Implementation of getRemoteGatewayLatestProvenBlockNumber

contracts/consensus-gateway/ConsensusCogateway.sol

@@ -198,6 +198,19 @@ contract ConsensusCogateway is MasterCopyNonUpgradable, MessageBus, ConsensusGat
         );
     }
 
+    /**
+     * @notice Gets the remote gateway latest proven block number.
+     *
+     * @return blockNumber_ Remote gateway latest proven block number.
+     */
+    function getRemoteGatewayLatestProvenBlockNumber()
+        external
+        view
+        returns (uint256 blockNumber_)
+    {
+        blockNumber_ = CircularBufferUint.head();
+    }
+
     /**
      * @notice Confirms the initiation of opening a kernel at auxiliary chain.
      *

contracts/consensus-gateway/ConsensusGateway.sol

@@ -311,4 +311,17 @@ contract ConsensusGateway is
             "Token transfer to the beneficiary must succeed."
         );
     }
+
+    /**
+     * @notice Gets the remote gateway latest proven block number.
+     *
+     * @return blockNumber_ Remote gateway latest proven block number.
+     */
+    function getRemoteGatewayLatestProvenBlockNumber()
+        external
+        view
+        returns (uint256 blockNumber_)
+    {
+        blockNumber_ = CircularBufferUint.head();
+    }
 }

contracts/erc20-gateway/ERC20Cogateway.sol

@@ -152,6 +152,19 @@ contract ERC20Cogateway is
         emit GatewayProven(messageInbox, _blockNumber);
     }
 
+    /**
+     * @notice Gets the remote gateway latest proven block number.
+     *
+     * @return blockNumber_ Remote gateway latest proven block number.
+     */
+    function getRemoteGatewayLatestProvenBlockNumber()
+        external
+        view
+        returns (uint256 blockNumber_)
+    {
+        blockNumber_ = CircularBufferUint.head();
+    }
+
     /**
      * @notice It allows withdrawing Utility tokens. Withdrawer needs to
      *       approve erc20 cogateway contract for the amount to be

contracts/erc20-gateway/ERC20Gateway.sol

@@ -129,6 +129,19 @@ contract ERC20Gateway is MasterCopyNonUpgradable, MessageBus, ERC20GatewayBase {
         emit GatewayProven(messageInbox, _blockNumber);
     }
 
+    /**
+     * @notice Gets the remote gateway latest proven block number.
+     *
+     * @return blockNumber_ Remote gateway latest proven block number.
+     */
+    function getRemoteGatewayLatestProvenBlockNumber()
+        external
+        view
+        returns (uint256 blockNumber_)
+    {
+        blockNumber_ = CircularBufferUint.head();
+    }
+
     /**
      * @notice Deposit ERC20 token to mint utility token on the auxiliary chain.
      *

test/consensus_cogateway/prove_consensus_gateway.js

@@ -79,6 +79,13 @@ contract('CoConsensusgateway::proveConsensusGateway', (accounts) => {
         ProveConsensusGatewayProof.storageHash,
         'Incorrect storage hash',
       );
+
+      const latestProvenBlockNumber = await consensusCogateway
+        .getRemoteGatewayLatestProvenBlockNumber.call();
+      assert.isOk(
+        latestProvenBlockNumber.eqn(ProveConsensusGatewayProof.blockNumber),
+        'Invalid latest proven block number.',
+      );
     });
   });
 });

test/erc20_gateway/erc20_cogateway/prove_gateway.js

@@ -96,6 +96,13 @@ contract('ERC20Cogateway::proveGateway', (accounts) => {
         `Expected block number is ${ProveERC20GatewayProof.blockNumber} but
         found to be ${eventObject.args.blockNumber.toString(10)}.`,
       );
+
+      const latestProvenBlockNumber = await erc20Cogateway.getRemoteGatewayLatestProvenBlockNumber
+        .call();
+      assert.isOk(
+        latestProvenBlockNumber.eqn(ProveERC20GatewayProof.blockNumber),
+        'Invalid latest proven block number.',
+      );
     });
   });
 });

test/erc20_gateway/erc20_gateway/prove_gateway.js

@@ -90,6 +90,13 @@ contract('ERC20Gateway::proveGateway', () => {
         `Expected block number is ${ProveERC20CogatewayProof.blockNumber} but
         found to be ${eventObject.args.blockNumber.toString(10)}.`,
       );
+
+      const latestProvenBlockNumber = await erc20Gateway.getRemoteGatewayLatestProvenBlockNumber
+        .call();
+      assert.isOk(
+        latestProvenBlockNumber.eqn(ProveERC20CogatewayProof.blockNumber),
+        'Invalid latest proven block number.',
+      );
     });
   });
 });