Before https://github.com/facebook/react/pull/14917, I used to get this:

<img width="502" alt="screen shot 2019-02-21 at 5 38 03 pm" src="https://user-images.githubusercontent.com/810438/53190100-cbe20d00-3600-11e9-9ffa-b230f3bb78fe.png">

const button = document.getElementById('run-test-button');
      button.click();
      const items = document.querySelectorAll('[data-value]');
      if (items.length === 0) {
        return 'No results were found.';
      }
      for (let i = 0; i < items.length; i++) {
        const item = items[i];
        if (item.getAttribute('data-value') !== 'All checks pass') {
          return `Unexpected result, "${item.getAttribute('data-value')}"`;
        }
      }
      return null;
    });
  } finally {
    await browser.close();
  }
};
const run = async ({cwd}) => {
  const errorMessage = await logPromise(
    validate({cwd}),
    'Verifying "scheduler/tracing" fixture'
  );
  if (errorMessage) {
    console.error(theme.error(errorMessage));
    process.exit(1);
  }
};
module.exports = run;