NewMessageForm.js.diff

 import React, { Component } from 'react';
 import {
+  Button,
   TextInput,
   View,
 } from 'react-native';
...
         <TextInput
           testID="messageText"
         />
+        <Button
+          title="Send"
+          testID="sendButton"
+        />
       </View>
     );
   }