// src/test/AstariaTest.t.sol
function testBuyoutLienWrongSlope_AUDIT() public {
  TestNFT nft = new TestNFT(1);
  address tokenContract = address(nft);
  uint256 tokenId = uint256(0);

  uint256 initialBalance = WETH9.balanceOf(address(this));

  // create a PublicVault with a 14-day epoch
  address publicVault = _createPublicVault({
    strategist: strategistOne,
    delegate: strategistTwo,
    epochLength: 14 days
  });
  vm.label(publicVault, "PublicVault");

  // lend 50 ether to the PublicVault as address(1)
  _lendToVault(
    Lender({addr: address(1), amountToLend: 50 ether}),
    publicVault
  );

  // borrow 10 eth against the dummy NFT
  (uint256[] memory liens, ILienToken.Stack[] memory stack) = _commitToLien({
    vault: publicVault,
    strategist: strategistOne,
    strategistPK: strategistOnePK,
    tokenContract: tokenContract,
    tokenId: tokenId,
    lienDetails: standardLienDetails,
    amount: 10 ether,
    isFirstLien: true
  });

  // Right after the lien was created the slope of the vault equals to the slope of the lien.
  assertEq(PublicVault(publicVault).getSlope(), LIEN_TOKEN.calculateSlope(stack[0]));

  vm.warp(block.timestamp + 3 days);

  IAstariaRouter.Commitment memory refinanceTerms = _generateValidTerms({
    vault: publicVault,
    strategist: strategistOne,
    strategistPK: strategistOnePK,
    tokenContract: tokenContract,
    tokenId: tokenId,
    lienDetails: refinanceLienDetails,
    amount: 10 ether,
    stack: stack
  });

  (stack, ) = VaultImplementation(publicVault).buyoutLien(
    stack,
    uint8(0),
    refinanceTerms
  );

  // After a buyout the slope of the vault is 0, however it must be equal to the slope of the lien.
  // Error: a == b not satisfied [uint]
  //  Expected: 481511019363
  //  Actual: 0
  assertEq(PublicVault(publicVault).getSlope(), LIEN_TOKEN.calculateSlope(stack[0]));

  // A lien exists after the buyout, so the slope of the vault cannot be 0.
  uint256 collId = stack[0].lien.collateralId;
  assertEq(LIEN_TOKEN.getCollateralState(collId), bytes32(hex"7c2c35af3fb5f00ff3995cdddd95dcbbad96eea7bca39b305f2d0f8a55d838f8"));
}
