Fix RN batching and effect behavior (reduxjs#1444)

* Add React Native deps for testing

* Add a Jest config to run tests in an RN environment

* Add initial RN tests

* Add test for RN batch export

* Add jest-native testing assertions

* Extract useIsomorphicLayoutEffect utility

* Add additional RN batching-related tests

* 7.1.2-alpha.0

jest.config.js

@@ -0,0 +1,29 @@
+const defaults = {
+  coverageDirectory: './coverage/',
+  collectCoverage: true,
+  testURL: 'http://localhost'
+}
+
+const testFolderPath = folderName => `<rootDir>/test/${folderName}/**/*.js`
+
+const NORMAL_TEST_FOLDERS = ['components', 'hooks', 'integration', 'utils']
+
+const standardConfig = {
+  ...defaults,
+  displayName: 'ReactDOM',
+  testMatch: NORMAL_TEST_FOLDERS.map(testFolderPath)
+}
+
+const rnConfig = {
+  ...defaults,
+  displayName: 'React Native',
+  testMatch: [testFolderPath('react-native')],
+  preset: 'react-native',
+  transform: {
+    '^.+\\.js$': '<rootDir>/node_modules/react-native/jest/preprocessor.js'
+  }
+}
+
+module.exports = {
+  projects: [standardConfig, rnConfig]
+}

package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-redux",
-  "version": "7.1.1",
+  "version": "7.1.2-alpha.0",
   "description": "Official React bindings for Redux",
   "keywords": [
     "react",
@@ -65,8 +65,10 @@
     "@babel/plugin-transform-runtime": "^7.5.5",
     "@babel/preset-env": "^7.5.5",
     "@testing-library/jest-dom": "^4.1.0",
+    "@testing-library/jest-native": "^3.0.2",
     "@testing-library/react": "^8.0.8",
     "@testing-library/react-hooks": "^1.1.0",
+    "@testing-library/react-native": "^4.2.0",
     "babel-eslint": "^10.0.3",
     "babel-jest": "^24.9.0",
     "codecov": "^3.5.0",
@@ -83,6 +85,7 @@
     "prettier": "^1.18.2",
     "react": "^16.8.6",
     "react-dom": "^16.8.6",
+    "react-native": "^0.61.4",
     "react-test-renderer": "^16.8.6",
     "redux": "^4.0.4",
     "rimraf": "^3.0.0",
@@ -97,10 +100,5 @@
     "transform": [
       "loose-envify"
     ]
-  },
-  "jest": {
-    "coverageDirectory": "./coverage/",
-    "collectCoverage": true,
-    "testURL": "http://localhost"
   }
 }

src/components/connectAdvanced.js

@@ -1,15 +1,9 @@
 import hoistStatics from 'hoist-non-react-statics'
 import invariant from 'invariant'
-import React, {
-  useContext,
-  useMemo,
-  useEffect,
-  useLayoutEffect,
-  useRef,
-  useReducer
-} from 'react'
+import React, { useContext, useMemo, useRef, useReducer } from 'react'
 import { isValidElementType, isContextConsumer } from 'react-is'
 import Subscription from '../utils/Subscription'
+import { useIsomorphicLayoutEffect } from '../utils/useIsomorphicLayoutEffect'
 
 import { ReactReduxContext } from './Context'
 
@@ -32,18 +26,6 @@ function storeStateUpdatesReducer(state, action) {
 
 const initStateUpdates = () => [null, 0]
 
-// React currently throws a warning when using useLayoutEffect on the server.
-// To get around it, we can conditionally useEffect on the server (no-op) and
-// useLayoutEffect in the browser. We need useLayoutEffect because we want
-// `connect` to perform sync updates to a ref to save the latest props after
-// a render is actually committed to the DOM.
-const useIsomorphicLayoutEffect =
-  typeof window !== 'undefined' &&
-  typeof window.document !== 'undefined' &&
-  typeof window.document.createElement !== 'undefined'
-    ? useLayoutEffect
-    : useEffect
-
 export default function connectAdvanced(
   /*
     selectorFactory is a func that is responsible for returning the selector function used to

src/hooks/useSelector.js

@@ -1,31 +1,10 @@
-import {
-  useReducer,
-  useRef,
-  useEffect,
-  useMemo,
-  useLayoutEffect,
-  useContext
-} from 'react'
+import { useReducer, useRef, useMemo, useContext } from 'react'
 import invariant from 'invariant'
 import { useReduxContext as useDefaultReduxContext } from './useReduxContext'
 import Subscription from '../utils/Subscription'
+import { useIsomorphicLayoutEffect } from '../utils/useIsomorphicLayoutEffect'
 import { ReactReduxContext } from '../components/Context'
 
-// React currently throws a warning when using useLayoutEffect on the server.
-// To get around it, we can conditionally useEffect on the server (no-op) and
-// useLayoutEffect in the browser. We need useLayoutEffect to ensure the store
-// subscription callback always has the selector from the latest render commit
-// available, otherwise a store update may happen between render and the effect,
-// which may cause missed updates; we also must ensure the store subscription
-// is created synchronously, otherwise a store update may occur before the
-// subscription is created and an inconsistent state may be observed
-const useIsomorphicLayoutEffect =
-  typeof window !== 'undefined' &&
-  typeof window.document !== 'undefined' &&
-  typeof window.document.createElement !== 'undefined'
-    ? useLayoutEffect
-    : useEffect
-
 const refEquality = (a, b) => a === b
 
 function useSelectorWithStoreAndSubscription(

src/utils/useIsomorphicLayoutEffect.js

@@ -0,0 +1,19 @@
+import { useEffect, useLayoutEffect } from 'react'
+
+// React currently throws a warning when using useLayoutEffect on the server.
+// To get around it, we can conditionally useEffect on the server (no-op) and
+// useLayoutEffect in the browser. We need useLayoutEffect to ensure the store
+// subscription callback always has the selector from the latest render commit
+// available, otherwise a store update may happen between render and the effect,
+// which may cause missed updates; we also must ensure the store subscription
+// is created synchronously, otherwise a store update may occur before the
+// subscription is created and an inconsistent state may be observed
+
+const isHopefullyDomEnvironment =
+  typeof window !== 'undefined' &&
+  typeof window.document !== 'undefined' &&
+  typeof window.document.createElement !== 'undefined'
+
+export const useIsomorphicLayoutEffect = isHopefullyDomEnvironment
+  ? useLayoutEffect
+  : useEffect

src/utils/useIsomorphicLayoutEffect.native.js

@@ -0,0 +1,5 @@
+import { useLayoutEffect } from 'react'
+
+// Under React Native, we know that we always want to use useLayoutEffect
+
+export const useIsomorphicLayoutEffect = useLayoutEffect