Relevant Spring Boot Testing Resources (2024)

Spring Boot Testing Documentation & Guides

Let's start with the most obvious resource for testing Spring Boot applications: the official documentation itself. However, navigating this documentation can be tricky, especially for those new to the field. This is because the information is spread across two main sources, not just one.

Spring Boot, in essence, expands the core Spring Framework by offering a layer of convenience in the form of automatic configuration. That's why we'll find information on testing Spring Boot applications both in the core Spring Framework documentation and in the Spring Boot documentation.

• Spring Test documentation of the core Spring Framework documentation (latest documentation)
• Spring Boot-specific testing documentation (latest documentation)

For those keen on staying updated with the newest testing features, it's beneficial to regularly check the official release notes for both Spring Test and Spring Boot:

• Spring Framework release notes: The Spring Framework core team maintains a list of new features of the core Spring Test module on GitHub as part of their wiki. There's a dedicated “What's New” page for each major Spring Core framework version where they split the new features by the Spring Core module, which lets us easily find the Testing-relevant changes (Spring Core 6.1 testing example)
• Spring Boot release notes: The Spring Boot team provides detailed release notes for every major and minor release. These notes offer a clear view of the upcoming changes in testing (e.g., Spring Boot 3.2 updates).

Getting Started with Testing Spring Boot Applications

Beginning your journey in testing Spring Boot applications involves a focus on the fundamental aspects and the support the framework provides for testing. This includes familiarizing yourself with JUnit, the primary testing framework in Java, alongside Mockito, the standard library for mocking in Java. Additionally, understanding various assertion libraries is crucial.

It's also valuable to understand the role of the Spring Boot Starter Test dependency (aka. “The Testing Swiss-Army Knife”). This component is integral to each new Spring Boot project, offering out-of-the-box testing support and having batteries included.

Moreover, a comprehensive understanding of the testing features of your build tools, typically Maven or Gradle, is essential. This includes knowledge of conventions, plugins, and best practices in the context of testing.

Equally important is a deeper understanding of Spring Boot's auto-configuration mechanism. This insight is vital not only for setting up tests effectively but also for troubleshooting when issues arise.

Consider exploring the following resources:

• Tutorials on JUnit for foundational knowledge in testing:
  • JUnit 5 Crash Course by Marco Behler
• Guides or tutorials on Mockito for mastering Java mocking techniques:
  • Next Gen JUnit 5 & Mockito – Kenneth Kousen
  • Hands-On Mocking with Mockito Online Course
• Information on the Spring Boot Starter Test to understand its contribution to testing:
  • Things I Wish I Knew When I Started Testing Spring Boot Applications talk by Philip Riecks
• Marco Behler's Spring Boot course for a comprehensive learning experience: The Confident Spring Professional
• Guides or tutorials for your build tools:
  • Maven Setup for Testing Java Applications
  • Gradle Testing

Intermediate Resources for Testing Spring Boot Applications

Once you've mastered the fundamentals of testing Spring Boot applications, the next step is to dive into hands-on test writing. This goes beyond basic unit tests using JUnit and Mockito, delving into tests that involve starting a TestContext and interacting with Spring.

A key feature of Spring Boot to understand at this stage is the concept of sliced testing annotations. These annotations allow for the creation of a partial application context, focused only on the specific layer you're testing. For instance, if you're testing the web layer, there's no need to load the entire Spring context, especially the persistence-related components. This approach leads to quicker and more streamlined tests.

Spring Boot offers a variety of these sliced test annotations for different layers, such as the web layer, persistence, HTTP clients, and more. Some of the common annotations you might encounter are @WebMvcTest for web layer testing, @DataJpaTest for JPA repositories, and @RestClientTest for testing REST clients.

To deepen your understanding and effectively utilize these test slices, exploring talks and presentations by the Spring team can be immensely helpful. These resources often provide valuable insights and practical tips for using various test slices in Spring Boot.

• Testing Spring Boot Applications talk from Andy Wilkinson
• Spring Tips: Bootiful Testing talk from Josh Long
• Spring Boot test slices: Overview and Usage article on this site
• Spring Boot Testing Basics: How to Unit Test & Integration Test REST Controllers from Dan Vega
• Testing Spring Boot Applications Primer online course on this site

Advanced  Spring Boot Testing Resources

Progressing from the basics and sliced tests in Spring Boot applications, the next step is to dive into more complex topics like integration and end-to-end testing. This advanced stage involves leveraging the @SpringBootTest annotation, which initializes the full application context for thorough testing. Such comprehensive testing raises new challenges, including managing external infrastructure resources, interacting with the running application, and ensuring the speed of integration tests.

At this advanced level, certain Java testing tools become indispensable. These include Testcontainers for managing Docker containers in tests, Selenide for browser-based testing, and Awaitility for handling asynchronous operations. Additionally, mastering the @SpringBootTest annotation is crucial, as it offers an in-depth view of starting the entire application for testing.

Another key aspect to focus on is understanding the TestContext caching feature of the Spring Test framework. This feature is pivotal in saving time during integration tests by reusing the application context across different tests, reducing the overhead of repeatedly setting up and tearing down the context. This knowledge will greatly enhance the efficiency and effectiveness of your integration testing strategy in Spring Boot applications.

• Test Driven Development with Spring Boot from Sannidhi Jalukar and Madhura Bhave
• TDD with Spring Boot Done Right Online Course by rieckpil (us)
• Test with Spring Online Course by Petri Kainulaien
• Testing Spring Boot Applications Masterclass by rieckpil (us)

YouTube Channels & Social Media

• DanVega: Known for clear and practical tutorials on Spring Boot.
• Amigoscode: Offers a variety of tutorials, including those on Spring Boot.
• BoualiAli: Provides insights and tutorials focused on Spring Boot development.
• rieckpil: Delivers content on testing and developing Spring Boot applications.
• SpringDeveloper: The official channel for the Spring community, offering a wealth of information on all aspects of Spring.

On platforms like X (formerly Twitter), following individuals like Sam Brannen, one of the core maintainer of Spring Test, is highly beneficial for staying informed about the latest developments in Spring testing. Additionally, many other skilled engineers in the Spring ecosystem are active on these platforms, regularly posting updates and insights.

Our @rieckpil handle is another valuable resource where new and noteworthy information on testing Spring Boot applications is frequently shared.

For those interested in interactive learning, the “Spring Officer Hours” series hosted by Dan Vega and DaShaun Carter, both Developer Advocates for Spring, is an excellent resource. This series is a great way to keep abreast of the latest in Spring, involving discussions, demonstrations, and audience Q&A sessions.

Podcast enthusiasts might enjoy the “Bootiful Podcast”, hosted by Josh Long, a renowned Spring Developer Advocate. This podcast series celebrates key figures in the software ecosystem and covers a broad spectrum of topics related to Spring, Java, and software development, featuring conversations with various industry experts.

Getting Help

Navigating through testing Spring Boot applications can be challenging, especially when real-world scenarios differ significantly from the examples used in tutorials and courses. Framework versions, infrastructure, Java versions, etc., can vary, and encountering test setup issues or errors is a common part of the learning curve.

In such situations, knowing where to seek help is crucial. If you're lacking support within your team or company, there are several resources you can turn to:

1. Stack Overflow: This is often the first place for developers seeking code-related help. If you can't find an existing question that matches your issue, don't hesitate to ask your own. Be clear about your problem, include relevant code snippets, stack traces, and if possible, a minimal reproducible code example hosted on GitHub. Using appropriate tags like spring-boot-test and spring-test can direct your question to the right audience, enhancing your chances of getting a timely response.
2. GitHub Issue Tracker: It's easy to assume a bug in the framework prematurely, but oftentimes, the issue lies in our implementation. If you've exhausted other resources like Stack Overflow or suspect a genuine bug, consider reporting it to the maintainers. Identifying the correct repository (whether it's a testing library issue or a Spring Core/Spring Boot issue) is crucial. If in doubt, starting with the Spring Boot issue tracker is a reasonable approach. Always check for existing issues to avoid duplicates.
3. Ask ChatGPT or Your Preferred LLM: For a modern approach, consider consulting an AI like ChatGPT. You can provide your code, stack trace, and version details for assistance with debugging and understanding your issues. Remember not to share any sensitive data in your queries.
4. Reddit: The SpringBoot subreddit is another excellent place for assistance. It's more suited for broader questions and opinions, like whether to write tests for entities and repositories. While you can post code for help, Stack Overflow might be more effective for specific test setup issues. Be prepared for varying opinions, as software development often involves subjective choices.
5. X (formerly Twitter): If all else fails, reaching out to people in the ecosystem or even maintainers on Twitter can be a last resort. Exercise caution to avoid spamming, be patient for responses, and be concise in explaining your problem and the steps you've already taken to resolve it. This should be used sparingly and respectfully.

Seeking help is a normal part of the development process, and utilizing these resources effectively can significantly aid in resolving your testing challenges in Spring Boot applications.

Summary of Spring Boot Testing Resources

The Spring Boot ecosystem offers a variety of excellent testing resources. While the quantity may not match that of resources for implementing more fancy features, it's still impressive, especially when compared to what's available for other frameworks or languages.

This carefully selected list and summary aims to guide you through the complexities of testing in Spring Boot, helping you to locate valuable resources efficiently.

Keep in mind that new resources and articles are constantly emerging, so consider bookmarking this post or subscribing to our newsletter to receive the latest updates directly in your inbox.

Joyful testing,

Philip