Only way to test short duration is if their API allows for short duration. Some gateways allow for as short as 1 day duration. If 7 days is the minimum then unfortunately you have to wait 7 days, but since you're using the scheduler you can try manually changing scheduler_next_maturity within _cbsubs_payment_baskets to try and force it to trigger sooner.

Did you modify scheduler_next_maturity to be in the past? Basically set it to be a couple minutes after the subscription date and that should allow it to be checked against. Beyond that I don't know what to tell you. We don't provide custom development support. I recommend reviewing CCBill or Moneris Select Plus carefully which are using the scheduler.

Just to explain a bit our process regarding gateways consider the following. It takes thousands of dollars for us to develop a gateway and typically 1 to 2 months worth of time (it needs HEAVY security review and testing). 1/2 to 3/4th of that time is often entirely on recurring implementation as single payments are almost always universally simple to implement. It's not a simple task that can just be explained in a support topic. It also puts all other projects on hold while being developed. It is often just flat out not worth it financially for us to do that unless we can guarantee some customers have committed to purchasing CBSubs or funding the implementation (if time permits on our end, which at the moment it does not) to offset the steep price of implementation. It'd be one thing if that's all we provided (a subscription manager), but we've over 25 different projects including core CB to maintain so we have to pick and choose carefully what time is spent on and often when it comes to gateways it's better for us to invest in less niche markets like Stripe and PayPal which support a large amount of countries out of the box.

Where I am stuck right now is that I do not know if the attached payments are correct? Should there be two lines for the same basket - one for the subscription and one for the actual payment or is this a bug I have made in the gateway ? If there should only be one line, then maybe that is the reason why the recurring payment is not triggering afterwards.

It looks like there was a status change for the payment. I don't know what that says under Status, but it's possible for a payment to go from pending to completed. What doesn't make much sense is they have 2 different transaction ids. So there could be an error in the implementation unless for some reason they clear payments with a different transaction id from the original.