Unit Testing

Fix and Test Bugs you own this product

This project is part of the liveProject series Unit Testing with Java, JUnit 5, and IntelliJ IDEA
intermediate Java • JUnit 5 • Mockito
skills learned
using IntelliJ IDEA to write and execute tests • deriving tests from existing bugs • codifying current behavior as a test • using tests to drive bug fixes • changing tests so they fail until a bug is fixed
Max Guernsey, III
1 week · 10 hours per week · INTERMEDIATE

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liveProject This project is part of the liveProject series Unit Testing with Java, JUnit 5, and IntelliJ IDEA liveProjects give you the opportunity to learn new skills by completing real-world challenges in your local development environment. Solve practical problems, write working code, and analyze real data—with liveProject, you learn by doing. These self-paced projects also come with full liveBook access to select books for 90 days plus permanent access to other select Manning products. $19.99 $29.99 you save $10 (33%)
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Look inside
In this liveProject, you’ll find and fix some long-term bugs in a legacy library. You’ll write a test to characterize a bug in how certain assets are selected for a special display, then modify the test to turn it into a bugfix. Once you’ve squashed that bug, you’ll repeat the process to tackle two more common bugs for Java applications.
This project is designed for learning purposes and is not a complete, production-ready application or solution.

book resources

When you start your liveProject, you get full access to the following books for 90 days.

project author

Max Guernsey, III

Max Guernsey has over twenty years of experience in software development and is currently a managing member at DevCraft LLC. He has worked on a wide range of products and technologies, including C++ class libraries, financial analysis applications, C# and Java backends, and even multi-platform video games. He is an experienced consultant and his "coaching from the keyboard" approach provides hands-on experience to learners in all aspects of modern software development.


This liveProject is for Java developers who want to increase their testing capabilities. To begin this liveProject you will need to be familiar with:

  • Basic Java
  • Junit 5

you will learn

In this liveProject, you’ll learn to develop tests that fix specific bugs, and that stay in place to guard against regressions.

  • Using IntelliJ IDEA to write and execute tests
  • Deriving tests from existing bugs
  • Codify current behavior as a test
  • Using tests to drive bugfixes
  • Changing tests so they fail until a bug is fixed


You choose the schedule and decide how much time to invest as you build your project.
Project roadmap
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While within the liveProject platform, get help from other participants and our expert mentors.
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book resources
Get full access to select books for 90 days. Permanent access to excerpts from Manning products are also included, as well as references to other resources.