Chromium Unified Test Runner: Architecture and Workflows

The Unified Test Runner (UTR) is a specialized developer tool designed for the Chromium project to eliminate discrepancies between local testing and Continuous Integration (CI) environments. By utilizing the same LUCI recipes, configurations, and scripts as the official build bots, UTR allows engineers to reproduce test failures with high fidelity on their own workstations. The system integrates deeply with Google’s cloud infrastructure, leveraging Swarming for remote execution and ResultDB for detailed status reporting and failure analysis. This automation handles complex details like GN arguments and environment setup, significantly accelerating the edit-build-test cycle for developers. Beyond simple execution, the tool supports advanced workflows such as automated bisection and customized hardware testing through swarming dimensions. Ultimately, UTR provides a standardized interface that replaces fragmented legacy scripts, ensuring a consistent and efficient testing process across the entire Chromium ecosystem.