@ -216,36 +150,6 @@ module ActionController #:nodoc:
         rescue_responses[exception.class.name]
       end
 
-      def handler_for_rescue(exception)
-        # We go from right to left because pairs are pushed onto rescue_handlers
-        # as rescue_from declarations are found.
-        _, handler = *rescue_handlers.reverse.detect do |klass_name, handler|
-          # The purpose of allowing strings in rescue_from is to support the
-          # declaration of handler associations for exception classes whose
-          # definition is yet unknown.
-          #
-          # Since this loop needs the constants it would be inconsistent to
-          # assume they should exist at this point. An early raised exception
-          # could trigger some other handler and the array could include
-          # precisely a string whose corresponding constant has not yet been
-          # seen. This is why we are tolerant to unknown constants.
-          #
-          # Note that this tolerance only matters if the exception was given as
-          # a string, otherwise a NameError will be raised by the interpreter
-          # itself when rescue_from CONSTANT is executed.
-          klass = self.class.const_get(klass_name) rescue nil
-          klass ||= klass_name.constantize rescue nil
-          exception.is_a?(klass) if klass
-        end
-
-        case handler
-        when Symbol
-          method(handler)
-        when Proc
-          handler.bind(self)
-        end
-      end
-
       def clean_backtrace(exception)
         if backtrace = exception.backtrace
           if defined?(RAILS_ROOT)
diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index 9700a11531..2c6f4ed582 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *Edge*
 
+* Add ActiveSupport::Rescuable module abstracting ActionController::Base rescue_from features. [Norbert Crombach, Pratik]
+
 * Switch from String#chars to String#mb_chars for the unicode proxy.  [Manfred Stienstra]
 
   This helps with 1.8.7 compatibility and also improves performance for some operations by reducing indirection.
diff --git a/activesupport/lib/active_support.rb b/activesupport/lib/active_support.rb
index b30faff06d..0ff09067ec 100644
--- a/activesupport/lib/active_support.rb
+++ b/activesupport/lib/active_support.rb
@@ -56,6 +56,8 @@ require 'active_support/time_with_zone'
 
 require 'active_support/secure_random'
 
+require 'active_support/rescuable'
+
 I18n.load_path << File.dirname(__FILE__) + '/active_support/locale/en-US.yml'
 
 Inflector = ActiveSupport::Deprecation::DeprecatedConstantProxy.new('Inflector', 'ActiveSupport::Inflector')
diff --git a/activesupport/lib/active_support/rescuable.rb b/activesupport/lib/active_support/rescuable.rb
index d1a4366636..f2bc12e832 100644
--- a/activesupport/lib/active_support/rescuable.rb
+++ b/activesupport/lib/active_support/rescuable.rb
@@ -1,28 +1,49 @@
 module ActiveSupport
+  # Rescuable module adds support for easier exception handling.
   module Rescuable
     def self.included(base) # :nodoc:
-      base.class_inheritable_array :rescue_handlers
+      base.class_inheritable_accessor :rescue_handlers
       base.rescue_handlers = []
+
       base.extend(ClassMethods)
     end
 
     module ClassMethods
-      def enable_rescue_for(*methods)
-        methods.each do |method|
-          class_eval <<-EOS
-            def #{method}_with_rescue(*args, &block)
-              #{method}_without_rescue(*args, &block)
-            rescue Exception => exception
-              rescue_with_handler(exception)
-            end
-
-            alias_method_chain :#{method}, :rescue
-          EOS
-        end
-      end
-
+      # Rescue exceptions raised in controller actions.
+      #
+      # <tt>rescue_from</tt> receives a series of exception classes or class
+      # names, and a trailing <tt>:with</tt> option with the name of a method
+      # or a Proc object to be called to handle them. Alternatively a block can
+      # be given.
+      #
+      # Handlers that take one argument will be called with the exception, so
+      # that the exception can be inspected when dealing with it.
+      #
+      # Handlers are inherited. They are searched from right to left, from
+      # bottom to top, and up the hierarchy. The handler of the first class for
+      # which <tt>exception.is_a?(klass)</tt> holds true is the one invoked, if
+      # any.
+      #
+      #   class ApplicationController < ActionController::Base
+      #     rescue_from User::NotAuthorized, :with => :deny_access # self defined exception
+      #     rescue_from ActiveRecord::RecordInvalid, :with => :show_errors
+      #
+      #     rescue_from 'MyAppError::Base' do |exception|
+      #       render :xml => exception, :status => 500
+      #     end
+      #
+      #     protected
+      #       def deny_access
+      #         ...
+      #       end
+      #
+      #       def show_errors(exception)
+      #         exception.record.new_record? ? ...
+      #       end
+      #   end
       def rescue_from(*klasses, &block)
         options = klasses.extract_options!
+
         unless options.has_key?(:with)
           if block_given?
             options[:with] = block
@@ -46,18 +67,31 @@ module ActiveSupport
       end
     end
 
+    # Tries to rescue the exception by looking up and calling a registered handler.
     def rescue_with_handler(exception)
       if handler = handler_for_rescue(exception)
         handler.arity != 0 ? handler.call(exception) : handler.call
-      else
-        raise exception
+        true # don't rely on the return value of the handler
       end
     end
 
     def handler_for_rescue(exception)
-      # use reverse so what is added last is found first
-      _, handler = *rescue_handlers.reverse.detect do |klass_name, handler|
-        # allow strings to support constants that are not defined yet
+      # We go from right to left because pairs are pushed onto rescue_handlers
+      # as rescue_from declarations are found.
+      _, handler = Array(rescue_handlers).reverse.detect do |klass_name, handler|
+        # The purpose of allowing strings in rescue_from is to support the
+        # declaration of handler associations for exception classes whose
+        # definition is yet unknown.
+        #
+        # Since this loop needs the constants it would be inconsistent to
+        # assume they should exist at this point. An early raised exception
+        # could trigger some other handler and the array could include
+        # precisely a string whose corresponding constant has not yet been
+        # seen. This is why we are tolerant to unknown constants.
+        #
+        # Note that this tolerance only matters if the exception was given as
+        # a string, otherwise a NameError will be raised by the interpreter
+        # itself when rescue_from CONSTANT is executed.
         klass = self.class.const_get(klass_name) rescue nil
         klass ||= klass_name.constantize rescue nil
         exception.is_a?(klass) if klass
diff --git a/activesupport/test/rescuable_test.rb b/activesupport/test/rescuable_test.rb
new file mode 100644
index 0000000000..9f2b783b2e
--- /dev/null
+++ b/activesupport/test/rescuable_test.rb
@@ -0,0 +1,75 @@
+require 'abstract_unit'
+
+class WraithAttack < StandardError
+end
+
+class NuclearExplosion < StandardError
+end
+
+class MadRonon < StandardError
+  attr_accessor :message
+  
+  def initialize(message)
+    @message = message
+    super()
+  end
+end
+
+class Stargate
+  attr_accessor :result
+
+  include ActiveSupport::Rescuable
+
+  rescue_from WraithAttack, :with => :sos
+
+  rescue_from NuclearExplosion do
+    @result = 'alldead'
+  end
+  
+  rescue_from MadRonon do |e|
+    @result = e.message
+  end
+
+  def dispatch(method)
+    send(method)
+  rescue Exception => e
+    rescue_with_handler(e)
+  end
+
+  def attack
+    raise WraithAttack
+  end
+
+  def nuke
+    raise NuclearExplosion
+  end
+
+  def ronanize
+    raise MadRonon.new("dex")
+  end
+
+  def sos
+    @result = 'killed'
+  end
+end
+
+class RescueableTest < Test::Unit::TestCase
+  def setup
+    @stargate = Stargate.new
+  end
+
+  def test_rescue_from_with_method
+    @stargate.dispatch :attack
+    assert_equal 'killed', @stargate.result
+  end
+  
+  def test_rescue_from_with_block
+    @stargate.dispatch :nuke
+    assert_equal 'alldead', @stargate.result
+  end
+  
+  def test_rescue_from_with_block_with_args
+    @stargate.dispatch :ronanize
+    assert_equal 'dex', @stargate.result
+  end  
+end