React Js - Enzyme test if setState is triggered - reactjs

Question

I am using enzyme to test my react application. This is my react component:
import React from 'react';
const Child = ({name, setName}) => {
return (
<div>
<button onClick={() => setName('test')}>setName</button>
<h2>Name: {name}</h2>
</div>
);
};
export default Child;
By clicking the button i change the setName which is passed as bellow:
function App() {
const [name, setName] = useState();
return (
<div className="App">
<Child setName={setName} name={name}/>
</div>
);
}
export default App;
So, testing Child component i created the next test to test when user clicks the button should trigger setName.
describe('Should test Child component', () => {
const wrapper = (props) => shallow(<Child {...props}/>)
test('should trigger setName', () => {
const mockFun = jest.fn()
const r = wrapper({setName: jest.fn() });
const btn = r.find('button');
btn.simulate('click');
expect(r.props().setName).toHaveBeenCalled()
})
})
Running the test i get:
Error: expect(received).toHaveBeenCalled()
Matcher error: received value must be a mock or spy function
Received has value: undefined
Why i get this error and how to make my test to be valid?

Answer 1

I can't test it right now but I think modifying it like this should do it
describe('Should test Child component', () => {
const wrapper = (props) => shallow(<Child {...props}/>)
test('should trigger setName', () => {
const mockFun = jest.fn()
const r = wrapper({setName: mockFun });
const btn = r.find('button');
btn.simulate('click');
expect(mockFun).toHaveBeenCalled()
})
})
Also see this one as a reference same issue How to test onClick props of a button using Jest and Enzyme