A Consumer-Driven Contract (CDC) is a pattern used in microservices architecture to ensure service communication compatibility between a consumer (client) and a provider (service). It involves creating a contract that specifies the expectations of the consumer regarding the provider's responses to specific requests. This contract is then used to test the interactions between the consumer and the provider in isolation, ensuring that both sides adhere to the agreed-upon contract.
Key Points of Consumer-Driven Contract (CDC):
Definition and Purpose:
CDC is a testing methodology that focuses on the interactions between components of a system, ensuring that the provider meets the consumer's expectations[2][3][5].
It helps in overcoming the drawbacks of end-to-end (E2E) tests, which are often slow, brittle, and expensive to maintain[2][3].
Process:
Consumer Tests with Provider Mock: The consumer starts by creating integration tests against a mock of the provider. These tests define the expected responses for specific requests, effectively creating the contract[3][5].
Contract Generation: The contract is generated from the successful execution of these tests and is stored in a central repository accessible by both the consumer and the provider[3][5].
Provider Contract Verification: On the provider side, tests are executed to verify that the real responses match the expectations defined in the contract. Any discrepancies indicate a failure to meet the contract[3][5].
Benefits:
Isolation and Faster Feedback: CDC tests isolate components, providing quicker feedback on potential issues compared to E2E tests[5][12].
Enhanced Stability: CDC tests are less prone to breaking due to changes in other components, leading to more stable tests[5][12].
Cost-Effective Maintenance: CDC tests focus on specific contracts, reducing the maintenance burden and associated costs compared to E2E tests[5][12].
Efficient Testing of Large Systems: CDC tests break down large systems into manageable components, making it easier to test individual parts thoroughly[5][12].
Tools and Frameworks:
Pact: A popular CDC testing tool that allows for the creati...
