Beyond the unit: a holistic approach for testing serverless architectures

One of the peculiar aspects of microservices architecture is the possibility of designing a system as a set of independent but collaborative components. At the root of this collaboration there are well-defined contracts among all the microservices: breaking even a single contract might compromise the health of the entire system. With AWS Lambda, we have the ability to simply create an ever-increasing number of microservices and, therefore, it becomes crucial to find a way to catch errors in advance whenever one of these contracts has been broken.

Transcript

1. A HOLISTIC APPROACH FOR TESTING APPLICATIONS BEYOND THE UNIT
2. Come l’improbabile governa la nostra vita Nassim Nicholas Taleb Il Cigno nero
4. REDUCE UNPREDICTABILITY BLAST RADIOUS RULE #1 Stop deploying on Friday (especially at 5pm)! COROLLARY #1 Start deploying on Tuesday (after the first coffee)!
5. REDUCE UNPREDICTABILITY BLAST RADIOUS (FOR REAL) OPS SIDE Infrastructure as Code, pipelines, progressive deployments... DEV SIDE Tests
6. TESTING MONOLITHS
7. MONOLITH
8. UNIT TESTS Sum(a, b) a = 1 b = 2 verify result is 3
9. UNIT TESTS public class Calculator { public int Sum(int a, int b) { return a+b; } } public void TestSum() { // Arrange var calculator = new Calculator(); // Act var result = calculator.Sum(1, 2); // Assert Assert.Equal(3, result); }
10. UNIT TESTS 100% CODE COVERAGE
11. INTEGRATION TESTS GetCustomer(id) id=5 { ”Id": 5, "FirstName": "John", "LastName": "Doe" }
12. END-TO-END TESTS UI
13. E2E Integration tests Unit tests TEST PYRAMID
14. TESTING MICROSERVICES
15. UNIT TESTS 100% CODE COVERAGE 100% CODE COVERAGE WE ARE FAR FROM BEING 100% SAFE
16. THE WHOLE IS GREATER THAN T H E S U M O F ITS PARTS
17. THE PARTS
18. THE WHOLE
19. MICROSERVICES COMMUNICATION STYLES REQUEST/RESPONSE Checkout Customers GET /customers/5 { ”Id": 5, "FirstName": "John", "LastName": "Doe" }
20. MICROSERVICES COMMUNICATION STYLES REQUEST/RESPONSE Checkout Customers GET /customers/5 { ”Id": 5, "FirstName": "John", "Name": "John", "LastName": "Doe" ”Surname": "Doe” }
21. CONSUMER DRIVEN CONTRACT TESTING Checkout (consumer) Define expectations
22. UponReceiving("a GET request for a customer") .Given("there is a customer with id '5’”) .WithRequest(HttpMethod.Get, "/customers/5") .WillRespond() .WithStatus(HttpStatusCode.OK) .WithJsonBody(new { Id = 5, FirstName = "John", LastName = "Doe” }); CONSUMER DRIVEN CONTRACT TESTING DEFINE CONSUMER EXPECTATIONS
23. CONSUMER DRIVEN CONTRACT TESTING Customers (producer) Check the contract
24. .ServiceProvider("CustomerService", "<ENDPOINT>")) .WithFileSource(<PATH TO THE CONTRACT>) .Verify(); CONSUMER DRIVEN CONTRACT TESTING VERIFY PROVIDER AGAINST THE CONTRACT
25. MICROSERVICES COMMUNICATION STYLES MESSAGE BASED Orders Checkout { ”CustomerId": 5, ”OrderId": 18 } (consumer) (producer)
26. Checkout (consumer) CONSUMER DRIVEN CONTRACT TESTING Define expectations
27. ExpectsToReceive("an ‘order confirmed’ event") .WithJsonContent(new { OrderId = 5, CustomerId = 18 }); CONSUMER DRIVEN CONTRACT TESTING DEFINE CONSUMER EXPECTATIONS
28. CONSUMER DRIVEN CONTRACT TESTING Verify Orders (producer)
29. .MessagingProvider("Orders") .WithProviderMessages(s => { s.Add("an ‘order confirmed’ event", () => new OrderConfirmedEvent { OrderId = 5, CustomerId = 18, }); }) .WithFileSource(new FileInfo(pactPath)) .Verify(); CONSUMER DRIVEN CONTRACT TESTING VERIFY PROVIDER AGAINST THE CONTRACT
30. Consumer-Driven Contract Testing Integration tests Unit tests TESTING PYRAMID
31. TESTING SERVERLESS
32. SERVERLESS MICROSERVICES
33. TESTING HONEYCOMB Unit tests Integration tests CDCT
34. INTRODUCE UNPREDICTABILITY WHAT IF…?
35. «You don’t choose the moment, The moment chooses you. You only choose how prepared you are when it does.»
36. TAKE AWAY Unit test for testing business logic; Consumer-Driven Contract Testing for testing communications; Integration tests can be critical in a serverless environment; Make unpredictable predictable; Further reading (from blog) Why unit tests are not enough when it comes to microservices How chaos engineering will help you design better software
37. WHO AM I? Mariano Calandra Passionate about architectures and software development, work in Var Group as an AWS solutions architect. Co-founder of Serverless Days Rome. Blog Rate the session Careers