aws lambda js unit testing

Question

I've been looking into aws lambda. How are people testing the harness for api gateway requests responses? In Java I have a lambda that's a bit like this.

import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
...
@Test
void turnsBarToFooTest() {

    TestContext ctx = new TestContext(); //implements  com.amazonaws.services.lambda.runtime.Context

    Fooer handler = new Fooer();

    APIGatewayProxyRequestEvent request = new APIGatewayProxyRequestEvent();
    Map<String, String> params = HashMap.of("thing_to_foo", "bar");
    request.setPathParameters(params.toJavaMap());

    APIGatewayProxyResponseEvent response = handler.handleRequest(request, ctx);
    assertEquals(200, response.getStatusCode().intValue());
    assertEquals("foo", response.getBody());
}

I'd love to do something really simple with Jest and ES6 to replicate the above. Are there similar known events objects to use? How can I wire them up with jest.

Martin Nuc · Accepted Answer · 2017-11-13 16:22:09Z

I made function for adding security headers based on Host header in Lambda for CloudFront. For testing I used JEST and basically mocked objects in AWS like this.

google.test.js:

const handler = require('../../src/functions/google').handler;
const testEventGenerator = require('./cloudfront-event-template-generator');

test('it adds xss protection', () => {
  const event = testEventGenerator();
  const callback = jest.fn();
  handler(event, {}, callback);
  expect(event.Records[0].cf.response.headers['x-xss-protection'][0].key).toBe('X-XSS-Protection');
  expect(event.Records[0].cf.response.headers['x-xss-protection'][0].value).toBe('1; mode=block');
  expect(callback.mock.calls.length).toBe(1);
});

cloudfront-event-template-generator.js:

module.exports = () => ({
  Records: [
    {
      cf: {
        config: {
          distributionId: 'EXAMPLE'
        },
        request: {
          headers: {
            host: [
              {
                key: 'host',
                value: 'www.google.com'
              }
            ]
          }
        },
        response: {
          status: 200,
          headers: {
            'last-modified': [
              {
                key: 'Last-Modified',
                value: '2016-11-25'
              }
            ],
            vary: [
              {
                key: 'Vary',
                value: '*'
              }
            ],
            'x-amz-meta-last-modified': [
              {
                key: 'X-Amz-Meta-Last-Modified',
                value: '2016-01-01'
              }
            ]
          },
          statusDescription: 'OK'
        }
      }
    }
  ]
});

Oliver Shaw · Accepted Answer · 2017-11-13 19:15:36Z

0

I've got jest doing what I wanted. Martin's idea of the test responses will be helpful as it gets more involved, thanks.

test('fooer will foo a bar', done => {

  const context = {}
  const request = {pathParameters:{thing_to_foo:'foo'}}
  const callback = (bar, foo) => {
    expect(foo.body).toBe('bar')
    done()
  }
  myHandler.handler(request, context, callback)

})

answered Nov 13, 2017 at 19:15

Oliver Shaw

5,4224 gold badges29 silver badges36 bronze badges

Collectives™ on Stack Overflow

aws lambda js unit testing

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related