Run the [`fixtures/ssr` test harness](https://github.com/facebook/react/tree/master/fixtures/ssr). In the terminal, the following warning is logged:

```
Warning: Unknown prop `onClick` on <a> tag. Remove this prop from the element. For details, see https://fb.me/react-unknown-prop
  in a (at Page.js:12)
  in p (at Page.js:18)
  in div (at Page.js:17)
  in Page (at App.js:12)
  in div (at App.js:10)
  in body (at Chrome.js:17)
  in html (at Chrome.js:9)
  in Chrome (at App.js:9)
  in App (at render.js:18)
```

SSR behavior should match client-side behavior and not warn for a valid attribute.
it(`throws ${desc}`, () => {
    return testFn()
      .then(() =>
        expect(false).toBe('The promise resolved and should not have.'),
      )
      .catch(() => {});
  });
}
function itThrowsWhenRendering(desc, testFn) {
  itThrows(`when rendering ${desc} with server string render`, () =>
    testFn(serverRender),
  );
  itThrows(`when rendering ${desc} with clean client render`, () =>
    testFn(clientCleanRender),
  );
  
  
  itThrows(
    `when rendering ${desc} with client render on top of bad server markup`,
    () =>
      testFn((element, warningCount = 0) =>
        clientRenderOnBadMarkup(element, warningCount - 1),
      ),
  );
}
async function testMarkupMatch(serverElement, clientElement, shouldMatch) {