Frequently at writing classes and conferences that I have attended, the instructors will encourage attendees to take the Briggs Meyers personality test. They also stress the importance of taking the personality test for each main character in our novels.
For fun, I just took the test. It was interesting. I thought some of the questions could have been answered both ways.
Have you ever taken a personality test? If you are a writer, have you used this to learn more about your characters?