solve open TODOs

Author: d10r

packages/ethereum-contracts/contracts/interfaces/superfluid/ISuperToken.sol

@@ -82,6 +82,24 @@ interface ISuperToken is ISuperfluidToken, IERC20Metadata, IERC777, IERC20Permit
      */
     function getYieldBackend() external view returns (address yieldBackend);
 
+    /**
+     * @dev Yield backend enabled event
+     * @param yieldBackend The address of the yield backend that was enabled
+     * @param depositAmount The amount deposited to the yield backend
+     */
+    event YieldBackendEnabled(
+        address indexed yieldBackend,
+        uint256 depositAmount
+    );
+
+    /**
+     * @dev Yield backend disabled event
+     * @param yieldBackend The address of the yield backend that was disabled
+     */
+    event YieldBackendDisabled(
+        address indexed yieldBackend
+    );
+
     /**************************************************************************
     * Immutable variables
     *************************************************************************/

packages/ethereum-contracts/contracts/superfluid/SuperToken.sol

@@ -84,7 +84,7 @@ contract SuperToken is
     /// @dev ERC20 Nonces for EIP-2612 (permit)
     mapping(address account => uint256) internal _nonces;
 
-    // TODO: use a randomly located storage slot instead?
+    /// @dev optional contract using the underlying asset to generate yield
     IYieldBackend internal _yieldBackend;
 
     // NOTE: for future compatibility, these are reserved solidity slots
@@ -212,16 +212,17 @@ contract SuperToken is
             ? address(this).balance
             : _underlyingToken.balanceOf(address(this));
         delegateCallChecked(address(_yieldBackend), abi.encodeCall(IYieldBackend.deposit, (depositAmount)));
-        // TODO: emit event
+        emit YieldBackendEnabled(address(_yieldBackend), depositAmount);
     }
 
     // withdraws everything and removes allowances
     function disableYieldBackend() external onlyAdmin {
         require(address(_yieldBackend) != address(0), "yield backend not set");
+        address oldYieldBackend = address(_yieldBackend);
         delegateCallChecked(address(_yieldBackend), abi.encodeCall(IYieldBackend.withdrawMax, ()));
         delegateCallChecked(address(_yieldBackend), abi.encodeCall(IYieldBackend.disable, ()));
         _yieldBackend = IYieldBackend(address(0));
-        // TODO: emit event
+        emit YieldBackendDisabled(oldYieldBackend);
     }
 
     function getYieldBackend() external view returns (address) {
@@ -396,7 +397,6 @@ contract SuperToken is
 
         if (spender != holder) {
             require(amount <= _allowances[holder][spender], "SuperToken: transfer amount exceeds allowance");
-            // TODO: this triggers an `Approval` event, which shouldn't happen for transfers.
             _approve(holder, spender, _allowances[holder][spender] - amount, false);
         }
 
@@ -767,7 +767,6 @@ contract SuperToken is
     {
         if (!_skipSelfMint) {
             if (address(_yieldBackend) != address(0)) {
-                // TODO: shall we deposit all, or just the upgradeAmount?
                 delegateCallChecked(address(_yieldBackend), abi.encodeCall(IYieldBackend.deposit, (amount)));
             }
 
@@ -788,7 +787,6 @@ contract SuperToken is
 
        if (address(_yieldBackend) != address(0)) {
             _skipSelfMint = true;
-            // TODO: we may want to skip if enough underlying already in the contract
             delegateCallChecked(address(_yieldBackend), abi.encodeCall(IYieldBackend.withdraw, (amount)));
             _skipSelfMint = false;
         }

packages/ethereum-contracts/test/foundry/superfluid/yieldbackend/AaveYieldBackendIntegration.t.sol

@@ -4,6 +4,7 @@ pragma solidity ^0.8.23;
 import { Test } from "forge-std/Test.sol";
 import { AaveYieldBackend } from "../../../../contracts/superfluid/AaveYieldBackend.sol";
 import { IERC20, ISuperfluid } from "../../../../contracts/interfaces/superfluid/ISuperfluid.sol";
+import { ISuperToken } from "../../../../contracts/interfaces/superfluid/ISuperToken.sol";
 import { SuperToken } from "../../../../contracts/superfluid/SuperToken.sol";
 import { IPool } from "aave-v3/src/contracts/interfaces/IPool.sol";
 
@@ -88,7 +89,11 @@ contract AaveYieldBackendIntegrationTest is Test {
     }
 
     function _enableYieldBackend() public {
+        uint256 underlyingBalanceBefore = IERC20(USDC).balanceOf(address(superToken));
+
         vm.startPrank(ADMIN);
+        vm.expectEmit(true, false, false, true);
+        emit ISuperToken.YieldBackendEnabled(address(aaveBackend), underlyingBalanceBefore);
         superToken.enableYieldBackend(aaveBackend);
         vm.stopPrank();
     }
@@ -177,6 +182,8 @@ contract AaveYieldBackendIntegrationTest is Test {
         _enableYieldBackend();
 
         vm.startPrank(ADMIN);
+        vm.expectEmit(true, false, false, true);
+        emit ISuperToken.YieldBackendDisabled(address(aaveBackend));
         superToken.disableYieldBackend();
         vm.stopPrank();
         assertEq(address(superToken.getYieldBackend()), address(0), "Yield backend mismatch");