How to test if she likes me by making her blush?

Sincere compliments.

Well, before I got with my boyfriend, he used to be my best friend, and every time he got close to me then I would blush. Also when he teases me and flirts with me casually (like putting a starburst in his mouth and asking me if I wanted half). Though he didn't notice it before he took interest in me, I blushed around him all the time. Whenever he gives flattering compliments I sometimes blush as well. It depends on the girls as well. Some girls blush over everything, and others rarely blush unless the boy gets too close.

Probably if you tell her how beautiful/pretty she is in front of a lot of people or just wink at her and see what she does.

Well I blush VERY easy but when I do its because someone special made it happen I would say holding my hand or cuddling but if your testing this girl and don't really like her then just look into her eyes and smile that works every time or it should good luck!

Walk by her very closely and look her in the eyes and in a deep voice with a smile say, "Hey"

Either she'll blush and look annoyed, works every time - then ya know