He expects http://a.b.c/d/../e/ to be the same as http://a.b.c/e/.

There is a violation of 5.2 elsewhere, though.

use strict;
use warnings;

use Test::More tests => 1;

use URI qw( );

# if defined(R.scheme) then
#    T.scheme    = R.scheme;
#    T.authority = R.authority;
#    T.path      = remove_dot_segments(R.path);
#    T.query     = R.query;

is( URI->new_abs('http://a.b.c/d/../e/', 'http://a.b.c/'), 'http://a.b
+.c/e/' );

1;
[download]

1..1
not ok 1
#   Failed test at a.pl line 8.
#          got: 'http://a.b.c/d/../e/'
#     expected: 'http://a.b.c/e/'
# Looks like you failed 1 test of 1.
[download]

I would except cannonical to implement 6.2.2.3. It does implement other similar rules.

use strict;
use warnings;

use Test::More tests => 6;

use URI qw( );

is( URI->new('hTtP://a.b.c/'       )->canonical, 'http://a.b.c/',   'R
+FC 3986, 6.2.2.1' );

is( URI->new('http://a.b.c/d/../e/')->canonical, 'http://a.b.c/e/', 'R
+FC 3986, 6.2.2.3' );

is( URI->new('http://a.b.c'        )->canonical, 'http://a.b.c/',   'R
+FC 3986, 6.2.3' );
is( URI->new('http://a.b.c:'       )->canonical, 'http://a.b.c/',   'R
+FC 3986, 6.2.3' );
is( URI->new('http://a.b.c:/'      )->canonical, 'http://a.b.c/',   'R
+FC 3986, 6.2.3' );
is( URI->new('http://a.b.c:80/'    )->canonical, 'http://a.b.c/',   'R
+FC 3986, 6.2.3' );

1;
[download]

1..6
ok 1 - RFC 3986, 6.2.2.1
not ok 2 - RFC 3986, 6.2.2.3
#   Failed test 'RFC 3986, 6.2.2.3'
#   at a.pl line 10.
#          got: 'http://a.b.c/d/../e/'
#     expected: 'http://a.b.c/e/'
ok 3 - RFC 3986, 6.2.3
ok 4 - RFC 3986, 6.2.3
ok 5 - RFC 3986, 6.2.3
ok 6 - RFC 3986, 6.2.3
# Looks like you failed 1 test of 6.
[download]

5.2 describes how to make an absolute uri from a (possibly) relative URL.

In that context, "/d/../e/" is equivalent to "/e/", but the module already does that correctly.

Update: 6.2.2.3 seems more relevant here.