lambda-tester

Simplifies writing unit tests for AWS Lambda functions using Node.js.

Features

• Verifies correct handler behavior
• Works asynchronously
• Verifies Node.js runtime version
• AWS X-Ray support [experimental]
• Detects resource leaks [experimental]
• Supports Promises
• Easily integrates with test frameworks (Mocha and Jasmine)
• Handlers can be loaded and removed after execution
• Lightweight and won't impact performance
• Maps the environment variable LAMBDA_TASK_ROOT to the application's root
• Automatically loads .env files
• Works with Node 6.10.x

Installation

Install via npm.

npm install lambda-tester --save-dev

Getting Started

Lambda handlers with support for callbacks use the typical Node.js asynchronous signature:

exports.handler = function( event, context, callback ) {

    callback( null, 'success!' );
}

The following example shows a simple case for validating that the Lambda (handler) was called successfully (i.e. callback( null, result ):

const LambdaTester = require( 'lambda-tester' );

const myHandler = require( '../index' ).handler;

describe( 'handler', function() {

	it( 'test success', function() {

		return LambdaTester( myHandler )
			.event( { name: 'Fred' } )
			.expectResult();
	});
});

If the handler decides to call callback( err ) then the verification will fail and the test will fail.

Additionally, if one wanted to test for failure, then the following code would be used:

const LambdaTester = require( 'lambda-tester' );

const myHandler = require( '../index' ).handler;

describe( 'handler', function() {

	it( 'test failure', function() {

		return LambdaTester( myHandler )
			.event( { name: 'Unknown' } )
			.expectError();
	});
});

Please note that you must return the LambdaTester back to the framework since lambda-tester is asynchronous and uses Promises.

Documentation

Complete documentation can be found in our documentation page.

Projects Using lambda-tester

• vandium - Secures and simplifies AWS Lambda handlers

Feedback

We'd love to get feedback on how you're using lambda-tester and things we could add to make this tool better. Feel free to contact us at [email protected]

Compatibility

Version 3.x targets Lambda handlers using Node 6.10.x. If you require support for Node 4.x, please use version 2.x

License

BSD-3-Clause