Unit tests are indispensable to check and prove that our code functions properly. But in unit testing, we only test the scenarios that we are aware of. However, there are scenarios unknown to us that lead to security vulnerabilities or performance problems. To address these scenarios, you can add fuzz tests in order to effectively find security, reliability, and even logic bugs in your code.

Java is widely used for developing web applications and relies heavily on APIs (Application Programming Interfaces). Therefore, API testing is a critical practice, as it ensures seamless functionality, compatibility, security, and performance while facilitating integration and simplifying debugging.

As part of our efforts to improve the security of open-source software, we continuously test open-source projects with our JVM fuzzing engine Jazzer in Google’s OSS-Fuzz. One of our tests yielded a Denial of Service vulnerability in the Spring Framework (CVE-2023-20861). Spring is one of the most widely used frameworks for developing web applications in Java. As a result, vulnerabilities have an amplified impact on all applications that rely on the vulnerable version.

Unit testing is an important part of software development and is considered a crucial step in ensuring the quality and accuracy of the code. It helps in identifying bugs and issues early on in the development cycle, which ultimately results in delivering high-quality software. Java is renowned for being one of the most versatile languages in programming, and it offers a wide selection of unit testing frameworks and tools.