diff --git a/ChangeLog b/ChangeLog
index f2cdc0b2a5..8bf6e96781 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Nov 28 17:59:20 2003  NAKAMURA Usaku <usa@ruby-lang.org>
+
+	* test/ruby/test_env.rb: add tests for ENV.
+
 Fri Nov 28 17:47:46 2003  Masatoshi SEKI  <m_seki@mva.biglobe.ne.jp>
 
 	* lib/drb/drb.rb (DRbMessage#load): rescue Errno::* and raise
diff --git a/MANIFEST b/MANIFEST
index 3e2dbe5ffe..cb8d44dd2a 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -664,6 +664,7 @@ test/ruby/test_clone.rb
 test/ruby/test_condition.rb
 test/ruby/test_const.rb
 test/ruby/test_defined.rb
+test/ruby/test_env.rb
 test/ruby/test_eval.rb
 test/ruby/test_exception.rb
 test/ruby/test_file.rb
diff --git a/test/ruby/test_env.rb b/test/ruby/test_env.rb
new file mode 100644
index 0000000000..6a7fd97c23
--- /dev/null
+++ b/test/ruby/test_env.rb
@@ -0,0 +1,84 @@
+require 'test/unit'
+
+$KCODE = 'none'
+
+class TestEnv < Test::Unit::TestCase
+  IGNORE_CASE = /djgpp|bccwin|mswin|mingw|emx/ =~ RUBY_PLATFORM
+
+  def setup
+    @backup = ENV['test']
+    @BACKUP = ENV['TEST']
+    ENV['test'] = nil
+    ENV['TEST'] = nil
+  end
+
+  def teardown
+    ENV['test'] = @backup
+    ENV['TEST'] = @BACKUP
+  end
+
+  def test_bracket
+    assert_nil(ENV['test'])
+    assert_nil(ENV['TEST'])
+    ENV['test'] = 'foo'
+    assert_equal('foo', ENV['test'])
+    if IGNORE_CASE
+      assert_equal('foo', ENV['TEST'])
+    else
+      assert_nil(ENV['TEST'])
+    end
+    ENV['TEST'] = 'bar'
+    assert_equal('bar', ENV['TEST'])
+    if IGNORE_CASE
+      assert_equal('bar', ENV['test'])
+    else
+      assert_equal('foo', ENV['test'])
+    end
+
+    assert_raises(TypeError) {
+      tmp = ENV[1]
+    }
+    assert_raises(TypeError) {
+      ENV[1] = 'foo'
+    }
+    assert_raises(TypeError) {
+      ENV['test'] = 0
+    }
+  end
+
+  def test_has_value
+    val = 'a'
+    val.succ! while ENV.has_value?(val) && ENV.has_value?(val.upcase)
+
+    assert_equal(false, ENV.has_value?(val))
+    assert_equal(false, ENV.has_value?(val.upcase))
+    ENV['test'] = val
+    assert_equal(true, ENV.has_value?(val))
+    assert_equal(false, ENV.has_value?(val.upcase))
+    ENV['test'] = val.upcase
+    assert_equal(false, ENV.has_value?(val))
+    assert_equal(true, ENV.has_value?(val.upcase))
+  end
+
+  def test_index
+    val = 'a'
+    val.succ! while ENV.has_value?(val) && ENV.has_value?(val.upcase)
+
+    assert_nil(ENV.index(val))
+    assert_nil(ENV.index(val.upcase))
+    ENV['test'] = val
+    if IGNORE_CASE
+      assert_equal('TEST', ENV.index(val).upcase)
+    else
+      assert_equal('test', ENV.index(val))
+    end
+    assert_nil(ENV.index(val.upcase))
+    ENV['test'] = val.upcase
+    assert_nil(ENV.index(val))
+    if IGNORE_CASE
+      assert_equal('TEST', ENV.index(val.upcase).upcase)
+    else
+      assert_equal('test', ENV.index(val.upcase))
+    end
+  end
+end