I was experiencing this issue as well and most online help weren't addressing the underlying cause.

You also have to add the following to your test files to use event emitters from chai matchers:

const chai = require('chai');

chai.use(solidity)

You can find a more detailed example and explanation here:

I was experiencing this issue as well and most online help weren't addressing the underlying cause.

You also have to add the following to your test files to use event emitters from chai matchers:

const { solidity } = require('ethereum-waffle')
const chai = require('chai');
chai.use(solidity);

You can find a more detailed example and explanation here: