Probs – Flexible Multi-Environment Testing Framework

Custom-built test runner for modern JavaScript projects, designed to exceed the limitations of Jest.

Probs is a powerful testing framework built to support deeply nested test structures with different configuration and runtime environment needs. Originally developed to support projects like Pymakr 2 and Routify, Probs quickly became an internal tool for fast testing of code that requires specific runtime environments.

Creator and sole developer. Built the framework to solve unmet needs in test orchestration across environments.

Features
  • Supports CJS & ESM
  • Flexible and deep test nesting beyond the standard describe/it model
  • Scoped configuration with local probs.config.js files
  • Runs in native, worker, and shell environments
  • Customizable loaders, environments, and test runners
  • Minimal setup, fast execution, and developer-friendly syntax
  • Lightning fast parallel tests
  • Interactive CLI
Technical
  • Written in JavaScript with native Node.js APIs
  • Modular test runner core
  • Supports dynamic config loading and environment injection
  • Used internally for testing VSCode extensions, CLIs, and SPAs
  • Compatible with CI pipelines and runtime-based testing
Impact
  • Replaced heavier tools like Jest and Mocha in internal projects
  • Significantly reduced test execution time
  • Enabled real runtime testing inside constrained or isolated environments
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Jakob Rosenberg