new(tests): Blockhash at 255/256/257 (ethereum/execution-specs#374)

tests/frontier/opcodes/test_chain_sync.py

@@ -0,0 +1,70 @@
+"""
+abstract: Test the chain synchronization feature.
+    Ensure that the chain synchronization feature accurately validates the transaction chain
+"""
+
+import pytest
+
+from ethereum_test_forks import Frontier, Homestead
+from ethereum_test_tools import Account, Alloc, Block, BlockchainTestFiller, Environment
+from ethereum_test_tools import Opcodes as Op
+from ethereum_test_tools import Transaction
+
+
+@pytest.mark.parametrize(
+    "offset,expected",
+    [
+        (254, 0x59E4655F093809C72B7655D2C4E17A29E1AFC868D50D074AE33FAE4FF7F45B57),
+        (255, 0x3B37DF5B367774496FEB057125414B8B02C6A16BE37C5CFEE48F6EA310476895),
+        (256, 0xCA4B3DF81146433C8B710608B2AE7D59CB949F721D87DDBA579339E9452188F1),
+        (257, 0x0),
+    ],
+)
+@pytest.mark.with_all_evm_code_types
+@pytest.mark.valid_from("Frontier")
+@pytest.mark.valid_until(
+    "Frontier"
+)  # Can only do one right now because of how hashes change between forks
+def test_blockhash(
+    offset: int, expected: int, blockchain_test: BlockchainTestFiller, fork: str, pre: Alloc
+):
+    """
+    Tests the BLOCKHASH opcode when the blocks are in extreme positions near the limit of the chain
+
+    Note: Hardcoded blockhashes to get us started. Will look for a better
+    way of doing this in future
+    """
+    env = Environment()
+    sender = pre.fund_eoa()
+    blockhash_code = Op.SSTORE(
+        0,
+        Op.BLOCKHASH(Op.SUB(Op.NUMBER, offset)),
+    )
+    generated_blocks = [Block() for _ in range(offset - 1)]
+
+    # Deploy the contract to the chain (to be called later)
+    account = pre.deploy_contract(blockhash_code)
+    post = {
+        account: Account(
+            storage={"0x0": expected},
+        ),
+    }
+
+    blockhash_transaction = Transaction(
+        ty=0x0,
+        nonce=0,
+        to=account,
+        gas_limit=500000,
+        gas_price=10,
+        protected=fork not in [Frontier, Homestead],
+        sender=sender,
+    )
+
+    blockhash_block = Block(txs=[blockhash_transaction])
+
+    blockchain_test(
+        env=env,
+        pre=pre,
+        post=post,
+        blocks=generated_blocks + [blockhash_block],
+    )