For what is worth and being somewhat answered already I apologize for chiming in...
I have an alphabet friend and we've had discussions about this very topic regarding not just test but pain killers, cancer drugs etc...
@Millard Baker is absolutely correct that 99% of the battle is getting it home and though there is still risk, it is minimized a great deal.
As for having script and having other products that are not exactly what you were prescribed and them not being in their original container, you can still get in trouble but will more than likely get the case dismissed. This is in regards to personal possession of course and not having a bottle of Tren or some mix when you have a Rx for test.
I've been pulled over and charged with possession of a controlled substance, pain killers. I have a script that I get monthly from my doc, 240/mo at that. The case was dropped but that was only because I had the same tabs as from the pharmacy I filled my script.
If I fill at Walgreens, which carry Watson, for the past few months and have the yellow qualitest tabs in my possession in that bottle or any other bottle you can still get pinched and run the possibility of not getting out of it, altho more than likely would only get a small fine and supervision.
I have had instances where they have actually counted to see how many I've had in the bottle abs then done the math as to how many should be left. If there's a lot more missing than should be per prescription instructions then I could've been charged with dwi and/or abusing the controlled substance.
It's a large gray area that can be manipulated at the cop or agents discretion. More often than not, as long as you're not on anyone's radar for distro the DA will either drop it or let you plea out to a lesser and get you on your way. Sorry for the novel guys