@jagtalon @mwmiller I'm not able to reproduce that behaviour. I just tried removing the `is_cached` line from both Calculator.pm and t/Calculator.t and both `prove -I /lib t/Calculator.t` and `duckpan test` passed. 

@mwmiller try again and let me know if it throws the error. DuckPAN doesn't (shouldn't) be changing anything to do with `is_cached`. It ignores it for both the server and the tests.