Here's my example (because yours had several problems, e.g. switched $self and $orig in 'around'):

MyRole.pm:

package MyRole;
use Moo::Role;

sub foo {
    $_[1] ? 'true' : 'false';
}

__PACKAGE__
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MyClass.pm

package MyClass;

use warnings;
use strict;

use Moo;
with 'MyRole';

around foo => sub {
    my $orig = shift;
    my $self = shift;
    my $value = $self->$orig(@_);
    return 'true' eq $value ? 'probably' : $value
};

__PACKAGE__
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To test the role, just create its consumer:

#!/usr/bin/perl

{   package ConsumerOf::MyRole;
    use Moo;
    with 'MyRole';
}

use Test::Spec;
use Test::Exception;

describe MyRole => sub {
    my $o;
    before each => sub {
        $o = 'ConsumerOf::MyRole'->new;
    };

    it 'knows the foo method' => sub {
        lives_ok { $o->foo };
    };

    it 'foos truth' => sub {
        is $o->foo(1), 'true';
    };

    it 'foos false' => sub {
        is $o->foo(0), 'false';
    };
};

runtests();
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To test the class, just test its behaviour. The fact that it wraps the role is an implementation detail.

#! /usr/bin/perl
use Test::Spec;

use MyClass;

describe MyClass => sub {
    my $o;
    before each => sub {
        $o = 'MyClass'->new;
    };

    it 'instantiates' => sub {
        isa_ok $o, 'MyClass';
    };

    it 'returns false' => sub {
        is $o->foo(0), 'false';
    };

    it "isn't sure" => sub {
        is $o->foo(1), 'probably';
    };
};

runtests();
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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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