aws-lambda-mock-context/index.js

AWS Lambda mock context object

'use strict';
const uuid = require('uuid');
const moment = require('moment');
const defer = require('pinkie-defer');
const pkg = require('./package.json');

module.exports = options => {
	const id = uuid.v1();
	const stream = uuid.v4().replace(/-/g, '');

	const opts = Object.assign({
		region: 'us-west-1',
		account: '123456789012',
		functionName: pkg.name,
		functionVersion: '$LATEST',
		memoryLimitInMB: '128',
		timeout: 3
	}, options);

	const deferred = defer();

	const start = Date.now();
	let end;

	const context = {
		callbackWaitsForEmptyEventLoop: true,
		functionName: opts.functionName,
		functionVersion: opts.functionVersion,
		invokedFunctionArn: `arn:aws:lambda:${opts.region}:${opts.account}:function:${opts.functionName}:${opts.alias || opts.functionVersion}`,
		memoryLimitInMB: opts.memoryLimitInMB,
		awsRequestId: id,
		invokeid: id,
		logGroupName: `/aws/lambda/${opts.functionName}`,
		logStreamName: `${moment().format('YYYY/MM/DD')}/[${opts.functionVersion}]/${stream}`,
		getRemainingTimeInMillis: () => {
			const endTime = end || Date.now();
			const remainingTime = (opts.timeout * 1000) - (endTime - start);

			return Math.max(0, remainingTime);
		},
		succeed: result => {
			end = Date.now();

			deferred.resolve(result);
		},
		fail: err => {
			end = Date.now();

			if (typeof err === 'string') {
				err = new Error(err);
			}

			deferred.reject(err);
		},
		done: (err, result) => {
			if (err) {
				context.fail(err);
				return;
			}

			context.succeed(result);
		},
		Promise: new Promise(deferred)
	};

	setTimeout(() => {
		if (context.getRemainingTimeInMillis() === 0) {
			context.fail(new Error(`Task timed out after ${opts.timeout}.00 seconds`));
		}
	}, opts.timeout * 1000);

	return context;
};