Yes, tested is a Scrabble word!

Adjective

1. Tested and proved useful or correct

2. Tested and proved to be reliable

Verb

1. Put to the test, as for its quality, or give experimental use to

2. Test or examine for the presence of disease or infection

3. Examine someone's knowledge of something

4. Show a certain characteristic when tested

5. Achieve a certain score or rating on a test

6. Determine the presence or properties of (a substance)

7. Undergo a test