AWS CDK is an IaC Framework which enables you to easily create serverless applications and plug together several AWS resources like Lambda, API Gateway and DynamoDB tables with just a few lines of code. But how do I verify if the application works as expected? This talk covers the different ways of testing CDK apps and thereby comprises unit testing Lambda functions, snapshot testing and fine-grained assertion testing of CDK stacks. Since integration testing is an essential part of gaining confidence in your application, we will split an application into several smaller parts, deploy and test them.

1. Testing serverless
apps with CDK
1

2. codecentric AG
Gartenstr. 69a
76135 Karlsruhe
X: @raphaelmanke
Github: RaphaelManke
LinkedIn: Raphael Manke
Raphael Manke
Consultant
manke@codecentric.de
www.codecentric.de
Innovative - Trustful - Competent - Pragmatic

3. More than 550
employees
3
13 locations
in Germany
founded in
2004
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Innovation & Knowledge Sharing

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5. // Welcome Serverless Sven
6
// ECommerce Inc.
// Onlineshop
// Cloud
// Sven

6. // Sven’s world
7
// Container
// Self hosted Database
// Infrastructure as Code
// Cross-functional team
// High test coverage

7. // Challenges
8
// Operational complexity
// Security
// Scalability

8. // Sven’s Idea – Let’s do serverless
9
// Scalability and elasticity
// Reduced operational overhead
// Cost-effectiveness
// Security and high availability
Go Serverless!

9. // But wait – what about testing?
10
// Testing locally
// Deploy to the cloud
// What needs to be tested
Testing?

10. // Hackweek – build a POC
11
Go Serverless! Testing?
Hackweek!?

11. // Architecture
12
Apigateway Lambda DynamoDB Queue
Pipe

12. // Setup
13
// AWS Cloud development Kit (CDK)
Source
code
CDK
CLI
Cloudformation
template
execute generate

13. // AWS Cloud development Kit (CDK)
14
App

14. // AWS Cloud development Kit (CDK)
15
App
Stack

15. // AWS Cloud development Kit (CDK)
16
App
Stack
Construct Construct

16. // Architecture
17
Apigateway Lambda DynamoDB Queue
Pipe

17. // Create Order
18
// Apigateway
• Route
• Integration
// Lambda Function
• Validate Input
• Store in Database

18. // Create Order
19
// Apigateway // Lambda Function

19. // Create Order
20
// Apigateway // Lambda Function

20. // Create Order
21
// Apigateway // Lambda Function

21. // Create Order - testing
22
// Unit-test
• Mock externals
// Template-test
• Synth template
• Assert on template

22. // Create Order - testing
23
// Apigateway // Lambda Function

23. // Create Order - testing
24
// Apigateway // Lambda Function

24. // Create Order - testing
25
// Apigateway // Lambda Function

25. // Create Order - testing
26
// Apigateway // Lambda Function

26. // Architecture
27
Apigateway Lambda DynamoDB Queue
Pipe

27. // Store Order
28
// Lambda
• Policy
• DynamoDB query
// DynamoDB
• Table name

28. // Store Order
29
// Lambda Function // Dynamo DB

29. // Store Order - testing
30
// Integration tests (local)
• Local Mocks
• Test Database
// Synth spy
• Synth template
• Spy on function calls

30. // Store Order - testing
31
// Lambda Function // Dynamo DB

31. // Store Order - testing
32
// Lambda Function // Dynamo DB

32. // Store Order - testing
33
// Lambda Function // Dynamo DB

33. // Architecture
34
Apigateway Lambda DynamoDB Queue
Pipe

34. // Put Order on queue
35
// Pipe
• Read Policy
• Put Policy
• Payload transformation
// Queue
• Exists
• Is exported

35. // Put Order on queue
36
// Stack // Pipe

36. // Put Order on queue
37
// Stack // Pipe

37. // Put Order on queue - testing
38
// Integration tests (cloud)
• Deploy construct
• Replace external resources
// Integration test runner (alpha)
• Deploy to the cloud
• Test in the cloud

38. // Integration test runner
39
// Stack under test
• Deployed to the cloud
// Integration test runner (alpha)
• Step function
• Deployed to the cloud
• Make AWS api calls
• Make Assertions on responses

39. // Put Order on queue - testing
40

40. // Put Order on queue - testing
41

41. // Put Order on queue - testing
42

42. // Architecture
43
Apigateway Lambda DynamoDB Queue
Pipe

43. // End 2 End - testing
44
// E2E tests (cloud)
• Deploy (seperatly) to cloud
• Test boundaries

44. // Hackweek – build a POC
45
Go Serverless! Testing works!
App
Stack
Construct Construct

45. // Hackweek – presentation
46
// Runtime code
Unittests
Integration tests with (local)
mock services
// Infrastructure as code
Fine grained template assertions
Spy on class calls
// Serverless services
Testing in the cloud
Deploy, Test, Destroy

46. // Hackweek – presentation
47
// Winner

47. codecentric AG
Gartenstr. 69a
76135 Karlsruhe
X: @raphaelmanke
Github: RaphaelManke
LinkedIn: Raphael Manke
Raphael Manke
Consultant
manke@codecentric.de
www.codecentric.de
Innovative - Trustful - Competent - Pragmatic

48. 49
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