Add mocked message passing contracts

packages/contracts/contracts/optimistic-ethereum/bridge/CrossDomainMessenger.interface.sol

@@ -0,0 +1,27 @@
+pragma solidity ^0.5.0;
+
+contract ICrossDomainMessenger {
+    address public crossDomainMsgSender;
+
+    /**
+     * Relays a message to a given target contract.
+     * @param _target Address of the target contract.
+     * @param _sender Address of the message sender.
+     * @param _message Calldata to relay.
+     */
+    function relayMessage(
+        address _target,
+        address _sender,
+        bytes memory _message
+    ) public;
+
+    /**
+     * Sends a message to another cross domain messenger to be relayed.
+     * @param _target Address of the target contract.
+     * @param _message Calldata to relay.
+     */
+    function sendMessage(
+        address _target,
+        bytes memory _message
+    ) public;
+}

packages/contracts/contracts/optimistic-ethereum/bridge/MockCrossDomainMessenger.sol

@@ -0,0 +1,70 @@
+pragma solidity ^0.5.0;
+
+/* Interface Imports */
+import { ICrossDomainMessenger } from "./CrossDomainMessenger.interface.sol";
+
+/**
+ * @title MockCrossDomainMessenger
+ */
+contract MockCrossDomainMessenger is ICrossDomainMessenger {
+    /*
+     * Contract Variables
+     */
+
+    ICrossDomainMessenger targetMessenger;
+    address public crossDomainMsgSender;
+
+    /*
+     * Public Functions
+     */
+
+    /**
+     * Relays a message to a target contract.
+     * .inheritdoc ICrossDomainMessenger
+     */
+    function relayMessage(
+        address _target,
+        address _sender,
+        bytes memory _message
+    )
+        public
+    {
+        crossDomainMsgSender = _sender;
+        (bool success,) = _target.call(_message);
+        require(success, "Received message reverted during execution.");
+    }
+
+    /**
+     * Sends a message to the target messenger.
+     * .inheritdoc ICrossDomainMessenger
+     */
+    function sendMessage(
+        address _target,
+        bytes memory _message
+    )
+        public
+    {
+        require(
+            address(targetMessenger) != address(0),
+            "Cannot send a message without setting the target messenger."
+        );
+
+        targetMessenger.relayMessage(
+            _target,
+            msg.sender,
+            _message
+        );
+    }
+
+    /**
+     * Sets the target messenger.
+     * @param _messenger Target messenger address.
+     */
+    function setTargetMessenger(
+        address _messenger
+    )
+        public
+    {
+        targetMessenger = ICrossDomainMessenger(_messenger);
+    }
+}

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

@@ -0,0 +1,18 @@
+pragma solidity ^0.5.0;
+
+import { ICrossDomainMessenger} from "../optimistic-ethereum/bridge/CrossDomainMessenger.interface.sol";
+import { SimpleStorage } from "./SimpleStorage.sol";
+
+contract CrossDomainSimpleStorage is SimpleStorage {
+    ICrossDomainMessenger crossDomainMessenger;
+    address public crossDomainMsgSender;
+
+    function setMessenger(address _crossDomainMessengerAddress) public {
+        crossDomainMessenger = ICrossDomainMessenger(_crossDomainMessengerAddress);
+    }
+
+    function crossDomainSetStorage(bytes32 key, bytes32 value) public {
+        crossDomainMsgSender = crossDomainMessenger.crossDomainMsgSender();
+        setStorage(key, value);
+    }
+}

packages/contracts/package.json

@@ -26,9 +26,11 @@
     "test:contracts": "cross-env SOLPP_FLAGS=\"FLAG_IS_TEST,FLAG_IS_DEBUG\" buidler test --show-stack-traces",
     "coverage": "yarn run coverage:contracts",
     "coverage:contracts": "cross-env SOLPP_FLAGS=\"FLAG_IS_TEST\" buidler coverage --network coverage --show-stack-traces --testfiles \"test/contracts/**/*.spec.ts\"",
-    "build": "yarn run build:contracts && yarn run build:typescript",
+    "build": "yarn run build:contracts && yarn run build:typescript && yarn run build:copy",
     "build:contracts": "buidler compile",
     "build:typescript": "tsc -p .",
+    "build:copy": "yarn run build:copy:contracts",
+    "build:copy:contracts": "copyfiles -u 2 \"contracts/optimistic-ethereum/**/*.sol\" \"build/contracts\"",
     "clean": "rm -rf ./artifacts ./build ./cache",
     "lint": "yarn run lint:typescript",
     "lint:typescript": "tslint --format stylish --project .",
@@ -61,6 +63,7 @@
     "typescript": "^3.9.5"
   },
   "devDependencies": {
+    "copyfiles": "^2.3.0",
     "cross-env": "^7.0.2",
     "glob": "^7.1.6",
     "solidity-coverage": "^0.7.9"

packages/contracts/test/contracts/bridge/MockCrossDomainMessenger.spec.ts

@@ -0,0 +1,126 @@
+import { expect } from '../../setup'
+
+/* External Imports */
+import { ethers } from '@nomiclabs/buidler'
+import { ContractFactory, Contract, Signer } from 'ethers'
+import { NULL_ADDRESS } from '@eth-optimism/core-utils'
+
+describe('MockCrossDomainMessenger', () => {
+  let wallet: Signer
+  before(async () => {
+    ;[wallet] = await ethers.getSigners()
+  })
+
+  let MockCrossDomainMessengerFactory: ContractFactory
+  let CrossDomainSimpleStorageFactory: ContractFactory
+  before(async () => {
+    MockCrossDomainMessengerFactory = await ethers.getContractFactory(
+      'MockCrossDomainMessenger'
+    )
+    CrossDomainSimpleStorageFactory = await ethers.getContractFactory(
+      'CrossDomainSimpleStorage'
+    )
+  })
+
+  let L1MockCrossDomainMessenger: Contract
+  let L2MockCrossDomainMessenger: Contract
+  beforeEach(async () => {
+    L1MockCrossDomainMessenger = await MockCrossDomainMessengerFactory.deploy()
+    L2MockCrossDomainMessenger = await MockCrossDomainMessengerFactory.deploy()
+
+    await L1MockCrossDomainMessenger.setTargetMessenger(
+      L2MockCrossDomainMessenger.address
+    )
+    await L2MockCrossDomainMessenger.setTargetMessenger(
+      L1MockCrossDomainMessenger.address
+    )
+  })
+
+  let L2SimpleStorage: Contract
+  beforeEach(async () => {
+    L2SimpleStorage = await CrossDomainSimpleStorageFactory.deploy()
+
+    await L2SimpleStorage.setMessenger(L2MockCrossDomainMessenger.address)
+  })
+  describe('relayMessage', () => {
+    it('should successfully relay a message to the target receiver', async () => {
+      const expectedStorageKey = ethers.utils.keccak256('0x1234')
+      const expectedStorageValue = ethers.utils.keccak256('0x5678')
+
+      const calldata = L2SimpleStorage.interface.encodeFunctionData(
+        'crossDomainSetStorage',
+        [expectedStorageKey, expectedStorageValue]
+      )
+
+      const expectedMessage = [await wallet.getAddress(), calldata]
+
+      await L2MockCrossDomainMessenger.relayMessage(
+        L2SimpleStorage.address,
+        ...expectedMessage
+      )
+
+      const actualStorageValue = await L2SimpleStorage.getStorage(
+        expectedStorageKey
+      )
+      expect(actualStorageValue).to.equal(expectedStorageValue)
+      expect(await L2SimpleStorage.crossDomainMsgSender()).to.equal(
+        await wallet.getAddress()
+      )
+    })
+  })
+
+  describe('sendMessage', () => {
+    it('should successfully send a message to another messenger', async () => {
+      const expectedStorageKey = ethers.utils.keccak256('0x1234')
+      const expectedStorageValue = ethers.utils.keccak256('0x5678')
+
+      const calldata = L2SimpleStorage.interface.encodeFunctionData(
+        'crossDomainSetStorage',
+        [expectedStorageKey, expectedStorageValue]
+      )
+
+      await L1MockCrossDomainMessenger.sendMessage(
+        L2SimpleStorage.address,
+        calldata,
+        {
+          from: await wallet.getAddress(),
+        }
+      )
+
+      const currentBlock = await ethers.provider.getBlock('latest')
+      const expectedMessage = [await wallet.getAddress(), calldata]
+
+      const actualStorageValue = await L2SimpleStorage.getStorage(
+        expectedStorageKey
+      )
+      expect(actualStorageValue).to.equal(expectedStorageValue)
+      expect(await L2SimpleStorage.crossDomainMsgSender()).to.equal(
+        await wallet.getAddress()
+      )
+    })
+
+    it('should revert if its target messenger is not set', async () => {
+      const expectedStorageKey = ethers.utils.keccak256('0x1234')
+      const expectedStorageValue = ethers.utils.keccak256('0x5678')
+
+      const calldata = L2SimpleStorage.interface.encodeFunctionData(
+        'setStorage',
+        [expectedStorageKey, expectedStorageValue]
+      )
+
+      await L1MockCrossDomainMessenger.setTargetMessenger(NULL_ADDRESS)
+
+      await expect(
+        L1MockCrossDomainMessenger.sendMessage(
+          L2SimpleStorage.address,
+          calldata,
+          {
+            from: await wallet.getAddress(),
+          }
+        )
+      ).to.be.revertedWith(
+        'Cannot send a message without setting the target messenger.'
+      )
+    })
+  })
+})