What are the major microservices testing strategies and their types?

What is microservices architecture?
Most businesses are adopting the microservices architecture in order to test, build, and deploy services separately and more quickly. The microservices architectures are complicated, and in order to test these systems properly, we must have a thorough understanding of the system architecture.

Let’s begin with a basic architectural understanding of microservices. We may have some downstream or external services that perform business-essential functions such as customer data-related operations, loyalty operations, and keep some of the company’s critical data. The nature of these operations and data are determined by the industry in which the company operates. We have a middleware layer between clients and external systems that handles communication, translation, and some business operations.

Major Microservice testing strategies:
Microservices software tests ensure that microservices perform as expected in a timely and efficient manner. The three main methods of software testing for microservices in the industry are:

Load testing assists to identify portions of an application that are not well-designed and may crash as a result of excessive visitor flow. Because each call to a microservice travels over the network, other network activities can affect response times.

Testing for resiliency to see how the program reacts to possible infrastructure breakdowns. For example, if a server providing a specific service is unreachable, crashes, or a part of a network halts transmitting data. In these circumstances, the developer must test the microservices application to see if it can continue to function on endpoints and elsewhere.

Functional testing is used to check the service’s business logic and behavior. Because microservices lack a UI for straightforward testing, this is more difficult than testing in a traditional monolithic design. Functional test depicts the communication through HTTP or another protocol for the clients.

What type of testing is needed for microservices?
Microservices architecture enables developers to create highly scalable applications, flexible apps, and apps for organizations or industries such as banking, healthcare, insurance, telecommunications, IoT, and AI. This strategy breaks down a program into individual services (microservices) that perform specialized functions.

The more coarse-grained a test is, the more brittle and time-consuming it is to execute, design, and maintain in microservices testing. The notion aids us in comprehending the number of tests that must be written at each level of granularity.

Let’s look at different types of microservices testing.

Unit Testing: Unit testing is a frequently overlooked practice when testing microservices. Unit tests ensure the methods and classes that developers create perform as expected. While unit testing is a highly technical task for developers, a robust suite of unit tests serves as an important safety net for catching unintended consequences when developers change the code.

Typically, developers use unit testing frameworks such as mockito, JUnit, and others to write unit tests. In unit tests, they call the implementation methods directly. They don’t have to run the service locally and only need to access it through its endpoint. For each unit-level functional test, they can directly call the implemented methods.

This is a useful technique for creating high-quality software. However, unit testing is insufficient on its own. It also pays dividends by alerting developers to the exact location in the code where they have broken existing functionality.

Pre-Deployment Tests: These tests should be built inside the service project and performed before the deployment phase for each service’s CI/CD pipeline. You can also customize the commands to meet your own needs and microservice requirements. You can modify the sequence of component and contract testing, but contract tests should be run before component tests.

Integration Tests: Integration tests are used to detect interface issues by verifying communication channels and interactions between components. Connections to data stores don’t need to start the service locally for integration tests. For the critical test, we can employ any implemented process, which needs to examine the integration with external systems, such as a database connection or another service connection. External system integration should be included in our test scope.

Component Testing: This microservices testing focuses on operating the microservice as a black box and testing the traffic going over the interface, rather than on how the developer created the microservices code. Before testing the engine, the developer has to check the criteria.

If the tester wants automated tests that serve as clients of the service, sending it a variety of positive and negative requests and verifying the results it delivers. Testing microservices can be complicated and challenging due to the frequent response to the test client requests of other microservices.

Contract Tests (Consumer-Driven Contract Tests): A contract is a set of accords between a service provider and a consumer. Providers can verify their service against these contracts to ensure that they are not infringing on the rights of any customers, ensuring that the service remains backward compatible.

End-to-end testing: End-to-end testing is a term that refers to the process of testing from beginning to System testing. A large web of microservices has entry points where the application’s end-users interact at some point.

It’s necessary for key routes and user journeys, but being able to portray these complete or end-to-end transactions as a sequence of microservice calls from the end user’s perspective has several advantages.

Users can effectively remove the UI and replicate all of the API calls that the UI makes to your microservices architecture in order to ensure that all microservices are working correctly for the bigger end-user/business need context.