"Cannot read property 'test' of undefined." when undefined passed to matches

[JoshuaKGoldberg]

• @testing-library/dom version: 7.19.0
• Testing Framework and version: jest@26.1.0 and @testing-library/react@10.4.7
• DOM Environment: jsdom@11.12.0

Relevant code or config:

const view = render(<div />);

view.getByRole(undefined);

What you did:

In a project that does not use TypeScript (alas!), I passed undefined instead of a valid matcher to getByRole.

What happened:

TypeError: Cannot read property 'test' of undefined

       9 |     const view = render(<div />);
      10 | 
    > 11 |     view.getByRole(undefined);
         |          ^
      13 | 

      at matches (../../node_modules/@testing-library/dom/dist/matches.js:39:20)
      at ../../node_modules/@testing-library/dom/dist/queries/role.js:78:47
          at Array.some (<anonymous>)
      at ../../node_modules/@testing-library/dom/dist/queries/role.js:78:26
          at Array.filter (<anonymous>)
      at queryAllByRole (../../node_modules/@testing-library/dom/dist/queries/role.js:57:54)
      at ../../node_modules/@testing-library/dom/dist/query-helpers.js:89:17
      at ../../node_modules/@testing-library/dom/dist/query-helpers.js:64:17
      at getByRole (../../node_modules/@testing-library/dom/dist/query-helpers.js:108:19)

Reproduction:

https://codesandbox.io/s/react-testing-library-getbytext-undefined-r6ygs for a version showing null and getByText causing the same issue.

Problem description:

For all matchers that eventually call to matches, including getByText and getByRole, passing an invalid matcher such as null or undefined crashes with a confusing error message. Users likely did not mean to pass an invalid matcher to the search.

dom-testing-library/src/matches.js

Line 27 in 639294c

return matcher.test(normalizedText)

Suggested solution:

Similar to #609, I'd like to send a PR that adds an explicit error message for this case.

[kentcdodds]

Sure 👍 thanks!