How to automate the performance check of improvements after the update in CMS/Bitrix 24?

Question

Software testing

I sometimes carry out improvements in some sites on popular CMS or in Bitrix 24. Sometimes, after updating the core or modules, the element itself disappears or its performance "breaks".
For example, I made a new button with some functionality in the left Bitrix menu, the customer updated the portal and all modules - the button disappeared. Sometimes it happens that the element remains, but the functionality implemented by means of JS (pop-up window) no longer works.
When there are at least 2-3 dozen improvements on one portal, then after the updates you can quickly go over and check everything with your hands. If there are several projects and in some the number of minor improvements has exceeded 4 hundred ...
I am ready to spend on each revisionstill time and describe some scripts, tests, just to be guaranteed to check the performance of at least 90-95% of all improvements.
Ideally, monitoring should be daily. For example, run a cron check every night for each site/portal separately. But a simple solution for a one-time manual launch, which will be carried out after each update, will also suit.
What are the options for solving the problem?

Answer 1

What are the options for solving the problem?

1. Write autotests.
   Judging by the text of the question, you already know this, but then it is not clear what the problem is.

Answer 2

Are you sure that you are writing the code correctly following the Bitrix recommendations?
It sounds like you are editing a menu component/template directly in the /bitrix/components/menu/ folder. If so, it's no surprise that when you upgrade, all your changes are gone.
For several years of development on Bitrix, there has never been a situation in which my custom components / templates / modules stopped working after updating Bitrix (maybe there were 1 or 2 times, but I don’t remember this).