ArchUnit is a Java architecture test library that checks dependencies between packages and classes, layers and slices, and detects cyclic dependencies by analyzing Java bytecode and importing classes into a code structure.
The problem ArchUnit solves is the difficulty of enforcing architectural constraints and coding rules across a codebase as it grows. Rather than relying on code reviews or documentation, ArchUnit lets developers write explicit architecture tests using plain Java and any standard unit testing framework. It works by analyzing compiled Java bytecode, building an in-memory representation of the codebase's structure, then allowing developers to query and assert rules against that structure using a fluent API.
Teams should adopt ArchUnit when they want to prevent architectural decay and enforce layering, dependency direction, and naming conventions automatically. It suits projects of any size where maintaining clear separation of concerns matters, particularly those with multiple modules or layers. The tool integrates directly into existing test suites, requiring no special build configuration beyond adding the library as a dependency.
Development activity shows consistent engagement with the codebase. The project maintains an active issue tracker where problems are addressed. Pull requests are regularly reviewed and merged, indicating ongoing maintenance. Documentation is kept current through updates to the user guide and example repositories. The maintainers respond to community contributions and incorporate feedback into releases.
