Fix tests by mocking invariant

Author: thebuilder

package.json

@@ -26,7 +26,7 @@
     "lint": "eslint {src,stories,tests}/. ",
     "precommit": "flow && lint-staged",
     "postcommit": "git reset",
-    "prepublish": "npm run build",
+    "prepare": "npm run build",
     "pretty": "prettier '**/*.{js,md,json}' --write",
     "storybook": "start-storybook -p 9000",
     "test": "eslint {src,stories,tests}/. && jest"

tests/Observer.test.js

@@ -1,8 +1,10 @@
 import React from 'react'
 import { mount } from 'enzyme'
 import Observer from '../src/index.js'
+import invariant from 'invariant'
 
 jest.mock('../src/intersection')
+jest.mock('invariant')
 
 it('Should render <Observer />', () => {
   const callback = jest.fn()
@@ -60,11 +62,15 @@ it('Should render <Observer /> render when in view', () => {
 })
 
 it('Should throw error when not passing ref', () => {
-  expect(() =>
-    mount(
-      <Observer
-        render={({ inView, ref }) => <div>Inview: {inView.toString()}</div>}
-      />,
-    ),
-  ).toThrow()
+  invariant.mockReset()
+
+  mount(
+    <Observer
+      render={({ inView, ref }) => <div>Inview: {inView.toString()}</div>}
+    />,
+  )
+  expect(invariant).toHaveBeenLastCalledWith(
+    null,
+    'react-intersection-observer: No DOM node found. Make sure you forward "ref" to the root DOM element you want to observe, when using render prop.',
+  )
 })

tests/__snapshots__/Observer.test.js.snap

@@ -61,5 +61,3 @@ exports[`Should render <Observer /> with children outside view 1`] = `
   </div>
 </Observer>
 `;
-
-exports[`Should throw error when not passing ref 1`] = `"An error was thrown inside one of your components, but React doesn't know what it was. This is likely due to browser flakiness. React does its best to preserve the \\"Pause on exceptions\\" behavior of the DevTools, which requires some DEV-mode only tricks. It's possible that these don't work in your browser. Try triggering the error in production mode, or switching to a modern browser. If you suspect that this is actually an issue with React, please file an issue."`;