Fix calling enumerator methods such as with_index on Enumerator::Chain

This previously raised a TypeError.  Wrap the Enumerator::Chain in
an Enumerator to work around the problem.

Fixes [Bug #17216]

1 files changed, 4 insertions, 0 deletions

diff --git a/test/ruby/test_enumerator.rb b/test/ruby/test_enumerator.rb
index 718bcb74b6..9b615ff9db 100644
--- a/test/ruby/test_enumerator.rb
+++ b/test/ruby/test_enumerator.rb
@@ -816,6 +816,10 @@ class TestEnumerator < Test::Unit::TestCase
     )
   end
 
+  def test_chain_with_index
+    assert_equal([[3, 0], [4, 1]], [3].chain([4]).with_index.to_a)
+  end
+
   def test_produce
     assert_raise(ArgumentError) { Enumerator.produce }