Cut Your Test Times in
Half and Ship Faster!

spdr is a Python 3 tool that works with pytest, and all major CI platforms. All you need is pipx or uv to install it, and a command line to run it. Currently, it is pytest-only, but we plan to add support for unittest soon.

spdr parses and statically analyzes your Python code to form a module dependency graph. It uses this to exclude tests that cannot possibly be affected by code changes. This leads to quicker feedback and reduced bottlenecks.

By default, spdr runs the full test suite, since it can't be sure the file won't affect the tests. Certain safe files are ignored, though, like READMEs and most media assets. We plan to add a .spdrignore file so people can fine-tune this behavior in the future.

These are fuzzy, imprecise techniques. They're ok for test ordering, but not test selection. There's no guarantee they won't exclude relevant tests, whereas spdr never will.

pytest-testmon is a great plugin! Unfortunately, it's no help for CI. Since it's based on code coverage, it requires a full run of all tests before it can determine which ones are irrelevant. This works fine for local development, since you can start it up once, and get accelerated testing afterwards, but this saves no time for CI environments, which are started from scratch every time.

Well, if your test runs finish in seconds, spdr won't help you much. It shines on longer test types, like integration tests running for minutes or hours.

It varies, depending on the size and nature of the code changes, as well as the structure of your code.

Larger changes that affect more files will naturally  have to run more tests. If you have unused imports, they will trigger unnecessary tests; package __init__.py files that import every module are an anti-pattern for spdr. Likewise, large files (both test and code) will typically result in more work.

spdr is free for local, non-commercial use and always will be. While we're in beta, spdr is free for freelance, commercial, and business use, both for local development and in CI environments.

Once we launch, commercial uses will require a license. Educational users may request a free license, subject to approval. Non-commercial open source may request free licenses, also subject to approval. Commercial open-source will require a license.

At this time, no, spdr is not licensed as open source, though we're considering non-closed-source possibilities for the future.

Very. spdr never sends your code anywhere, it stays on your developers' machines and your CI boxes. spdr may send general telemetry data, like the number of files or lines of code, but it will never send sensitive information.