Now a days the word "Microservices" is one of the most trending in the IT Industry. And, testing microservices is more important as many of the new applications and old legacy systems are building using Microservices architecture.
Before we see how to test microservices, let's first understand what they are.
What are Microservices?
Microservices is defined as an architectural style also known as microservice architecture. Microservices applications are a collection or a suite of services. Microservices, or microservices architecture, are the modern methods of designing software applications that compartmentalize the software into chunks of small and independent services.
Benefits of Microservices:
- Highly maintainable and testable
- Independently deployable
- Loosely coupled services
- Easier debugging with smaller module
- Owned by a small team
How to Test Microservices?
A microservice may be smaller by its definition, but with unit testing, you can go even more granular. A unit test needs to focus on the smallest part of a testable software to ascertain whether that component works as it should.
In unit testing most importantly, need to test 'API Gateway' also known as 'Backends for Frontends' where each service interacts with common Gateway. API gateway handles requests. Where some requests are just routed to the appropriate service and other requests by fanning out to multiple services.
Testing microservice itself in isolation. Typically, an application would be composed of several microservices, so to test in isolation, we need to mock the other microservices.
Component tests will also include the interaction of microservice with the database, all as one unit.
Once the functionality of each individual microservice has been verified, then we need to test the inter-service (Services-to-Service) communications. An integration verify that the subsystem (or a concrete module) can communicate correctly, rather than testing the external element. Integration tests should cover only basic success-and-error paths for integration between the subsystem and the external component.
Contract testing is a methodology to verify the interactions between two separate microservices which are compatible with one another. It collects the interactions that are exchanged between each service, storing them in a contract, which can be later used to verify that both parties to be connected.
The end-to-end tests means all components work well together for complete user workflows correctly including all service and DB integration. Thorough testing of operations that affect multiple services ensures that the system works together as a whole and meets all the requirements and achieves its goals.
This blog covers a general approach of 'how to test microservices'. There may be different approaches, methods, and strategies to test the microservices. It also depends on company-to-company, different methodologies, and other project requirement factors.