CPAN breaks blead: Change in Test-Simple would cause test failure dist/PathTools #23164
Description
Today I attempted to synch CPAN distribution Test-Simple-1.302210 into blead at 3ab0369:
$ perl Porting/synch-with-cpan Test::Simple --yes
The program executed without difficulty; you can see the resulting code here. The most relevant changes can be found in https://github.com/Perl/perl5/compare/blead...jkeenan:perl5:synch-test-simple-20250331?expand=1#diff-d39e6642c9e2bdbd92225d87ce19c560caf9c404f420045aed7aefc1b867257b
and
https://github.com/Perl/perl5/compare/blead...jkeenan:perl5:synch-test-simple-20250331?expand=1#diff-d83f7e66bba7f8752334cd671971a17cb10b2bec768dbbf2882cf73d7e018e91. The program runs the tests under cpan/Test-Simple; they all PASS.
However, when I run make test_harness I get the following failure in a different distro shipped with the core:
$ cd t; ./perl harness -v ../dist/PathTools/t/cwd_enoent.t; cd -
Can't locate Config_heavy.pl in @INC (@INC entries checked: ../../lib ../../t) at ../../lib/Config.pm line 80.
# Looks like your test exited with 2 just after 4.
ok 1 - regular getcwd result on non-existent directory
ok 2 - regular getcwd errno on non-existent directory
ok 3 - regular abs_path result on non-existent directory
ok 4 - regular abs_path errno on non-existent directory
Dubious, test returned 2 (wstat 512, 0x200)
Failed 4/8 subtests
Test Summary Report
-------------------
../dist/PathTools/t/cwd_enoent.t (Wstat: 512 (exited 2) Tests: 4 Failed: 0)
Non-zero exit status: 2
Parse errors: Bad plan. You planned 8 tests but ran 4.
Files=1, Tests=4, 0 wallclock secs ( 0.00 usr 0.00 sys + 0.03 cusr 0.00 csys = 0.03 CPU)
Result: FAIL
The expected output for this test file is this:
ok 1 - regular getcwd result on non-existent directory
ok 2 - regular getcwd errno on non-existent directory
ok 3 - regular abs_path result on non-existent directory
ok 4 - regular abs_path errno on non-existent directory
ok 5 - perl getcwd result on non-existent directory
ok 6 - perl getcwd errno on non-existent directory
ok 7 - perl abs_path result on non-existent directory
ok 8 - perl abs_path errno on non-existent directory
After considerable re-testing to reproduce the problem in other checkouts and on a different platform, I went to Test-Simple's GH repository and examined the individual commits to that codebase that went into CPAN version 1.302210. The following commit caught my attention because its commit message mentions Config_heavy.pl -- the file not found in @INC in the failing test in Perl 5 blead.
commit 1653a15c33673a63a5c2b56bed4d10b0c8d32dfc
Author: Graham Knop <[email protected]>
AuthorDate: Sat Mar 29 07:15:22 2025
Commit: Graham Knop <[email protected]>
CommitDate: Sat Mar 29 07:26:11 2025
calculate CAN_SIGSYS when called rather than as a constant
CAN_SIGSYS is not used by Test2 anymore since the removal of the shm
code in 4c1bdd27e7f7694cbdfe4ec83b79b1cf791b4bc5. It is however still
used by Test2::Harness.
%Config has magic behavior where some values exist in Config.pm, and
others need to load Config_heavy.pl. Checking the sig_name value will
always force Config_heavy.pl to be loaded. Since CAN_SIGSYS is mostly
not used, having it always force loading the heavy config provides a
minor slowdown of loading Test::More. We can provide the function as a
runtime check rather than a constant to avoid this.
If I now return to the branch in my checkout of the core in which I am attempting to bring in Test-Simple and revert the changes from test-more-1653a15c33673a63a5c2b56bed4d10b0c8d32dfc, all tests in dist/PathTools/t/cwd_enoent.t once again PASS.
I don't understand why a test under dist/PathTools would be so affected by a change in a module under cpan/Test-Simple.
@haarg, can you take a look? Thank you very much.