### Exercise Solution Let's go over the solution for the first exercise. The first exercise is to call `exactInputSingle` on the `swapRouter02` contract. Here is the initial code: ```javascript router.exactInputSingle ``` We need to pass in a parameter. Navigating to the `ISwapRouter` interface, we see this is the struct parameter that we need to prepare: ```javascript struct ExactInputSingleParams { address tokenIn; address tokenOut; uint24 fee; address recipient; uint256 amountIn; uint256 amountOutMinimum; uint160 sqrtPriceLimitX96; } ``` We'll copy this and paste it in. Inside this test file, the struct `ExactInputSingleParams` is not defined. It is imported as `ISwapRouter`, so we need to correct this: ```javascript ISwapRouter.ExactInputSingleParams ``` `tokenIn` will be `DAI`, and `tokenOut` will be `WETH`. ```javascript tokenIn: DAI, tokenOut: WETH, ``` The `fee` is the pool fee that determines the pool. We are swapping on the `DAI/WETH` pool with a 0.3% fee. The fee is defined as `POOL_FEE`. ```javascript fee: POOL_FEE, ``` `recipient` will be the address that will receive the token out. In this case, it will be this contract. ```javascript recipient: address(this), ``` For `amountIn` we will send 1000 `DAI`. ```javascript amountIn: 1000 * 1e18, ``` `amountOutMinimum` we will set to 1, and `sqrtPriceLimitX96` we will set to 0. ```javascript amountOutMinimum: 1, sqrtPriceLimitX96: 0, ``` That completes exercise 1. Let's try executing this test. We will execute this test against the main network, so first we'll set up the fork URL. ```bash forge test --fork-url https://eth-mainnet.g.alchemy.com/v2/... ``` Then we will execute the test by typing: ```bash forge test --fork-url $FORK_URL --match-path test/uniswap-v3/exercises/UniswapV3Swap.test.sol -vvv ``` Our test passed. For putting in 1000 `DAI`, we get about 0.332 `WETH`.