Enumrable#each_with_index return Enumerator if non block given

2 files changed, 6 insertions, 0 deletions

diff --git a/mrbgems/mruby-enumerator/test/enumerator.rb b/mrbgems/mruby-enumerator/test/enumerator.rb
index 4ab857ae8..45d86685e 100644
--- a/mrbgems/mruby-enumerator/test/enumerator.rb
+++ b/mrbgems/mruby-enumerator/test/enumerator.rb
@@ -438,6 +438,10 @@ assert 'Integral#times' do
   assert_equal [0,1,2], c
 end
 
+assert 'Enumerable#each_with_index' do
+  assert_equal [['a',0],['b',1],['c',2]], ['a','b','c'].each_with_index.to_a
+end
+
 assert 'Enumerable#map' do
   a = [1,2,3]
   b = a.map
diff --git a/mrblib/enum.rb b/mrblib/enum.rb
index 5a33ed3c5..04a27294c 100644
--- a/mrblib/enum.rb
+++ b/mrblib/enum.rb
@@ -108,6 +108,8 @@ module Enumerable
   #
   # ISO 15.3.2.2.5
   def each_with_index(&block)
+    return to_enum :each_with_index unless block_given?
+
     i = 0
     self.each{|*val|
       block.call(val.__svalue, i)