Add Enumerable#exclude? to bring parity to Enumerable#include? and avoid if !x.include?/else calls [DHH]

activesupport/CHANGELOG

@@ -1,5 +1,7 @@
 *Edge*
 
+* Add Enumerable#exclude? to bring parity to Enumerable#include? and avoid if !x.include?/else calls [DHH]
+
 * Update Edinburgh TimeZone to use "Europe/London" instead of "Europe/Dublin" #3310 [Phil Ross]
 
 * Update bundled TZInfo to v0.3.15 [Geoff Buesing]

activesupport/lib/active_support/core_ext/enumerable.rb

@@ -101,6 +101,11 @@ module Enumerable
     size = block_given? ? select(&block).size : self.size
     size > 1
   end
+  
+  # The negative of the Enumerable#include?. Returns true if the collection does not include the object.
+  def exclude?(object)
+    !include?(object)
+  end
 end
 
 class Range #:nodoc:

activesupport/test/core_ext/enumerable_test.rb

@@ -89,4 +89,9 @@ class EnumerableTests < Test::Unit::TestCase
     assert ![ 1, 2 ].many? {|x| x > 1 }
     assert [ 1, 2, 2 ].many? {|x| x > 1 }
   end
+  
+  def test_exclude?
+    assert [ 1 ].exclude?(2)
+    assert ![ 1 ].exclude?(1)
+  end
 end