<!--
  Note: if the issue is about documentation or the website, please file it at:
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**Do you want to request a *feature* or report a *bug*?**

bug.

**What is the current behavior?**

```js
  renderer.create(
    <Fragment>
      <Fragment>foo</Fragment>
    </Fragment>
  )
  .toTree()
```

> Invariant Violation: toTree() does not yet know how to handle nodes with tag=10

https://codesandbox.io/s/olky92m01y

**What is the expected behavior?**

returns a tree.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**

16.2.0

{createNodeMock},
    );
    const root = renderer.getInstance();
    expect(root).toEqual(refInst);
  });
  it('toTree() renders complicated trees of composites and hosts', () => {
    
    const Qoo = () => <span className="Qoo">Hello World!</span>;
    
    const Foo = ({className, children}) => (
      <div className={'Foo ' + className}>
        <span className="Foo2">Literal</span>
        {children}
      </div>
    );
    
    class Bar extends React.Component {
      render() {
        const {special, children} = this.props;
        return <Foo className={special ? 'special' : 'normal'}>{children}</Foo>;
      }
    }
    
    class Bam extends React.Component {
      render() {
        return (
          <Bar special={true}>
            <Qoo />
          </Bar>
        );