Many teams working with microservices need confidence they don't break functionality when making changes. System integration tests, functional tests, and sometimes manual tests are older ways to obtain that confidence. These processes may take more than 1 day or even more if different teams or a different company own the services. To ensure the same level of confidence and speed up delivery, we can create Contracts for integrations between consumers and providers. Contracts created by consumer services need to pass with every build going in production to guarantee the integrations between systems/services work fine. Checking these contracts in a CI/CD pipeline makes feedback loops even faster. A Contract is a collection of agreements between a Consumer and a Provider that describes the interactions that can take place between them. Consumer Driven Contracts (CDCs) is a pattern that drives the development of the Providers from its Consumer's point of view. It is TDD for microservices. This talk covers an end to end demo of contract testing between two microservices to show how to release microservices with confidence, get early feedback, speed up delivery, and comparison with other testing strategies.

1. GopinathLangote
Confidently Releasing Microservices
With Consumer Driven Contracts
Software Engineer

2. Confidently
Releasing Microservices With Consumer Driven Contracts

3. Confidently
Releasing
Microservices With Consumer Driven Contracts

4. Confidently Releasing
Microservices
With Consumer Driven Contracts

5. Confidently Releasing Microservices With
Consumer Driven
Contracts
Client / Consumer Server / Provider

6. Confidently Releasing Microservices With Consumer Driven
Contracts

7. Payments Team Growth Team
Problem Statement

8. Refactoring

9. Unit Tests
Mocked Integration Tests
Functional Tests
Manual Tests
Test Pyramid

10. Unit Test
Limited to method level
Not aware of other service
Trustworthy

11. Mocked
Integration
Test

12. Mocked User Service
Not aware of other service Changes
No Feedback Loop
Trustworthy
Mocked Integration Test

13. Real User Service
Time Consuming
Longer Feedback Loop
Trustworthy
Functional Test

14. Manual Test

15. Unit Tests
Contract Test
Functional
Manual Tests
Test Pyramid

16. Account Service
Consumer Service
Contract Test
User Service
Producer Service
Payments Team Growth Team

17. Consumer Contract Test
Register expectation
Request
Account Service User Service
Mock Contract Server
TEST
Response
Contract File

18. User Service
Get the contracts
Assert the expectations from
consumer
Consumer
Provider
Mock Contract Server
Account Service
Provider Verification

19. Initialize Mock Server

20. Setup Expectations

21. Running Test

22. Demo
Consumer Contract Test

23. Get the contracts
Assert the expectations from
consumer
Provider Service
Provider Verification

24. Provider Verification

25. Demo
Provider Verification

26. Provider State

27. Setup Provider State

28. CDC In Action

29. Test As Part Of Source Code
Separate Contract Test Code
Consumer Test

30. Cloud Storage
Contract Brokers
Contract Sharing

31. Contract Verification Test
External tools
Provider Verification

32. Against Current Build
Provider Verification In CI
Against Stable Build

33. Tools

34. 1. JVM
2. .Net
3. Ruby
4. Go
5. JavaScript
6. Python
7. Php
8. Swift
You can implement you own https://pact.io
Pact

35. Other Tool
janus
VCRPACTO

36. Convince Me
https://docs.pact.io/faq/convinceme

37. Resources
https://github.com/gopinath-langote/Pact-JVM-Implementation
https://pact.io
https://martinfowler.com/articles/microservice-testing/
https://www.martinfowler.com/articles/consumerDrivenContracts.html

38. Questions?

39. Thank You
GopinathLangote