I may not be the best person for this question since I don't consider myself to have a favorite author! I'm always trying new writers out! But for me it's not a matter of testing the author, rather just finding a book intriguing on its own.
My best examples are these:
1) I love horror and I enjoy Stephen King. But I've not read even half his work. He's got a very distinctive voice and I find myself tiring of it (or anything overly recognizable or repetitive in fiction) after a story or two.
2) JK Rowling: LOVED the Harry Potter series. I grew up with them and still reread them. I think she has vast talent for YA and fantasy and world-building. Perhaps her adult novels are well written too. But I wouldn't know because while I adore her, her new books sounded dull to me personally, based on what I like to read, and so I didn't pick them up.
Oh, and back to the general topic: price is always a factor. I find it insane when an author is just starting out that publishers release the first book as hardcover only with a $20 or more price tag. At the library I may easily pick it up, but I very rarely buy books at their "new" cost unless I intend to keep it as a part of a collection - which would be unlikely with a new author since I've formed no opinion yet.