Make Phase0 -> Altair fork transition tests compatible with Altair -> Merge

[hwwhww]

Issue

I really want to reuse test/altair/transition/ tests instead of duplicating it for Merge fork transition.

How did I fix it

High-level

1. Add ForkMeta dataclass for passing pre_fork_name, post_fork_name and fork_epoch.
2. Replace @fork_transition_test(PHASE0, ALTAIR, fork_epoch=2) with @with_fork_metas(Sequence[ForkMeta]).
3. Replace do_altair_fork with do_fork, which handles both Altair and The Merge updates.

Decorators

1. Modify build_transition_test into yield_fork_meta.
2. Modify with_phases:
   • Refactoring:
     • Replace the if PHASE0: ... if ALTAIR: ... code with for-loop. The phases should be been limited with DEFAULT_PYTEST_FORKS.
   • Add for fork_meta in fork_metas loop to run test cases for each fork meta.

Other

• Make test_transition_with_voluntary_exit_* only run with minimal presets.
• Make transition test generator run with Merge.

Note

• Run pytest with --fork=phase0 will get you Phase0 -> Altair fork transition; run pytest with --fork=altair will get you Altair -> Merge fork transition.

---

TODO

• Verify the test vectors.

[ralexstokes]

still digesting but so far it looks great! one general comment is that this would be easier to review if it split apart the various concerns.

I see the following that could be N separate PRs:

1. refactor of with_phases and additional typing in that file
2. the extension of the fork transition tests to re-use them across multiple pairs of forks/phases

The with_phases refactor isn't huge but it is an important enough function to the integrity of the spec tests that changes to it should be very carefully reviewed! It would be a bit nicer to be able to consider it independently without the cognitive load of the other changes to the fork transition testing.

No worry on this PR but it is something to keep in mind in the future :)

[ralexstokes]

this looks great!

i like that we can reuse the fork transition tests across multiple pairs of forks.

i left some things below, lets address those and then i'll make another round of review... in particular, it would be good to see the tests actually generated, so we can see all of the new code exercised

[ralexstokes]

lgtm!

ill verify if we have verified the test vectors, otherwise i think we can ship this

[hwwhww]

tarball files of the transition tests (only make gen_transition) at 63c9e5e (at current dev branch head commit: fb34e16):

mainnet.tar.gz
minimal.tar.gz