Splitting all_tests wrapper

[mjfh]

Running some unit tests in a separate file attempts to mitigate the global symbols overflow on Github ci when compiling with nim
version <= 1.2.

[arnetheduck]

the error in the test indicates that there are too many globals - the better fix would be to reduce the overall count of globals by moving them into test - this also makes for better tests that are more independent - in particular, it seems that the new collections are producing many globals

[mjfh]

Could you please explain or give an example? As far as I understand, the latest addition has not many globals. So it was just the literal straw that broke the camel's neck.

[arnetheduck]

3 things should be done:

• switch to unittest2 (this ensures each test runs in a separate proc, thus not creating globals) - this can be done for all tests in here
• code like https://github.com/status-im/nim-stew/blob/master/tests/test_interval_set.nim#L37 should be a const, not a let
• code like

  nim-stew/tests/test_interval_set.nim

  Line 111 in 4cab7b0

  let br = FancyRanges.init()

  should move into test or setup, else it creates a global

[mjfh]

ok, I see.

I guess unittest2 was avoided in order to reduce the imported packages? Otherwise i would prefer to use unittest2 and wrap in the main function wrapper.

[arnetheduck]

I'm guessing it hasn't been needed until now - @zah started using it in #122 (stew predates unittest2) - when migrating, it's best to do all unittests in one go so as to avoid issues - it's mostly doable with a search/replace of the import

[mjfh]

Well, then I prefer to do it now. I see that is the most clean solution.

It is widely used in nim-eth though there are pockets using testutils/unittest.

[mjfh]

.. or tomorrow morning :)

[mjfh]

superseded by #125