Make renderNothing as a classComponent (#289)

* Fixes #288

* Test on render null

src/packages/recompose/__tests__/renderNothing-test.js

@@ -1,8 +1,11 @@
 import test from 'ava'
+import React from 'react'
 import { renderNothing } from '../'
+import { shallow } from 'enzyme'
 
 test('renderNothing returns a component that renders null', t => {
-  const nothing = renderNothing('div')
-  t.is(nothing(), null)
-  t.is(nothing.displayName, 'Nothing')
+  const Nothing = renderNothing('div')
+  const wrapper = shallow(<Nothing />)
+  t.is(wrapper.type(), null)
+  t.is(Nothing.displayName, 'Nothing')
 })

src/packages/recompose/renderNothing.js

@@ -1,9 +1,14 @@
+import { Component } from 'react'
 import createHelper from './createHelper'
 
-const renderNothing = _ => {
-  const Nothing = () => null
-  Nothing.displayName = 'Nothing'
-  return Nothing
+class Nothing extends Component {
+  render() {
+    return null
+  }
 }
 
+Nothing.displayName = 'Nothing'
+
+const renderNothing = _ => Nothing
+
 export default createHelper(renderNothing, 'renderNothing', false, true)