CONTRACT
TESTING
Who are we?
Sai Krishna
Lead Consultant
ThoughtWorks
Srinivasan Sekar
Lead Consultant
ThoughtWorks
Monolithic vs Microservices
A sad story ....
Payment
Users
{
"user":[]
}
{
"users":[]
}
How do we avoid problems like this?
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
-
The idea of Consumer-Driven Contracts is to formalize the interactions between a consumer and a provider.
-
Consumer creates a contract, which is an agreement between the consumer and a provider on the interactions that will take place between them.
-
Provider has agreed on the contract, both consumer and provider can take a copy of the contract and use tests to verify that their corresponding implementations don’t violate the contract. The advantage of these new tests is that they are pretty much unit-tests: they can be run locally and independently, and they are fast and reliable
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 Client
CONSUMER
API
PRODUCER MOCK
API
Request
Response
CONTRACT TESTING
Contract
PRODUCER VERIFIER
PRODUCER
API
Request
Response
Contract
{
"user":
}{
"users":
}
Consumer Side
Provider Side
DEMO
PACT BROKER
Conclusion
By formalising 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.
- Introduction to Consumer Contract Testing
- Consumer-Driven Contract Testing using Pact.js
- Consumer-Driven Contract Testing using Pact Java
- Consumer-Driven Contract Testing using Spring Cloud Contracts
- Event Driven Architecture: How to Perform Contract Testing in Kafka/PubSub
-
Integrating Contract Testing in Build Pipeline
Blog Summary
Contract Testing
By Sai Krishna
