Just about every time I set up a new `Context.Provider`, I end up accidentally specifying a `values` prop rather than `value`.  While it's a minor error, generally I build the container in which the provider resides and commit it to the code base before I ever use it.  It's only later when I go to use it that I realize I did it again.  Since the `Context.Provider` seems pretty much useless without a `value` prop specified, I'd love it if there was a prop error if it is missing... especially if another prop is defined on the `Context.Provider` instead.
nodeType: 'host',
          props: {},
          instance: null,
          rendered: ['Four'],
        },
      ]),
    );
  });
  it('root instance and createNodeMock ref return the same value', () => {
    const createNodeMock = ref => ({node: ref});
    let refInst = null;
    const renderer = ReactTestRenderer.create(
      <div ref={ref => (refInst = ref)} />,
      {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 {