block header validation in context of blockchain test

[winsvega]

🗒️ Description

this is a unit test setup for blockheader schema validation in context of blockchain tests

it sets up a fork for validation of blockheader model.
and a unit test that will check missing or extra fields errors

🔗 Related Issues

#940

✅ Checklist

• All: Set appropriate labels for the changes.
• All: Considered squashing commits to improve commit history.
• All: Added an entry to CHANGELOG.md.
• All: Considered updating the online docs in the ./docs/ directory.
• Tests: All converted JSON/YML tests from ethereum/tests have been added to converted-ethereum-tests.txt.
• Tests: A PR with removal of converted JSON/YML tests from ethereum/tests have been opened.
• Tests: Included the type and version of evm t8n tool used to locally execute test cases: e.g., ref with commit hash or geth 1.13.1-stable-3f40e65.
• Tests: Ran mkdocs serve locally and verified the auto-generated docs for new tests in the Test Case Reference are correctly formatted.

[winsvega]

But in any code if we don't provide fork value to FixtureHeader before pydantic validation, it will not validate the corectness of the fields.

there is one approach is the we derive fork field when validating FixtureHeader by looking at what fields are there.
and then on blockchain fixture level we will verify the header fork value.
but that requires rethinking FixtureHeader validation style.

[marioevz]

Looks good overall, just a minor suggestion to make this more future-proof. Thanks!

[marioevz]

We could use get_forks to make the fork resolution by name more dynamic.

Suggested change

	from ethereum_test_forks import (
	Cancun,
	Constantinople,
	Fork,
	Frontier,
	Homestead,
	Istanbul,
	Paris,
	Prague,
	)
	from ethereum_test_forks import Fork, Paris, get_forks

And then simply define something like:

all_forks_by_name = {fork.name(): fork for fork in get_forks()}

[marioevz]

Suggested change

	if network == "Frontier":
	header["fork"] = Frontier
	elif network == "Homestead":
	header["fork"] = Homestead
	elif network == "Constantinople":
	header["fork"] = Constantinople
	elif network == "Istanbul":
	header["fork"] = Istanbul
	elif network == "Paris":
	header["fork"] = Paris
	elif network == "Cancun":
	header["fork"] = Cancun
	elif network == "Prague":
	header["fork"] = Prague
	if network in all_forks_by_name:
	header["fork"] = all_forks_by_name[network]

Follow up to the previous comment.