use Perl

I tried to cover in my last post the basic guidelines I have for testing in POE. Testing in POE is different since we want to test a flow and not just subroutines. This time I want to try go over the first type of tests that I find necessary. It's called ordered tests - at least that's how I call it.

This method was first hinted at me by the great Adam Kennedy who used it in his POE::Declare module. Basically it describes the following scenario: I have a POE::Session event flow and I want to make sure that every event is run at the specific order.

package MyPackage;
use MooseX::POE;
use Test::More;

# this is taken from POE::Declare's t/04-stop.t
my $order = 0;
sub order {
    my $position = shift;
    my $message  = shift;
    is( $order++, $position, "$message ($position)" );
}

# then we can do this (written in MX::POE)
event 'eg' => sub {
    order( 0, 'Started eg event' );
};

Now, each event could run this subroutine with a number indicating the order of this event in our overall flow of the session. Here, for example, with the order( 0, 'event name' ) code if any event is running at a time that wasn't meant for it, it will fail.

However, it has a few disadvantages:

• If any of the events repeat, it creates a problem. You'll have to set up a system to check which iteration of the event it is and execute the correct order()
• What if you're yelding the kernel for two events and you aren't sure which one will run first?
• What if it doesn't matter which one will run first?
• What about running two sessions of the same object? It has the exact same events, with the exact same code. It will fail for sure.

My suggestion: allow a test that checks for event dependency. Instead of saying "this runs first", you could say "this runs ONLY after that" and "this - this runs only after these two". That would allow to have an order based on a sequence of events. Each event can only come after different events.

This is what the next post will discuss.