How to reference a contract's library function in hardhat testing

Question

I have a contract that uses an eth/usd price feed library to convert a uint value into its USD equivalent.

pragma solidity 0.8.0;

import "@chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol";

library PriceConverter {
  // No state variables inside of libraries
  // All functions must be internal

  function getPrice(AggregatorV3Interface priceFeed)
    internal
    view
    returns (uint256 _price)
  {
    (, int256 price, , , ) = priceFeed.latestRoundData();
    return uint256(price * 1e10);
  }

  function getConversionRate(uint256 ethAmount, AggregatorV3Interface priceFeed)
    internal
    view
    returns (uint256)
  {
    uint256 price = getPrice(priceFeed);
    uint256 ethAmountInUsd = (price * ethAmount) / 1e18;
    return (ethAmountInUsd);
  }
}

pragma solidity 0.8.0;

import "./PriceConverter.sol";

contract Foo {
  using priceConverter for uint256;
  MINIMUM_USD = 7000000000000
  
  function bar() public payable {
     require(msg.value.getConversionRate() > MINIMUM_USD)
  }
function getBalanceInUSD() public view returns (uint256) {
    uint256 balanceInUSD = (balances[msg.sender].getConversionRate(priceFeed));
    return (balanceInUSD);
  }
}

In my hardhat test I am trying to call the getConversionRate() uint256 function in my contract to test some values, but I am unsure how to access it. (I know I need to send 2 parameters when I call the getConversionRate() function and I will edit the code to reflect that once it at least recognizes the function)

describe("getBalanceInUSD", function () {
        it.only("should return the user's balance in terms of USD", async function () {
          const tx = await bank.MINIMUMUSD()
          console.log(tx.toString())
          const bal = await bank.getBalanceInUSD()
          console.log(bal)
          const expectedValue = await bank.sendValue.getConversionRate()
          console.log(expectedValue)
        })
      })

Here is the error message: TypeError: Cannot read properties of undefined (reading 'getConversionRate')

Answer 1

To reference them use the library name, like this PriceConverter.getConversionRate. Then fill the parameters as needed

AggregatorV3Interface _priceFeed; // required price feed

function bar() public payable {
    uint amount = PriceConverter.getConversionRate(msg.value, _priceFeed);
    require(amount >= MINIMUM_USD, "Insufficient amount");
}