Java's Hidden Gems: Tools and Libraries by Johan Janssen

ArcUnit allows verifying application architecture rules and dependencies between layers/packages in unit tests to prevent circular dependencies and architectural violations

Test Containers provides an easy way to spin up Docker containers (databases, message queues, etc.) for integration testing, removing the need for local installations

GraphQL can be used as an alternative to multiple REST endpoints when clients need to filter/query specific data fields, reducing over-fetching of data

Java Poet enables dynamic Java code generation through a fluent API, useful for creating classes, methods and other code artifacts programmatically

JReleaser automates release processes including changelog generation, Docker publishing, and other release-related tasks

Mutation testing (PITest) helps verify test quality by making small code changes and ensuring tests catch the mutations

Gatling provides performance testing capabilities with a Java DSL for load testing scenarios and detailed reporting

TimeFault helps optimize scheduling and resource allocation problems through constraint-based planning

Renovate automates dependency updates by creating pull requests when new versions are available

JDK Mission Control and Flight Recorder provide deep runtime insights into application performance, garbage collection, and memory usage

OWASP Dependency Check scans dependencies for known security vulnerabilities

Awaitility simplifies testing of asynchronous code by providing better ways to handle waits and assertions