Show example of using package tests as workload(s)?

Thanks for this useful package!

It seems workloads would (should?) be redundant with things also run in the tests. Could the workload include() (certain) tests?
E.g.
```julia
include(joinpath(@__DIR__, "test", "common_calls.jl"))
```

I don't know if `using Test` could be eval'd in the setup, or if this would require Test to be an actual dep of the package (usually undesireable).

I.e., I'd envision runtests.jl to include() the individual test set files, as is done with many packages. Then the workload could include() a subset of those.

I suppose I could test this idea out.

Just a thought.