I'm mocking an ES6 class that is imported from a node module with jest, like this:

// creating mocks
const mockMethodName = jest.fn()

jest.mock('../node_modules/my-module', () => {
    const actualMyModule = jest.requireActual('../node_modules/my-module')
    
    return {
        ...actualMyModule,
        ClassName: jest.fn().mockImplementation(() => {
            return {
                methodName: mockMethodName
            }
        })
    }
})

const { ClassName } = require('my-module')

// the test
it('does something successfully', () => {
    // test logic that triggers ClassName.methodName()

    expect(mockMethodName).toHaveBeenCalledTimes(1)
})

But I get the following error:

[UnhandledPromiseRejection: This error originated either by throwing inside of an async function
without a catch block, or by rejecting a promise which was not handled with .catch().
The promise rejected with the reason 
"TypeError: ClassName.methodName is not a function".] {
  code: 'ERR_UNHANDLED_REJECTION'
}

I've also tried defining the method mock like this:

const mockMethodName = jest.fn(() => {})

const mockMethodName = jest.fn(() => null)

const mockMethodName = jest.fn(() => true)

const mockMethodName = jest.fn(() => jest.fn)

but the error is still there.

What am I doing wrong? How do I mock the class correctly?

PS: The ClassName.methodName() method is called within an async function but ClassName.methodName() does not return a promise