Added mock bridge contract

packages/contracts/contracts/optimistic-ethereum/OVM/bridge/OVM_L2CrossDomainMessenger.sol

@@ -47,31 +47,6 @@ contract OVM_L2CrossDomainMessenger is iOVM_L2CrossDomainMessenger, OVM_BaseCros
      * Public Functions *
      ********************/
 
-    /**
-     * Sends a cross domain message to the target messenger.
-     * @inheritdoc iOVM_L2CrossDomainMessenger
-     */
-    function sendMessage(
-        address _target,
-        bytes memory _message,
-        uint256 _gasLimit
-    )
-        override
-        public
-    {
-        bytes memory xDomainCalldata = _getXDomainCalldata(
-            _target,
-            msg.sender,
-            _message,
-            messageNonce
-        );
-
-        _sendXDomainMessage(xDomainCalldata, _gasLimit);
-
-        messageNonce += 1;
-        sentMessages[keccak256(xDomainCalldata)] = true;
-    }
-
     /**
      * Relays a cross domain message to a contract.
      * @inheritdoc iOVM_L2CrossDomainMessenger
@@ -113,6 +88,31 @@ contract OVM_L2CrossDomainMessenger is iOVM_L2CrossDomainMessenger, OVM_BaseCros
         receivedMessages[keccak256(xDomainCalldata)] = true;
     }
 
+    /**
+     * Sends a cross domain message to the target messenger.
+     * @inheritdoc iOVM_L2CrossDomainMessenger
+     */
+    function sendMessage(
+        address _target,
+        bytes memory _message,
+        uint256 _gasLimit
+    )
+        override
+        public
+    {
+        bytes memory xDomainCalldata = _getXDomainCalldata(
+            _target,
+            msg.sender,
+            _message,
+            messageNonce
+        );
+
+        _sendXDomainMessage(xDomainCalldata, _gasLimit);
+
+        messageNonce += 1;
+        sentMessages[keccak256(xDomainCalldata)] = true;
+    }
+
 
     /**********************
      * Internal Functions *

packages/contracts/contracts/optimistic-ethereum/iOVM/bridge/iOVM_L2CrossDomainMessenger.sol

@@ -15,28 +15,28 @@ interface iOVM_L2CrossDomainMessenger is iOVM_BaseCrossDomainMessenger {
      ********************/
 
     /**
-     * Sends a cross domain message to the target messenger.
+     * Relays a cross domain message to a contract.
      * @param _target Target contract address.
+     * @param _sender Message sender address.
      * @param _message Message to send to the target.
-     * @param _gasLimit Gas limit for the provided message.
+     * @param _messageNonce Nonce for the provided message.
      */
-    function sendMessage(
+    function relayMessage(
         address _target,
+        address _sender,
         bytes memory _message,
-        uint256 _gasLimit
+        uint256 _messageNonce
     ) external;
 
     /**
-     * Relays a cross domain message to a contract.
+     * Sends a cross domain message to the target messenger.
      * @param _target Target contract address.
-     * @param _sender Message sender address.
      * @param _message Message to send to the target.
-     * @param _messageNonce Nonce for the provided message.
+     * @param _gasLimit Gas limit for the provided message.
      */
-    function relayMessage(
+    function sendMessage(
         address _target,
-        address _sender,
         bytes memory _message,
-        uint256 _messageNonce
+        uint256 _gasLimit
     ) external;
 }

packages/contracts/contracts/optimistic-ethereum/mockOVM/bridge/mockOVM_CrossDomainMessenger.sol

+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.7.0;
+pragma experimental ABIEncoderV2;
+
+/* Contract Imports */
+import { OVM_BaseCrossDomainMessenger } from "../../OVM/bridge/OVM_BaseCrossDomainMessenger.sol";
+
+/**
+ * @title mockOVM_CrossDomainMessenger
+ */
+contract mockOVM_CrossDomainMessenger is OVM_BaseCrossDomainMessenger {
+
+    /***********
+     * Structs *
+     ***********/
+
+    struct ReceivedMessage {
+        uint256 timestamp;
+        address target;
+        address sender;
+        bytes message;
+        uint256 messageNonce;
+        uint256 gasLimit;
+    }
+
+
+    /**********************
+     * Contract Variables *
+     **********************/
+
+    ReceivedMessage[] internal fullReceivedMessages;
+    uint256 internal lastRelayedMessage;
+    uint256 internal delay;
+
+
+    /***************
+     * Constructor *
+     ***************/
+
+    /**
+     * @param _delay Time in seconds before a message can be relayed.
+     */
+    constructor(
+        uint256 _delay
+    ) {
+        delay = _delay;
+    }
+
+
+    /********************
+     * Public Functions *
+     ********************/
+
+    /**
+     * Sends a message to another mock xdomain messenger.
+     * @param _target Target for the message.
+     * @param _message Message to send.
+     * @param _gasLimit Amount of gas to send with the call.
+     */
+    function sendMessage(
+        address _target,
+        bytes memory _message,
+        uint32 _gasLimit
+    )
+        public
+    {
+        mockOVM_CrossDomainMessenger targetMessenger = mockOVM_CrossDomainMessenger(
+            targetMessengerAddress
+        );
+
+        // Just send it over!
+        targetMessenger.receiveMessage(ReceivedMessage({
+            timestamp: block.timestamp,
+            target: _target,
+            sender: msg.sender,
+            message: _message,
+            messageNonce: messageNonce,
+            gasLimit: _gasLimit
+        }));
+
+        messageNonce += 1;
+    }
+
+    /**
+     * Receives a message to be sent later.
+     * @param _message Message to send later.
+     */
+    function receiveMessage(
+        ReceivedMessage memory _message
+    )
+        public
+    {
+        fullReceivedMessages.push(_message);
+    }
+
+    /**
+     * Checks whether we have messages to relay.
+     * @param _exists Whether or not we have more messages to relay.
+     */
+    function hasNextMessage()
+        public
+        view
+        returns (
+            bool _exists
+        )
+    {
+        return fullReceivedMessages.length < lastRelayedMessage;
+    }
+
+    /**
+     * Relays the last received message not yet relayed.
+     */
+    function relayNextMessage()
+        public
+    {
+        if (hasNextMessage() == false) {
+            return;
+        }
+
+        ReceivedMessage memory nextMessage = fullReceivedMessages[lastRelayedMessage];
+        if (nextMessage.timestamp + delay > block.timestamp) {
+            return;
+        }
+
+        xDomainMessageSender = nextMessage.sender;
+        nextMessage.target.call{gas: nextMessage.gasLimit}(nextMessage.message);
+
+        lastRelayedMessage += 1;
+    }
+}