What are microservices testing strategies?

The microservice architecture consists of many independent microservices that communicate with each other over application programming interfaces (APIs). Most modern services have this architecture because it’s easy to develop and scale up.

Testing strategies for microservices

Testing of microservices is crucial, as a failure of one service can cause the failure of the whole system. Testing of microservices is very different from the usual monolithic architecture.

There are five strategies, of which two strategies are additional to monolithic testing strategies. These testing strategies for microservices are described below:

Unit testing

Unit testing is used to test the smallest components in the microservice, like a class or a function. These tests are written by developers who have written those APIs because they know the complexity of their code more than anyone else. This makes unit testing easy in the future. In case of any change in that function or class, the unit test checks whether the new modification doesn’t give any unrequired results. These tests are also easy to modify as they test a small portion of the code.

Component testing

Component testing comprises testing a whole microservice as a unit in which we check the expected results for the given business calls. This can mean that we have to mock up many other microservices of the system on which the microservice that needs to be tested relies. So, it’s a bit hard but it’s as crucial as the other microservice strategies.

Integration testing

In microservices, integration testing is done to check the request flow between different microservices, as a microservice may be working properly in isolation, but a wrong request flow can change and impact the results required.

Contract testing

Contract testing ensures that each microservice fulfills the contract signed between the producer and the consumer of the API or microservice.

The communication, requests, and responses should follow the contract signed between the parties.

End-to-end testing

In a microservice architecture, just like the monolithic architecture, end-to-end testing is done by taking up all the microservices as one system and checking the user-related responses for each request. It’s easy to understand, but it’s difficult to perform as it requires all the microservices to be functional and can’t be done even if one of them isn’t functional. Also, if a problem is discovered in the result of this testing, it will be difficult to identify where the problem occurred. But if all other testing strategies are also used, this strategy will be helpful to ensure the proper working of our system.