new(tests): EOF - EIP-3540 EXTCODE* mid-creation

Tests ipsilon/eof#128

tests/prague/eip7692_eof_v1/eip3540_eof_v1/test_extcode.py

@@ -1,6 +1,8 @@
 """
 test execution semantics changes
 """
+from typing import List
+
 import pytest
 from ethereum.crypto.hash import keccak256
 
@@ -77,3 +79,73 @@ def test_legacy_calls_eof_sstore(
         post=post,
         tx=tx,
     )
+
+
+smallest_runtime_subcontainer = Section.Container(
+    container=Container(
+        sections=[
+            Section.Code(code=Op.STOP),
+        ],
+    )
+)
+empty_code_hash = "0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470"
+
+
+@pytest.mark.parametrize(
+    ["opcode", "expected_result", "call_suffix", "load_code"],
+    [
+        pytest.param(Op.EXTCODESIZE, "0x00", [], b"", id="extcodesize"),
+        pytest.param(Op.EXTCODEHASH, empty_code_hash, [], b"", id="extcodehash"),
+        pytest.param(Op.EXTCODECOPY, b"", [0, 0, 32], Op.MLOAD(0), id="extcodecopy"),
+    ],
+)
+def test_extcode_mid_creation(
+    state_test: StateTestFiller,
+    pre: Alloc,
+    opcode: Op,
+    expected_result: bytes,
+    call_suffix: List[int],
+    load_code: bytes,
+):
+    """
+    Verifies behavior of EXTCODE* opcodes when they target EOF contract mid-creation.
+    """
+    env = Environment()
+    sender = pre.fund_eoa()
+    callback_address = pre.deploy_contract(
+        code=opcode(Op.CALLDATALOAD(0), *call_suffix) + load_code + Op.SSTORE(0, unchecked=True),
+        storage={0: 0xB17D},  # a canary to be overwritten
+    )
+    contract_address = pre.deploy_contract(
+        code=Container(
+            sections=[
+                Section.Code(
+                    code=Op.SSTORE(0, Op.EOFCREATE[0](0, 0, 0, 0)) + Op.STOP,
+                    max_stack_height=4,
+                ),
+                Section.Container(
+                    container=Container(
+                        sections=[
+                            Section.Code(
+                                code=Op.MSTORE(0, Op.ADDRESS)
+                                + Op.EXTCALL(callback_address, 0, 32, 0)
+                                + Op.RETURNCONTRACT[0](0, 0),
+                                max_stack_height=4,
+                            ),
+                            smallest_runtime_subcontainer,
+                        ]
+                    )
+                ),
+            ],
+        ),
+    )
+    # Storage in 0 should have the address,
+    post = {callback_address: Account(storage={0: expected_result})}
+    tx = Transaction(
+        to=contract_address,
+        gas_limit=10_000_000,
+        gas_price=10,
+        protected=False,
+        sender=sender,
+    )
+    state_test(env=env, pre=pre, post=post, tx=tx)