Testing Serverless Applications - AWS Summit Santa Clara

Testing serverless applications brings reduced risk, speeds up delivery and improved design of your serverless apps.

Key Takeaways

1. Many think testing serverless applications is unnecessary.
2. Testing is very important on all levels both unit, integrated and end-to-end-testing.
3. Testing speeds up software delivery and reduces risk.
4. Testing gives improved design of your serverless apps.
5. By testing and properly designing using Hexagonal architecture you’re even out of vendor lock-in.

Transcript

1. simalexan AWS Summit 
 Santa Clara 2019 Meet Slobodan
2. simalexan AWS Summit 
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4. simalexan AWS Summit 
 Santa Clara 2019 Build with serverless! Its me!
5. simalexan AWS Summit 
 Santa Clara 2019 Business is 
 more profitable Focus on 
 business logic
6. simalexan AWS Summit 
 Santa Clara 2019 Ok, lets try…
7. simalexan AWS Summit 
 Santa Clara 2019 AWS Lambda DynamoDB API Gateway AWS S3
8. AWS Summit 
 Santa Clara 2019 simalexan It is serverless, 
 the same way WIFI is wireless. Gojko Adzic
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11. AWS Summit 
 Santa Clara 2019 simalexan Many think testing applications is unnecessary
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15. AWS Summit 
 Santa Clara 2019 simalexan How do you test a serverless app?
16. AWS Summit 
 Santa Clara 2019 simalexan Testing Serverless Applications
17. AWS Summit 
 Santa Clara 2019 simalexan Aleksandar Simovic Senior Software Engineer @ ScienceExchange AWS Serverless Hero Co-author of “Serverless Applications with Node.js” book Core team member @ Claudia.js AWS SAM & Lambda Builders Contributor
18. AWS Summit 
 Santa Clara 2019 simalexan How do you test a serverless app?
19. AWS Summit 
 Santa Clara 2019 simalexan First, the tools…
20. AWS Summit 
 Santa Clara 2019 simalexan • Jest • Jasmine • Mocha • any other popular tool For example, for Node.js you can use:
21. AWS Summit 
 Santa Clara 2019 simalexan What to test in a serverless app?
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24. AWS Summit 
 Santa Clara 2019 simalexan Integration tests are cheaper, but also more important, because a common serverless app is split into many small pieces
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 Santa Clara 2019 simalexan const AWS = require('aws-sdk'), stripe = require('stripe'), qs = require('querystring'), processResponse = require('./process-response'), stripe = require('stripe')(process.env.STRIPE_SECRET_KEY); exports.handler = (event) => { if (event.httpMethod === 'OPTIONS') { return Promise.resolve(processResponse(true)); } if (!event.body) { return Promise.resolve(processResponse(true, 'invalid', 400)); } const newCharge = qs.parse(event.body); if (!newCharge.amount || !newCharge.currency) { return Promise.resolve(processResponse(true, 'invalid arguments, please provide amount and currency fields as mentioned in the app README', 400)); } return stripe.charges.create({ source: newCharge.stripeToken, amount: newCharge.amount, currency: newCharge.currency, description: 'Charge Description' }) .then(charge => processResponse(true, {charge})) .catch((err) => { console.log(err); return processResponse(true, 'stripe-error', 500); }); };
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30. AWS Summit 
 Santa Clara 2019 simalexan One of the purposes of testing is to Reduce Risk
31. AWS Summit 
 Santa Clara 2019 simalexan • configuration risks • technical workflow risks • business logic risks • integration risks
32. AWS Summit 
 Santa Clara 2019 simalexan How do we write testable functions
 to address those risks
33. AWS Summit 
 Santa Clara 2019 simalexan Hexagonal Architecture
34. AWS Summit 
 Santa Clara 2019 simalexan Alistair Cockburn Allow an application to equally be driven by users, programs, automated test or batch scripts, and to be developed and tested in isolation from its eventual run-time devices and databases.
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 Santa Clara 2019 simalexan const pubsubRepository = require('./pubsub-repository'), paymentProcessorRepository = require('./payment-processor'), TOPIC_ARN = process.env.TOPIC_ARN; module.exports = function chargeCustomer(secretKey, token, email, amount, currency, description = 'Charge Description', paymentProcessor = paymentProcessorRepository, pubsub = pubsubRepository) { let createdCharge; return paymentProcessor.createCharge(secretKey, token, amount, currency, description) .then(chargeResponse => { createdCharge = chargeResponse; createdCharge.email = email; return pubsub.publish(createdCharge, TOPIC_ARN); }) .then(() => createdCharge) .catch((err) => { console.log(err); throw err; }); }
38. AWS Summit 
 Santa Clara 2019 simalexan const AWS = require('aws-sdk'), sns = new AWS.SNS(), NO_DATA_REPLY = 'You must provide data to the your PubSub'; module.exports = { publish: function publish(data, topic, pubSub = sns) { if (!data) { return Promise.reject(NO_DATA_REPLY); } return pubSub.publish({ Message: JSON.stringify(data), TopicArn: topic }) .promise() .catch(err => { console.log(err); throw err; }); } };
39. AWS Summit 
 Santa Clara 2019 simalexan Separate interface risk from your Business logic risk
40. AWS Summit 
 Santa Clara 2019 simalexan const convertFromSentry = require('../src/convert-from-sentry'), lambdaProxyEvent = require('./test-events/lambda-proxy-event'), wrapEvent = (event) => { const result = JSON.parse(JSON.stringify(lambdaProxyEvent)); result.body = JSON.stringify(event); return result; }; describe('Convert from Sentry', () => { describe('Error type', () => { test('should pickup the error type if defined', () => { const event = wrapEvent(require('./test-events/raven-exception')); expect(convertFromSentry(event).type).toBe('TypeError'); }); test('should use runtime error type if undefined', () => { const event = wrapEvent(require('./test-events/raven-manually-tracked')); expect(convertFromSentry(event).type).toBe('RuntimeError'); }); }); describe('Error message', () => { test('should pickup the message if exception value defined', () => { const event = wrapEvent(require('./test-events/raven-exception')); expect(convertFromSentry(event).message).toBe(`Cannot read property 'captureException' of undefined`); }); test('should use body message if exception value undefined', () => { const event = wrapEvent(require('./test-events/raven-manually-tracked')); expect(convertFromSentry(event).message).toBe('error'); }); }); });
41. AWS Summit 
 Santa Clara 2019 simalexan If you test and properly design using Hexagonal architecture you’re even out of “vendor lock-in”.
42. AWS Summit 
 Santa Clara 2019 simalexan Testing is very important on all levels both unit, integrated and end-to-end-testing.
43. AWS Summit 
 Santa Clara 2019 simalexan Integration tests are now more important than ever
44. AWS Summit 
 Santa Clara 2019 simalexan • hexagonal architecture • be smart • test integrations that you own • or test your code with a different adapter
45. AWS Summit 
 Santa Clara 2019 simalexan How does this look in practice?
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47. AWS Summit 
 Santa Clara 2019 simalexan UI testing
48. AWS Summit 
 Santa Clara 2019 simalexan Benefits of serverless are cheap infrastructure and easy fast parallelization
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50. AWS Summit 
 Santa Clara 2019 simalexan CI/CD
51. AWS Summit 
 Santa Clara 2019 simalexan It works the same way as any other app
52. AWS Summit 
 Santa Clara 2019 simalexan Use your favorite deployment tool from CI to deploy your serverless app
53. AWS Summit 
 Santa Clara 2019 simalexan Popular CI/CD tools
54. AWS Summit 
 Santa Clara 2019 simalexan • Jenkins • Travis CI • AWS CodePipeline • Semaphore CI • and many more
55. AWS Summit 
 Santa Clara 2019 simalexan Having test environments was never cheaper
56. AWS Summit 
 Santa Clara 2019 simalexan Automate deployment from git branches to different stages (ie. production, dev, staging, qa)
57. AWS Summit 
 Santa Clara 2019 simalexan Testing your serverless apps quickens your software delivery even more.
58. AWS Summit 
 Santa Clara 2019 simalexan Real life example @ ScienceExchange
59. AWS Summit 
 Santa Clara 2019 simalexan Hexagonal Architecture 3 months > 2 weeks Unit / Integration testing + =
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62. AWS Summit 
 Santa Clara 2019 simalexan • Testing your serverless applications is important • One of the goals of testing is to reduce risk • use hexagonal architecture to stay flexible • Hexagonal Architecture also significantly removes the “vendor lock-in” • use CI/CD for tests and deployment to different stages • Testing serverless applications speeds up delivery even more • use mature and tested deployment tools, and track and analyze errors • serverless helps testers to do their job faster and cheaper Key takeaways
63. AWS Summit 
 Santa Clara 2019 simalexan serverless.pub/book Serverless Applications with Node.js @simalexan claudia40 40% off
64. AWS Summit 
 Santa Clara 2019 simalexan Thank you