Testing with Roles

tj_thompson has asked for the wisdom of the Perl Monks concerning the following question:

Hello monks. I have a rather simple question regarding testing and roles. After my reference books and Google have failed me I come to you expert types :)

Assume I have an object $object that I'm playing with in one manner or another. I want to be able to fake that it implements some role such that $object->does('Some::Role') returns true for testing purposes. What is the best way to accomplish this?

EDIT: fixed a grammar typo

Comment on Testing with Roles

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Re: Testing with Roles by chromatic (Archbishop) on Dec 17, 2011 at 03:52 UTC
What does this role do such that you want to fake it? In my experience, roles rarely mean I need to fake things. With that said, you can always override `DOES()` in the class, though if you lie to the type system, you might get weird results. Improve your skills with Modern Perl: the free book.	[reply] [d/l]
Re: Testing with Roles by educated_foo (Vicar) on Dec 17, 2011 at 06:57 UTC
Stripping away the goofy jargon, you want to override the method `$obj->does()`, i.e. you want to replace the function that gets called. Doing so is no different than replacing any other function: `*{ref($obj).'::does'} = sub { # do stuff you want }` [download]	[reply] [d/l] [select]
Re^2: Testing with Roles by tj_thompson (Monk) on Dec 19, 2011 at 22:10 UTC
This was my original plan but I couldn't seem to get it to work right. That of course was caused by me shooting myself in the foot elsewhere :) Once I resolved the real issue, the problem went away and it passed as expected. As always, thank you kind folks for your assistance!	[reply]
Re: Testing with Roles by tobyink (Canon) on Dec 17, 2011 at 09:52 UTC
Maybe something like this? `$object->meta->add_around_method_modifier(does => sub { my ($orig, $self, $role) = @_; return 1 if $role eq 'Some::Role'; $self->$orig($role); });` [download]	[reply] [d/l]