Pattern: Service Integration Contract Test
patternContext
You have applied the Microservice architecture pattern. The application consists of numerous services. Services often invoke other services. You must write automated tests that verify that a service behaves correctly.
Problem
How to easily test that a service provides an API that its clients expect?
Forces
- End to end testing (i.e. tests that launch multiple services) is difficult, slow, brittle, and expensive.
Solution
A test suite for a service that is written by the developers of another service that consumes it. The test suite verifies that the service meets the consuming service’s expectations.
Examples
Spring Cloud Contract is an open source project that supports this style of testing.
Resulting context
This pattern has the following benefits:
- Testing a service in isolation is easier, faster, more reliable and cheap
This pattern has the following drawbacks:
- Tests might pass but the application will fail in production
This pattern has the following issues:
- How to ensure that the consumer provided tests match what the consumer actually requires?
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