Employers have a wide range of tests they can perform on employees, it kind of depends on how much they want to spend. Many like a 5 panel(5 drugs usually THC, cocaine, PCP, opiates, amphetamines) test but they can test for 6,7,8,9,10 or even more. They can go with urine or saliva or hair. If it is urine they can add tests for dilution or adulteration. It is good that you ask about the test so you know which kind (urine, hair, saliva) but as far as which drugs they are testing for, if all you are doing is pot then you can almost bet your ass any test they perform will include pot.

What is your smoking history before Tuesday?