use this.attest.selector

Author: mgretzke

src/allocators/SimpleAllocator.sol

@@ -86,7 +86,7 @@ contract SimpleAllocator is ISimpleAllocator {
             revert InsufficientBalance(from_, id_, balance, fullAmount);
         }
 
-        return 0x1a808f91;
+        return this.attest.selector;
     }
 
     /// @inheritdoc IERC1271

test/SimpleAllocator.t.sol

@@ -486,6 +486,34 @@ contract SimpleAllocator_Attest is Deposited {
         compactContract.transfer(user, attacker, defaultAmount, address(usdc), address(simpleAllocator));
     }
 
+    function test_successfullyAttested_returnsSelector() public {
+        bytes4 selector = bytes4(0x1a808f91);
+
+        uint32 transferAmount = 10;
+        uint32 lockedAmount = 90;
+
+        address otherUser = makeAddr('otherUser');
+
+        // Lock tokens
+        uint256 defaultExpiration_ = vm.getBlockTimestamp() + defaultResetPeriod;
+        vm.prank(user);
+        simpleAllocator.lock(
+            Compact({
+                arbiter: arbiter,
+                sponsor: user,
+                nonce: defaultNonce,
+                id: usdcId,
+                expires: defaultExpiration_,
+                amount: lockedAmount
+            })
+        );
+        compactContract.transfer(user, otherUser, transferAmount, address(usdc), address(simpleAllocator));
+
+        vm.prank(address(compactContract));
+        bytes4 returnedSelector = simpleAllocator.attest(user, user, otherUser, usdcId, transferAmount);
+        assertEq(returnedSelector, selector);
+    }
+
     function test_successfullyAttested(uint32 lockedAmount_, uint32 transferAmount_) public {
         transferAmount_ = uint32(bound(transferAmount_, 0, defaultAmount));
         lockedAmount_ = uint32(bound(lockedAmount_, 0, defaultAmount - transferAmount_));