No, I want to test a behavior that is defined in around(), so I want to mock MyRole::foo to return something specific. I've already tested my class and my role separately. I want to test their interaction.

Here's another example, a little closer to my actual code (which I can't post):

package MyRole2
use Moo::Role;

sub call {
    my $self = shift;
    # Connect to server, retrieve a document
    my $document = $self->get_document;
    return $document;
}

package MyClass2;
use Moo;
with 'MyRole2';

around call = sub { 
    my ($orig, $self) = @_;
    my $document = $self->$orig;
    if (has_error($document)) {
        die 'Error';
    }
    return parse($document);
};
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So what I want to do here is to mock MyRole2::call to return a static document, defined in my test fixtures, that contains errors and test that the exception is thrown properly. I know how to test it using Test::More::throws_ok or similar. What I don't know how to do is to mock MyRole2::call and not MyClass2::call.