I don't see a problem with knowing more about a diagnosis and clarifying what you can see as your symptoms, but I wouldn't put too much faith in online tests really. Reading here or reading about the criteria for a disorder is a better way to become acquainted with it.

Actual diagnosis is a complicated and sometimes delicate matter. There are many different ways to do it. Some people do use various kinds of tests to help assess someone. These tests though need training and scoring to produce reliable results. And still they need to be interpreted by means of clinical skills.

A large number of providers use an intake interview/information to make a provisional diagnosis that then they refine or adjust. Some people are anti-diagnosis, but still provide one due to pressures from outside. It really depends. And clients vary widely on what having a diagnosis means to them.