Use describe/it to creater smaller tests

[averissimo]

WIP

Closes #

Changes description

• Use {testthat} describe() and it() functions to move towards more tests that have a smaller scope.
  • test-auxiliary is the best example
  • other are rewrites that prefer using these function instead of multiple test_that() calls with same prefix

Definition of done

• Have you read the Contributing Guidelines?
• NEWS.md file has been updated
• Development version has been bumped (x.y.z.90XX)
• Issue has been linked with this PR (via Closing keywords or right sidebar under Development)