eth_simulateV1: spec conformance fixes (86/91 tests passing)

[ivanzzeth]

Summary

eth_simulateV1 (added in #10227, #11253) has several spec conformance issues when tested against the official ethereum/execution-apis test suite. Before fixes: 46/91 passed. After fixes: 86/91 passed (94.5% conformance).

Issues Found and Fixed

1. Wrong error codes (fixed 14 tests)

The spec defines custom error codes for eth_simulateV1 that anvil was not using:

• -38012 BaseFee too low → was returning -32003
• -38013 Intrinsic gas too low → was returning -32000
• -38014 Insufficient funds → was returning -32003
• -38020 Block numbers not in order → not validated
• -38021 Block timestamps not in order → not validated
• -38022 movePrecompileToAddress self-reference → not validated
• -38026 Too many blocks → was returning -32603

2. Transaction build failure on missing to field (fixed 9 tests)

When a call has no to field (empty {} or create-style tx), EVM execution succeeds but post-execution build_unsigned() fails because it requires to. Fixed by setting TxKind::Create when to is missing.

3. Missing block number/timestamp ordering validation (fixed 8 tests)

The spec requires:

• Block numbers must be strictly increasing (error -38020)
• Block timestamps must be strictly increasing (error -38021)
• Intermediate empty blocks generated when block number gaps exist

4. validation: true mode broken (fixed in prior commit)

build_call_env() unconditionally sets disable_nonce_check = true, disable_base_fee = true, disable_block_gas_limit = true. When validation: true, these should be re-enabled per the spec.

5. Missing movePrecompileToAddress validation (fixed 3 tests)

• Source must be a precompile (0x01-0x09), else error -32000
• Source ≠ destination, else error -38022

6. Future block returns wrong error code (fixed 2 tests)

When block parameter references a block beyond head, should return -32000 "header not found", was returning -32602.

7. parent_hash always zero in multi-block simulation (fixed)

Multi-block simulation had parent_hash: Default::default() for all blocks instead of chaining from previous block.

8. Revert error missing output data (fixed)

SimulateError was missing the data field with revert bytes.

Remaining 5 Failures

Test	Root Cause
blocknumber-increment	Timestamp env-dependent: spec expects genesis-based timestamps (~462) but anvil uses wallclock
use-as-many-features-as-possible	Same timestamp issue
eth-send-should-produce-more-logs-on-forward	CALL+value forwarding behavior difference
overflow-nonce-validation	revm returns NonceTooLow instead of NonceMaxValue on overflow
run-out-of-gas-in-block-38015	Per-block gas accounting not enforced in simulation mode

Spec Test Runner

Included a Python runner script that downloads and runs all 91 official spec tests against a running anvil instance. Can be used as CI regression gate.

How to reproduce

# Start anvil and mine 45 blocks to match spec test expectations
anvil --port 18547 &
cast rpc anvil_mine 0x2d --rpc-url http://localhost:18547
# Run spec tests
python3 crates/anvil/tests/it/spec_eth_simulateV1/run_spec_tests.py http://localhost:18547