[test/vm] Replace evmc::MockedHost with an in-tree mock host

[khordadi]

Closes EXE-161, part of EXE-162. The VM unit tests no longer depend on evmc::MockedHost, so the vm::Host port (EXE-173) has one test host to move instead of two, and evmc::mocked_host leaves the test link line.

What changes. test/vm/utils/mocked_host.hpp replaces the test/vm/unit/runtime wrapper, which layered MIP-8 page tracking over evmc's mock. It implements vm::Host directly, including update_page, carries the page tracking over on the production compute_page_key, and keys its state on Address/bytes32_t; evmc types remain only where the vm::Host virtuals require them. It sits in monad-vm-test-utils so the fuzzer and benchmark targets can pick it up later without a new target.

Storage status. The EIP-2200 status is the one piece of logic rewritten rather than moved. mocked_host_tests.cpp checks the fifteen original -> current -> new transitions listed on evmc_storage_status; they partition the three values by zero-ness and pairwise equality, so the table is exhaustive. The runtime storage tests reach only the six clean-slot cases, and the spec comparison drives both VMs through the same mock, so neither would notice a wrong dirty-slot status.

Behaviour. No test-observable change. evm_fixture.hpp and monad_vm_interface_tests.cpp used evmc::MockedHost directly and now get the wrapper's semantics: access_storage warmth per page rather than per slot, and update_page from the page set rather than from the storage status. The only SSTORE either reaches runs under execute_and_compare, pinned to MONAD_EIGHT where MIP-8 is inactive.

Dropped, nothing uses them:

• the 100/200 caps on recorded calls and account accesses
• the copy of call input bytes behind recorded_calls (its pointer fields are nulled on record)
• MockedAccount::nonce
• the per-slot access flag the wrapper never returned
• access_storage's side effect of creating the account and slot (account_exists after SLOAD on an absent account is now false)
• the second recorded_account_accesses entry per SSTORE from the wrapper's extra get_storage
• evmc's always-warm rule for 0x01..0x09 in access_account (production decides that per fork in EvmcHost; tests that need a warm address pre-warm it)

Verification.

vm-unit-tests	main	this PR
gcc-15 RelWithDebInfo	1291 passed / 34 skipped	1292 / 34
clang-19 ASAN+UBSAN, spec comparison on	1785 / 196	1786 / 196

The difference is the new test. monad-compiler-fuzzer, execution-benchmarks, vm-micro-benchmarks and mce build. clang-format-19 and clang-tidy-19 clean on the new files.

Review map: test/vm/utils/mocked_host.hpp (storage_status, then the virtuals) → test/vm/unit/mocked_host_tests.cpp → the five include/type swaps → the deleted wrapper.

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[Copilot]

🟢 Approval recommended

No unresolved issues were identified, and all assessments indicate readiness.

Pull request overview

Replaces EVMC’s mocked host with an in-tree vm::Host implementation for VM tests.

Changes:

• Adds page-aware storage and exhaustive EIP-2200 status tests.
• Migrates fixtures and interface tests to the shared mock host.
• Removes the obsolete wrapper and EVMC mock linkage.

File summaries

File	Description
test/vm/utils/mocked_host.hpp	Adds the in-tree mock host.
test/vm/utils/CMakeLists.txt	Registers the shared mock header.
test/vm/unit/runtime/mocked_host.hpp	Removes the obsolete wrapper.
test/vm/unit/runtime/fixture.hpp	Uses the shared mock host.
test/vm/unit/runtime/fixture.cpp	Updates account construction.
test/vm/unit/monad_vm_interface_tests.cpp	Migrates interface tests.
test/vm/unit/mocked_host_tests.cpp	Adds storage-status transition tests.
test/vm/unit/evm_fixture.hpp	Uses the shared mock host.
test/vm/unit/CMakeLists.txt	Adds tests and removes EVMC mock linkage.

Review details

• Files reviewed: 9/9 changed files
• Comments generated: 0
• Review effort level: Lite

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[github-actions]

Reviewed this replacement of evmc::MockedHost with the in-tree monad::vm::test::MockedHost.

What was verified:

• The new storage_status implementation matches evmc's EIP-2200 logic exactly; the new MockedHost.StorageStatus test covers all 15 (original, current, value) transition classes and passes (verified by building and running it standalone).
• access_account, selfdestruct, get_storage, set_storage, account_exists, get_balance, copy_code, transient storage, and block-hash recording all reproduce the vendored evmc::MockedHost semantics, including the EIP-2929 precompile warm range (0x01–0x09) and the record-then-check warmth behavior.
• The page-based access_storage / update_page behavior (compute_page_key from storage_page.hpp, PAGE_KEY_SHIFT == 7) is identical to the deleted test/vm/unit/runtime/mocked_host.hpp wrapper, so the runtime fixture tests keep their previous semantics. The tests migrated off pure evmc::MockedHost (evm_fixture, monad_vm_interface_tests) don't exercise storage warmth, so no behavior-sensitive test is affected.
• No remaining references to evmc/mocked_host.hpp anywhere in the tree, so dropping the evmc::mocked_host link from vm-unit-tests is safe. The new header compiles standalone, and the fixture.cpp designated initializer matches the new MockedAccount field order.

One non-blocking note posted inline: the dangling input_data/code pointers retained in recorded_calls (documented, but worth hardening).

Verdict: CORRECT

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