The project implied development of payment modules to be quickly installed in site engines 1C-Bitrix and WordPress to provide prompt integration of the payment system into these CMSs. We may not disclose the name of the payment system, as it should be kept confidential according to the non-disclosure agreement (NDA).
One of payment processing companies (a payment aggregator) approached us to outsource the creation of modules for easy integration of the payment system into popular CMSs, specifically into 1C-Bitrix and WordPress.
If everything is clear with the WordPress site creation engine, and its popularity helps in solving any problems related to the development of its functionality, then 1C-Bitrix took much more time to create a working module.
The main challenge was in the requirements for the module to work on older versions of this CMS. For testing it was necessary to find many versions and test each change or fix in all versions at the same time. It should be mentioned that just finding the distribution kit of an old version is a problem.
As a result, we took into account all wishes of the client, performed a lot of tests, adjusted the module versions for different versions of the CMS, and helped the client with publication in the app stores.