I would say it is more than obvious he is using again.
We do have drug testing in my relationship as an option. Both of us are recovering (me for 2 years, him for 9 years) and when we moved in together we have the stipulation that either of us can request a random test from the other at any time for any or for no reason at all. A positive test means we break up. A refusal to test counts as positive in our world. This is just something we agreed on because neither of us wants to be around active addiction. I think for us, it helps keep us honest. It is a deterrent for us. I don't think it works for most people. It's just that we know both of us are capable of relapse at any time, if we don't remain vigilant. It's an awful, awful disease. Get out if you can, or at least start attending alanon and reading all you can if you decide to stay.
Love,
KJ