From dd96e8e3337c04c5c37ece7983d012a9353804ac Mon Sep 17 00:00:00 2001
From: Genadi Samokovarov <gsamokovarov@gmail.com>
Date: Tue, 9 Dec 2014 12:04:50 +0200
Subject: [PATCH] Add class level case operator support for error dispatching
 in Rescuable

---
 activesupport/CHANGELOG.md                    | 16 ++++++++++
 activesupport/lib/active_support/rescuable.rb |  4 +--
 activesupport/test/rescuable_test.rb          | 29 +++++++++++++++++--
 3 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 912b0287af..3f340958ea 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,19 @@
+*   Added support for error dispatcher classes in ActiveSupport::Rescuable. Now it acts closer to Ruby's rescue.
+
+        class BaseController < ApplicationController
+          module ErrorDispatcher
+            def self.===(other)
+              Exception === other && other.respond_to?(:status)
+            end
+          end
+
+          rescue_from ErrorDispatcher do |error|
+            render status: error.status, json: { error: error.to_s }
+          end
+        end
+
+    *Genadi Samokovarov*
+
 *   Added `#verified` and `#valid_message?` methods to `ActiveSupport::MessageVerifier`
 
     Previously, the only way to decode a message with `ActiveSupport::MessageVerifier` was to use `#verify`, which would raise an exception on invalid messages. Now `#verified` can also be used, which returns `nil` on messages that cannot be decoded.
diff --git a/activesupport/lib/active_support/rescuable.rb b/activesupport/lib/active_support/rescuable.rb
index a7eba91ac5..1a02acd5b1 100644
--- a/activesupport/lib/active_support/rescuable.rb
+++ b/activesupport/lib/active_support/rescuable.rb
@@ -60,7 +60,7 @@ module ActiveSupport
         end
 
         klasses.each do |klass|
-          key = if klass.is_a?(Class) && klass <= Exception
+          key = if klass.is_a?(Module) && klass.respond_to?(:===)
             klass.name
           elsif klass.is_a?(String)
             klass
@@ -101,7 +101,7 @@ module ActiveSupport
         # 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
+        klass === exception if klass
       end
 
       case rescuer
diff --git a/activesupport/test/rescuable_test.rb b/activesupport/test/rescuable_test.rb
index b8af888f7c..bd43ad0797 100644
--- a/activesupport/test/rescuable_test.rb
+++ b/activesupport/test/rescuable_test.rb
@@ -12,6 +12,12 @@ end
 class CoolError < StandardError
 end
 
+module WeirdError
+  def self.===(other)
+    Exception === other && other.respond_to?(:weird?)
+  end
+end
+
 class Stargate
   attr_accessor :result
 
@@ -29,6 +35,10 @@ class Stargate
     @result = e.message
   end
 
+  rescue_from WeirdError do
+    @result = 'weird'
+  end
+
   def dispatch(method)
     send(method)
   rescue Exception => e
@@ -47,6 +57,16 @@ class Stargate
     raise MadRonon.new("dex")
   end
 
+  def weird
+    StandardError.new.tap do |exc|
+      def exc.weird?
+        true
+      end
+
+      raise exc
+    end
+  end
+
   def sos
     @result = 'killed'
   end
@@ -91,14 +111,19 @@ class RescuableTest < ActiveSupport::TestCase
     assert_equal 'dex', @stargate.result
   end
 
+  def test_rescue_from_error_dispatchers_with_case_operator
+    @stargate.dispatch :weird
+    assert_equal 'weird', @stargate.result
+  end
+
   def test_rescues_defined_later_are_added_at_end_of_the_rescue_handlers_array
-    expected = ["WraithAttack", "WraithAttack", "NuclearExplosion", "MadRonon"]
+    expected = ["WraithAttack", "WraithAttack", "NuclearExplosion", "MadRonon", "WeirdError"]
     result = @stargate.send(:rescue_handlers).collect(&:first)
     assert_equal expected, result
   end
 
   def test_children_should_inherit_rescue_definitions_from_parents_and_child_rescue_should_be_appended
-    expected = ["WraithAttack", "WraithAttack", "NuclearExplosion", "MadRonon", "CoolError"]
+    expected = ["WraithAttack", "WraithAttack", "NuclearExplosion", "MadRonon", "WeirdError", "CoolError"]
     result = @cool_stargate.send(:rescue_handlers).collect(&:first)
     assert_equal expected, result
   end