NodeJs npm requestretry package Not Work on AWS Lambda Nodejs8.10 - node.js

Question

Here is my nodejs8.10 test code:
var request = require('requestretry');
const testRequest = async() =>{
request({
url: 'https://jsonplaceholder.typicode.com/posts/1',
json: true,
maxAttempts: 5, // (default) try 5 times
retryDelay: 5000, // (default) wait for 5s before trying again
retryStrategy: request.RetryStrategies.HTTPOrNetworkError
}, function(err, response, body){
if (response) {
console.log('The number of request attempts: ' + response.attempts);
console.log(body);
}else{
console.log('error: ', err);
}
});
}
testRequest(); // for local implementation
exports.handler = async (event) => {
let x = await testRequest();
const response = {
statusCode: 200,
body: JSON.stringify('Hello from Test Lambda!'),
};
return response;
};
vs. nodejs6.10 test code:
var request = require('requestretry');
function testRequest () {
request({
url: 'https://jsonplaceholder.typicode.com/posts/1',
json: true,
// The below parameters are specific to request-retry
maxAttempts: 5, // (default) try 5 times
retryDelay: 5000, // (default) wait for 5s before trying again
retryStrategy: request.RetryStrategies.HTTPOrNetworkError // (default) retry on 5xx or network errors
}, function(err, response, body){
// this callback will only be called when the request succeeded or after maxAttempts or on error
if (response) {
console.log(body);
}
});
}
testRequest();
exports.handler = (event, context, callback) => {
testRequest();
const response = {
statusCode: 200,
body: JSON.stringify('Hello from Lambda!'),
};
callback(null, response);
};
It won't display the log that related to requestretry package on lambda Nodejs 8.10 and no any error messages. However, it can get the response and logs by running with command node <filename> in the local machine after npm install with the necessary packages like 'requestretry' and its required packages. If the above file converted into Nodejs6.10 format and it won't have the issue on both aws lambda and local machine.
I need to find out the causing before I convert the codes from nodejs6.10 (callback format)to nodejs8.10 (async format).