fix: Improve curve executor tests and docstrings

--- don't change below this line ---
ENG-4305 Took 34 minutes


Took 8 seconds

foundry/src/executors/CurveExecutor.sol

@@ -13,10 +13,42 @@ contract CurveExecutor is IExecutor {
     ICurveRouter public immutable curveRouter;
     address public immutable nativeToken;
 
-    struct SwapParams {
+    /**
+     * @dev Struct representing the parameters for a Curve swap.
+     *
+     * `route` is an array of [initial token, pool or zap, token, pool or zap, token, ...]
+     * The array is iterated until a pool address of 0x00, then the last given token is transferred to `receiver`.
+     *
+     * `swapParams` is a multidimensional array of [i, j, swap_type, pool_type, n_coins] where:
+     * - i is the index of input token
+     * - j is the index of output token
+     *
+     * The swap_type should be:
+     * 1. for `exchange`
+     * 2. for `exchange_underlying`
+     * 3. for underlying exchange via zap: factory stable metapools with lending base pool `exchange_underlying`
+     *    and factory crypto-meta pools underlying exchange (`exchange` method in zap)
+     * 4. for coin -> LP token "exchange" (actually `add_liquidity`)
+     * 5. for lending pool underlying coin -> LP token "exchange" (actually `add_liquidity`)
+     * 6. for LP token -> coin "exchange" (actually `remove_liquidity_one_coin`)
+     * 7. for LP token -> lending or fake pool underlying coin "exchange" (actually `remove_liquidity_one_coin`)
+     * 8. for ETH <-> WETH, ETH -> stETH or ETH -> frxETH, stETH <-> wstETH, frxETH <-> sfrxETH, ETH -> wBETH, USDe -> sUSDe
+     *
+     * pool_type: 1 - stable, 2 - twocrypto, 3 - tricrypto, 4 - llamma
+     *            10 - stable-ng, 20 - twocrypto-ng, 30 - tricrypto-ng
+     *
+     * n_coins is the number of coins in the pool.
+     *
+     * `receiver` is the address of the receiver of the final token.
+     *
+     * `needsApproval` is a flag indicating whether the initial token needs approval before the swap.
+     *
+     * For more see https://github.com/curvefi/curve-router-ng/blob/9ab006ca848fc7f1995b6fbbecfecc1e0eb29e2a/contracts/Router.vy
+     *
+     */
+    struct CurveSwapParams {
         address[11] route;
         uint256[5][5] swapParams;
-        uint256 minAmountOut;
         address receiver;
         bool needsApproval;
     }
@@ -35,7 +67,7 @@ contract CurveExecutor is IExecutor {
         payable
         returns (uint256)
     {
-        SwapParams memory params = _decodeData(data);
+        CurveSwapParams memory params = _decodeData(data);
 
         if (params.needsApproval) {
             // slither-disable-next-line unused-return
@@ -47,21 +79,18 @@ contract CurveExecutor is IExecutor {
         address[5] memory pools;
         return curveRouter.exchange{
             value: params.route[0] == nativeToken ? amountIn : 0
-        }(
-            params.route,
-            params.swapParams,
-            amountIn,
-            params.minAmountOut,
-            pools,
-            params.receiver
-        );
+        }(params.route, params.swapParams, amountIn, 0, pools, params.receiver);
     }
 
     function _decodeData(bytes calldata data)
         internal
         pure
-        returns (SwapParams memory params)
+        returns (CurveSwapParams memory params)
     {
-        return abi.decode(data, (SwapParams));
+        return abi.decode(data, (CurveSwapParams));
+    }
+
+    receive() external payable {
+        require(msg.sender.code.length != 0);
     }
 }