Vitest Parallel Execution: Deterministic Test Ordering Across OS Environments

Vitest utilizes a worker pool architecture to parallelize test execution, which is essential for maintaining performance in large-scale test suites. While the sequence configuration allows developers to toggle between parallel and sequential execution, the behavior of test ordering during parallel runs remains inconsistent.

When running the same suite across different operating system environments (such as Linux and macOS), the order in which tests are dispatched to workers can vary. This creates uncertainty when tests have implicit dependencies or when debugging specific race conditions that only appear in certain execution sequences.

Technical Constraints

• Requirement for deterministic execution order in CI/CD pipelines.
• Reliance on poolOptions to manage resource contention.
• Need for consistency across heterogeneous OS environments.

Does Vitest provide a mechanism to enforce a deterministic execution sequence while maintaining parallel worker distribution? If not, how can a consistent order be guaranteed across different operating systems?