Service Component test

Context

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 do you easily test a service?

Forces

End to end testing (i.e. tests that launch multiple services) is difficult, slow, brittle, and expensive.

Solution

A test suite that tests a service in isolation using test doubles for any services that it invokes.

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 test doubles always correctly emulate the behavior of the invoked services?

See [[Service Integration Contract Test]]