1. Contract testing: Beyond
API functional tests
Gaurav Singh

2. Hi 👋🏼
I’m Gaurav Singh 🏼🏼
Test automation 🏼 at Gojek, Bangalore
Full stack tester …. (mobile 📱, web 🏼, backend 🏼)
Find me on below:
• https://automationhacks.blog/
• https://www.linkedin.com/in/automationhacks/
• https://twitter.com/automationhacks
• https://github.com/gaurav-singh
• https://stackoverflow.com/users/5336432/gaurav-singh

3. Learning goals
• What is consumer driven contract testing?
• What problems does it solve over integration tests?
• Understand it’s nuts and bolts ⚙️
• Implement a contract test for a twitter like API using PACT
framework with JVM
• When not to use? 🏼

4. Let’s get started. Shall we? 😇

5. What are consumer driven contract tests?

6. Consumer driven contracts 🏼
• Confirms contract between a consumer and provider (called
Pact) 📃
• Written from the consumer’s perspective 📲 🏼 🌍
• Allows testing them in isolation
• Supports testing HTTP, message queues

7. Example AUT: Twitter API
Select “Run in postman” to import the collection in desktop client

8. Let’s run through a test scenario
• Login as a user and get login token

11. But first a bit of terminology 😇
• Consumer
• Provider
• Contract
• Interaction
• Broker

12. Consumer
• Any component that initiates an HTTP request to a provider
• Some Examples:
• Web or mobile app frontend
• Another service
• Desktop Client

13. Provider
• Component that responds to the HTTP request
• Might have multiple HTTP endpoints as part of the micro-service
(CRUD operations)
• A single deployable unit

14. Interaction
• Request
• Response expectations
💡Note: A Pact file is a
collection of interactions in
JSON format

15. Broker
• Keeps all the captured PACT’s
• Allows the provider to run its checks independently across
different projects

16. How does contract testing work?

17. Tests consumer first
• Checks if consumer generates correct request
• Checks if it can handle the different responses from the mock
provider

18. Test provider
• Driven entirely by PACT framework
• Sends actual request to provider
• Compare the actual response to minimum expected response
(described in interaction)

19. Talk 🏼 is cheap.
Show me the code 👨🏼💻

20. If all you have a hammer…
• Dos
• Check minimal shared understanding of what the provider should
return to us.
• Works best if you/your org/partner org are developing the consumer
and provider
• Dont’s
• Write to substitute all functional integration tests (don’t check side-
effects)
• Use it for performance and load testing
• To Test Pass through APIs

21. Not convinced?
• Read this link

22. For further meditation ☯
• GitHub code sample
• Pact
• Twitter API
• Provider states
• Pact best practices
• Effective pact setup guide
• Another JVM example
• JVM consumer Junit 4
• JVM provider

23. Thanks for your attention 🙇🏼
♂️
Questions?