Add new Uniswap transfer fee adapter

Author: richardliang

contracts/protocol/integration/UniswapV2TransferFeeExchangeAdapter.sol

@@ -0,0 +1,107 @@
+/*
+    Copyright 2021 Set Labs Inc.
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+
+    SPDX-License-Identifier: Apache License, Version 2.0
+*/
+
+pragma solidity 0.6.10;
+pragma experimental "ABIEncoderV2";
+
+/**
+ * @title UniswapV2TransferFeeExchangeAdapter
+ * @author Set Protocol
+ *
+ * Exchange adapter for Uniswap V2 Router02 that supports trading tokens with transfer fees
+ */
+contract UniswapV2TransferFeeExchangeAdapter {
+
+    /* ============ State Variables ============ */
+
+    // Address of Uniswap V2 Router02 contract
+    address public immutable router;
+
+    /* ============ Constructor ============ */
+
+    /**
+     * Set state variables
+     *
+     * @param _router       Address of Uniswap V2 Router02 contract
+     */
+    constructor(address _router) public {
+        router = _router;
+    }
+
+    /* ============ External Getter Functions ============ */
+
+    /**
+     * Return calldata for Uniswap V2 Router02 when trading a token with a transfer fee
+     *
+     * @param  _sourceToken              Address of source token to be sold
+     * @param  _destinationToken         Address of destination token to buy
+     * @param  _destinationAddress       Address that assets should be transferred to
+     * @param  _sourceQuantity           Amount of source token to sell
+     * @param  _minDestinationQuantity   Min amount of destination token to buy
+     * @param  _data                     Arbitrary bytes containing trade call data
+     *
+     * @return address                   Target contract address
+     * @return uint256                   Call value
+     * @return bytes                     Trade calldata
+     */
+    function getTradeCalldata(
+        address _sourceToken,
+        address _destinationToken,
+        address _destinationAddress,
+        uint256 _sourceQuantity,
+        uint256 _minDestinationQuantity,
+        bytes memory _data
+    )
+        external
+        view
+        returns (address, uint256, bytes memory)
+    {   
+        address[] memory path;
+
+        if(_data.length == 0){
+            path = new address[](2);
+            path[0] = _sourceToken;
+            path[1] = _destinationToken;
+        } else {
+            path = abi.decode(_data, (address[]));
+        }
+
+        bytes memory callData = abi.encodeWithSignature(
+            "swapExactTokensForTokensSupportingFeeOnTransferTokens(uint256,uint256,address[],address,uint256)",
+            _sourceQuantity,
+            _minDestinationQuantity,
+            path,
+            _destinationAddress,
+            block.timestamp
+        );
+        return (router, 0, callData);
+    }
+
+    /**
+     * Returns the address to approve source tokens to for trading. This is the Uniswap router address
+     *
+     * @return address             Address of the contract to approve tokens to
+     */
+    function getSpender()
+        external
+        view
+        returns (address)
+    {
+        return router;
+    }
+} 

test/protocol/integration/uniswapV2TransferFeeExchangeAdapter.spec.ts

@@ -0,0 +1,167 @@
+import "module-alias/register";
+
+import { BigNumber } from "@ethersproject/bignumber";
+import { defaultAbiCoder } from "ethers/lib/utils";
+
+import { Address, Bytes } from "@utils/types";
+import { Account } from "@utils/test/types";
+import {
+  EMPTY_BYTES,
+  ZERO,
+} from "@utils/constants";
+import { UniswapV2TransferFeeExchangeAdapter } from "@utils/contracts";
+import DeployHelper from "@utils/deploys";
+import {
+  ether,
+} from "@utils/index";
+import {
+  addSnapshotBeforeRestoreAfterEach,
+  getAccounts,
+  getSystemFixture,
+  getUniswapFixture,
+  getWaffleExpect,
+  getLastBlockTimestamp
+} from "@utils/test/index";
+
+import { SystemFixture, UniswapFixture } from "@utils/fixtures";
+
+const expect = getWaffleExpect();
+
+describe("UniswapV2TransferFeeExchangeAdapter", () => {
+  let owner: Account;
+  let mockSetToken: Account;
+  let deployer: DeployHelper;
+  let setup: SystemFixture;
+  let uniswapSetup: UniswapFixture;
+
+  let uniswapV2TransferFeeExchangeAdapter: UniswapV2TransferFeeExchangeAdapter;
+
+  before(async () => {
+    [
+      owner,
+      mockSetToken,
+    ] = await getAccounts();
+
+    deployer = new DeployHelper(owner.wallet);
+    setup = getSystemFixture(owner.address);
+    await setup.initialize();
+
+    uniswapSetup = getUniswapFixture(owner.address);
+    await uniswapSetup.initialize(
+      owner,
+      setup.weth.address,
+      setup.wbtc.address,
+      setup.dai.address
+    );
+
+    uniswapV2TransferFeeExchangeAdapter = await deployer.adapters.deployUniswapV2TransferFeeExchangeAdapter(uniswapSetup.router.address);
+  });
+
+  addSnapshotBeforeRestoreAfterEach();
+
+  describe("constructor", async () => {
+    let subjectUniswapRouter: Address;
+
+    beforeEach(async () => {
+      subjectUniswapRouter = uniswapSetup.router.address;
+    });
+
+    async function subject(): Promise<any> {
+      return await deployer.adapters.deployUniswapV2TransferFeeExchangeAdapter(subjectUniswapRouter);
+    }
+
+    it("should have the correct router address", async () => {
+      const deployedUniswapV2TransferFeeExchangeAdapter = await subject();
+
+      const actualRouterAddress = await deployedUniswapV2TransferFeeExchangeAdapter.router();
+      expect(actualRouterAddress).to.eq(uniswapSetup.router.address);
+    });
+  });
+
+  describe("getSpender", async () => {
+    async function subject(): Promise<any> {
+      return await uniswapV2TransferFeeExchangeAdapter.getSpender();
+    }
+
+    it("should return the correct spender address", async () => {
+      const spender = await subject();
+
+      expect(spender).to.eq(uniswapSetup.router.address);
+    });
+  });
+
+  describe("getTradeCalldata", async () => {
+    let sourceAddress: Address;
+    let destinationAddress: Address;
+    let sourceQuantity: BigNumber;
+    let destinationQuantity: BigNumber;
+
+    let subjectMockSetToken: Address;
+    let subjectSourceToken: Address;
+    let subjectDestinationToken: Address;
+    let subjectSourceQuantity: BigNumber;
+    let subjectMinDestinationQuantity: BigNumber;
+    let subjectData: Bytes;
+
+    beforeEach(async () => {
+      sourceAddress = setup.wbtc.address;          // WBTC Address
+      sourceQuantity = BigNumber.from(100000000);  // Trade 1 WBTC
+      destinationAddress = setup.dai.address;      // DAI Address
+      destinationQuantity = ether(30000);         // Receive at least 30k DAI
+
+      subjectSourceToken = sourceAddress;
+      subjectDestinationToken = destinationAddress;
+      subjectMockSetToken = mockSetToken.address;
+      subjectSourceQuantity = sourceQuantity;
+      subjectMinDestinationQuantity = destinationQuantity;
+      subjectData = EMPTY_BYTES;
+    });
+
+    async function subject(): Promise<any> {
+      return await uniswapV2TransferFeeExchangeAdapter.getTradeCalldata(
+        subjectSourceToken,
+        subjectDestinationToken,
+        subjectMockSetToken,
+        subjectSourceQuantity,
+        subjectMinDestinationQuantity,
+        subjectData,
+      );
+    }
+
+    it("should return the correct trade calldata", async () => {
+      const calldata = await subject();
+      const callTimestamp = await getLastBlockTimestamp();
+      const expectedCallData = uniswapSetup.router.interface.encodeFunctionData("swapExactTokensForTokensSupportingFeeOnTransferTokens", [
+        sourceQuantity,
+        destinationQuantity,
+        [sourceAddress, destinationAddress],
+        subjectMockSetToken,
+        callTimestamp,
+      ]);
+      expect(JSON.stringify(calldata)).to.eq(JSON.stringify([uniswapSetup.router.address, ZERO, expectedCallData]));
+    });
+
+    describe("when passed in custom path to trade data", async () => {
+      beforeEach(async () => {
+        const path = [sourceAddress, setup.weth.address, destinationAddress];
+        subjectData = defaultAbiCoder.encode(
+          ["address[]"],
+          [path]
+        );
+      });
+
+      it("should return the correct trade calldata", async () => {
+        const calldata = await subject();
+        const callTimestamp = await getLastBlockTimestamp();
+        const expectedCallData = uniswapSetup.router.interface.encodeFunctionData("swapExactTokensForTokensSupportingFeeOnTransferTokens", [
+          sourceQuantity,
+          destinationQuantity,
+          [sourceAddress, setup.weth.address, destinationAddress],
+          subjectMockSetToken,
+          callTimestamp,
+        ]);
+        expect(JSON.stringify(calldata)).to.eq(JSON.stringify([uniswapSetup.router.address, ZERO, expectedCallData]));
+      });
+    });
+  });
+});