Most Popular Microservice Testing Strategies

Most Popular Microservice Testing Strategies

Lately, enterprises have shifted from monolithic architecture to microservices. This is mainly because the latter architecture allows for parallel development across multiple teams, bigger scaling opportunities, and the possibility to deploy elements independently.

However, testing is a challenging part when it comes to choosing microservices as a primary architecture model. Each microservice has its own codebase, database schema, and dependency management. How do you approach such a complex procedure?

In this post, we’ll share 5 efficient microservice testing strategies startups can benefit from

  1. Who Can Benefit From Microservice Testing?
  2. Advantages Of Microservice Testing
  3. A Microservice Testing Strategy
  4. Unit Testing
  5. Integration Testing
  6. Component Testing
  7. Contract Testing
  8. End-to-end Testing

Who Can Benefit From Microservice Testing?

Who Can Benefit From Microservice Testing?

When it comes to microservices, a lot of developers and company managers are left wondering if the perks of the architecture can make up for the long and time-consuming testing process.

The question then becomes: “Does my company need a microservices architecture?”

Testing a microservice application is an essential part of the process of deciding whether to switch from monolithic to microservice architecture. Here are some types of business who should consider testing microservices:

  • Startups who build apps from scratch. Companies that are working on their first product are often advised to stick with monolithic architecture. On the one hand, speed is everything – and microservices don’t exactly provide it. On the other hand, while developing microservices is challenging, tools like AWS and Google Cloud create new possibilities for deploying smaller chunks of the project. So if your project needs to work at a high pace, with quick service delivery, developing and testing microservices is a must.
  • Existing companies that experience large growth. The most logical time to shift from a monolithic architecture is a traffic increase. For companies like Netflix, with over 100 million daily users, using microservices are essential. If you want to scale your business and use microservices to help you out, testing is crucial to get a well-performing product.
  • Big businesses that are already using microservices. Even if your company already uses microservices, it doesn’t hurt to expand the array of testing strategies in a microservice architecture.
  • Managers who are not satisfied with the performance of the current microservice-based product. If it seems that your current microservice-based product is underperforming, it might not be a fault of the architecture itself. Instead, it could be a lack of thorough testing. If you’re a manager and you see a lower performance of the product after shifting to microservices, talk to your developers about expanding the range of testing algorithms – it can improve the product tremendously.

Advantages of Microservice Testing

Advantages of Microservice Testing

Challenging as conducting tests for microservices can be, they are crucial to ensuring the product will run the way it’s mapped out in a developer’s head. Releasing a product without testing is a lot like sending an email with spelling errors – it’ll ruin your image and trust.

Here are some of the most crucial microservice testing advantages:

  • Tests help flag important changes in the system. Microservices are known to require a fair amount of talent involved. Keeping control of any changes one of your developers does to the code can be difficult. It’s through testing that these modifications will be pinpointed precisely. A tester will be able to understand the impact of a single unit of change on the entire microservice.
  • Running the most common use cases of the architecture is the only way to know it works well end-to-end. Predicting how a user might interact with a system and testing these scenarios is a developer’s opportunity to ensure that each operation runs as predicted. Determining all possible scenarios can be challenging – that’s why a lot of developers resort to public testing to allow users to create scenarios and pinpoint bugs. Still, it’s mainly a tester’s job to ensure that all the most popular scenarios run smoothly and with no bugs. Finally, rather than testing the microservice unit by unit, it’s crucial to run the entire string of actions from A to Z.
  • While testing the product, a team can find new insights to improve its overall performance. Running tests can provide more opportunities than simple bug fixing. While testing, a team can discover new opportunities to improve the product and features they didn’t even see coming. Perhaps a test will uncover a shortcut that’ll make the user’s action easier while delivering the same value.
  • If someone else modified the code, it’s crucial to know that the system still works as planned. Even if devs keep a journal of their actions, it’s essential to know these changes are not redundant and actually benefit the product. Testing allows you to see if a total of changes made by the team works as a whole. This helps avoid misunderstandings within the team.

A Microservice Testing Strategy

A Microservice Testing Strategy

Now that it’s clear that microservice testing is essential for a project’s success, the question is how to choose an effective testing strategy that would be effective and fit the company’s budget at the same time.

There are 5 commonly known microservice testing strategies. All of them were started by Mike Cohn in ‘Test Pyramid’:

  • Unit testing;
  • Component testing;
  • Contract testing;
  • Integration testing;
  • End-to-end testing.


While you can choose only one of the strategies listed above, it’s not an either-or choice. In fact, you can run all of them consecutively – and it would probably be the best thing to do.

However, as each of the 5 strategies has their advantages and drawbacks, the post will follow up on each of these approaches and analyze it in detail.

1. Unit testing

Unit testing

The aim of unit testing is to take the smallest piece of a microservice (a unit) and examine it to see if it behaves the way a developer intended.

What is a unit? There is no strict definition of a chunk of code that’s considered to be a unit. However, most testers consider classes to be units. Breaking the code into such little fractions allows developers to be more precise during examination and determine even the smallest flaws.

Advantages of unit testing

  • It’s precise. Unit testing is a fit solution for debugging the code. After testing your services by running little chunks of code, you’re more likely to notice and fix issues that would otherwise be left unnoticed.
  • Can be used as code documentation – an essential for big companies. After writing and running unit tests, you’ll have a better understanding as to what every line of code is supposed to do. Not only that, but you’ll also be able to define this function and document it so that any person on the team can take over if needed.
  • Relatively cheap. While writing unit tests for the entire product might seem like a lot of time (and it is), the good news is, the procedure is not as technically complex as other strategies are. This means you can either do it yourself or with a small group of people, none of whom have to possess exceptional tech talent.

Disadvantages of unit testing

  • Doesn’t provide any guarantees about the app’s high-level performance. While unit testing is effective at pinpointing bugs and issues in the product, all of the units are tested in isolation. After the tests are written, a project team can conclude that all the fractions of the code function separately. Still, unit testing doesn’t give the possibility to see the system performance as a whole.
  • Time-consuming. Unit testing is not difficult to perform. However, it takes a lot of time to test the entire product by units. If your team’s overloaded with projects, perhaps it’s better to choose a less time-consuming strategy.

When to use unit testing

Unit testing is a good idea for a low-budget startup. Generally, unit testing is quite strong in debugging. If you’re looking for a microservice testing strategy that will pinpoint the smallest bugs in the cost, unit testing is the way to go. It is, however, predictable – you will only fix the bugs you’re looking for instead of detecting new ones as you go.

2. Integration testing

Integration testing

An integration testing strategy allows a tech team to evaluate the performance of the communication paths between components. This framework allows testers to examine the possible interface flaws and fix them before releasing the product.

Advantages of integration testing

  • Uncovers interaction failures. Where unit testing tends to miss on the evaluation of the performance of user-facing features of a product, integration testing, on the other hand, allows a developer to pay more attention to the path between two actions.
  • You can start testing while developing. A huge benefit of integration testing is that of being able to conduct load performance testing between two components as soon as you’ve finished developing them. This way, you can fix bugs with all the code fresh in mind.
  • A variety of testing techniques. Integration testing offers plenty of options. To make sure your approach on how to test microservice applications tailors to the needs of the team in the best way possible, you can experiment with different approaches to integration testing. There is, for instance, a bottom-down approach which allows developers to test the behavior of lower-level modules even if they are still in development. There are other possibilities to consider as well – such as a ‘Sandwich” strategy or a bottom-up approach.

Disadvantages of integration testing

  • The strategy is error-prone. When writing the test, one can make a typo or omit a small step in the algorithm and the entire work would have to be re-done. The issue can be solved by automating microservice testing – this, however, would require additional budget and manpower.
  • Take a fair share of the workforce. Another issue with an integration test is that it requires too much manpower. Smaller companies just don’t find the ROI satisfying enough to hire big teams for testing.
  • No confidence that business requirements will be satisfied. Much like unit testing, integration testing doesn’t give a tester the bigger picture above the microservices. While it has a broader examination area than the previous type (as both the components and the paths are tested), it doesn’t guarantee the high performance of the end product either.

When to use integration testing

The testing strategy isn’t as independent and self-sufficient as unit testing. It’s not an either-or choice for developers, rather, it should follow unit testing to broaden what was examined.

3. Component testing

Component testing

The component testing strategy consists of taking a piece of the system and testing it in isolation from the rest of the system by creating a test double. The system is then manipulated through internal code interfaces.

Advantages of using component testing

  • Quicker testing than that of broader stacks. By limiting the scope of the test to a fraction of the system, one can examine this piece of code more thoroughly. Testing an isolated component is way quicker and easier to execute than the evaluation of broad stacks.
  • A controlled testing environment that allows easy error detection. This avoids an unsolicited reaction between two systems during the testing. Also, all the error cases will be repeatable – thus, easier to detect.
  • Isolating the components from their peers makes the test easier to execute. It opens a broader array of options for a single component – for instance, you can test the access to test doubles within the network as well as externally.

Disadvantages of component testing

  • Possible loss of control over the system. When conducting a test in an isolated environment, a developer doesn’t have enough control over the evolution of the product. As a result, incompatibility challenges can arise when assembling the components into a microservice.
  • Possible misunderstanding of the test doubles. In order to get more flexibility, test doubles are used during the testing. These are fakes, mocks, and stubs. If a tester is not familiar with a methodology and starts mixing test doubles, design and refactoring issues occur. It’s suggested to use each kind of doubles separately for a particular use case.

When to use component testing

It is a common practice to test the component as soon as it’s created. This strategy can be implemented after functional testing. It’s recommended to do component testing on the earliest stages of development to be able to test the paths between the components that are already performing like clockwork.

4. Contract testing

Contract testing

Contract tests are conducted to ensure that an external service meets the contract of the consumer service.

Advantages of contract testing

  • Makes a service customer-driven. Ideally, all the contract tests should be packaged and reusable for different build pipelines. Apart from their convenience, contract tests are useful to give the producer of the service an understanding of its impact on consumers.
  • Allows developers to know which changes in the service won’t impact customers. Whenever a tech team wants to make a change in the service, through the contract testing they can ensure a modification will have no negative implications on the consumers’ contracts.

Disadvantages of contract testing

  • It’s expensive. Contract testing requires writing a separate suite for every service. This requires a considerable amount of developers involved in the testing and, as a result, is quite expensive.
  • Doesn’t test the behavior of the system. Unlike component tests, the contract ones have nothing to do with evaluating the performance of the system. Rather, they evaluate the server response and make sure that the throughput is within the limits.

When to use contract testing

This strategy is a good fit for small microservices with limited data structures. Companies that position themselves as consumer-driven (such as social media products) should also consider running this type of test.

5. End-to-end testing

End-to-end testing

The aim of end-to-end (E2E) testing is to evaluate the performance of the entire system and ensure it meets all the business requirements it was set to achieve.

End-to-end testing advantages

  • End-to-end tests are business-facing. While all the other testing strategies are tech-driven and don’t allow the client to get an idea of what’s happening to the project, end-to-end testing is targeting business goals only.
  • The strategy covers the gaps between the services. The microservice architecture is complex. By testing each of its many moving parts on its own, one risks missing out on gaps between them that – while they aren’t visible during an isolated testing session – will prevent the entire system from performing as intended.
  • Allows the architecture to evolve. As the business develops, microservices are likely to change – merge, split, etc. With the results of an E2E test, the development system can be sure that the system persists after any change possible.
  • Tests give confidence regarding a business’ performance. After conducting an E2E test, a business owner can be sure not only about the quality of the architecture itself but of all the additions to it as well – firewalls, load-balancers, proxies, etc.

End-to-end testing disadvantages

  • Large room for error. When you’re testing a complex system, there are more things that can get out of control within the system or on the server-side level.
  • Excessive test run time. Running E2E tests at the early stages of development would be a mistake – analyzing the entire system is so time-consuming that it should only be used in extreme cases for a limited number of tries.
  • A higher cost of maintenance. Last but not least, testing a system’s end-to-end costs much more time than evaluating the performance of a unit, component, or integration. Mainly, that happens due to the fact that an E2E test partly contains those mentioned above (though, when conducted simultaneously, none of the small-scale tests will be as efficient as they would have been on their own).

When to use end-to-end testing

The use of E2E testing should be limited – it’s recommended that a developer sets a fixed number of test attempts. This type of testing should only be used when all the other strategies are exhausted as the last stroke of quality assurance.


Microservice testing is an essential stage in product development as it helps to ensure that the system runs smoothly. It should be noted, however, that testing microservices is more complex than evaluating the performance of a monolithic structure.

Thankfully, there are different ways to approach microservice testing. The main ones are unit testing, integration testing, component testing, contract testing, and end-end testing. A technical team can either choose all of these strategies or focus on the most affordable ones for the team.

At Newizze, we have a wealth of experience in testing and web developing. Our team has worked with different types of architecture, microservices included. Take a look at our portfolio or contact us to discuss your project.

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