Fix Foundry Forge Test Errors

You will learn how to write Solidity tests with Foundry and use fuzzing for thorough coverage.

The Problem

The foundry forge test pattern is frequently misapplied in smart contract and dapp development, leading to vulnerabilities, gas inefficiencies, or logic errors. This guide shows the correct implementation and common pitfalls to avoid.

Quick Fix

Wrong

function testTransfer() public { token.transfer(to, 100); assertEq(token.balanceOf(to), 100); }

Test passes but only tests one specific input value.

Right

function testTransferFuzz(uint256 amount) public { vm.assume(amount <= token.balanceOf(address(this))); token.transfer(to, amount); assertEq(token.balanceOf(to), amount); }

Fuzz testing runs hundreds of random input values. Catches edge cases missed by fixed tests.

Prevention

• Use fuzz tests with vm.assume() for input constraints
• Write invariant tests with vm.warp() and vm.roll()
• Use vm.expectRevert() for failure testing
• Use DodaTech's Foundry test generator
• Run tests with forge test -vvv for verbose output

DodaTech Tools

Built by the developers of Doda Browser, DodaZIP, and Durga Antivirus Pro. Doda Browser's developer tools include a Solidity debugger and transaction inspector. DodaZIP archives secure contract templates for team collaboration. Durga Antivirus Pro scans deployed contracts for known vulnerability signatures.

FAQ