def test_mv_symlink
    touch 'tmp/cptmp'
    # src==dest (2) symlink and its target
    File.symlink 'cptmp', 'tmp/cptmp_symlink'
    assert_raise(ArgumentError) {
      mv 'tmp/cptmp', 'tmp/cptmp_symlink'
    }
    assert_raise(ArgumentError) {
      mv 'tmp/cptmp_symlink', 'tmp/cptmp'
    }
    # src==dest (3) looped symlink
    File.symlink 'symlink', 'tmp/symlink'
    assert_raise(Errno::ELOOP) {
      mv 'tmp/symlink', 'tmp/symlink'
    }
    # unexist symlink
    File.symlink 'xxx', 'tmp/src'
    assert_nothing_raised {
      mv 'tmp/src', 'tmp/dest'
    }
    assert_equal true, File.symlink?('tmp/dest')
  end if have_symlink?