added Option's

w3vm/vm.go

@@ -2,17 +2,34 @@ package w3vm
 
 import (
 	"math/big"
+	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/params"
+	"github.com/lmittmann/w3"
 	"github.com/lmittmann/w3/w3types"
+	"github.com/lmittmann/w3/w3vm/state"
 )
 
-type VM struct{}
+type VM struct {
+	opts *vmOptions
+}
+
+type vmOptions struct {
+	chainConfig     *params.ChainConfig
+	preState        w3types.State
+	blockCtx        *vm.BlockContext
+	header          *types.Header
+	forkClient      *w3.Client
+	forkBlockNumber *big.Int
+	fetcher         state.Fetcher
+	tb              testing.TB
+}
 
 func New(opts ...Option) *VM {
-	c := &VM{}
+	c := &VM{opts: new(vmOptions)}
 	for _, opt := range opts {
 		opt(c)
 	}
@@ -78,14 +95,37 @@ func (vm *VM) StorageAt(addr common.Address, slot common.Hash) common.Hash {
 // An Option configures a VM.
 type Option func(*VM)
 
+// WithChainConfig configures the VM's chain config.
 func WithChainConfig(cfg *params.ChainConfig) Option {
-	return func(vm *VM) {}
+	return func(vm *VM) { vm.opts.chainConfig = cfg }
 }
 
+// WithBlockContext configures the VM's block context.
 func WithBlockContext(ctx *vm.BlockContext) Option {
-	return func(vm *VM) {}
+	return func(vm *VM) { vm.opts.blockCtx = ctx }
+}
+
+// WithState sets the VM's pre state.
+func WithState(state w3types.State) Option {
+	return func(vm *VM) { vm.opts.preState = state }
+}
+
+func WithFork(client *w3.Client, blockNumber *big.Int) Option {
+	return func(vm *VM) {
+		vm.opts.forkClient = client
+		vm.opts.forkBlockNumber = blockNumber
+	}
+}
+
+// WithHeader configures the VM's block context based on the given header.
+func WithHeader(header *types.Header) Option {
+	return func(vm *VM) { vm.opts.header = header }
+}
+
+func WithFetcher(fetcher state.Fetcher) Option {
+	return func(vm *VM) { vm.opts.fetcher = fetcher }
 }
 
-func WithState(s w3types.State) Option {
-	return func(vm *VM) {}
+func WithTB(tb testing.TB) Option {
+	return func(vm *VM) { vm.opts.tb = tb }
 }