'test' functions as an adjective. 'result' functions as a noun. The subject is 'My test result' or 'My test results'. The verb is 'is' for singular nouns and 'are' for plural nouns.
1. My test result is pretty good.

(One result)
2. My test results are pretty good.

(More than one result/test)
3. My tests results are pretty good.
4. My tests result are pretty good.
All the best,
