2026.03.04 Andrei Solntsev – Flaky unit-tests

While the industry often blames UI tests for instability, flaky unit tests represent a more insidious threat to CI/CD pipelines and developer trust. In this session, Andrei Solntsev challenges the assumption that mocking external dependencies automatically guarantees test determinism. TL;DR: Technical Takeaways - Root Cause Analysis: Identifying non-deterministic behavior in tests that lack external I/O or database connections. - Shared State Hazards: How static variables, thread locals, and singleton leakage compromise test isolation. - Time & Locale Dependencies: Debugging failures caused by system clock drift and environment-specific configurations. - Refactoring for Stability: Practical strategies for rewriting "nightmare" tests into resilient, deterministic units. The Tech Stack - Languages: Java, JVM-based environments. - Frameworks: JUnit, Mockito, Selenide. - Tools: CI/CD Runners, Build Profilers. About the Speaker Andrei Solntsev is a seasoned Software Developer at Codeborne, a prominent voice in the European Java community, and the creator of the Selenide framework. He specializes in building maintainable automated testing ecosystems. Connect with Andrei: - LinkedIn: https://www.linkedin.com/in/asolntsev/ Facebook: https://www.facebook.com/asolntsev Subscribe: https://www.youtube.com/channel/UC9lRNfzenw_7MVmDPFyRFjQ?sub_confirmation=1 Our website: https://devclub.ee Our blog: https://blog.devclub.ee Facebook-group: https://www.facebook.com/groups/devclub.ee