rickvanlieshout.com/src/templates/not-found-template.test.js

import React from 'react';
import renderer from 'react-test-renderer';
import { useStaticQuery, StaticQuery } from 'gatsby';
import NotFoundTemplate from './not-found-template';
import siteMetadata from '../../jest/__fixtures__/site-metadata';

describe('NotFoundTemplate', () => {
  beforeEach(() => {
    StaticQuery.mockImplementationOnce(
      ({ render }) => (
        render(siteMetadata)
      ),
      useStaticQuery.mockReturnValue(siteMetadata)
    );
  });

  it('renders correctly', () => {
    const tree = renderer.create(<NotFoundTemplate />).toJSON();
    expect(tree).toMatchSnapshot();
  });
});