<!--
  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

}
    }
    const renderer = ReactTestRenderer.create(<Bam />);
    const tree = renderer.toTree();
    
    expect(tree.instance).toBeInstanceOf(Bam);
    expect(tree.rendered.instance).toBeInstanceOf(Bar);
    cleanNodeOrArray(tree);
    expect(prettyFormat(tree)).toEqual(
      prettyFormat({
        type: Bam,
        nodeType: 'component',
        props: {},
        instance: null,
        rendered: {
          type: Bar,
          nodeType: 'component',
          props: {special: true},
          instance: null,
          rendered: {
            type: Foo,
            nodeType: 'component',
            props: {className: 'special'},
            instance: null,
            rendered: {
              type: 'div',
              nodeType: 'host',
              props: {className: 'Foo special'},
              instance: null,
              rendered: [