Added Uniswap into Channel implementation

contracts/ChannelImplementation.sol

@@ -5,6 +5,7 @@ import { ECDSA } from "@openzeppelin/contracts/cryptography/ECDSA.sol";
 import { SafeMath } from "@openzeppelin/contracts/math/SafeMath.sol";
 import { IERC20Token } from "./interfaces/IERC20Token.sol";
 import { IHermesContract } from "./interfaces/IHermesContract.sol";
+import { IUniswapV2Router } from "./uniswap/IUniswapV2Router.sol";
 import { FundsRecovery } from "./FundsRecovery.sol";
 
 contract ChannelImplementation is FundsRecovery {
@@ -28,7 +29,7 @@ contract ChannelImplementation is FundsRecovery {
     ExitRequest public exitRequest;
     Hermes public hermes;
     address public operator;          // channel operator = sha3(IdentityPublicKey)[:20]
-    address public dex;
+    IUniswapV2Router internal dex;    // any uniswap v2 compatible dex router address
 
     event PromiseSettled(address beneficiary, uint256 amount, uint256 totalSettled);
     event ChannelInitialised(address operator, address hermes);
@@ -39,22 +40,25 @@ contract ChannelImplementation is FundsRecovery {
       ------------------------------------------- SETUP -------------------------------------------
     */
 
-    // Fallback function - redirect ethers topup into DEX
+    // Fallback function - exchange received ETH into MYST
     receive() external payable {
-        (bool success, ) = address(dex).call{value: msg.value}(msg.data);
-        require(success, "Tx was rejected by DEX");
+        address[] memory path = new address[](2);
+        path[0] = dex.WETH();
+        path[1] = address(token);
+
+        dex.swapExactETHForTokens{value: msg.value}(0, path, address(this), block.timestamp);
     }
 
     // Because of proxy pattern this function is used insted of constructor.
     // Have to be called right after proxy deployment.
-    function initialize(address _token, address _dex, address _identityHash, address _hermesId, uint256 _fee) public {
+    function initialize(address _token, address _dexAddress, address _identityHash, address _hermesId, uint256 _fee) public {
         require(!isInitialized(), "Is already initialized");
         require(_identityHash != address(0), "Identity can't be zero");
         require(_hermesId != address(0), "HermesID can't be zero");
         require(_token != address(0), "Token can't be deployd into zero address");
 
         token = IERC20Token(_token);
-        dex = _dex;
+        dex = IUniswapV2Router(_dexAddress);
 
         // Transfer required fee to msg.sender (most probably Registry)
         if (_fee > 0) {

test/channel.js

@@ -6,7 +6,8 @@
 const { BN } = require('@openzeppelin/test-helpers')
 const {
     topUpTokens,
-    topUpEthers
+    topUpEthers,
+    setupDEX
 } = require('./utils/index.js')
 const wallet = require('./utils/wallet.js')
 const { generatePromise, signExitRequest, constructPayload } = require('./utils/client.js')
@@ -26,8 +27,9 @@ contract('Channel Contract Implementation tests', ([txMaker, ...otherAccounts])
     let token, channel
     before(async () => {
         token = await MystToken.new()
+        const dex = await setupDEX(token, txMaker)
         hermesImplementation = await TestHermesImplementation.new(token.address, hermes.address, 0, OneToken)
-        channel = await TestChannelImplementation.new(token.address, identityHash, hermesImplementation.address, Zero)
+        channel = await TestChannelImplementation.new(token.address, dex.address, identityHash, hermesImplementation.address, Zero)
 
         // Give some ethers for gas for hermes
         topUpEthers(txMaker, hermes.address, OneEther)
@@ -202,4 +204,24 @@ contract('Channel Contract Implementation tests', ([txMaker, ...otherAccounts])
         const exitRequest = await channel.exitRequest()
         expect(exitRequest.beneficiary).to.be.equal(beneficiary)
     })
+
+    /**
+     * Testing topup with ETH via DEX
+     */
+    it('should exchange ethers into tokens', async () => {
+        const userAccount = otherAccounts[0]
+        const initialChannelBalance = await token.balanceOf(channel.address)
+        const ethersAmount = new BN('2000')
+        const expectedTokens = new BN('3987')
+
+        // Send some ethers into payment channel
+        await channel.sendTransaction({
+            from: userAccount,
+            value: ethersAmount,
+            gas: 200000
+        })
+
+        const channelBalance = await token.balanceOf(channel.address)
+        channelBalance.should.be.bignumber.equal(initialChannelBalance.add(expectedTokens))
+    })
 })

test/contracts/TestChannelImplementation.sol

@@ -2,17 +2,14 @@
 pragma solidity >=0.7.0;
 
 import { ChannelImplementation } from "../../contracts/ChannelImplementation.sol";
-import { MystDEX } from "../../contracts/MystDEX.sol";
-
 
 // Helper functions to be used in tests
 contract TestChannelImplementation is ChannelImplementation {
     uint256 constant TEST_DELAY_BLOCKS = 4;
 
     // Constructor is needed only in tests where we don't use minimal Proxies and testing implementation directly
-    constructor (address _token, address _identityHash, address _hermesAddress, uint256 _fee) {
-        MystDEX _dex = new MystDEX();
-        initialize(_token, address(_dex), _identityHash, _hermesAddress, _fee);
+    constructor (address _token, address _dex, address _identityHash, address _hermesAddress, uint256 _fee) {
+        initialize(_token, _dex, _identityHash, _hermesAddress, _fee);
     }
 
     function getTimelock() internal view override returns (uint256) {

test/utils/index.js

@@ -8,6 +8,7 @@ const IUniswapV2Router = artifacts.require("IUniswapV2Router")
 
 const deployRouter02Tx = require('../../scripts/UniswapV2Router02.json')
 const OneToken = web3.utils.toWei(new BN('1000000000000000000'), 'wei')
+const HalfETH = web3.utils.toWei(new BN('500000000000000000'), 'wei')
 
 // CREATE2 address is calculated this way:
 // keccak("0xff++msg.sender++salt++keccak(byteCode)")
@@ -106,16 +107,17 @@ async function setupDEX(token, txMaker) {
     // Map with abi
     const dex = await IUniswapV2Router.at(deployRouter02Tx.contractAddr)
 
-    // Setup traiding pair and provide liquidity
-    const farFuture = 2147483646 // year 2038, end of unix time epoch
-    await topUpTokens(token, txMaker, OneToken)
-    await token.approve(dex.address, OneToken)
-
-    await dex.addLiquidityETH(token.address, 10000000, 10000000, 5000000, txMaker, farFuture, {
-        from: txMaker,
-        value: 5000000
-    })
+    // Setup traiding pair and provide liquidity (if there is none)
+    if ((await token.balanceOf(deployRouter02Tx.contractAddr)).toNumber() === 0) {
+        const farFuture = 2147483646 // year 2038, end of unix time epoch
+        await topUpTokens(token, txMaker, OneToken)
+        await token.approve(dex.address, OneToken)
 
+        await dex.addLiquidityETH(token.address, OneToken, OneToken, HalfETH, txMaker, farFuture, {
+            from: txMaker,
+            value: HalfETH
+        })
+    }
     return dex
 }