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.
return <div />;
      }
    }
    class ComponentB extends React.Component {
      static childContextTypes = {
        foo: PropTypes.string.isRequired,
      };
      render() {
        return <div />;
      }
    }
    expect(() => ReactTestUtils.renderIntoDocument(<ComponentA />)).toErrorDev(
      'Warning: ComponentA.childContextTypes is specified but there is no ' +
        'getChildContext() method on the instance. You can either define ' +
        'getChildContext() on ComponentA or remove childContextTypes from it.',
    );
    
    ReactTestUtils.renderIntoDocument(<ComponentA />);
    expect(() => ReactTestUtils.renderIntoDocument(<ComponentB />)).toErrorDev(
      'Warning: ComponentB.childContextTypes is specified but there is no ' +
        'getChildContext() method on the instance. You can either define ' +
        'getChildContext() on ComponentB or remove childContextTypes from it.',
    );
  });
  
  
  it('should pass parent context if getChildContext method is missing', () => {
    class ParentContextProvider extends React.Component {