I have a simple function that I want to test with Jest. I have read https://jestjs.io/docs/en/mock-functions many many times but I'm not sure whats going wrong and can't find a clear answer on stackoverflow. I feel like this is an extremely simple test.

Here is my function:

public hello(name: string) {

  return 'Hello ' + name

}

Here is my Test:

let hello = jest.fn()

jest.mock('./myfile.ts', () => {

  return hello

})



beforeEach(() => {

  hello('world')

})



describe('hello test', (){

  it('expects to return concatenated string', () => {

    expect(hello.mock.results[0].value).toBe('Hello world') // returns as undefined - Test fails

  })

})

I keep getting undefined for the mock.results instead of 'Hello world'.

What am I doing wrong? I feel like I'm overlooking something very simple.