Once we are sure that the individual methods inside a microservice work properly, we need to make sure that a microservice, in its complete independence, is able to function without any kind of issues. This happens because most of the microservices are a complete package in themselves. They come with their own set of dependencies, as well as the data sources through which they can manage their data.

As a developer, it is important for us to make sure that the microservice is able to interact properly with its dependencies. For this, we work on implementing the functionality testing for the microservices.

Also, during the functionality testing, we need to take care of certain things. Since each API endpoint inside a microservice may need to interact with some other microservice to produce the correct result, we might need to mock the presence of some microservices for the functionality testing to complete successfully.