That is the bummer about working for large companys, they test no matter what, smaller companys are out there that only test if there is suspision or an accident. Thats what the 2 places I work for do. I wish you luck bro, & God has not turned his head on you , He is teaching you something believe it or not, Wisdom. Your right at that age where you will be making choices that will effect the rest of your life.
A buddy of mine went thru the same thing with AAA, he was told he was going to be tested & he just flat out told the truth, he said, " I have smoked recently and I am willing to test again to prove Im not doing it, they agreed and did the test after his probation 60 day period, he passed and his life is better than it ever was making good $$ & not working at a movie theater so to speak.
Im not against weed I think it somewhat of a tool to use to deal with stress n stuff in hard times but the laws dont think that, although it wont get you ahead in life to your full potential. JMO
Again I wish you the best bro, when Im feeling left out I always watch this video, it reminds me why we are really here. A friend of mine created this video, its touching for spirited people.
http://vimeo.com/8898059