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.
getChildContext() {
        return {
          foo: this.props.fooValue,
        };
      }
      render() {
        return <Component />;
      }
    }
    ComponentInFooNumberContext.childContextTypes = {
      foo: PropTypes.number,
    };
    expect(() =>
      ReactTestUtils.renderIntoDocument(
        <ComponentInFooNumberContext fooValue={123} />,
      ),
    ).toErrorDev(
      'Warning: Failed context type: ' +
        'Invalid context `foo` of type `number` supplied ' +
        'to `Component`, expected `string`.\n' +
        '    in Component (at **)\n' +
        '    in ComponentInFooNumberContext (at **)',
    );
  });
  it('should check child context types', () => {
    class Component extends React.Component {