TSwapPool::sellPoolTokens proof-of-code error. Need help

[SquilliamX]

Hi everyone, I am attempting to write the test for the " TSwapPool::sellPoolTokens mismatches input and output tokens causing users to receive the incorrect amount of tokens " error and it keeps spitting out an error. Can anyone explain how to write this test to prove that the swapExactOutput function needs to be swapped with the swapExactInput function?

This is my test:

 function testSellPoolTokensBug() public {
        vm.startPrank(liquidityProvider);
        weth.approve(address(pool), 100e18);
        poolToken.approve(address(pool), 100e18);
        pool.deposit(100e18, 100e18, 100e18, uint64(block.timestamp));
        vm.stopPrank();
        
        vm.startPrank(user);
        poolToken.approve(address(pool), 9e18);
        uint256 expectedWethAmount =
            pool.getOutputAmountBasedOnInput(9e18, poolToken.balanceOf(address(pool)), weth.balanceOf(address(pool)));
        uint256 actualWethAmount = pool.sellPoolTokens(9e18);
        assertEq(actualWethAmount, expectedWethAmount, "Incorrect amount of WETH received");
    }

This is my error:

$ forge test --mt testSellPoolTokensBug -vvvv
[⠒] Compiling...
[⠒] Compiling 1 files with 0.8.20
[⠢] Solc 0.8.20 finished in 1.92s
Ran 1 test for test/unit/TSwapPool.t.sol:TSwapPoolTest
[FAIL. Reason: ERC20InsufficientAllowance(0xF62849F9A0B5Bf2913b396098F7c7019b51A820a, 89999999999999999998 [8.999e19], 99198694986057072315 [9.919e19])] testSellPoolTokensBug() (gas: 249589)
Traces:
  [2713126] TSwapPoolTest::setUp()
    ├─ [449186] → new ERC20Mock@0x5615dEB798BB3E4dFa0139dFa1b3D433Cc23b72f
    │   └─ ← [Return] 2018 bytes of code
    ├─ [449186] → new ERC20Mock@0x2e234DAe75C793f67A35089C9d99245E1C58470b
    │   └─ ← [Return] 2018 bytes of code
    ├─ [1516432] → new TSwapPool@0xF62849F9A0B5Bf2913b396098F7c7019b51A820a
    │   └─ ← [Return] 7330 bytes of code
    ├─ [46789] ERC20Mock::mint(liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], 200000000000000000000 [2e20])
    │   ├─ emit Transfer(from: 0x0000000000000000000000000000000000000000, to: liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], value: 200000000000000000000 [2e20])
    │   └─ ← [Stop] 
    ├─ [46789] ERC20Mock::mint(liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], 200000000000000000000 [2e20])
    │   ├─ emit Transfer(from: 0x0000000000000000000000000000000000000000, to: liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], value: 200000000000000000000 [2e20])
    │   └─ ← [Stop] 
    ├─ [24889] ERC20Mock::mint(user: [0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D], 10000000000000000000 [1e19])
    │   ├─ emit Transfer(from: 0x0000000000000000000000000000000000000000, to: user: [0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D], value: 10000000000000000000 [1e19])
    │   └─ ← [Stop] 
    ├─ [24889] ERC20Mock::mint(user: [0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D], 10000000000000000000 [1e19])
    │   ├─ emit Transfer(from: 0x0000000000000000000000000000000000000000, to: user: [0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D], value: 10000000000000000000 [1e19])
    │   └─ ← [Stop] 
    └─ ← [Stop] 

  [209789] TSwapPoolTest::testSellPoolTokensBug()
    ├─ [0] VM::startPrank(liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d])
    │   └─ ← [Return] 
    ├─ [24739] ERC20Mock::approve(TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], 100000000000000000000 [1e20])
    │   ├─ emit Approval(owner: liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], spender: TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], value: 100000000000000000000 [1e20])
    │   └─ ← [Return] true
    ├─ [24739] ERC20Mock::approve(TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], 100000000000000000000 [1e20])
    │   ├─ emit Approval(owner: liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], spender: TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], value: 100000000000000000000 [1e20])
    │   └─ ← [Return] true
    ├─ [113659] TSwapPool::deposit(100000000000000000000 [1e20], 100000000000000000000 [1e20], 100000000000000000000 [1e20], 1)
    │   ├─ emit Transfer(from: 0x0000000000000000000000000000000000000000, to: liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], value: 100000000000000000000 [1e20])
    │   ├─ emit LiquidityAdded(liquidityProvider: liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], wethDeposited: 100000000000000000000 [1e20], poolTokensDeposited: 100000000000000000000 [1e20])
    │   ├─ [30862] ERC20Mock::transferFrom(liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], 100000000000000000000 [1e20])
    │   │   ├─ emit Transfer(from: liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], to: TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], value: 100000000000000000000 [1e20])
    │   │   └─ ← [Return] true
    │   ├─ [30862] ERC20Mock::transferFrom(liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], 100000000000000000000 [1e20])
    │   │   ├─ emit Transfer(from: liquidityProvider: [0xE9323E1440012e53E2DDb91Fc38EF24C20F2628d], to: TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], value: 100000000000000000000 [1e20])
    │   │   └─ ← [Return] true
    │   └─ ← [Return] 100000000000000000000 [1e20]
    ├─ [0] VM::stopPrank()
    │   └─ ← [Return] 
    ├─ [0] VM::startPrank(user: [0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D])
    │   └─ ← [Return] 
    ├─ [562] ERC20Mock::balanceOf(TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a]) [staticcall]
    │   └─ ← [Return] 100000000000000000000 [1e20]
    ├─ [562] ERC20Mock::balanceOf(TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a]) [staticcall]
    │   └─ ← [Return] 100000000000000000000 [1e20]
    ├─ [861] TSwapPool::getOutputAmountBasedOnInput(9000000000000000000 [9e18], 100000000000000000000 [1e20], 100000000000000000000 [1e20]) [staticcall]
    │   └─ ← [Return] 8234149743514448533 [8.234e18]
    ├─ [562] ERC20Mock::balanceOf(TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a]) [staticcall]
    │   └─ ← [Return] 100000000000000000000 [1e20]
    ├─ [562] ERC20Mock::balanceOf(TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a]) [staticcall]
    │   └─ ← [Return] 100000000000000000000 [1e20]
    ├─ [937] TSwapPool::getInputAmountBasedOnOutput(8234149743514448533 [8.234e18], 100000000000000000000 [1e20], 100000000000000000000 [1e20]) [staticcall]
    │   └─ ← [Return] 89999999999999999998 [8.999e19]
    ├─ [24739] ERC20Mock::approve(TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], 89999999999999999998 [8.999e19])
    │   ├─ emit Approval(owner: user: [0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D], spender: TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], value: 89999999999999999998 [8.999e19])
    │   └─ ← [Return] true
    ├─ [29910] TSwapPool::sellPoolTokens(9000000000000000000 [9e18])
    │   ├─ [562] ERC20Mock::balanceOf(TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a]) [staticcall]
    │   │   └─ ← [Return] 100000000000000000000 [1e20]
    │   ├─ [562] ERC20Mock::balanceOf(TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a]) [staticcall]
    │   │   └─ ← [Return] 100000000000000000000 [1e20]
    │   ├─ emit Swap(swapper: user: [0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D], tokenIn: ERC20Mock: [0x5615dEB798BB3E4dFa0139dFa1b3D433Cc23b72f], amountTokenIn: 99198694986057072315 [9.919e19], tokenOut: ERC20Mock: [0x2e234DAe75C793f67A35089C9d99245E1C58470b], amountTokenOut: 9000000000000000000 [9e18])
    │   ├─ [959] ERC20Mock::transferFrom(user: [0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D], TSwapPool: [0xF62849F9A0B5Bf2913b396098F7c7019b51A820a], 99198694986057072315 [9.919e19])
    │   │   └─ ← [Revert] ERC20InsufficientAllowance(0xF62849F9A0B5Bf2913b396098F7c7019b51A820a, 89999999999999999998 [8.999e19], 99198694986057072315 [9.919e19])
    │   └─ ← [Revert] ERC20InsufficientAllowance(0xF62849F9A0B5Bf2913b396098F7c7019b51A820a, 89999999999999999998 [8.999e19], 99198694986057072315 [9.919e19])
    └─ ← [Revert] ERC20InsufficientAllowance(0xF62849F9A0B5Bf2913b396098F7c7019b51A820a, 89999999999999999998 [8.999e19], 99198694986057072315 [9.919e19])

Suite result: FAILED. 0 passed; 1 failed; 0 skipped; finished in 2.08ms (433.79µs CPU time)

Ran 1 test suite in 409.26ms (2.08ms CPU time): 0 tests passed, 1 failed, 0 skipped (1 total tests)

Failing tests:
Encountered 1 failing test in test/unit/TSwapPool.t.sol:TSwapPoolTest
[FAIL. Reason: ERC20InsufficientAllowance(0xF62849F9A0B5Bf2913b396098F7c7019b51A820a, 89999999999999999998 [8.999e19], 99198694986057072315 [9.919e19])] testSellPoolTokensBug() (gas: 249589)

Encountered a total of 1 failing tests, 0 tests succeeded    

[SquilliamX]

Update: This is my new test that passed, I think i did it correctly, can anyone verify it?

function testSellPoolTokensBug() public {
        vm.startPrank(liquidityProvider);
        weth.approve(address(pool), 100e18);
        poolToken.approve(address(pool), 100e18);
        pool.deposit(100e18, 100e18, 100e18, uint64(block.timestamp));
        vm.stopPrank();

        vm.startPrank(user);
        poolToken.approve(address(pool), 9e18);
        uint256 expectedWethAmount =
            pool.getOutputAmountBasedOnInput(9e18, poolToken.balanceOf(address(pool)), weth.balanceOf(address(pool)));

        vm.expectRevert();
        pool.sellPoolTokens(9e18);
    }

[EngrPips]

Seem correct

[EngrPips]

Glad you figured it out keep crushing it.