This document introduces consumer-driven contract testing using Pact. It discusses problems with traditional unit, integration and end-to-end tests. Contract testing captures the interactions between a consumer and provider as tests. It registers expectations of the request and validates the response. This allows each component to be tested independently and improves test isolation, speed and reliability over other strategies. Pact is a framework for contract testing that supports multiple languages and platforms.

1. Consumer Driven Contract Testing
Using Pact

2. Introduction
Gopinath Langote
Application Developer, ThoughtWorks

3. Problem
Payment Service Customer Service
Request
Response

4. Problem
Payment Service
Request
Response
{
“customerName” : ”John”
}
{
“customerName” : ”John”
}
Customer Service

5. Refactor !!!
Payment Service
Request
Response
{
“name” : ”John”
}
{
“customerName” : ”John”
}
Customer Service

6. Test Pyramid
End To End
Test
Integration
Test
Unit Test

7. Unit Test

8. Unit Test
➢Does not know about external service
➢Limited to the method level

9. Integration Test

10. Integration Test
Request
Response
Payment Service
Mocked Customer Service Client

11. ➢Not Trustworthy
➢Entire application should be up
Integration Test

12. End to end Test

13. End to End Test
Request
Response
Payment Service User Service

14. ➢Slow
➢All services need to be up before
running the test
➢Trustworthy
➢Solves our problem. Finally !!!
End to End Test

15. Functional Test

16. Manual Test

17. Contract Test

18. Test Pyramid
End To End
Test
Integration
Test
Contract Test
Unit Test

19. Contract Test
Payment Service User Service
Request
Response
Consumer Provider

21. Contract Test
Register expectation
Request
Payment Service
Customer Service
PACT
TEST
Response

22. Contract Test
Payment Service
User Service
Get the contract
Assert the expectations from
consumer
Consumer
Provider
PACT

23. PACT
File
File System URL / Cloud
storage
Pact Broker

24. Initialize Mock Server

25. Specify the request - response

26. Test the response

27. Interactions to the server captured by pact

28. Providing State To the Provider

29. Pact Broker

30. Why should I use Pact
• Faster execution.
• Framework independent
• Reliable responses, not flakey tests.
• Causes of failure are easier to identify as only one component is being
tested at a time.
• No separate integration environment(s) required to be managed for
automated integration tests - pact tests run in standalone CI builds.
NOT YET CONVINCED ? https://docs.pact.io/faq/convinceme.html

31. Alternative to pacts
• Spring cloud contract https://cloud.spring.io/spring-cloud-contract/
• Swagger Validator http://bigstickcarpet.com/swagger-
parser/www/index.html

32. Read More
• Pact https://docs.pact.io/
• Pact JVM https://github.com/DiUS/pact-jvm
• Pact JVM implementations: https://github.com/gopinath-
langote/Pact-JVM-Implementation
• Pact All language support :
https://docs.pact.io/documentation/implementation_guides.html
• https://martinfowler.com/articles/consumerDrivenContracts.html
• Join the community at https://gitter.im/realestate-com-au/pact?utm_source=share-
link&utm_medium=link&utm_campaign=share-link

33. THANK YOU
For questions or suggestions:
Gopinath Langote
gopinathlangote11@gmail.com
33