test: TestState implements StateView

Implement `StateView` interface in `TestState`. This will be used later.

test/state/test_state.cpp

@@ -7,13 +7,33 @@
 
 namespace evmone::test
 {
+std::optional<state::StateView::Account> TestState::get_account(const address& addr) const noexcept
+{
+    const auto it = find(addr);
+    if (it == end())
+        return std::nullopt;
+
+    const auto& acc = it->second;
+    // TODO: Cache code hash for MTP root hash calculation?
+    return Account{acc.nonce, acc.balance, keccak256(acc.code), !acc.storage.empty()};
+}
+
+bytes TestState::get_account_code(const address& addr) const noexcept
+{
+    const auto it = find(addr);
+    if (it == end())
+        return {};
+
+    return it->second.code;
+}
+
 state::State TestState::to_intra_state() const
 {
     state::State intra_state;
     for (const auto& [addr, acc] : *this)
     {
         auto& intra_acc = intra_state.insert(
-            addr, {.nonce = acc.nonce, .balance = acc.balance, .code = acc.code});
+            addr, {.nonce = acc.nonce, .balance = acc.balance, .code = get_account_code(addr)});
         auto& storage = intra_acc.storage;
         for (const auto& [key, value] : acc.storage)
             storage[key] = {.current = value, .original = value};
@@ -43,6 +63,16 @@ void TestState::apply(const state::StateDiff& diff)
         erase(addr);
 }
 
+bytes32 TestState::get_storage(const address& addr, const bytes32& key) const noexcept
+{
+    const auto ait = find(addr);
+    if (ait == end())  // TODO: When?
+        return bytes32{};
+    const auto& storage = ait->second.storage;
+    const auto it = storage.find(key);
+    return (it != storage.end()) ? it->second : bytes32{};
+}
+
 [[nodiscard]] std::variant<state::TransactionReceipt, std::error_code> transition(TestState& state,
     const state::BlockInfo& block, const state::Transaction& tx, evmc_revision rev, evmc::VM& vm,
     int64_t block_gas_left, int64_t blob_gas_left)

test/state/test_state.hpp

@@ -3,6 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0
 #pragma once
 
+#include "state_view.hpp"
 #include <evmc/evmc.hpp>
 #include <intx/intx.hpp>
 #include <map>
@@ -45,11 +46,15 @@ struct TestAccount
 /// This is a simplified variant of state::State:
 /// it hides some details related to transaction execution (e.g. original storage values)
 /// and is also easier to work with in tests.
-class TestState : public std::map<address, TestAccount>
+class TestState : public state::StateView, public std::map<address, TestAccount>
 {
 public:
     using map::map;
 
+    std::optional<Account> get_account(const address& addr) const noexcept override;
+    bytes get_account_code(const address& addr) const noexcept override;
+    bytes32 get_storage(const address& addr, const bytes32& key) const noexcept override;
+
     /// Inserts new account to the state.
     ///
     /// This method is for compatibility with state::State::insert().