add foundry test

foundry-flashloans/README.md

@@ -9,6 +9,134 @@
 
 #### 🛠 we leverage [foundry](https://github.com/foundry-rs/foundry) to compare flashloans from **lending protocols on ethereum**, including deployment cost, and deployment size. 
 
+#### 💾 here is how the foundry test file looks:
+
+```solidity
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.16;
+
+import "forge-std/Test.sol";
+import "../src/AaveV2.sol";
+import "../src/Balancer.sol";
+import "../src/Euler.sol";
+import "../src/UniswapV2.sol";
+import "../src/UniswapV3.sol";
+
+
+/////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////
+// note: this test is not meant to be optimized for gas
+// it is meant to be a easy to read test for this problem
+/////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////
+
+
+contract getFlashloansData is Test {
+
+    ////////////////////////////////////
+    // define all constants in the test
+    ///////////////////////////////////
+
+    uint32 constant SIMULATION_CUTOFF = 20;
+    uint256 constant INTEREST_RATE = 0;
+    uint256 constant AMOUNT = 1 ether;
+    address constant WETH_ADDRESS = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
+
+    AAVE aave;
+    Balancer balancer;
+    Euler euler;
+    UniswapV2 uniswapv2;
+    UniswapV3 uniswapv3;
+
+
+    ////////////////////////////////////////////////////////////////
+    // simulation: create a vm storage for testing weth flashloans
+    ////////////////////////////////////////////////////////////////
+
+    function create_weth_storage(address addr) internal {
+        // https://github.com/foundry-rs/forge-std/blob/master/src/StdStorage.sol#L6
+        vm.store(
+            WETH_ADDRESS,
+            keccak256(abi.encode(addr, uint256(3))),
+            bytes32(uint256(10 ether))
+        );
+    }
+
+
+    //////////////////
+    // TESTS: setup
+    //////////////////
+
+    function setUp() public {
+        aave = new AAVE();
+        create_weth_storage(address(aave));
+
+        balancer = new Balancer();
+        create_weth_storage(address(balancer));
+
+        euler = new Euler();
+        create_weth_storage(address(euler));
+
+        uniswapv2 = new UniswapV2();
+        create_weth_storage(address(uniswapv2));
+
+        uniswapv3 = new UniswapV3();
+        create_weth_storage(address(uniswapv3));
+    }
+
+   
+    ///////////////
+    // TESTS: run
+    //////////////
+
+    function testAAVE() public {
+        address[] memory assets = new address[](1);
+        assets[0] = WETH_ADDRESS;
+
+        uint256[] memory amounts = new uint256[](1);
+        amounts[0] = AMOUNT;
+
+        uint256[] memory modes = new uint256[](1);
+        modes[0] = INTEREST_RATE; 
+
+        for (uint32 i; i < SIMULATION_CUTOFF; i++) {
+            aave.flashLoan(assets, amounts, modes);
+        }
+    }
+
+    function testBalancer() public {
+        address[] memory assets = new address[](1);
+        assets[0] = WETH_ADDRESS;
+
+        uint256[] memory amounts = new uint256[](1);
+        amounts[0] = AMOUNT;
+
+        for (uint32 i; i < SIMULATION_CUTOFF; i++) {
+            balancer.flashLoan(assets, amounts);
+        }
+    }
+
+    function testEulerFinance() public {
+        for (uint32 i; i < SIMULATION_CUTOFF; i++) {
+            euler.flashLoan(AMOUNT);
+        }
+    }
+
+    function testUniswapV2() public {
+        for (uint32 i; i < SIMULATION_CUTOFF; i++) {
+            uniswapv2.flashLoan(AMOUNT);
+        }
+    }
+        
+    function testUniswapV3() public {
+        for (uint32 i; i < SIMULATION_CUTOFF; i++) {
+            uniswapv3.flashLoan(AMOUNT);
+        }
+    }
+
+}
+```
+
 
 #### 🕹 these boilerplates can be expanded for several purposes, including testing vulnerabilities or extracting mev data. this work is adapted from **[jeiwan's code](https://github.com/Jeiwan/flash-loans-comparison)**.