gistfile1.txt

use v6;
use Test;
use AttrX::PrivateAccessor;

...

eval-lives-ok q[
    use AttrX::PrivateAccessor;
    class Duplicate {
        has $!private is providing-private-accessor;

        method !private() {
            "Just need a private method";
        }
    }
}], "Collide as a private method with the same name already exists";

Without use AttrX::PrivateAccessor; of line 8:

# Failed test 'Collide as a private method with the same name already exists'
# at t/020-basic.t line 27
# Error: Can't use unknown trait 'is providing-private-accessor' in an attribute declaration.
# Looks like you failed 1 test of 3

with the use:

# Failed test 'Collide as a private method with the same name already exists'
# at t/020-basic.t line 27
# Error: Private method 'private' already declared in package Test::Duplicate
# Looks like you failed 1 test of 3