This is a digestible guide on testing of microservices. No overly complex notions. No confusing jargon. Just straightforward info and insights to actually help you.
Today, we’ll discuss:
Don’t buckle up. Exhale and absorb.
Let’s begin with the fundamentals.
Microservices are small, independent components that handle specific functions in an app. For example, you can have a “Product Catalog Service.” It’s responsible only for managing and serving product-related information:
Such a service would also store its own product-related data and provide communication protocols (e.g., APIs) for other services (e.g., retrieving product recommendations or reviews).
Basically, microservices are focused building blocks for the entire application.
And so, testing in microservices is the process of investigating each building block. It checks how they function on their own, when combined, and whether they comply with intended performance and value delivery.
Microservices have many special traits:
Here’s how these affect your testing efforts.
How you approach testing can also change. Since microservices can be developed by separate crews, there might be a shift in responsibilities and autonomy. This doesn’t mean that you need to break apart your dedicated QA team. Just that this or that team of developers and engineers is focused more on the microservice they’re handling.
A central QA group is still needed, especially for cross-service testing and tooling.
There are also peculiar challenges that no microservices testing strategies will help you avoid completely. But good ones should be proactive to mitigate any possible issues. Here are the key ones to look out for.
Don’t get discouraged by these microservices testing difficulties. There are ways to make them less “painful” and minimize your worries. That’s what we’ll focus on for the rest of this article.
The best approach to testing microservices is a layered one (the good old Testing Pyramid finds its way back yet again). Let’s see how it looks.
Unit testing checks the smallest functions (piece of code that performs a specific task) in a microservice. These tests are isolated, simple, and very fast. So, it’s good to have a lot of them to secure internal logic early on.
Component testing investigates a microservice as a whole. It looks at how a service behaves in isolation and includes internal dependencies such as databases. Such tests are nothing short of critical. Without them, there’s no point in proceeding with further checks.
Integration testing assesses how services work together. It accounts for possible mismatched assumptions, network issues, or misconfigured endpoints. Integration testing for microservices typically uses mocks or stubs to simulate unavailable services. This allows you to test specific parts of the system without requiring a full environment.
Microservices API testing services focus on the connections between modules. They ensure that the endpoints respond correctly, handle input validation and error conditions properly, and follow defined contracts. Briefly, here, you’re making sure your microservices can communicate with each other.
Contract testing verifies that services interacting via APIs “agree” on what that interaction should look like. This is important because microservices can be developed and deployed separately. And when you bring them together, you need to ensure there are no disparities that could prevent them from collaborating. So, contract tests check whether APIs adhere to the defined protocols, including required fields, data formats, and status codes.
End-to-end (e2e) testing validates complete workflows that span multiple microservices. They simulate how a real user would interact with the system, verifying user journeys. E2E tests are slow and complex to run due to the number of components involved. That’s why they need to be designed wisely and applied in a targeted manner.
Microservices performance testing evaluates how well they function under different traffic, numerous concurrent users, etc. It involves simulating both normal and extreme loads to identify response time issues, resource bottlenecks, and scalability limits.
Performance testing for microservices includes:
Each type of test is designed to evaluate microservices from different angles. So skipping any of them shouldn’t cross any team’s minds.
Microservices security testing, logically, centers of protection. It includes standard practices like automated scanning and penetration testing. But because of microservices’ unique traits, your team may need to prepare for a few changes.
Okay. Now that we know how we should approach testing in microservices, let’s talk about how you can maximize the value of your effort.
Don’t worry. There’s no reinventing the wheel here. Each approach is well-known and has predictable, proven outcomes. And that’s exactly why you should consider the following for your microservices testing framework.
As you can imagine, if microservices are developed independently, you’d simply need to wait before you could, for example, test two of them together. If you find an issue in one of them later, that’s a big step back. And the longer you wait, the more you’ll have to fix.
Shift-left testing addresses this drawback by encouraging as-early-as-possible checks. Basically, as soon as you have something to test—test it.
By testing early and often, you catch defects when they’re still small and inexpensive to fix. This prevents flawed logic or misaligned APIs from spreading into downstream services. It also encourages developers to think about quality from the start, reducing technical debt and improving collaboration with QA crews.
Microservices systems are highly dynamic. Services change often, deploy frequently, and interact in complex ways. Manual testing just can’t keep up with this pace. So, as they often do, automated testing services come to the rescue. They let you run validations at scale—quickly, reliably, and across many services at once.
Microservices automation testing is particularly invaluable for regression runs. When a service changes, you want to make sure you haven’t broken anything that other services depend on (and you’ll be doing this very often). Automated contract, API, and integration tests can run after every build or deployment. This reduces the need for coordination and manual verification.
As always, we’ll issue a small warning regarding automated testing for microservices.
No matter the project, manual testing services are still needed. In fact, in certain cases, they’re better than automated checks.
Essentially, you definitely should use automation. But you should apply it where it’s actually beneficial and doesn’t compromise quality.
Microservices architectures often rely on CI/CD, where updates are made in small increments and deployed frequently. Continuous testing is what ensures those updates are safe. It embeds testing into the pipeline so that every code change, no matter how small, is automatically validated before it goes live.
This is particularly useful in microservices because one team’s change can unintentionally affect another service. This can happen through shared APIs, events, or data formats. Continuous testing helps detect these issues early by various checks right in the delivery pipeline. It also improves feedback loops between teams. Instead of learning about broken behavior days later in staging or production, teams get alerts immediately.
We should also mention one more way (arguably the best one) to maximize the value of your testing. And that’s working with skilled experts. No matter how you look at it, it’s people who are behind every project. So, the equation is really simple: experienced professionals = great product. Whether you want to build your team from the ground up or rely on QA outsourcing services, make sure that every person on your team is a professional.
Our QA company is obsessed with quality. And we want you to have all the tools possible for a superb microservices testing strategy. So, we’ve asked our QA crew to share their tips and best practices. Here are the key points they highlighted.
Keep in mind that implementing all the best practices may be somewhat unrealistic. At least, so far, we haven’t encountered a project that did everything perfectly. But that’s not an issue. Perfection doesn’t exist. Non-stop improvement does. So, don’t think that if you’re not doing things a certain way, you’re doing them wrong. Just focus on doing better than you were before. Using even just one best practice is a lot better than using none.
Finally, let’s take a look at some tools for microservices testing at every level. Keep in mind that we’re not saying that either of these is the best microservices testing solution. What a team considers their ideal tool depends on many factors. So, the selection below is simply options that we’ve found useful in our practice.
Unit testing:
Component testing:
Integration testing:
API testing:
Contract testing:
End-to-end testing:
Performance testing:
Security testing:
We do encourage you to approach tool selection very carefully. They play a huge role in your microservices testing strategy: supporting your team, affecting testing outcomes, influencing the testing process, and many more. So, don’t jump at the first good option you see. Review all impact points and risks and include your teams in the decision-making process.
Microservices are very peculiar. They were created to make development easier, not so boxed in. But they also came with a handful of difficulties we now have to handle. And yet, that’s not a bad thing. That’s just how evolution works. Solve one problem. Move on to another. The tech is quickly progressing. And our team is here to help you to not just keep up, but stay ahead of the curve.
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