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flash loan tested, there is a niggle in FlashBorrower.sol
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alcueca
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Jul 25, 2023
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// SPDX-License-Identifier: UNLICENSED | ||
pragma solidity >=0.8.19 <0.9.0; | ||
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import { PRBTest } from "@prb/test/PRBTest.sol"; | ||
import { console2 } from "forge-std/console2.sol"; | ||
import { StdCheats } from "forge-std/StdCheats.sol"; | ||
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import { FlashLender } from "../src/FlashLender.sol"; | ||
import { FlashBorrower } from "../src/test/FlashBorrower.sol"; | ||
import { ERC20Mock } from "../src/test/ERC20Mock.sol"; | ||
import { IERC20 } from "../src/interfaces/IERC20.sol"; | ||
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/// @dev If this is your first time with Forge, read this tutorial in the Foundry Book: | ||
/// https://book.getfoundry.sh/forge/writing-tests | ||
contract FlashLenderTest is PRBTest, StdCheats { | ||
FlashLender internal lender; | ||
FlashBorrower internal borrower; | ||
IERC20 internal asset; | ||
IERC20 internal otherAsset; | ||
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/// @dev A function invoked before each test case is run. | ||
function setUp() public virtual { | ||
// Instantiate the contract-under-test. | ||
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asset = IERC20(address(new ERC20Mock("Asset", "AST"))); | ||
otherAsset = IERC20(address(new ERC20Mock("Other", "OTH"))); | ||
IERC20[] memory supportedAssets = new IERC20[](2); | ||
supportedAssets[0] = asset; | ||
supportedAssets[1] = otherAsset; | ||
lender = new FlashLender(supportedAssets, 10); | ||
borrower = new FlashBorrower(lender); | ||
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asset.transfer(address(lender), 999e18); // Keeping 1e18 for the flash fee. | ||
otherAsset.transfer(address(lender), 999e18); // Keeping 1e18 for the flash fee. | ||
} | ||
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/// @dev Simple flash loan test. | ||
function test_flashLoan() external { | ||
console2.log("test_flashLoan"); | ||
uint256 lenderBalance = asset.balanceOf(address(lender)); | ||
uint256 loan = 1e18; | ||
uint256 fee = lender.flashFee(asset, loan); | ||
asset.transfer(address(borrower), fee); | ||
borrower.flashBorrow(asset, loan); | ||
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assertEq(borrower.flashInitiator(), address(borrower)); | ||
assertEq(address(borrower.flashAsset()), address(asset)); | ||
assertEq(borrower.flashAmount(), loan); | ||
assertEq(borrower.flashBalance(), loan + fee); // The amount we transferred to pay for fees, plus the amount we borrowed | ||
assertEq(borrower.flashFee(), fee); | ||
assertEq(asset.balanceOf(address(lender)), lenderBalance + fee); | ||
} | ||
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function test_flashLoanAndReenter() external { | ||
console2.log("test_flashLoanAndReenter"); | ||
uint256 lenderBalance = asset.balanceOf(address(lender)); | ||
uint256 firstLoan = 1e18; | ||
uint256 secondLoan = 2e18; | ||
uint256 fees = lender.flashFee(asset, firstLoan) + lender.flashFee(asset, secondLoan); | ||
asset.transfer(address(borrower), fees); | ||
borrower.flashBorrowAndReenter(asset, firstLoan); | ||
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assertEq(borrower.flashInitiator(), address(borrower)); | ||
assertEq(address(borrower.flashAsset()), address(asset)); | ||
assertEq(borrower.flashAmount(), firstLoan + secondLoan); | ||
assertEq(borrower.flashBalance(), firstLoan + secondLoan + fees); // The amount we transferred to pay for fees, plus the amount we borrowed | ||
assertEq(borrower.flashFee(), fees); | ||
assertEq(asset.balanceOf(address(lender)), lenderBalance + fees); | ||
} | ||
} |
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// SPDX-License-Identifier: MIT | ||
pragma solidity ^0.8.0; | ||
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import { IERC3156PPFlashLender } from "lib/erc3156pp/src/interfaces/IERC3156PPFlashLender.sol"; | ||
import { IERC20 } from "lib/erc3156pp/src/interfaces/IERC20.sol"; | ||
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contract LoanReceiver { | ||
function retrieve(IERC20 asset) external { | ||
asset.transfer(msg.sender, asset.balanceOf(address(this))); | ||
} | ||
} | ||
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contract FlashBorrower { | ||
IERC3156PPFlashLender lender; | ||
LoanReceiver loanReceiver; | ||
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uint256 public flashBalance; | ||
address public flashInitiator; | ||
IERC20 public flashAsset; | ||
uint256 public flashAmount; | ||
uint256 public flashFee; | ||
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constructor (IERC3156PPFlashLender lender_) { | ||
lender = lender_; | ||
loanReceiver = new LoanReceiver(); | ||
} | ||
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/// @dev ERC-3156++ Flash loan callback | ||
function onFlashLoan(address initiator, address paymentReceiver, IERC20 asset, uint256 amount, uint256 fee, bytes calldata data) external returns(bytes memory) { | ||
require(msg.sender == address(lender), "FlashBorrower: Untrusted lender"); | ||
require(initiator == address(this), "FlashBorrower: External loan initiator"); | ||
flashInitiator = initiator; | ||
flashAsset = asset; | ||
flashAmount = amount; | ||
flashFee = fee; | ||
loanReceiver.retrieve(asset); | ||
flashBalance = IERC20(asset).balanceOf(address(this)); | ||
asset.transfer(paymentReceiver, amount + fee); | ||
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return ""; // abi.encode(data, paymentReceiver, fee); // TODO: Returning anything here causes a revert | ||
} | ||
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function onSteal(address initiator, address paymentReceiver, IERC20 asset, uint256 amount, uint256 fee, bytes calldata data) external returns(bytes memory) { | ||
require(msg.sender == address(lender), "FlashBorrower: Untrusted lender"); | ||
require(initiator == address(this), "FlashBorrower: External loan initiator"); | ||
flashInitiator = initiator; | ||
flashAsset = asset; | ||
flashAmount = amount; | ||
flashFee = fee; | ||
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// do nothing | ||
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return abi.encode(data, paymentReceiver, fee); | ||
} | ||
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function onReenter(address initiator, address paymentReceiver, IERC20 asset, uint256 amount, uint256 fee, bytes calldata data) external returns(bytes memory) { | ||
require(msg.sender == address(lender), "FlashBorrower: Untrusted lender"); | ||
require(initiator == address(this), "FlashBorrower: External loan initiator"); | ||
flashInitiator = initiator; | ||
flashAsset = asset; | ||
loanReceiver.retrieve(asset); | ||
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flashBorrow(asset, amount * 2); | ||
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asset.transfer(paymentReceiver, amount + fee); | ||
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// flashBorrow will have initialized these | ||
flashAmount += amount; | ||
flashFee += fee; | ||
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return abi.encode(data, paymentReceiver, fee); | ||
} | ||
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function flashBorrow(IERC20 asset, uint256 amount) public returns(bytes memory) { | ||
return lender.flashLoan(address(loanReceiver), asset, amount, "", this.onFlashLoan); | ||
} | ||
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function flashBorrowAndSteal(IERC20 asset, uint256 amount) public returns(bytes memory) { | ||
return lender.flashLoan(address(loanReceiver), asset, amount, "", this.onSteal); | ||
} | ||
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function flashBorrowAndReenter(IERC20 asset, uint256 amount) public returns(bytes memory) { | ||
return lender.flashLoan(address(loanReceiver), asset, amount, "", this.onReenter); | ||
} | ||
} |
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// SPDX-License-Identifier: UNLICENSED | ||
pragma solidity >=0.8.19 <0.9.0; | ||
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import { PRBTest } from "@prb/test/PRBTest.sol"; | ||
import { console2 } from "forge-std/console2.sol"; | ||
import { StdCheats } from "forge-std/StdCheats.sol"; | ||
import { IERC3156FlashLender } from "lib/erc3156/contracts/interfaces/IERC3156FlashLender.sol"; | ||
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import { FlashBorrower } from "../src/test/FlashBorrower.sol"; | ||
import { IERC20, ERC3156Wrapper } from "../src/erc3156/ERC3156Wrapper.sol"; | ||
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/// @dev If this is your first time with Forge, read this tutorial in the Foundry Book: | ||
/// https://book.getfoundry.sh/forge/writing-tests | ||
contract ERC3156WrapperTest is PRBTest, StdCheats { | ||
ERC3156Wrapper internal wrapper; | ||
FlashBorrower internal borrower; | ||
IERC20 internal dai; | ||
IERC3156FlashLender internal makerFlash; | ||
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/// @dev A function invoked before each test case is run. | ||
function setUp() public virtual { | ||
// Revert if there is no API key. | ||
string memory alchemyApiKey = vm.envOr("API_KEY_ALCHEMY", string("")); | ||
if (bytes(alchemyApiKey).length == 0) { | ||
revert("API_KEY_ALCHEMY variable missing"); | ||
} | ||
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vm.createSelectFork({ urlOrAlias: "mainnet", blockNumber: 16_428_000 }); | ||
makerFlash = IERC3156FlashLender(0x60744434d6339a6B27d73d9Eda62b6F66a0a04FA); | ||
dai = IERC20(0x6B175474E89094C44Da98b954EedeAC495271d0F); | ||
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IERC20[] memory assets = new IERC20[](1); | ||
assets[0] = dai; | ||
IERC3156FlashLender[] memory lenders = new IERC3156FlashLender[](1); | ||
lenders[0] = makerFlash; | ||
wrapper = new ERC3156Wrapper(assets, lenders); | ||
borrower = new FlashBorrower(wrapper); | ||
} | ||
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/// @dev Basic test. Run it with `forge test -vvv` to see the console log. | ||
function test_flashFee() external { | ||
console2.log("test_flashFee"); | ||
assertEq(wrapper.flashFee(dai, 1e18), 0, "Fee not zero"); | ||
assertEq(wrapper.flashFee(dai, type(uint256).max), type(uint256).max, "Fee not max"); | ||
} | ||
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function test_flashLoan() external { | ||
console2.log("test_flashLoan"); | ||
uint256 lenderBalance = dai.balanceOf(address(wrapper)); | ||
uint256 loan = 1e18; | ||
uint256 fee = wrapper.flashFee(dai, loan); | ||
dai.transfer(address(borrower), fee); | ||
bytes memory result = borrower.flashBorrow(dai, loan); | ||
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// TODO: Temporary test to ensure we receive the correct callback result | ||
assertEq(uint256(wrapper.CALLBACK_SUCCESS()), uint256(abi.decode(result, (bytes32)))); | ||
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assertEq(borrower.flashInitiator(), address(borrower)); | ||
assertEq(address(borrower.flashAsset()), address(dai)); | ||
assertEq(borrower.flashAmount(), loan); | ||
assertEq(borrower.flashBalance(), loan + fee); // The amount we transferred to pay for fees, plus the amount we borrowed | ||
assertEq(borrower.flashFee(), fee); | ||
assertEq(dai.balanceOf(address(wrapper)), lenderBalance + fee); | ||
} | ||
} |
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