foundry-template/test/Foo.t.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity >=0.8.19 <0.9.0;

import { PRBTest } from "@prb/test/PRBTest.sol";
import { console2 } from "forge-std/console2.sol";
import { StdCheats } from "forge-std/StdCheats.sol";

interface IERC20 {
    function balanceOf(address account) external view returns (uint256);
}

/// @dev See the "Writing Tests" section in the Foundry Book if this is your first time with Forge.
/// https://book.getfoundry.sh/forge/writing-tests
contract FooTest is PRBTest, StdCheats {
    /// @dev An optional function invoked before each test case is run
    function setUp() public virtual {
        // solhint-disable-previous-line no-empty-blocks
    }

    /// @dev Simple test. Run Forge with `-vvvv` to see console logs.
    function test_Example() external {
        console2.log("Hello World");
        assertTrue(true);
    }

    /// @dev Test that fuzzes an unsigned integer.
    function testFuzz_Example(uint256 x) external {
        vm.assume(x != 0);
        assertGt(x, 0);
    }

    /// @dev Test that runs against a fork of Ethereum Mainnet. You need to set `API_KEY_ALCHEMY` in your environment
    /// for this test to run - you can get an API key for free at https://alchemy.com.
    function testFork_Example() external {
        string memory alchemyApiKey = vm.envOr("API_KEY_ALCHEMY", string(""));
        // Silently pass this test if the user didn't define the API key.
        if (bytes(alchemyApiKey).length == 0) {
            return;
        }

        // Run the test normally, otherwise.
        vm.createSelectFork({ urlOrAlias: "mainnet", blockNumber: 16_428_000 });
        address usdc = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;
        address holder = 0x7713974908Be4BEd47172370115e8b1219F4A5f0;
        uint256 actualBalance = IERC20(usdc).balanceOf(holder);
        uint256 expectedBalance = 196_307_713.810457e6;
        assertEq(actualBalance, expectedBalance);
    }
}