My product integrates with 3rd party websites. It does this on the backend level, not affecting the original UI in any way.
I'm looking for a solution to test that simple user actions are unaffected; basically, perform actions exactly the way a user would do, and see if they (still) work or not (by looking for specific error/success message in certain areas of the page).
Example: I write a tool that intercepts traffic sent to/from Amazon S3 and does things based on the content. Once I do deploy that tool, I need to be sure that users can still CRUD files using the browser in their S3 Amazon Console, the way they would normally do.
I'm new to this domain, so I don't even know what the reasonable starting points would be.
What tools should I consider / look into ?
Would Selenium be an option, considering that I have no control on the content & structure of the webpages where I test the functionality ?