...

my $run = $des->_run_end();
is $run, undef, "_run_end() is undef when called out of context";
 
$run = $des->_run_end(1);
is $run, 1, "_run_end() sets itself to true properly";
 
$run = $des->_run_end(0);
is $run, 0, "_run_end() sets itself to false properly";