In forge tests, how can I import events?

Question

In forge tests I've been redeclaring events within the test file so that I can use vm.assertEmit. Is there a way to import events from the contract I am testing instead?

e.g.

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

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

contract RegistryDeployerTest is Test {

  // re-declare event for assertions
  event Deployed();
  // ^^^^^^^^^^
  // I don't want to have to do this
  // ^^^^^^^^^^

  function testDeployer() public {
    vm.expectEmit(true, true, true, true);
    emit Deployed();
    new RegistryDeployer();
  }
}

Answer 1

You can create an interface where the event is defined, and import it both in your source contract and your tests contract:

interface MyEvents {
  event Deployed();
}

contract RegistryDeployer is MyEvents {
  // ...
}

In your tests you wouldn't need to re-declare it:

contract RegistryDeployerTest is Test, MyEvents {

  function testDeployer() public {
    vm.expectEmit(true, true, true, true);
    emit Deployed();
    new RegistryDeployer();
  }
}

I think your example is cleaner. AFAIK there is no direct access to the event with RegistryDeployer.Deployer, so I would do what you showed in your example.