[ruby/reline] Add Enumerable to KillRing for debugging

https://github.com/ruby/reline/commit/d208874152

lib/reline/kill_ring.rb

@@ -1,4 +1,6 @@
 class Reline::KillRing
+  include Enumerable
+
   module State
     FRESH = :fresh
     CONTINUED = :continued
@@ -110,4 +112,14 @@ class Reline::KillRing
       nil
     end
   end
+
+  def each
+    start = head = @ring.head
+    loop do
+      break if head.nil?
+      yield head.str
+      head = head.backward
+      break if head == start
+    end
+  end
 end

test/reline/test_kill_ring.rb

@@ -253,4 +253,16 @@ class Reline::KillRing::Test < Reline::TestCase
     assert_equal(['AB', 'abcde'], @kill_ring.yank_pop)
     assert_equal(Reline::KillRing::State::YANK, @kill_ring.instance_variable_get(:@state))
   end
+
+  def test_enumerable
+    @kill_ring.append('a')
+    @kill_ring.process
+    @kill_ring.process
+    @kill_ring.append('b')
+    @kill_ring.process
+    @kill_ring.process
+    @kill_ring.append('c')
+    @kill_ring.process
+    assert_equal(%w{c b a}, @kill_ring.to_a)
+  end
 end