I think this shouldn't pass:

```js
    expect(() => {
      expect(() => {
        throw new Error('haha') // no warning
      }).toWarnDev(
        'nope',
      );
    }).toThrow('haha');
```

but it does.
/**
 * Copyright (c) 2013-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @emails react-core
 */
'use strict';
describe('toWarnDev', () => {
  it('does not fail if a warning contains a stack', () => {
    expect(() => {
      if (__DEV__) {
        console.error('Hello\n    in div');
      }
    }).toWarnDev('Hello');
  });
  it('does not fail if all warnings contain a stack', () => {
    expect(() => {
      if (__DEV__) {
        console.error('Hello\n    in div');
        console.error('Good day\n    in div');
        console.error('Bye\n    in div');
      }
    }).toWarnDev(['Hello', 'Good day', 'Bye']);