@testset Scope

[lukem12345]

During last week's hackathon, a non-negligible amount of developer time was spent tracking down the following error:

• A @test was written which assigned a local variable the name d
• A later test loaded CombinatorialSpaces with using CombinatorialSpaces
• CombinatorialSpaces exports a function for the exterior derivative d
• Later code trying to allocate an exterior derivative matrix threw an unhelpful error message
• Moving the order of the @testsets meant that a helpful error message was thrown at the line where the local variable d was declared

Errors in our test suite should not depend on the order in which testsets are included. Each testset should be contained.

So, we should look into how to prevent this behavior. I immediately want to use let ... end blocks, but it appears that there is some advice on testset scoping that I haven't fully grasped: https://discourse.julialang.org/t/testset-scoping/17025
Perhaps we have poor module management in the test suite.

[lukem12345]

On the topic of test management, we should consider executing testsets in parallel. In the best case this can reduce the time spent testing from sum(time.(tests)) to maxmimum(time.(tests)).