Dir.chdir with no arguments is supposed to default to $HOME but JRuby is not doing that: require "test/unit" class TC_Dir_Chdir_Class < Test::Unit::TestCase def setup @pwd = Dir.pwd @old_home = ENV["HOME"] || ENV["LOGDIR"] ENV["HOME"] = @pwd end def test_chdir_basic assert_respond_to(Dir, :chdir) assert_nothing_raised{ Dir.chdir } assert_nothing_raised{ Dir.chdir(@pwd) } assert_nothing_raised{ Dir.chdir(@pwd){} } end def test_chdir assert_equal(0, Dir.chdir(@pwd)) assert_nothing_raised{ Dir.chdir } assert_equal(@pwd, Dir.pwd) end def test_chdir_block assert_nothing_raised{ Dir.chdir{ @old_home } } assert_equal(@pwd, Dir.pwd) end def test_chdir_expected_errors assert_raises(ArgumentError){ Dir.chdir(@pwd, @pwd) } assert_raises(TypeError){ Dir.chdir(1) } ENV["HOME"] = "bogus" assert_raises(Errno::ENOENT){ Dir.chdir } end def teardown system("chdir #{@pwd}") ENV["HOME"] = @old_home @pwd = nil end end You'll see something like this: 1) Failure: test_chdir(TC_Dir_Chdir_Class) [test/core/Dir/class/tc_chdir.rb:25]: <"/export/home/djberge/workspace/ruby_test"> expected but was <"/export/home/djberge">. 2) Failure: test_chdir_expected_errors(TC_Dir_Chdir_Class) [test/core/Dir/class/tc_chdir.rb:38]: <Errno::ENOENT> exception expected but none was thrown. Regards, Dan