Open Source Scala Software Testing Tools

ScalaCheck is a library for property-based testing in Scala (and Java), inspired by Haskell’s QuickCheck. It automatically generates test inputs based on specifications, validating that properties hold across randomized scenarios, thereby enabling robust, declarative testing of edge cases and invariants.

This domain specific language lets you declare complex java objects with a Json-like notation. In addition to that, it lets you specify in a natural way what the mockito mocks should return when called with a given value.

IMPORTANT: This project is no longer maintained. All the effort is targeted on project Radargun: http://radargun.sourceforge.net

Diffy is a traffic-shadowing and response-diffing tool that helps you validate a new version of a service against a trusted baseline before a full cutover. It acts as a proxy that fans out real production requests to three backends: the current “primary,” a “candidate” (new build), and a “shadow” baseline, then compares responses to detect behavioral differences. By using live traffic rather than synthetic tests, Diffy surfaces edge cases and data-dependent discrepancies that unit tests often miss. It provides mechanisms to normalize noise (timestamps, IDs, ordering) so diffs reflect meaningful regressions rather than incidental variance. Results are aggregated and visualized so teams can triage by endpoint, response field, or error type, turning release validation into a data-driven process. Built on Twitter’s Finagle stack, Diffy demonstrates a practical pattern for continuous verification and safer deployments in microservice environments.