CodingItWrong

 {
   ...
   "detox": {
-    "test-runner": "jest"
+    "test-runner": "jest",
+    "configurations": {
+      "ios.sim": {
+        "binaryPath": "bin/Exponent.app",
+        "type": "ios.simulator",
+        "name": "iPhone 8"

CodingItWrong

+const { reloadApp } = require('detox-expo-helpers');
+
 describe('Example', () => {
   beforeEach(async () => {
-    await device.reloadReactNative();
+    await reloadApp();
   });

CodingItWrong

     "android": "expo start --android",
     "ios": "expo start --ios",
+    "test": "node_modules/.bin/jest test/**/*.spec.js",
     "eject": "expo eject"
   },
...
     "jest-expo": "^31.0.0"
   },
+  "jest": {
+    "preset": "jest-expo"

CodingItWrong

import React from 'react';
import {
  FlatList,
  Text,
} from 'react-native';

const MessageList = ({ data }) => (
  <FlatList
    data={data}
    keyExtractor={item => item}

CodingItWrong

 import NewMessageForm from './NewMessageForm';
+import MessageList from './MessageList';

...
   render() {
+    const { messages } = this.state;
     return (
       <View>
         <NewMessageForm onSend={this.handleSend} />
+        <MessageList data={messages} />

CodingItWrong

 export default class App extends Component {
+  state = { messages: [] }
+
   handleSend = (newMessage) => {
+    this.setState(state => ({ messages: [newMessage, ...state.messages] }));
   }

CodingItWrong

 export default class App extends Component {
+  handleSend = (newMessage) => {
+  }
+
   render() {
     return (
       <View>
-        <NewMessageForm />
+        <NewMessageForm onSend={this.handleSend} />
       </View>

CodingItWrong

   handleSend = () => {
+    const { inputText } = this.state;
+    const { onSend } = this.props;
+
+    onSend(inputText);
+
     this.setState({ inputText: '' });
   }

CodingItWrong

   describe('clicking send', () => {
     const messageText = 'Hello world';

+    let sendHandler;
     let getByTestId;

     beforeEach(() => {
+      sendHandler = jest.fn();

-      ({ getByTestId } = render(<NewMessageForm />));

CodingItWrong

 export default class NewMessageForm extends Component {
   state = { inputText: '' }

   handleChangeText = (text) => {
     this.setState({ inputText: text });
   }

+  handleSend = () => {
+    this.setState({ inputText: '' });
+  }