How to trigger unmounting of functional components while testing?

Question

I used "useEffect" to achieve functionality of "componentWillUnmount" in functional component. How to trigger that while testing the component using Jest/Enzyme?

My Component:

const myComp = () => {
  useEffect(() => () => {
    console.log('Unmounted');
  }, []);
  return <div>Test</div>;
}

Answer 1

According to this issue, we know that shallow render doesn't support the useEffect hook. We need to use mount and call .unmount() method manually.

E.g.

index.tsx:

import React, { useEffect } from 'react';

export const MyComp = () => {
  useEffect(
    () => () => {
      console.log('Unmounted');
    },
    []
  );
  return <div>Test</div>;
};

index.test.tsx:

import React from 'react';
import { mount } from 'enzyme';
import { MyComp } from './';

describe('67384129', () => {
  it('should pass', () => {
    const wrapper = mount(<MyComp />);
    wrapper.unmount();
  });
});

test result:

 PASS  examples/67384129/index.test.tsx (8.233 s)
  67384129
    ? should pass (53 ms)

  console.log
    Unmounted

      at examples/67384129/index.tsx:6:15

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        9.121 s

package versions:

"enzyme": "^3.11.0",
"enzyme-adapter-react-16": "^1.15.5",
"react": "^16.14.0"
"jest": "^26.6.3",
"jest-environment-enzyme": "^7.1.2",
"jest-enzyme": "^7.1.2",

Answer 2

If you are using react-testing-library then:

const { unmount } = render(<Component />);
unmount();