Testing Smart Contracts using Foundry

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In this section, you'll set up a smart contract test and test it using forge.

Step 1: Test Script

You will see a directory called test in the root of your project. This is where you can view/write your tests. The demo counter.sol comes with a test script counter.t.sol, which contains:

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.13;

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

contract CounterTest is Test {
  Counter public counter;

  function setUp() public {
    counter = new Counter();
    counter.setNumber(0);
  }

  function test_Increment() public {
    counter.increment();
    assertEq(counter.number(), 1);
  }

  function testFuzz_SetNumber(uint256 x) public {
    counter.setNumber(x);
    assertEq(counter.number(), x);
  }
}

Step 2: Run the Test

To run the test, execute the following command in the root of your project:

forge test

This will run the test script and display the results in the terminal.

forge test
[⠊] Compiling...
[⠊] Compiling 33 files with Solc 0.8.24
[⠒] Solc 0.8.24 finished in 947.64ms
Compiler run successful!
Ran 2 tests for test/Counter.t.sol:CounterTest
[PASS] testFuzz_SetNumber(uint256) (runs: 256, μ: 30899, ~: 31288)
[PASS] test_Increment() (gas: 31303)
Suite result: ok. 2 passed; 0 failed; 0 skipped; finished in 11.85ms (6.49ms CPU time)

Ran 2 test suites in 137.32ms (19.93ms CPU time): 6 tests passed, 0 failed, 0 skipped (6 total tests)

Additional tests

If you need additional tests, or want to go deep on this step, visit the Foundry Tests Documentation..