# Long and Short Exercises In this exercise, you'll learn how to create a long and short position with Aave V3. The starter code for this exercise is provided in `foundry/src/exercises/LongShort.sol` Solution is provided in `foundry/src/solutions/LongShort.sol` ## Task 1 - Open a long or a short position ```solidity function open(OpenParams memory params) public returns (uint256 collateralAmountOut) { // Task 1.1 - Check that params.minHealthFactor is greater than 1e18 // Task 1.2 - Transfer collateral from msg.sender // Task 1.3 // - Approve and supply collateral to Aave // - Send aToken to msg.sender // Task 1.4 // - Borrow token from Aave // - Borrow on behalf of msg.sender // Task 1.5 - Check that health factor of msg.sender is > params.minHealthFactor // Task 1.6 // - Swap borrowed token to collateral token // - Send swapped token to msg.sender } ``` Implement the `open` function which will deposit the collateral token into Aave, borrow another token and then swap it for more collateral token. > Hints: > > - Call functions inside `Aave` and `Swap` contracts ## Task 2 - Close a long or a short position ```solidity function close(CloseParams memory params) public returns ( uint256 collateralWithdrawn, uint256 debtRepaidFromMsgSender, uint256 borrowedLeftover ) { // Task 2.1 - Transfer collateral from msg.sender into this contract // Task 2.2 - Swap collateral to borrowed token // Task 2.3 // - Repay borrowed token // - Amount to repay is the minimum of current debt and params.maxDebtToRepay // - If the amount to repay is greater that the amount swapped, // then transfer the difference from msg.sender // Task 2.4 - Withdraw collateral to msg.sender // Task 2.5 - Transfer profit = swapped amount - repaid amount // Task 2.6 - Return amount of collateral withdrawn, // debt repaid and profit from closing this position } ``` Implement the `close` function which will transfer the collateral token from `msg.sender`, swap it with the borrowed token, repay debt to Aave and withdraw the collateral and profit from this strategy. > Hints: > > - Call functions inside `Aave` and `Swap` contracts ## Test ```shell forge test --fork-url $FORK_URL --fork-block-number $FORK_BLOCK_NUM --match-path test/LongShort.test.sol -vvv ```