CONSUMER
DRIVEN
CONTRACTS
Srinivasan Sekar
Lead Consultant
ThoughtWorks
Monolithic vs Microservices
A sad story ....
Payment
Users
{
"users":[]
}{
"user":[]
}
Test Pyramid
Mocked
Dependencies
Payment Service
Mocked User service
Request
Response
Mocked Test are
Targeted
Cheap
Fast
Not Trustworthy
Integration
Test
Integration test are
TrustWorthy
Slow
Brittle
Whose fault ?
CONSUMER
DRIVEN
CONTRACTS
- Formalize the interactions between a consumer and a provider.
- The consumer creates a contract, which is an agreement between consumer & provider on the interactions that will take place between them
- The provider has agreed on the contract, both consumer and provider can take a copy of the contract and use tests to verify that implementations don't violate the contract.
How pact works?
A contract between a consumer and provider is called a pact. Each pact is a collection of interactions. Each interaction describes:
- An expected request - describing what the consumer is expected to send to the provider.
- A minimal expected response - describing the parts of the response the consumer wants the provider to return.
Who would typically implement Pact?
- The consumer team is responsible for implementing the Pact tests in the consumer codebase that will generate the contract.
- The provider team is responsible for setting up the Pact verification task in the provider codebase, and for writing the code that sets up the correct data for each provider state described in the contract.
- Both teams are responsible for collaborating and communicating about the API and its usage!
PACT Clients
CONSUMER
API
PRODUCER MOCK
API
Request
Response
CONTRACT TESTING
Contract
PRODUCER VERIFIER
PRODUCER
API
Request
Response
Contract
{
"user":
}{
"users":
}
PIPELINES
Demo
Pact
Broker
References
https://martinfowler.com/articles/consumerDrivenContracts.html
https://blog.testproject.io/2020/04/27/introduction-to-consumer-contract-testing/
https://blog.testproject.io/2020/05/27/consumer-driven-contract-testing-using-pact-java/
Conclusion
By formalizing the interaction between consumer and provider, and verifying that both services stick to the contract they’ve agreed upon, we see that we have no need to perform integration tests between them. Instead, we’re using new tests that are specific, fast, and robust.
Consumer Driven Contracts
By Srinivasan Sekar
