You really need to learn how to read the situation. This is something you will learn to calibrate simply by going out a lot and opening or interacting with a lot of sets.
However, a "Shit Test" is not simply a girl giving you shit. A perfect example of that would be a girl unwarrantedly becoming overly sexual with you. Meaning you haven't done anything to earn her sexually explicit advances. You do not want to buy into the frame she is imposing on you. For if you do she will know you are there with sexual intent and can then easily dismiss you. If it seems too easy it probably is.
If a girl is giving me shit and it is done in a playful manner I consider that to be flirting especially since I usually set the that frame from the get go. If it is done playful it is fine to react but never in a negative way otherwise you will look like you can't take a joke and you will be less attractive. Again it is about calibration.
When a girl is giving shit in a somewhat negative way being unaffected by the statement is good advice. However, don't overlook this excellent opportunity to disqualify yourself, a very strong attraction technique. An example of this would be:
HER: You a very sharp dresser are you gay?
ME: Ha no I'm not gay but this guy I was banging in the ass the other day, boy was he gay. He totally wanted to cuddle after. What a faggot!
I am showing her that I am not cut to the core by her statement as well as disqualifying because by saying something like that I am essentially saying that I don't care if she thinks I am gay. This is something that in her mind a guy who is hitting on her would probably not do. This is also a great tactic to disarm AMOG's.
The main focus here for you is know the seduction model, know where you want to take the interaction, and maintain
frame control while you avoid letting her impose frames on you. If you have some natural game and were not socially inept before learning this stuff don't bail on that knowledge. You know how to interact with people so don't become some stubborn guy who is so afraid to show any compliance. Girls will get frustrated in these situations and become totally turned off by you. Also don't get bent around the axle over "Supplication." If social etiquette makes not complying to something that would create supplication socially awkward, you stand to loose more value by not complying than you ever would through compliance. An example would be that you isolate a girl from her group by having her follow you to the bar so you can get a drink. It might make you look cheap if once there you don't offer to get her one. This is true provided she didn't tell you to buy her one before leaving the group or doesn't already have an amply filled one in her hand.