Bug#674625: libtest-mockmodule-perl: unmock() on an inherited method does not behave properly

[Frédéric Brière]

Package: libtest-mockmodule-perl
Version: 0.05-2
Severity: normal
Tags: upstream
Forwarded: https://rt.cpan.org/Ticket/Display.html?id=77439

When unmocking a method that was not originally defined in the mocked
module, but rather inherited from a parent class, unmock() will install
a copy of the inherited method in the child class. This will subtly
break if the parent method ever changes, such as illustrated in the
attached example.

I think that mock() should not bother with can() if &{$sub_name} does
not exist, and merely store undef. (OTOH, it may be argued that
original() should returned the inherited method. Hmm.) 


-- System Information:
Debian Release: wheezy/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: i386 (x86_64)

Kernel: Linux 3.2.0-2-amd64 (SMP w/3 CPU cores)
Locale: LANG=en_CA.UTF-8, LC_CTYPE=en_CA.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages libtest-mockmodule-perl depends on:
ii  perl  5.14.2-10

libtest-mockmodule-perl recommends no packages.

libtest-mockmodule-perl suggests no packages.

-- no debconf information

#!/usr/bin/perl

use 5.10.0;
use Test::MockModule;

@Bar::ISA = 'Foo';
@Baz::ISA = 'Bar';

sub Foo::motto { 'Foo!' };

say Foo->motto(), Bar->motto(), Baz->motto();

{
	my $mock_bar = new Test::MockModule('Bar', no_auto => 1);
	$mock_bar->mock('motto', sub { 'Bar!' });

	my $mock_baz = new Test::MockModule('Baz', no_auto => 1);
	$mock_baz->mock('motto', sub { 'Baz!' });

	say Foo->motto(), Bar->motto(), Baz->motto();
}

say Foo->motto(), Bar->motto(), Baz->motto();