use strict;
use Test::More tests => 3;
sub foo {}
my $i;
BEGIN { $i = 0; }
sub callback { $i++ }
\&foo => \&callback,
\&foo => \&callback,
\&callback => sub {};
BEGIN { is($i, 0) }
foo();
BEGIN { is($i, 2) }
no B::Hooks::OP::Check::EntersubForCV \&foo;
BEGIN { is($i, 2) }