I think I have adult adhd, what's the best online test?

No Single Test 4 Dx. Many people don't realize that there's no specific test that confirms diagnosis of attention-deficit/hyperactivity disorder (w/ or w/out hyperactivity). Important 2 rule out difficulties associated w/same symptoms of adhd, incl. Medical conditions, depression, anxiety, etc. Adhd can also be diagnosed in conjunction w/other conditions. 4 mayo clinic on adult adhd see http://mayocl.In/o69pd0.
Clinical Diagnosis. As per the previous answer - there's no test that diagnoses adhd. The key to diagnosis is a good psychiatric evaluation that considers other explanations for your symptoms. Testing can help support a diagnosis, but the diagnosis is always on the basis of clinical judgment.