new(tests): EIP-2935: Serve historical block hashes from state (#564)

* feat(forks): Add history contract to Prague

* new(tests): eip-2935: add file

* tests: eip-2935: new test

* fix(tests): EIP-2935: run HISTORY_SERVE_WINDOW tests

* chengelog

* refactor 1

* fix(fw): types: accept bool in `store_next`

* refactor 2

docs/CHANGELOG.md

@@ -16,6 +16,8 @@ Test fixtures for use by clients are available for each release on the [Github r
 - ✨ Add tests for [EIP-6110: Supply validator deposits on chain](https://eips.ethereum.org/EIPS/eip-6110) ([#530](https://github.com/ethereum/execution-spec-tests/pull/530)).
 - ✨ Add tests for [EIP-7002: Execution layer triggerable withdrawals](https://eips.ethereum.org/EIPS/eip-7002) ([#530](https://github.com/ethereum/execution-spec-tests/pull/530)).
 - ✨ Add tests for [EIP-7685: General purpose execution layer requests](https://eips.ethereum.org/EIPS/eip-7685) ([#530](https://github.com/ethereum/execution-spec-tests/pull/530)).
+- ✨ Add tests for [EIP-2935: Serve historical block hashes from state
+](https://eips.ethereum.org/EIPS/eip-2935) ([#564](https://github.com/ethereum/execution-spec-tests/pull/564)).
 
 ### 🛠️ Framework
 

src/ethereum_test_forks/forks/forks.py

@@ -508,8 +508,8 @@ def precompiles(cls, block_number: int = 0, timestamp: int = 0) -> List[int]:
     @classmethod
     def pre_allocation_blockchain(cls) -> Mapping:
         """
-        Prague requires pre-allocation of the beacon chain deposit contract for EIP-6110, and
-        the exits contract for EIP-7002.
+        Prague requires pre-allocation of the beacon chain deposit contract for EIP-6110,
+        the exits contract for EIP-7002, and the history storage contract for EIP-2935.
         """
         new_allocation = {}
 
@@ -542,6 +542,18 @@ def pre_allocation_blockchain(cls) -> Mapping:
                     },
                 }
             )
+
+        # Add the history storage contract
+        with open(CURRENT_FOLDER / "history_contract.bin", mode="rb") as f:
+            new_allocation.update(
+                {
+                    0x25A219378DAD9B3503C8268C9CA836A52427A4FB: {
+                        "nonce": 1,
+                        "code": f.read(),
+                    }
+                }
+            )
+
         return new_allocation | super(Prague, cls).pre_allocation_blockchain()
 
     @classmethod

src/ethereum_test_tools/common/types.py

@@ -252,7 +252,7 @@ def keys(self) -> set[StorageKeyValueType]:
         return set(self.root.keys())
 
     def store_next(
-        self, value: StorageKeyValueTypeConvertible | StorageKeyValueType
+        self, value: StorageKeyValueTypeConvertible | StorageKeyValueType | bool
     ) -> StorageKeyValueType:
         """
         Stores a value in the storage and returns the key where the value is stored.

tests/prague/eip2935_historical_block_hashes_from_state/__init__.py

@@ -0,0 +1,3 @@
+"""
+Cross-client EIP-2935 Tests
+"""

tests/prague/eip2935_historical_block_hashes_from_state/spec.py

@@ -0,0 +1,29 @@
+"""
+Defines EIP-2935 specification constants and functions.
+"""
+from dataclasses import dataclass
+
+
+@dataclass(frozen=True)
+class ReferenceSpec:
+    """
+    Defines the reference spec version and git path.
+    """
+
+    git_path: str
+    version: str
+
+
+ref_spec_2935 = ReferenceSpec("EIPS/eip-2935.md", "3ab311ccd6029c080fb2a8b9615d493dfc093377")
+
+
+@dataclass(frozen=True)
+class Spec:
+    """
+    Parameters from the EIP-2935 specifications as defined at
+    https://eips.ethereum.org/EIPS/eip-2935
+    """
+
+    HISTORY_STORAGE_ADDRESS = 0x25A219378DAD9B3503C8268C9CA836A52427A4FB
+    HISTORY_SERVE_WINDOW = 8192
+    BLOCKHASH_OLD_WINDOW = 256

tests/prague/eip2935_historical_block_hashes_from_state/test_block_hashes.py

@@ -0,0 +1,200 @@
+"""
+abstract: Tests [EIP-2935: Serve historical block hashes from state](https://eips.ethereum.org/EIPS/eip-2935)
+    Test [EIP-2935: Serve historical block hashes from state](https://eips.ethereum.org/EIPS/eip-2935)
+"""  # noqa: E501
+
+from itertools import count
+from typing import Dict, List
+
+import pytest
+
+from ethereum_test_tools import Account, Address, Block, BlockchainTestFiller, Environment
+from ethereum_test_tools import Opcodes as Op
+from ethereum_test_tools import Storage, TestAddress, Transaction
+
+from .spec import Spec, ref_spec_2935
+
+REFERENCE_SPEC_GIT_PATH = ref_spec_2935.git_path
+REFERENCE_SPEC_VERSION = ref_spec_2935.version
+
+FORK_TIMESTAMP = 15_000
+
+
+def generate_block_check_code(
+    block_number: int | None,
+    populated_blockhash: bool,
+    populated_contract: bool,
+    storage: Storage,
+    check_contract_first: bool = False,
+) -> bytes:
+    """
+    Generate EVM code to check that the blockhashes are correctly stored in the state.
+
+    Args:
+        block_number (int | None): The block number to check (or None to return empty code).
+        populated_blockhash (bool): Whether the blockhash should be populated.
+        populated_contract (bool): Whether the contract should be populated.
+        storage (Storage): The storage object to use.
+        check_contract_first (bool): Whether to check the contract first, for slot warming checks.
+    """
+    if block_number is None:
+        # No block number to check
+        return b""
+
+    blockhash_key = storage.store_next(not populated_blockhash)
+    contract_key = storage.store_next(not populated_contract)
+
+    check_blockhash = Op.SSTORE(blockhash_key, Op.ISZERO(Op.BLOCKHASH(block_number)))
+    check_contract = (
+        Op.MSTORE(0, block_number)
+        + Op.POP(Op.CALL(Op.GAS, Spec.HISTORY_STORAGE_ADDRESS, 0, 0, 32, 0, 32))
+        + Op.SSTORE(contract_key, Op.ISZERO(Op.MLOAD(0)))
+    )
+
+    if check_contract_first:
+        code = check_contract + check_blockhash
+    else:
+        code = check_blockhash + check_contract
+
+    if populated_contract and populated_blockhash:
+        # Both values must be equal
+        code += Op.SSTORE(storage.store_next(True), Op.EQ(Op.MLOAD(0), Op.BLOCKHASH(block_number)))
+
+    return code
+
+
+@pytest.mark.parametrize(
+    "blocks_before_fork",
+    [
+        pytest.param(1, id="fork_at_1"),
+        pytest.param(Spec.BLOCKHASH_OLD_WINDOW, id="fork_at_BLOCKHASH_OLD_WINDOW"),
+        pytest.param(
+            Spec.BLOCKHASH_OLD_WINDOW + 1,
+            id="fork_at_BLOCKHASH_OLD_WINDOW_plus_1",
+        ),
+        pytest.param(
+            Spec.BLOCKHASH_OLD_WINDOW + 2,
+            id="fork_at_BLOCKHASH_OLD_WINDOW_plus_2",
+        ),
+        pytest.param(
+            Spec.HISTORY_SERVE_WINDOW + 1,
+            id="fork_at_HISTORY_SERVE_WINDOW_plus_1",
+            marks=pytest.mark.slow,
+        ),
+    ],
+)
+@pytest.mark.valid_at_transition_to("Prague")
+def test_block_hashes_history_at_transition(
+    blockchain_test: BlockchainTestFiller,
+    blocks_before_fork: int,
+):
+    """
+    Test the fork transition and that the block hashes of previous blocks, even blocks
+    before the fork, are included in the state at the moment of the transition.
+    """
+    # Fork happens at timestamp 15_000, and genesis counts as a block before fork.
+    blocks: List[Block] = []
+    assert blocks_before_fork >= 1 and blocks_before_fork < FORK_TIMESTAMP
+
+    pre = {TestAddress: Account(balance=10_000_000_000)}
+    post: Dict[Address, Account] = {}
+    tx_nonce = count(0)
+
+    current_code_address = 0x10000
+    for i in range(1, blocks_before_fork):
+        txs: List[Transaction] = []
+        if i == blocks_before_fork - 1:
+            # On the last block before the fork, BLOCKHASH must return values for the last 256
+            # blocks but not for the blocks before that.
+            # And HISTORY_STORAGE_ADDRESS should be empty.
+            code = b""
+            storage = Storage()
+
+            # Check the last block before the window
+            code += generate_block_check_code(
+                block_number=(
+                    i - Spec.BLOCKHASH_OLD_WINDOW - 1
+                    if i > Spec.BLOCKHASH_OLD_WINDOW
+                    else None  # Chain not long enough, no block to check
+                ),
+                populated_blockhash=False,
+                populated_contract=False,
+                storage=storage,
+            )
+
+            # Check the first block inside the window
+            code += generate_block_check_code(
+                block_number=(
+                    i - Spec.BLOCKHASH_OLD_WINDOW
+                    if i > Spec.BLOCKHASH_OLD_WINDOW
+                    else 0  # Entire chain is inside the window, check genesis
+                ),
+                populated_blockhash=True,
+                populated_contract=False,
+                storage=storage,
+            )
+
+            txs.append(
+                Transaction(
+                    to=current_code_address,
+                    gas_limit=10_000_000,
+                    nonce=next(tx_nonce),
+                )
+            )
+            pre[Address(current_code_address)] = Account(code=code, nonce=1)
+            post[Address(current_code_address)] = Account(storage=storage)
+            current_code_address += 0x100
+        blocks.append(Block(timestamp=i, txs=txs))
+
+    # Add the fork block
+    current_block_number = len(blocks) + 1
+    txs = []
+    # On the block after the fork, BLOCKHASH must return values for the last
+    # Spec.HISTORY_SERVE_WINDOW blocks.
+    # And HISTORY_STORAGE_ADDRESS should be also serve the same values.
+    code = b""
+    storage = Storage()
+
+    # Check the last block before the window
+    code += generate_block_check_code(
+        block_number=(
+            current_block_number - Spec.HISTORY_SERVE_WINDOW - 1
+            if current_block_number > Spec.HISTORY_SERVE_WINDOW
+            else None  # Chain not long enough, no block to check
+        ),
+        populated_blockhash=False,
+        populated_contract=False,
+        storage=storage,
+    )
+
+    # Check the first block inside the window
+    code += generate_block_check_code(
+        block_number=(
+            current_block_number - Spec.HISTORY_SERVE_WINDOW
+            if current_block_number > Spec.HISTORY_SERVE_WINDOW
+            else 0  # Entire chain is inside the window, check genesis
+        ),
+        populated_blockhash=True,
+        populated_contract=True,
+        storage=storage,
+    )
+
+    txs.append(
+        Transaction(
+            to=current_code_address,
+            gas_limit=10_000_000,
+            nonce=next(tx_nonce),
+        )
+    )
+    pre[Address(current_code_address)] = Account(code=code, nonce=1)
+    post[Address(current_code_address)] = Account(storage=storage)
+    current_code_address += 0x100
+
+    blocks.append(Block(timestamp=FORK_TIMESTAMP, txs=txs))
+
+    blockchain_test(
+        genesis_environment=Environment(),
+        pre=pre,
+        blocks=blocks,
+        post=post,
+    )