Merge pull request #6258 from ethereum-optimism/refcell/steptest/chal…

…lenger

feat(op-challenger): Validate Step Function Manual ABI Packing

op-challenger/fault/abi_test.go

@@ -72,3 +72,25 @@ func TestBuildFaultAttackData(t *testing.T) {
 
 	require.Equal(t, data, tx.Data())
 }
+
+// TestBuildFaultStepData ensures that the manual ABI packing is the same as going through the bound contract.
+func TestBuildFaultStepData(t *testing.T) {
+	_, opts, _, contract, err := setupFaultDisputeGame()
+	require.NoError(t, err)
+
+	responder, _ := newTestFaultResponder(t, false)
+
+	data, err := responder.buildStepTxData(StepCallData{
+		ClaimIndex: 2,
+		IsAttack:   false,
+		StateData:  []byte{0x01},
+		Proof:      []byte{0x02},
+	})
+	require.NoError(t, err)
+
+	opts.GasLimit = 100_000
+	tx, err := contract.Step(opts, big.NewInt(2), false, []byte{0x01}, []byte{0x02})
+	require.NoError(t, err)
+
+	require.Equal(t, data, tx.Data())
+}

op-challenger/fault/responder.go

@@ -104,7 +104,6 @@ func (r *faultResponder) sendTxAndWait(ctx context.Context, txData []byte) error
 func (r *faultResponder) buildStepTxData(stepData StepCallData) ([]byte, error) {
 	return r.fdgAbi.Pack(
 		"step",
-		big.NewInt(int64(stepData.StateIndex)),
 		big.NewInt(int64(stepData.ClaimIndex)),
 		stepData.IsAttack,
 		stepData.StateData,

op-challenger/fault/types.go

@@ -14,7 +14,6 @@ var (
 
 // StepCallData encapsulates the data needed to perform a step.
 type StepCallData struct {
-	StateIndex uint64
 	ClaimIndex uint64
 	IsAttack   bool
 	StateData  []byte