Function runTest

packages/react/src/__tests__/ReactES6Class-test.js:55–60

(element, expectedTag, expectedClassName)

  });

  function runTest(element, expectedTag, expectedClassName) {
    ReactDOM.flushSync(() => root.render(element));
    expect(container.firstChild).not.toBeNull();
    expect(container.firstChild.tagName).toBe(expectedTag);
    expect(container.firstChild.className).toBe(expectedClassName);
  }

  it('preserves the name of the class for use in error messages', () => {
    class Foo extends React.Component {}