Test failing on Windows but not elsewhere

On Mon, Mar 9, 2015 at 3:44 PM, James E Keenan wrote:

This weekend I gave my CPAN library CPAN-Mini-Visit-Simple an overhaul, a
large part of which was guaranteeing that CPAN Testers handled the absence
of a minicpan gracefully. As a result, for the first time I'm getting lots
of green on my results matrix (http://matrix.cpantesters.
org/?dist=CPAN-Mini-Visit-Simple).

Except on Windows. See, e.g., http://www.cpantesters.org/
cpan/report/88cc1179-8782-1014-9710-f1002b825c07, where this failure is
reported:

#####
C:\strawberry\perl\bin\perl.exe "-MExtUtils::Command::MM"
"-MTest::Harness" "-e" "undef *Test::Harness::Switches; test_harness(0,
'blib\lib', 'blib\arch')" t/*.t

# Failed test 'Got expected error message for malformed minicpan
repository'
# at t/001_new.t line 78.
# 'Absence of C:\Users\SOLIMA~1\AppData\
Local\Temp\FLXGKPwo7N\authors\id implies no valid minicpan at t/001_new.t
line 74.
# '
# doesn't match '(?^:Absence of C:\Users\SOLIMA~1\AppData\
Local\Temp\FLXGKPwo7N\authors\id implies no valid minicpan)'
# Looks like you failed 1 test of 16.
t/001_new.t .......................
Dubious, test returned 1 (wstat 256, 0x100)
#####

Here's the relevant source code:

#####
my $id_dir = File::Spec->catdir($data{minicpan}, qw/authors id/);
croak "Absence of $id_dir implies no valid minicpan"
unless -d $id_dir;
$data{id_dir} = $id_dir;
#####

And here's the relevant testing code:

#####
{
my ($tdir, $id_dir, $self);
$tdir = tempdir();
$id_dir = File::Spec->catdir($tdir, qw/authors id/);
eval {
$self = CPAN::Mini::Visit::Simple->new({
minicpan => $tdir,
});
};
like($@, qr/Absence of $id_dir implies no valid minicpan/,
"Got expected error message for malformed minicpan repository" );
}
#####

Note that in both cases I compose directories by File::Spec->catdir(). My
understanding is that this should handle the Windows path separators
issue. So having Done The Right Thing in that respect, I can't figure out
why I'm getting this failure.

Suggestions?

Thank you very much.
Jim Keenan