Say I have contract Foo:

contract Foo {

event OwnerAdded(address indexed owner);

address public owner;

constructor(address _owner) {
    owner = _owner
    emit OwnerAdded(owner)

How would I write my hardhat test to check for the OwnerAdded() emit?

I was trying to do:

await expect(fooFactory.deploy(testAddr)).to.emit(Foo, "OwnerAdded).withArgs("0x83h342e46571f77h0531d")

But obviously, that doesn't work because you need the contract object to pass to the Chai emit assertion.

  • 1
    I know this is now what you're looking for but testing things like this is easy-peasy in Foundry Apr 8, 2023 at 20:05

2 Answers 2


You would need to send the deploy transaction and wait for the receipt, and then check if it emitted the desired event, something like this:

const tx = fooFactory.deploy(testAddr);
const receipt = await tx.wait();
const event = receipt.events
        ?.filter(({ event }) => event == "OwnerAdded")
  • 2
    I tried this but I get the error: "tx.wait is not a function"
    – Rohan Nero
    Oct 30, 2022 at 17:14

This is the right way to do it as the previous answer fails with tx.wait is not a function:

const tx = fooFactory.deploy(testAddr);
const receipt = await tx.deployTransaction.wait();
const event = receipt.events.find(event => event.event === "OwnerAdded");
const [owner] = event.args;

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