document forge coverage

[devtooligan]

see foundry-rs/foundry#1576

[onbjerg]

Blocked since coverage is still not considered stable even for foundry.

[artdgn]

Information on usage (and even the availability of the feature) was hard to find.

Perhaps it's worth to find some sort of a solution for new / potentially unstable features that would balance the usefulness of being able to find basic documentation using a search engine, with maintenance effort. I don't know how it's currently set up, but maybe some auto-generated documentation from the latest implementation docstrings can be an option.

[Cezarry]

Hey, I'm trying forge coverage on test project and it's not detecting all branches (for me 1 branch is missing by coverage).
Function to test:

    function deposit() external payable {
        if (msg.value == 0) {
            revert CanNotDepositZeroEthers();
        }

        if (charity.canDonate()) {
            uint256 charityAmount = (msg.value * charityPercentage) / 1000;
            charity.donate{value: charityAmount}();
        }
    }

Tests:

    function test_Deposit_WithDonation() public {
        uint256 expectedDonatedAmount = (depositAmount * charityPercentage) / 1000;
        uint256 expectedDepositAmount = depositAmount - expectedDonatedAmount;

        _deposit(address(this), depositAmount);

        assertEq(address(charity).balance, expectedDonatedAmount);
        assertEq(address(wallet).balance, expectedDepositAmount);
    }

    function test_Deposit_WithoutDonation() public {
        uint256 expectedDonatedAmount = 0;
        uint256 expectedDepositAmount = depositAmount;
        uint256 charityDeadline = charity.moneyCollectingDeadline();
        vm.warp(charityDeadline);

        _deposit(address(this), depositAmount);

        assertEq(address(charity).balance, expectedDonatedAmount);
        assertEq(address(wallet).balance, expectedDepositAmount);
    }

so my if statement is covered by those two tests, but coverage debug says:

- Function "" (location: source ID 28, line 16, chars 332-537, hits: 0)
- Line (location: source ID 28, line 17, chars 423-437, hits: 0)
- Statement (location: source ID 28, line 17, chars 423-437, hits: 0)
- Line (location: source ID 28, line 18, chars 447-482, hits: 0)
- Statement (location: source ID 28, line 18, chars 447-482, hits: 0)
- Line (location: source ID 28, line 19, chars 492-530, hits: 0)
- Statement (location: source ID 28, line 19, chars 492-530, hits: 0)
- Branch (branch: 1, path: 0) (location: source ID 28, line 29, chars 723-877, hits: 0)

where line 29 is if (charity.canDonate()). Any ideas? :)

[zerosnacks]

Marking as resolved by https://book.getfoundry.sh/reference/forge/forge-coverage#forge-coverage and people generally seem to find their way around the command