go-ethereum/libevm/ethtest/evm.go
Arran Schlosberg 9021836d7d
feat: vm.Hooks.PreprocessingGasCharge() (#235)
## Why this should be merged

In lieu of modifications to `core.IntrinsicGas()`, required for support
of Warp in SAE.

If we were to introduce variadic `options.Option`s to `IntrinsicGas()`,
it's impossible to guarantee that they would always be passed. The
`types.Transaction` itself isn't actually passed to `IntrinsicGas()`
either, so we can't rely on it to carry payloads/hooks.

## How this works

`vm.Hooks` are extended to include `PreprocessingGasCharge(tx
common.Hash) (uint64, error)`, which returns the amount of gas to be
charged between `core.IntrinsicGas` and `vm.EVM` execution charges. The
two entry points to execution, `vm.EVM.Call()` and `vm.EVM.Create()` are
modified to first spend said charge before running upstream logic.

The new hook is defined on a separate interface definition, embedded in
`vm.Hooks`, to allow types to implement just that method and enforce it
with the `var _ vm.Preprocessor = (*impl)(nil)` pattern.

## How this was tested

Integration tests via both `core.ApplyTransaction()` and
`core.ApplyMessage()`. The former is more comprehensive, while the
latter allows for inspection of interim error values.

---------

Signed-off-by: Arran Schlosberg <519948+ARR4N@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Austin Larson <78000745+alarso16@users.noreply.github.com>
2025-12-15 20:49:13 +00:00

111 lines
3.1 KiB
Go

// Copyright 2024 the libevm authors.
//
// The libevm additions to go-ethereum are free software: you can redistribute
// them and/or modify them under the terms of the GNU Lesser General Public License
// as published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The libevm additions are distributed in the hope that they will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see
// <http://www.gnu.org/licenses/>.
// Package ethtest provides utility functions for use in testing
// Ethereum-related functionality.
package ethtest
import (
"testing"
"github.com/stretchr/testify/require"
"github.com/ava-labs/libevm/core"
"github.com/ava-labs/libevm/core/rawdb"
"github.com/ava-labs/libevm/core/state"
"github.com/ava-labs/libevm/core/types"
"github.com/ava-labs/libevm/core/vm"
"github.com/ava-labs/libevm/ethdb"
"github.com/ava-labs/libevm/params"
)
// NewEmptyStateDB returns a fresh database from [rawdb.NewMemoryDatabase], a
// [state.Database] wrapping it, and a [state.StateDB] wrapping that, opened to
// [types.EmptyRootHash].
func NewEmptyStateDB(tb testing.TB) (ethdb.Database, state.Database, *state.StateDB) {
tb.Helper()
db := rawdb.NewMemoryDatabase()
cache := state.NewDatabase(db)
sdb, err := state.New(types.EmptyRootHash, cache, nil)
require.NoError(tb, err, "state.New()")
return db, cache, sdb
}
// NewZeroEVM returns a new EVM backed by a [rawdb.NewMemoryDatabase]; all other
// arguments to [vm.NewEVM] are the zero values of their respective types,
// except for the use of [core.CanTransfer] and [core.Transfer] instead of nil
// functions.
func NewZeroEVM(tb testing.TB, opts ...EVMOption) (*state.StateDB, *vm.EVM) {
tb.Helper()
_, _, sdb := NewEmptyStateDB(tb)
args := &evmConstructorArgs{
vm.BlockContext{
CanTransfer: core.CanTransfer,
Transfer: core.Transfer,
},
vm.TxContext{},
sdb,
&params.ChainConfig{},
vm.Config{},
}
for _, o := range opts {
o.apply(args)
}
return sdb, vm.NewEVM(
args.blockContext,
args.txContext,
args.stateDB,
args.chainConfig,
args.config,
)
}
type evmConstructorArgs struct {
blockContext vm.BlockContext
txContext vm.TxContext
stateDB vm.StateDB
chainConfig *params.ChainConfig
config vm.Config
}
// An EVMOption configures the EVM returned by [NewZeroEVM].
type EVMOption interface {
apply(*evmConstructorArgs)
}
type funcOption func(*evmConstructorArgs)
var _ EVMOption = funcOption(nil)
func (f funcOption) apply(args *evmConstructorArgs) { f(args) }
// WithBlockContext overrides the default context.
func WithBlockContext(c vm.BlockContext) EVMOption {
return funcOption(func(args *evmConstructorArgs) {
args.blockContext = c
})
}
// WithBlockContext overrides the default context.
func WithChainConfig(c *params.ChainConfig) EVMOption {
return funcOption(func(args *evmConstructorArgs) {
args.chainConfig = c
})
}