constant-prop.e2e.js — react Source File

Source Code

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import * as React from 'react';
import {render} from '@testing-library/react';

globalThis.constantValue = 'global test value';

test('literal-constant-propagation', () => {
  function Component() {
    'use memo';
    const x = 'test value 1';
    return <div>{x}</div>;
  }
  const {asFragment, rerender} = render(<Component />);

  expect(asFragment()).toMatchInlineSnapshot(`
    <DocumentFragment>
      <div>
        test value 1
      </div>
    </DocumentFragment>
  `);

  rerender(<Component />);

  expect(asFragment()).toMatchInlineSnapshot(`
    <DocumentFragment>
      <div>
        test value 1
      </div>
    </DocumentFragment>
  `);
});

test('global-constant-propagation', () => {
  function Component() {
    'use memo';
    const x = constantValue;

    return <div>{x}</div>;
  }
  const {asFragment, rerender} = render(<Component />);

  expect(asFragment()).toMatchInlineSnapshot(`
    <DocumentFragment>
      <div>
        global test value
      </div>
    </DocumentFragment>
  `);

  rerender(<Component />);

  expect(asFragment()).toMatchInlineSnapshot(`
    <DocumentFragment>
// ... (72 more lines)