diff --git a/ChangeLog b/ChangeLog
index 7a6c9b50bc..5a92f238a3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Dec 11 20:38:26 2008  Akinori MUSHA  <knu@iDaemons.org>
+
+	* test/ruby/test_enumerator.rb: Add tests for the recently added
+	  features.
+
 Thu Dec 11 20:36:26 2008  Akinori MUSHA  <knu@iDaemons.org>
 
 	* lib/generator.rb (Enumerator#__generator): Now that
diff --git a/test/ruby/test_enumerator.rb b/test/ruby/test_enumerator.rb
index 152390cab2..d5edb01b8e 100644
--- a/test/ruby/test_enumerator.rb
+++ b/test/ruby/test_enumerator.rb
@@ -58,6 +58,7 @@ class TestEnumerator < Test::Unit::TestCase
   def test_initialize
     assert_equal([1, 2, 3], @obj.to_enum(:foo, 1, 2, 3).to_a)
     assert_equal([1, 2, 3], Enumerator.new(@obj, :foo, 1, 2, 3).to_a)
+    assert_equal([1, 2, 3], Enumerator.new { |y| i = 0; loop { y << (i += 1) } }.take(3))
     assert_raise(ArgumentError) { Enumerator.new }
   end
 
@@ -66,6 +67,10 @@ class TestEnumerator < Test::Unit::TestCase
     e = @obj.to_enum(:foo, 1, 2, 3)
     assert_nothing_raised { assert_equal(1, e.next) }
     #assert_raise(TypeError) { e.dup }
+
+    e = Enumerator.new { |y| i = 0; loop { y << (i += 1) } }.dup
+    assert_nothing_raised { assert_equal(1, e.next) }
+    #assert_raise(TypeError) { e.dup }
   end
 
   def test_gc
@@ -91,6 +96,29 @@ class TestEnumerator < Test::Unit::TestCase
     assert_equal([[1,0],[2,1],[3,2]], @obj.to_enum(:foo, 1, 2, 3).with_index.to_a)
   end
 
+  def test_with_object
+    obj = [0, 1]
+    ret = (1..10).each.with_object(obj) {|i, memo|
+      memo[0] += i
+      memo[1] *= i
+    }
+    assert_same(obj, ret)
+    assert_equal([55, 3628800], ret)
+
+    a = [2,5,2,1,5,3,4,2,1,0]
+    obj = {}
+    ret = a.delete_if.with_object(obj) {|i, seen|
+      if seen.key?(i)
+        true
+      else
+        seen[i] = true
+        false
+      end
+    }
+    assert_same(obj, ret)
+    assert_equal([2, 5, 1, 3, 4, 0], a)
+  end
+
   def test_next_rewind
     e = @obj.to_enum(:foo, 1, 2, 3)
     assert_equal(1, e.next)