tests: refactor: tidy up util functions (#1491) #1533

1. 
   theStack commented at 1:25 am on May 27, 2024: contributor

   This PR is an attempt at tidying up test util functions, as suggested in #1491. The following changes are done:

   • rename _group_element... functions to _ge...
   • rename _field_element... functions to _fe...
   • move random_ helpers from tests.c to testutil.h (the alternative would be testrand.h, but to my understanding, this one is meant to contain the actual RNG implementation rather than helpers using it; happy to move the helpers there if that is preferred though)
   • prefix testutil.h functions with testutil_
   • prefix testrand.h functions with testrand_ (this is currently done in a sloppy way by simply dropping the secp256k1_ prefix, so some functions don’t have the full prefix, like e.g. testrand256; naming suggestions welcome)
2. tests: refactor: rename `random_group_element_...` -> `random_ge_...`

   The rename was done with the following command:
   
   $ sed -i 's/random_group_element_/random_ge_/g' $(git grep -l random_group_element_)

   59db007f0f
3. tests: refactor: rename `random_field_element_magnitude` -> `random_fe_magnitude`

   Note that the already existing function `random_fe_magnitude` is removed
   and the call-sites are adapted to pass the magnitude range of 8
   (the maximum for secp256k1_fe_mul and secp256k1_fe_sqr) explicitly.

   0fef8479be
4. tests: refactor: move `random_` helpers from tests.c to testutil.h

   Can be reviewed via `--color-moved=dimmed-zebra`.

   0c6bc76dcd
5. tests: refactor: add `testutil_` prefix to testutil.h functions 0ee7453a99
6. tests: refactor: drop `secp256k1_` prefix from testrand.h functions

   The rename was done with the following command:
   
   $ sed -i 's/secp256k1_testrand/testrand/g' $(git grep -l secp256k1_testrand)

   e73f6f8fd9
7. theStack force-pushed on May 27, 2024
8. real-or-random approved
9. 
   real-or-random commented at 12:34 pm on May 27, 2024: contributor

   utACK e73f6f8fd9158a044c6fb22653105446f3542bb0
10. real-or-random added the label assurance on May 27, 2024
11. real-or-random added the label refactor/smell on May 27, 2024
12. 
    sipa commented at 4:01 pm on May 27, 2024: contributor

    What is up with the macOS CI?
13. 
    real-or-random commented at 8:42 pm on May 27, 2024: contributor

    What is up with the macOS CI?

    See https://github.com/bitcoin-core/secp256k1/issues/1536

14. 
    real-or-random commented at 8:25 am on June 11, 2024: contributor

    @sipa Want to review this?
15. 
    sipa commented at 1:25 pm on June 12, 2024: contributor

    utACK e73f6f8fd9158a044c6fb22653105446f3542bb0
16. real-or-random merged this on Jun 12, 2024
17. real-or-random closed this on Jun 12, 2024

    ---

18. theStack deleted the branch on Jun 13, 2024

Contributors
theStack real-or-random sipa

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assurance refactor/smell