1 files changed, 23 insertions, 3 deletions
diff --git a/activesupport/test/core_ext/enumerable_test.rb b/activesupport/test/core_ext/enumerable_test.rb
index dada058d56..3d116e8d93 100644
--- a/activesupport/test/core_ext/enumerable_test.rb
+++ b/activesupport/test/core_ext/enumerable_test.rb
@@ -3,6 +3,9 @@ require File.dirname(__FILE__) + '/../../lib/active_support/core_ext/symbol'
 require File.dirname(__FILE__) + '/../../lib/active_support/core_ext/enumerable'
 
 Payment = Struct.new(:price)
+class SummablePayment < Payment
+  def +(p) self.class.new(price + p.price) end
+end
 
 class EnumerableTests < Test::Unit::TestCase
   def test_group_by
@@ -19,13 +22,31 @@ class EnumerableTests < Test::Unit::TestCase
       assert group.all? {|person| person.name == name}
     end
   end
-  
+
   def test_sums
+    assert_equal 30, [5, 15, 10].sum
+    assert_equal 30, [5, 15, 10].sum { |i| i }
+
+    assert_equal 'abc', %w(a b c).sum
+    assert_equal 'abc', %w(a b c).sum { |i| i }
+
     payments = [ Payment.new(5), Payment.new(15), Payment.new(10) ]
     assert_equal 30, payments.sum(&:price)
     assert_equal 60, payments.sum { |p| p.price * 2 }
+
+    payments = [ SummablePayment.new(5), SummablePayment.new(15) ]
+    assert_equal SummablePayment.new(20), payments.sum
+    assert_equal SummablePayment.new(20), payments.sum { |p| p }
   end
-  
+
+  def test_nil_sums
+    assert_raise(TypeError) { [5, 15, nil].sum }
+
+    payments = [ Payment.new(5), Payment.new(15), Payment.new(10), Payment.new(nil) ]
+    assert_raise(TypeError) { payments.sum(&:price) }
+    assert_equal 60, payments.sum { |p| p.price.to_i * 2 }
+  end
+
   def test_index_by
     payments = [ Payment.new(5), Payment.new(15), Payment.new(10) ]
     assert_equal(
@@ -33,5 +54,4 @@ class EnumerableTests < Test::Unit::TestCase
       payments.index_by(&:price)
     )
   end
-  
 end