fix: Allow Multiple Fraud Proofs per State Root (#72)

* feat: allow multiple state transitioners per pre-state root by tx hash

* test: specify tx hash when finalizing fraud verification

* test: specify tx hash when recording gas spent

* test: add test for multiple fraud proofs per stateroot

* chore: remove redundant test

* fix up test indexing and mock interface
Co-authored-by: ben-chain <ben@pseudonym.party>

packages/contracts/contracts/optimistic-ethereum/OVM/verification/OVM_BondManager.sol

@@ -65,9 +65,9 @@ contract OVM_BondManager is iOVM_BondManager, Lib_AddressResolver {
      ********************/
 
     /// Adds `who` to the list of witnessProviders for the provided `preStateRoot`.
-    function recordGasSpent(bytes32 _preStateRoot, address who, uint256 gasSpent) override public {
+    function recordGasSpent(bytes32 _preStateRoot, bytes32 _txHash, address who, uint256 gasSpent) override public {
         // The sender must be the transitioner that corresponds to the claimed pre-state root
-        address transitioner = address(iOVM_FraudVerifier(resolve("OVM_FraudVerifier")).getStateTransitioner(_preStateRoot));
+        address transitioner = address(iOVM_FraudVerifier(resolve("OVM_FraudVerifier")).getStateTransitioner(_preStateRoot, _txHash));
         require(transitioner == msg.sender, Errors.ONLY_TRANSITIONER);
 
         witnessProviders[_preStateRoot].total += gasSpent;

packages/contracts/contracts/optimistic-ethereum/OVM/verification/OVM_FraudContributor.sol

@@ -9,10 +9,10 @@ import { Lib_AddressResolver } from "../../libraries/resolver/Lib_AddressResolve
 abstract contract OVM_FraudContributor is Lib_AddressResolver {
     /// Decorate your functions with this modifier to store how much total gas was
     /// consumed by the sender, to reward users fairly
-    modifier contributesToFraudProof(bytes32 preStateRoot) {
+    modifier contributesToFraudProof(bytes32 preStateRoot, bytes32 txHash) {
         uint startGas = gasleft();
         _;
         uint gasSpent = startGas - gasleft();
-        iOVM_BondManager(resolve('OVM_BondManager')).recordGasSpent(preStateRoot, msg.sender, gasSpent);
+        iOVM_BondManager(resolve('OVM_BondManager')).recordGasSpent(preStateRoot, txHash, msg.sender, gasSpent);
     }
 }

packages/contracts/contracts/optimistic-ethereum/OVM/verification/OVM_FraudVerifier.sol

@@ -52,7 +52,8 @@ contract OVM_FraudVerifier is Lib_AddressResolver, OVM_FraudContributor, iOVM_Fr
      * @return _transitioner Corresponding state transitioner contract.
      */
     function getStateTransitioner(
-        bytes32 _preStateRoot
+        bytes32 _preStateRoot,
+        bytes32 _txHash
     )
         override
         public
@@ -61,7 +62,7 @@ contract OVM_FraudVerifier is Lib_AddressResolver, OVM_FraudContributor, iOVM_Fr
             iOVM_StateTransitioner _transitioner
         )
     {
-        return transitioners[_preStateRoot];
+        return transitioners[keccak256(abi.encodePacked(_preStateRoot, _txHash))];
     }
 
 
@@ -90,9 +91,11 @@ contract OVM_FraudVerifier is Lib_AddressResolver, OVM_FraudContributor, iOVM_Fr
     )
         override
         public
-        contributesToFraudProof(_preStateRoot)
+        contributesToFraudProof(_preStateRoot, Lib_OVMCodec.hashTransaction(_transaction))
     {
-        if (_hasStateTransitioner(_preStateRoot)) {
+        bytes32 _txHash = Lib_OVMCodec.hashTransaction(_transaction);
+
+        if (_hasStateTransitioner(_preStateRoot, _txHash)) {
             return;
         }
 
@@ -123,13 +126,18 @@ contract OVM_FraudVerifier is Lib_AddressResolver, OVM_FraudContributor, iOVM_Fr
             "Pre-state root global index must equal to the transaction root global index."
         );
         
-        transitioners[_preStateRoot] = iOVM_StateTransitionerFactory(
+        deployTransitioner(_preStateRoot, _txHash, _preStateRootProof.index);
+    }
+
+    // NB: Stack too deep :/
+    function deployTransitioner(bytes32 _preStateRoot, bytes32 _txHash, uint256 _stateTransitionIndex) private {
+        transitioners[keccak256(abi.encodePacked(_preStateRoot, _txHash))] = iOVM_StateTransitionerFactory(
             resolve("OVM_StateTransitionerFactory")
         ).create(
             address(libAddressManager),
-            _preStateRootProof.index,
+            _stateTransitionIndex,
             _preStateRoot,
-            Lib_OVMCodec.hashTransaction(_transaction)
+            _txHash
         );
     }
 
@@ -138,6 +146,7 @@ contract OVM_FraudVerifier is Lib_AddressResolver, OVM_FraudContributor, iOVM_Fr
      * @param _preStateRoot State root before the fraudulent transaction.
      * @param _preStateRootBatchHeader Batch header for the provided pre-state root.
      * @param _preStateRootProof Inclusion proof for the provided pre-state root.
+     * @param _txHash The transaction for the state root
      * @param _postStateRoot State root after the fraudulent transaction.
      * @param _postStateRootBatchHeader Batch header for the provided post-state root.
      * @param _postStateRootProof Inclusion proof for the provided post-state root.
@@ -146,15 +155,16 @@ contract OVM_FraudVerifier is Lib_AddressResolver, OVM_FraudContributor, iOVM_Fr
         bytes32 _preStateRoot,
         Lib_OVMCodec.ChainBatchHeader memory _preStateRootBatchHeader,
         Lib_OVMCodec.ChainInclusionProof memory _preStateRootProof,
+        bytes32 _txHash,
         bytes32 _postStateRoot,
         Lib_OVMCodec.ChainBatchHeader memory _postStateRootBatchHeader,
         Lib_OVMCodec.ChainInclusionProof memory _postStateRootProof
     )
         override
         public
-        contributesToFraudProof(_preStateRoot)
+        contributesToFraudProof(_preStateRoot, _txHash)
     {
-        iOVM_StateTransitioner transitioner = transitioners[_preStateRoot];
+        iOVM_StateTransitioner transitioner = getStateTransitioner(_preStateRoot, _txHash);
         iOVM_StateCommitmentChain ovmStateCommitmentChain = iOVM_StateCommitmentChain(resolve("OVM_StateCommitmentChain"));
         iOVM_BondManager ovmBondManager = iOVM_BondManager(resolve("OVM_BondManager"));
 
@@ -192,6 +202,16 @@ contract OVM_FraudVerifier is Lib_AddressResolver, OVM_FraudContributor, iOVM_Fr
             "State transition has not been proven fraudulent."
         );
         
+        cancelStateTransition(_postStateRootBatchHeader, _preStateRoot);
+    }
+
+    // NB: Stack too deep :/
+    function cancelStateTransition(
+        Lib_OVMCodec.ChainBatchHeader memory _postStateRootBatchHeader,
+        bytes32 _preStateRoot
+    ) private {
+        iOVM_StateCommitmentChain ovmStateCommitmentChain = iOVM_StateCommitmentChain(resolve("OVM_StateCommitmentChain"));
+        iOVM_BondManager ovmBondManager = iOVM_BondManager(resolve("OVM_BondManager"));
         // delete the state batch
         ovmStateCommitmentChain.deleteStateBatch(
             _postStateRootBatchHeader
@@ -219,7 +239,8 @@ contract OVM_FraudVerifier is Lib_AddressResolver, OVM_FraudContributor, iOVM_Fr
      * @return _exists Whether or not we already have a transitioner for the root.
      */
     function _hasStateTransitioner(
-        bytes32 _preStateRoot
+        bytes32 _preStateRoot,
+        bytes32 _txHash
     )
         internal
         view
@@ -227,6 +248,6 @@ contract OVM_FraudVerifier is Lib_AddressResolver, OVM_FraudContributor, iOVM_Fr
             bool _exists
         )
     {
-        return address(transitioners[_preStateRoot]) != address(0);
+        return address(getStateTransitioner(_preStateRoot, _txHash)) != address(0);
     }
 }

packages/contracts/contracts/optimistic-ethereum/OVM/verification/OVM_StateTransitioner.sol

@@ -167,7 +167,7 @@ contract OVM_StateTransitioner is Lib_AddressResolver, OVM_FraudContributor, iOV
         override
         public
         onlyDuringPhase(TransitionPhase.PRE_EXECUTION)
-        contributesToFraudProof(preStateRoot)
+        contributesToFraudProof(preStateRoot, transactionHash)
     {
         // Exit quickly to avoid unnecessary work.
         require(
@@ -215,7 +215,7 @@ contract OVM_StateTransitioner is Lib_AddressResolver, OVM_FraudContributor, iOV
         override
         public
         onlyDuringPhase(TransitionPhase.PRE_EXECUTION)
-        contributesToFraudProof(preStateRoot)
+        contributesToFraudProof(preStateRoot, transactionHash)
     {
         // Exit quickly to avoid unnecessary work.
         require(
@@ -251,7 +251,7 @@ contract OVM_StateTransitioner is Lib_AddressResolver, OVM_FraudContributor, iOV
         override
         public
         onlyDuringPhase(TransitionPhase.PRE_EXECUTION)
-        contributesToFraudProof(preStateRoot)
+        contributesToFraudProof(preStateRoot, transactionHash)
     {
         // Exit quickly to avoid unnecessary work.
         require(
@@ -307,7 +307,7 @@ contract OVM_StateTransitioner is Lib_AddressResolver, OVM_FraudContributor, iOV
         override
         public
         onlyDuringPhase(TransitionPhase.PRE_EXECUTION)
-        contributesToFraudProof(preStateRoot)
+        contributesToFraudProof(preStateRoot, transactionHash)
     {
         require(
             Lib_OVMCodec.hashTransaction(_transaction) == transactionHash,
@@ -346,7 +346,7 @@ contract OVM_StateTransitioner is Lib_AddressResolver, OVM_FraudContributor, iOV
         override
         public
         onlyDuringPhase(TransitionPhase.POST_EXECUTION)
-        contributesToFraudProof(preStateRoot)
+        contributesToFraudProof(preStateRoot, transactionHash)
     {
         require(
             ovmStateManager.commitAccount(_ovmContractAddress) == true,
@@ -381,7 +381,7 @@ contract OVM_StateTransitioner is Lib_AddressResolver, OVM_FraudContributor, iOV
         override
         public
         onlyDuringPhase(TransitionPhase.POST_EXECUTION)
-        contributesToFraudProof(preStateRoot)
+        contributesToFraudProof(preStateRoot, transactionHash)
     {
         require(
             ovmStateManager.commitContractStorage(_ovmContractAddress, _key) == true,

packages/contracts/contracts/optimistic-ethereum/iOVM/verification/iOVM_BondManager.sol

@@ -76,6 +76,7 @@ interface iOVM_BondManager {
     
     function recordGasSpent(
         bytes32 _preStateRoot,
+        bytes32 _txHash,
         address _who,
         uint256 _gasSpent
     ) external;

packages/contracts/contracts/optimistic-ethereum/iOVM/verification/iOVM_FraudVerifier.sol

@@ -17,7 +17,7 @@ interface iOVM_FraudVerifier {
      * Public Functions: Transition Status *
      ***************************************/
 
-    function getStateTransitioner(bytes32 _preStateRoot) external view returns (iOVM_StateTransitioner _transitioner);
+    function getStateTransitioner(bytes32 _preStateRoot, bytes32 _txHash) external view returns (iOVM_StateTransitioner _transitioner);
 
 
     /****************************************
@@ -38,6 +38,7 @@ interface iOVM_FraudVerifier {
         bytes32 _preStateRoot,
         Lib_OVMCodec.ChainBatchHeader calldata _preStateRootBatchHeader,
         Lib_OVMCodec.ChainInclusionProof calldata _preStateRootProof,
+        bytes32 _txHash,
         bytes32 _postStateRoot,
         Lib_OVMCodec.ChainBatchHeader calldata _postStateRootBatchHeader,
         Lib_OVMCodec.ChainInclusionProof calldata _postStateRootProof

packages/contracts/contracts/optimistic-ethereum/mockOVM/verification/mockOVM_BondManager.sol

@@ -10,6 +10,7 @@ import { iOVM_BondManager } from "../../iOVM/verification/iOVM_BondManager.sol";
 contract mockOVM_BondManager is iOVM_BondManager {
     function recordGasSpent(
         bytes32 _preStateRoot,
+        bytes32 _txHash,
         address _who,
         uint256 _gasSpent
     )

packages/contracts/contracts/test-helpers/Mock_FraudVerifier.sol

@@ -12,12 +12,21 @@ contract Mock_FraudVerifier {
         bondManager = _bondManager;
     }
 
-    function setStateTransitioner(bytes32 preStateRoot, address addr) public {
-        transitioners[preStateRoot] = addr;
+    function setStateTransitioner(bytes32 preStateRoot, bytes32 txHash, address addr) public {
+        transitioners[keccak256(abi.encodePacked(preStateRoot, txHash))] = addr;
     }
 
-    function getStateTransitioner(bytes32 preStateRoot) public view returns (address) {
-        return transitioners[preStateRoot];
+    function getStateTransitioner(
+        bytes32 _preStateRoot,
+        bytes32 _txHash
+    )
+        public
+        view
+        returns (
+            address
+        )
+    {
+        return transitioners[keccak256(abi.encodePacked(_preStateRoot, _txHash))];
     }
 
     function finalize(bytes32 _preStateRoot, address publisher, uint256 timestamp) public {

packages/contracts/test/bond.ts

@@ -22,6 +22,7 @@ describe('BondManager', () => {
   const witnessProvider2 = wallets[5]
 
   const sender = wallets[0].address
+  const txHash = ethers.constants.HashZero
 
   const ONE_WEEK = 3600 * 24 * 7
 
@@ -56,6 +57,7 @@ describe('BondManager', () => {
     ).deploy()
     await fraudVerifier.setStateTransitioner(
       preStateRoot,
+      txHash,
       stateTransitioner.address
     )
     await manager.setAddress('OVM_FraudVerifier', fraudVerifier.address)
@@ -143,13 +145,28 @@ describe('BondManager', () => {
     beforeEach(async () => {
       await bondManager
         .connect(stateTransitioner)
-        .recordGasSpent(preStateRoot, witnessProvider.address, user1Gas[0])
+        .recordGasSpent(
+          preStateRoot,
+          txHash,
+          witnessProvider.address,
+          user1Gas[0]
+        )
       await bondManager
         .connect(stateTransitioner)
-        .recordGasSpent(preStateRoot, witnessProvider.address, user1Gas[1])
+        .recordGasSpent(
+          preStateRoot,
+          txHash,
+          witnessProvider.address,
+          user1Gas[1]
+        )
       await bondManager
         .connect(stateTransitioner)
-        .recordGasSpent(preStateRoot, witnessProvider2.address, user2Gas)
+        .recordGasSpent(
+          preStateRoot,
+          txHash,
+          witnessProvider2.address,
+          user2Gas
+        )
     })
 
     describe('post witnesses', () => {
@@ -167,7 +184,12 @@ describe('BondManager', () => {
 
       it('cannot post witnesses from non-transitioners for that state root', async () => {
         await expect(
-          bondManager.recordGasSpent(preStateRoot, witnessProvider.address, 100)
+          bondManager.recordGasSpent(
+            preStateRoot,
+            txHash,
+            witnessProvider.address,
+            100
+          )
         ).to.be.revertedWith(Errors.ONLY_TRANSITIONER)
       })
     })

packages/contracts/test/contracts/OVM/accounts/OVM_ProxyEOA.spec.ts

@@ -100,7 +100,8 @@ describe('OVM_ProxyEOA', () => {
     })
   })
   describe('upgrade()', () => {
-    const implSlotKey = '0xdeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddead'
+    const implSlotKey =
+      '0xdeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddeaddead'
     it(`should upgrade the proxy implementation`, async () => {
       const newImpl = `0x${'81'.repeat(20)}`
       const newImplBytes32 = addrToBytes32(newImpl)

packages/contracts/test/contracts/OVM/verification/OVM_FraudVerifier.spec.ts

@@ -14,18 +14,21 @@ import {
   DUMMY_OVM_TRANSACTIONS,
   NON_NULL_BYTES32,
   NULL_BYTES32,
+  hashTransaction,
 } from '../../../helpers'
 
-const DUMMY_TX_CHAIN_ELEMENTS = [...Array(10)].map(() => {
+const DUMMY_TX_CHAIN_ELEMENTS = [...Array(10).keys()].map((i) => {
   return {
     isSequenced: false,
     queueIndex: BigNumber.from(0),
-    timestamp: BigNumber.from(0),
+    timestamp: BigNumber.from(i),
     blockNumber: BigNumber.from(0),
     txData: NULL_BYTES32,
   }
 })
 
+const DUMMY_HASH = hashTransaction(DUMMY_OVM_TRANSACTIONS[0])
+
 const DUMMY_BATCH_PROOFS_WITH_INDEX = [
   {
     index: 11,
@@ -181,7 +184,10 @@ describe('OVM_FraudVerifier', () => {
           ).to.not.be.reverted
 
           expect(
-            await OVM_FraudVerifier.getStateTransitioner(NULL_BYTES32)
+            await OVM_FraudVerifier.getStateTransitioner(
+              NULL_BYTES32,
+              DUMMY_HASH
+            )
           ).to.equal(Mock__OVM_StateTransitioner.address)
         })
 
@@ -233,6 +239,7 @@ describe('OVM_FraudVerifier', () => {
             NULL_BYTES32,
             DUMMY_BATCH_HEADERS[0],
             DUMMY_BATCH_PROOFS[0],
+            DUMMY_HASH,
             NON_NULL_BYTES32,
             DUMMY_BATCH_HEADERS[0],
             DUMMY_BATCH_PROOFS[0]
@@ -260,6 +267,7 @@ describe('OVM_FraudVerifier', () => {
               NULL_BYTES32,
               DUMMY_BATCH_HEADERS[0],
               DUMMY_BATCH_PROOFS[0],
+              DUMMY_HASH,
               NON_NULL_BYTES32,
               DUMMY_BATCH_HEADERS[0],
               batchProof
@@ -287,6 +295,7 @@ describe('OVM_FraudVerifier', () => {
                 NULL_BYTES32,
                 DUMMY_BATCH_HEADERS[0],
                 DUMMY_BATCH_PROOFS[0],
+                DUMMY_HASH,
                 NON_NULL_BYTES32,
                 DUMMY_BATCH_HEADERS[0],
                 batchProof
@@ -317,6 +326,7 @@ describe('OVM_FraudVerifier', () => {
                   NULL_BYTES32,
                   DUMMY_BATCH_HEADERS[0],
                   DUMMY_BATCH_PROOFS[0],
+                  DUMMY_HASH,
                   NON_NULL_BYTES32,
                   DUMMY_BATCH_HEADERS[0],
                   batchProof
@@ -345,6 +355,7 @@ describe('OVM_FraudVerifier', () => {
                     NULL_BYTES32,
                     DUMMY_BATCH_HEADERS[0],
                     DUMMY_BATCH_PROOFS[0],
+                    DUMMY_HASH,
                     NON_NULL_BYTES32,
                     DUMMY_BATCH_HEADERS[0],
                     batchProof
@@ -367,6 +378,7 @@ describe('OVM_FraudVerifier', () => {
                   NULL_BYTES32,
                   DUMMY_BATCH_HEADERS[0],
                   DUMMY_BATCH_PROOFS[0],
+                  DUMMY_HASH,
                   NON_NULL_BYTES32,
                   DUMMY_BATCH_HEADERS[0],
                   batchProof
@@ -387,6 +399,155 @@ describe('OVM_FraudVerifier', () => {
           })
         })
       })
+
+      describe('multiple fraud proofs for the same pre-execution state', () => {
+        let state2: any
+        let DUMMY_HASH_2 = hashTransaction(DUMMY_OVM_TRANSACTIONS[1])
+        beforeEach(async () => {
+          state2 = smockit(
+            await ethers.getContractFactory('OVM_StateTransitioner')
+          )
+
+          Mock__OVM_StateTransitionerFactory.smocked.create.will.return.with(
+            state2.address
+          )
+
+          Mock__OVM_StateTransitioner.smocked.getPostStateRoot.will.return.with(
+            NULL_BYTES32
+          )
+
+          state2.smocked.getPostStateRoot.will.return.with(NULL_BYTES32)
+        })
+
+        it('creates multiple state transitioners per tx hash', async () => {
+          await expect(
+            OVM_FraudVerifier.initializeFraudVerification(
+              NULL_BYTES32,
+              DUMMY_BATCH_HEADERS[0],
+              DUMMY_BATCH_PROOFS[0],
+              DUMMY_OVM_TRANSACTIONS[1],
+              DUMMY_TX_CHAIN_ELEMENTS[0],
+              DUMMY_BATCH_HEADERS[0],
+              DUMMY_BATCH_PROOFS[0]
+            )
+          ).to.not.be.reverted
+
+          expect(
+            await OVM_FraudVerifier.getStateTransitioner(
+              NULL_BYTES32,
+              DUMMY_HASH
+            )
+          ).to.equal(Mock__OVM_StateTransitioner.address)
+          expect(
+            await OVM_FraudVerifier.getStateTransitioner(
+              NULL_BYTES32,
+              DUMMY_HASH_2
+            )
+          ).to.equal(state2.address)
+        })
+
+        const batchProof = {
+          ...DUMMY_BATCH_PROOFS[0],
+          index: DUMMY_BATCH_PROOFS[0].index + 1,
+        }
+
+        it('Case 1: allows proving fraud on the same pre-state root twice', async () => {
+          // finalize previous fraud
+          await OVM_FraudVerifier.finalizeFraudVerification(
+            NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[0],
+            DUMMY_BATCH_PROOFS[0],
+            DUMMY_HASH,
+            NON_NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[0],
+            batchProof
+          )
+
+          // start new fraud
+          await OVM_FraudVerifier.initializeFraudVerification(
+            NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[0],
+            DUMMY_BATCH_PROOFS[0],
+            DUMMY_OVM_TRANSACTIONS[1],
+            DUMMY_TX_CHAIN_ELEMENTS[1],
+            DUMMY_BATCH_HEADERS[1],
+            DUMMY_BATCH_PROOFS[0]
+          )
+
+          // finalize it as well
+          await OVM_FraudVerifier.finalizeFraudVerification(
+            NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[0],
+            DUMMY_BATCH_PROOFS[0],
+            DUMMY_HASH_2,
+            NON_NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[1],
+            batchProof
+          )
+
+          // the new batch was deleted
+          expect(
+            Mock__OVM_StateCommitmentChain.smocked.deleteStateBatch.calls[0]
+          ).to.deep.equal([
+            Object.values(DUMMY_BATCH_HEADERS[1]).map((value) => {
+              return Number.isInteger(value) ? BigNumber.from(value) : value
+            }),
+          ])
+        })
+
+        it('Case 2: does not get blocked by the first transitioner', async () => {
+          // start new fraud
+          await OVM_FraudVerifier.initializeFraudVerification(
+            NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[0],
+            DUMMY_BATCH_PROOFS[0],
+            DUMMY_OVM_TRANSACTIONS[1],
+            DUMMY_TX_CHAIN_ELEMENTS[1],
+            DUMMY_BATCH_HEADERS[1],
+            DUMMY_BATCH_PROOFS[0]
+          )
+
+          // finalize the new fraud first
+          await OVM_FraudVerifier.finalizeFraudVerification(
+            NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[0],
+            DUMMY_BATCH_PROOFS[0],
+            DUMMY_HASH_2,
+            NON_NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[1],
+            batchProof
+          )
+
+          // the new fraud's batch was deleted
+          expect(
+            Mock__OVM_StateCommitmentChain.smocked.deleteStateBatch.calls[0]
+          ).to.deep.equal([
+            Object.values(DUMMY_BATCH_HEADERS[1]).map((value) => {
+              return Number.isInteger(value) ? BigNumber.from(value) : value
+            }),
+          ])
+
+          // finalize previous fraud
+          await OVM_FraudVerifier.finalizeFraudVerification(
+            NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[0],
+            DUMMY_BATCH_PROOFS[0],
+            DUMMY_HASH,
+            NON_NULL_BYTES32,
+            DUMMY_BATCH_HEADERS[0],
+            batchProof
+          )
+
+          // the old fraud's batch was deleted
+          expect(
+            Mock__OVM_StateCommitmentChain.smocked.deleteStateBatch.calls[0]
+          ).to.deep.equal([
+            Object.values(DUMMY_BATCH_HEADERS[0]).map((value) => {
+              return Number.isInteger(value) ? BigNumber.from(value) : value
+            }),
+          ])
+        })
+      })
     })
   })
 })

packages/contracts/test/helpers/dummy/batches.ts

@@ -12,6 +12,16 @@ export const DUMMY_BATCH_HEADERS = [
       [NULL_BYTES32, NON_ZERO_ADDRESS]
     ),
   },
+  {
+    batchIndex: 1,
+    batchRoot: NULL_BYTES32,
+    batchSize: 0,
+    prevTotalElements: 0,
+    extraData: ethers.utils.defaultAbiCoder.encode(
+      ['uint256', 'address'],
+      [NULL_BYTES32, NON_ZERO_ADDRESS]
+    ),
+  },
 ]
 
 export const DUMMY_BATCH_PROOFS = [
@@ -19,4 +29,8 @@ export const DUMMY_BATCH_PROOFS = [
     index: 0,
     siblings: [NULL_BYTES32],
   },
+  {
+    index: 1,
+    siblings: [NULL_BYTES32],
+  },
 ]

packages/contracts/test/helpers/dummy/transactions.ts

 import { ZERO_ADDRESS, NULL_BYTES32 } from '../constants'
+import { ethers } from 'ethers'
 
-export const DUMMY_OVM_TRANSACTIONS = [
-  {
-    timestamp: 0,
+export interface Transaction {
+  timestamp: number
+  blockNumber: number
+  l1QueueOrigin: number
+  l1TxOrigin: string
+  entrypoint: string
+  gasLimit: number
+  data: string
+}
+
+export const DUMMY_OVM_TRANSACTIONS: Array<Transaction> = [
+  ...Array(10).keys(),
+].map((i) => {
+  return {
+    timestamp: i,
     blockNumber: 0,
     l1QueueOrigin: 0,
     l1TxOrigin: ZERO_ADDRESS,
     entrypoint: ZERO_ADDRESS,
     gasLimit: 0,
     data: NULL_BYTES32,
-  },
-]
+  }
+})
+
+export const hashTransaction = ({
+  timestamp,
+  blockNumber,
+  l1QueueOrigin,
+  l1TxOrigin,
+  entrypoint,
+  gasLimit,
+  data,
+}: Transaction): string => {
+  return ethers.utils.solidityKeccak256(
+    ['uint256', 'uint256', 'uint8', 'address', 'address', 'uint256', 'bytes'],
+    [
+      timestamp,
+      blockNumber,
+      l1QueueOrigin,
+      l1TxOrigin,
+      entrypoint,
+      gasLimit,
+      data,
+    ]
+  )
+}