Are you saying you are not required to submit urine tests as a condition of your probation? If not, then I am not sure about what you are concerned. You can only be revoked for violating a term of your community supervision.
When something like your "bladder fright" happens, though, its much easier on you to appear very soon afterwards, like the next morning, to make a god faith effort to pee in the cup for them. Of course, this asumes you do not have anything in your system that would implicate you in some other bond violation.
18 months is a long time. If you are already having problems, maybe you should meet with your lawyer and revisit your sentence. If it is within 10 days of your plea, you can try to change your sentence to a jail term. You may also be able to negotiate a jail term for a surrender of your probationary term. This is all up to the discretion of the judge.
I assume your questions is whether you will be revoked? It depends on how you left things with your probation officer. If you went awol, he could file a violation. "Refusing" to provide a UA is the same as failing a UA. He will say if you had stayed he would have given you more chances or simply rescheduled you. You need to contact him immediately if you left things up in the air.
The PO would not be giving you a UA if it was not a condition of probation. Sometimes no alcohol is a condition of DWI probation, and they do UA for that.
I doubt a judge would grant a motion to revoke for this reason, but if the PO files it you still have to go through the hassle and expense of being arrested and posting a bond on the pv. If you believe a pv is being filed, I would contact an attorney immediately. Sometimes this can be cut off at the pass by approaching the judge and letting her know what's going on.
If everything is not squared away with your PO, contact an attorney as soon as possible.
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