Foundry-test

1- Forge can run your tests with the forge test command

2- All tests are written in Solidity.

3- Forge will look for the tests anywhere in your source directory

4- Any contract with a function that starts with test is considered to be a test

5- Perfect! Let's start with a beginner-friendly example using a simple Counter Contract in Solidity

6- This will help you learn the fundamentals of writing tests with Foundry.

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

contract Counter {
    uint256 public count;

    function increment() public {
        count++;
    }
}

Test-Script

Contract: We'll define a simple contract named Counter that has a single function increment to increase a counter by 1 Test: We'll write a test script named Counter.test.sol to test the functionality of the increment function.

1- We import necessary utilities like Test from Foundry.

2- We define a test contract CounterTest that inherits from Test.

3- Use assertEq to check if the new value is equal to 1.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "forge-std/Test.sol";
import {Counter} from "../src/Counter.sol";

contract CounterTest is Test {
    Counter  counter;

    function setUp() public {
        counter = new Counter();
    }

    function testIncrement() public {
        counter.increment();
        assertEq(counter.count(), 1);
    }
}

you have to get outbut like this after run command forge test

Forge test

You can also run specific tests by passing a filter to test one function from contract by this command line

forge test --match-test testIncrement

You can also run specific tests by passing a filter to test only contract by passing contract name by command

forge test --match-contract Counter

run test by path command line

forge test --match-path test/Counter.t.sol