DeFi protocol fuzzing for getters questions

[accurec]

Hello!

For the stablecoin DeFi protocol invariant fuzz testing Patrick mentioned that we need to test getters so that they never revert.

The code like this is understandable for me:

    function invariant_gettersShouldNotRevert() public view {
        dsce.getPrecision();
        dsce.getLiquidationBonus();
        dsce.getAdditionalFeedPrecision();
        dsce.getLiquidationPrecision();
    }

In the above example we're basically testing pure getters on DSCEngine. In the meantime, would it be possible to test something like function getUsdValue(address token, uint256 amount) public view returns (uint256) and input different parameters like fuzzing does?

I tried to add parameter to the test, but then getting error:

FAIL: failed to set up invariant testing environment: Invariant test function should have no inputs

Let me know if something else can be done.

Thanks!

[EngrPips]

There are a number of tokens your Protocol support so fuzzing the token when trying to get the value of USD for any given amount does not actually make sense. You can fuzz the amount, and that makes total sense, but fuzzing the token does not make sense to me.

I don't understand what you mean when you said, I tried to add parameter to the test, but then getting error: Maybe show the code so I can be sure what you are saying.

[accurec]

I got the error when I changed test signature to something like this:

function invariant_gettersShouldNotRevert(uint256 tokenSeed) public view {

As for fuzzing tokens and amounts I think it all makes sense, because we want to test different scenarios and make sure that none of them make getters to revert.

[EngrPips]

You can't do this function invariant_gettersShouldNotRevert(uint256 tokenSeed) public view { as the invariant function does not take any arguments. You could create a handler and use the handler to give fuzz input to the getter function of the implementation contract.

For your argument that it makes to fuzz token input in a getter that should never revert, I leave you to do you.

[accurec]

That's what I thought, thank you!

[EngrPips]

You are welcome, Friend.