Most standardized drug tests do not test for psilocybin or psilocin the essential psychoactive substances. The standard drug test normally used by almost all corporate and sports testing programs check for these substances:
Cannabinoids (cannabis, hash)
Cocaine (crack, benzoylecgonine)
Amphetamines (methamphetamines, speed)
Opiates (heroin, opium, codeine, morphine)
Phencyclidine (PCP)
If a test is ordered specifically looking for psilocybin or psilocin it can be detected but ONLY if a specific test is ordered for it. Standard pre-employment tests do not include this because the tests are so expensive.