Foundry

Learn how to test using Foundry for ZKsync.

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For instructions on how to install foundry-zksync please refer to the Foundry Getting Started page.

foundry-zksync, a fork of Foundry, provides developers with a tailored testing framework designed specifically for ZKsync environments. Utilizing forge test --zksync, you can execute your smart contract tests efficiently. Tests are written in Solidity, and the framework is designed to recognize any contract function prefixed with test as a test case. By convention, tests are typically stored within the test/ directory and have a .t.sol extension.

For more detailed documentation related to Foundry testing please refer to the official upstream Foundry documentation.

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Cheatcodes

We support cheatcodes in the test code because it is run on the EVM. We do not support them on contracts that the test creates/invokes because they run on the zkEVM. For example, creating a contract that within itself calls vm.assume is not supported, but using that call at the root level of the test is.

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Writing Tests

Tests are structured as Solidity contracts, inheriting from the Forge Standard Library's Test contract for enhanced functionality, which includes basic assertions and logging:

pragma solidity 0.8.10;

import "forge-std/Test.sol";

contract ContractBTest is Test {
    uint256 testNumber;

    function setUp() public {
        testNumber = 42;
    }

    function test_NumberIs42() public {
        assertEq(testNumber, 42);
    }

    function testFail_Subtract43() public {
        testNumber -= 43;
    }
}

Key Concepts

• setUp: An optional function that runs before each test, used for initializing test conditions.

• test: Prefix for functions that are recognized as tests. These functions must either pass or revert to indicate success or failure, respectively.

• testFail: A prefix for test functions expected to revert. If such a function does not revert, the test is considered failed.

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Running Tests

To initiate your tests, use the forge test --zksync command with the --zksync flag, or incorporate vm.zkVm(true) within your tests. This command automatically locates and executes tests across your source directory.

Here's an example of executing tests in a standard project setup:

forge test --zksync

Running 2 tests for test/Counter.t.sol:CounterTest
[PASS] testFuzz_SetNumber(uint256) (runs: 256, μ: 27553, ~: 28409)
[PASS] test_Increment() (gas: 28379)
Test result: ok. 2 passed; 0 failed; 0 skipped; finished in 96.80ms

Filtering Tests

You can run specific tests by filtering based on the contract or test names:

forge test --match-contract CounterTest --match-test test_Increment --zksync

This command will execute only the tests within CounterTest that include test_Increment in their name.

Similarly, you can use --match-path to run tests in files that match a specific glob pattern:

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

Inverse filters are available through --no-match-contract, --no-match-test, and --no-match-path flags.

Watch Mode

To automatically re-run tests upon any file changes, use the forge test --watch --run-all --zksync command.