Tests: Reduce extra printing

[Andy Nowacki]

Rather than printing out that tests are being done, it is more usual to wrap each in a @testset, and also the whole set of tests too.

Consider removing the println and printstyled calls entirely and replace the println calls with named test sets. If there are any errors, you will see which test set errored immediately.

[Charlotte Haley]

See commit which uses@testset more.

[Andy Nowacki]

Thanks—this addresses my suggestion.