@vergiss/chooks/es/hooks/useMount/__tests__/index.test.js

React hooks library

import { act, renderHook } from '@testing-library/react-hooks';
import { useMount } from '../index';
describe('useMount', function () {
  it('should be defined', function () {
    expect(useMount).toBeDefined();
  });
  it('should invoke the callback only once', function () {
    var callback = jest.fn();
    var hook = renderHook(function () {
      return useMount(callback);
    });
    expect(callback).toBeCalledTimes(1);
    act(function () {
      hook.rerender();
    });
    expect(callback).toBeCalledTimes(1);
    act(function () {
      hook.unmount();
    });
    expect(callback).toBeCalledTimes(1);
  });
});