core: make SpawnVM a method of context

spawnVMWithInterops is rather long too type and
it doesn't use Blockchain in any way.

pkg/core/blockchain.go

@@ -657,7 +657,7 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 			}
 		case *transaction.InvocationTX:
 			systemInterop := bc.newInteropContext(trigger.Application, cache, block, tx)
-			v := bc.spawnVMWithInterops(systemInterop)
+			v := systemInterop.SpawnVM()
 			v.SetCheckedHash(tx.VerificationHash().BytesBE())
 			v.LoadScript(t.Script)
 			v.SetPriceGetter(getPrice)
@@ -1999,27 +1999,10 @@ func (bc *Blockchain) GetScriptHashesForVerifying(t *transaction.Transaction) ([
 
 }
 
-// spawnVMWithInterops returns a VM with script getter and interop functions set
-// up for current blockchain.
-func (bc *Blockchain) spawnVMWithInterops(interopCtx *interopContext) *vm.VM {
-	vm := vm.New()
-	vm.SetScriptGetter(func(hash util.Uint160) ([]byte, bool) {
-		cs, err := interopCtx.dao.GetContractState(hash)
-		if err != nil {
-			return nil, false
-		}
-		hasDynamicInvoke := (cs.Properties & smartcontract.HasDynamicInvoke) != 0
-		return cs.Script, hasDynamicInvoke
-	})
-	vm.RegisterInteropGetter(interopCtx.getSystemInterop)
-	vm.RegisterInteropGetter(interopCtx.getNeoInterop)
-	return vm
-}
-
 // GetTestVM returns a VM and a Store setup for a test run of some sort of code.
 func (bc *Blockchain) GetTestVM() *vm.VM {
 	systemInterop := bc.newInteropContext(trigger.Application, bc.dao, nil, nil)
-	vm := bc.spawnVMWithInterops(systemInterop)
+	vm := systemInterop.SpawnVM()
 	vm.SetPriceGetter(getPrice)
 	return vm
 }
@@ -2047,7 +2030,7 @@ func (bc *Blockchain) verifyHashAgainstScript(hash util.Uint160, witness *transa
 		return err
 	}
 
-	vm := bc.spawnVMWithInterops(interopCtx)
+	vm := interopCtx.SpawnVM()
 	vm.SetCheckedHash(checkedHash.BytesBE())
 	vm.LoadScript(verification)
 	vm.LoadScript(witness.InvocationScript)

pkg/core/gas_price_test.go

@@ -19,7 +19,7 @@ func TestGetPrice(t *testing.T) {
 	sdao := dao.NewSimple(storage.NewMemoryStore())
 	systemInterop := bc.newInteropContext(trigger.Application, sdao, nil, nil)
 
-	v := bc.spawnVMWithInterops(systemInterop)
+	v := systemInterop.SpawnVM()
 	v.SetPriceGetter(getPrice)
 
 	t.Run("Neo.Asset.Create", func(t *testing.T) {

pkg/core/interops.go

@@ -14,7 +14,9 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/dao"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
+	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"go.uber.org/zap"
 )
@@ -35,6 +37,23 @@ func newInteropContext(trigger trigger.Type, bc Blockchainer, d dao.DAO, block *
 	return &interopContext{bc, trigger, block, tx, dao, nes, log}
 }
 
+// SpawnVM returns a VM with script getter and interop functions set
+// up for current blockchain.
+func (ic *interopContext) SpawnVM() *vm.VM {
+	vm := vm.New()
+	vm.SetScriptGetter(func(hash util.Uint160) ([]byte, bool) {
+		cs, err := ic.dao.GetContractState(hash)
+		if err != nil {
+			return nil, false
+		}
+		hasDynamicInvoke := (cs.Properties & smartcontract.HasDynamicInvoke) != 0
+		return cs.Script, hasDynamicInvoke
+	})
+	vm.RegisterInteropGetter(ic.getSystemInterop)
+	vm.RegisterInteropGetter(ic.getNeoInterop)
+	return vm
+}
+
 // interopedFunction binds function name, id with the function itself and price,
 // it's supposed to be inited once for all interopContexts, so it doesn't use
 // vm.InteropFuncPrice directly.