test coverage: Ignore "mod tests" sections from (only unit-tested) coverage computation

[nrainer-materialize]

Feature request

Ignore unit test code from coverage computation, in particular, from "only unit-tested but not higher-level tested".

Example:

@@ -792,13 +781,6 @@ mod tests {
         let s1_state1 = states
             .get::<(), (), u64, i64, _, _>(
                 s1,
!                || {
!                    let did_work = Arc::clone(&did_work);
!                    async move {
!                        did_work.store(true, Ordering::SeqCst);
!                        Ok(new_state(s1))
!                    }
!                },
                 &Diagnostics::for_tests(),
             )

https://buildkite.com/materialize/coverage/builds/182

[nrainer-materialize]

@def-, could it be that you have already addressed this?

[def-]

Nope, I changed nothing about this.