Foundry Book

Deprecated features:

With foundry V1, we've decided to go ahead and start deprecating features that are considered anti-practices or might be misleading for developers. Deprecated means that while you can continue using these features, it is now a discouraged practice and you should plan on incrementally migrating away from using these.

Removing the Invariant keyword

The invariant keyword has now been deprecated, and the new keyword is now statefulFuzz. This means that now writing tests in this manner is valid:

/// Old, deprecated way of declaring an invariant test
function invariantTestEq() public {
    // Assert your invariants...
}

/// New
function statefulFuzzTestEq() public  {
    // Assert your invariants
}

Deprecating testFail

Using testFail to write failing tests is now discouraged. While it's usage is extremely common, we've decided to remove it because it can introduce footguns in a test. A warning will be thrown if it's used.

The now-recommended pattern is to refactor the actions that will make your test revert and subsequently fail in an utility function, and use expectRevert to ensure that this function call failed. This way, the test failure is expected explicitly, instead of introducing the possibility that the test fails in an unintended way silently.

An example:

contract Mock {
    function revert_() public {
        revert("This reverts");
    }
}

contract TestFailDeprecated is Test {
    Mock public mock;

    function setUp() public {
        mock = new Mock();
    }

    /// Deprecated way.
    function testFailReverter() public {
        mock.revert_();
    }

    /// New way, without using testFail.
    /// The call to revert_ has been refactored and is now expected to fail
    /// with expectRevert()
    function testReverterReverts() public {
        vm.expectRevert();
        // Call using this to increase depth
        this.exposed_call_Reverter();
    }

    function exposed_callReverter() public {
        mock.revert_();
    }

}

Removing cheatcode support on some precompiles

It is now impossible to use the following cheatcodes on precompiles: etch, load, store, deal.