selenium webdrive. What to test and what expected result can be?

Question

Java

Hello. I am only learning to use and understand the essence of SWD and I want to learn something from experts. Let's say I want to check the search or selection of goods in an online store, as we do it clearly: we look for xpath elements, enter data and submit. OK. Something went to look for. How to check that the selection or search was successful? Well, maybe the function found complete nonsense and not at all what it requires. How to be? Or let's say how to check that this or that error popped up when the information was entered incorrectly?

Answer 1

the fact of finding is checked, and not the content
or one-to-one correspondence
, in other words - tests should work where necessary, and not work where it is not necessary, both those and those options are written

Answer 2

What is meant by a function that returns incorrect information? Query?
If so, then at least we can create an array with expected results and check in regression that the selection will match and the query has not broken.
About the error:
Depending on how this error is caused. In the form of a normal, roughly speaking, html-window or through AJAX-modal.
In both cases, you can get the content of the window and verify its content.