React Fragments have UNDEFINED types in snapshots

Do you want to request a feature or report a bug? Bug

What is the current behavior? When using a snapshot test with a React Fragment The snapshot has UNDEFINED as node types.

If the current behavior is a bug, please provide the steps to reproduce and either a repl.it demo through https://repl.it/languages/jest or a minimal repository on GitHub that we can yarn install and yarn test. For example:

import React from 'react';

it('doesnt render Unknown for React Fragments', () => {
  expect(
    <React.Fragment>
      <span>Hello World</span>
    </React.Fragment>,
  ).toMatchSnapshot();
});

Generates this snapshot:

// Jest Snapshot v1, https://goo.gl/fbAQLP

exports[`doesnt render Unknown for React Fragments 1`] = `
<UNDEFINED>
  <span>
    Hello World
  </span>
</UNDEFINED>
`;

Here is an example repo: https://github.com/adriantoine/jest-fragment-bug (note that it’s not using Enzyme or enzyme-to-json, only Jest).

What is the expected behavior?

It renders the Fragment node with the <React.Fragment>...</React.Fragment> type or an empty node type as it is possible with Babel (<>...</>).

Please provide your exact Jest configuration It is in the example repo above and it is reproduceable with any config.

Run npx envinfo --preset jest in your project directory and paste the results here

  System:
    OS: macOS High Sierra 10.13.1
    CPU: x64 Intel(R) Core(TM) i7-6920HQ CPU @ 2.90GHz
  Binaries:
    Node: 9.7.1
    Yarn: 1.5.1
    npm: 5.7.1
  npmPackages:
    jest:
      wanted: ^22.4.2
      installed: 22.4.2

If you think that is an issue, I’m happy to look at a fix in pretty-format although we need to agree if it should be rendered as <React.Fragment>...</React.Fragment> or <>...</>.

Thanks!

[SimenB]

Fix should be here: https://github.com/facebook/jest/blob/84b17fb59c1d9fd7f964b5f2bfd9d7e2b898f89a/packages/pretty-format/src/plugins/react_element.js#L34-L42

[github-actions[bot]]

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