Add New Method to Fuzz State (#8823)

Author: nisdas

fuzz/state_fuzz.go

@@ -2,6 +2,7 @@ package fuzz
 
 import (
 	"context"
+	"fmt"
 
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	stateutil "github.com/prysmaticlabs/prysm/beacon-chain/core/state"
@@ -34,6 +35,7 @@ func BeaconStateFuzz(input []byte) {
 	if err != nil {
 		panic(err)
 	}
+	validateStateHTR(s)
 	nextEpoch := helpers.SlotToEpoch(s.Slot()) + 1
 	slot, err := helpers.StartSlot(nextEpoch)
 	if err != nil {
@@ -43,4 +45,27 @@ func BeaconStateFuzz(input []byte) {
 		_ = err
 		return
 	}
+	validateStateHTR(s)
+}
+
+func validateStateHTR(s *stateV0.BeaconState) {
+	rawState, ok := s.InnerStateUnsafe().(*pb.BeaconState)
+	if !ok {
+		panic("non valid type assertion")
+	}
+	rt, err := s.HashTreeRoot(context.Background())
+	nxtRt, err2 := rawState.HashTreeRoot()
+
+	if err == nil && err2 != nil {
+		panic("HTR from state had only and error from cached state HTR method")
+	}
+	if err != nil && err2 == nil {
+		panic("HTR from state had only and error from fast-ssz HTR method")
+	}
+	if err != nil && err2 != nil {
+		return
+	}
+	if rt != nxtRt {
+		panic(fmt.Sprintf("cached HTR gave a root of %#x while fast-ssz gave a root of %#x", rt, nxtRt))
+	}
 }