The best and safest way to test that is creating a copy of your site somewhere else, not visible to actual visitors, and there test if updates break something or not. If you have done everything in your child’s theme and have not modified the original theme it is probably OK the retrocompatibility is a WordPress big concern, but well, better safe then sorry right?

There is a text explaining how to set up an development env that can help you out. In doubt you can always come back here ??