spylang

Spy — Testing skill for Claude Code

Testing community intermediate

by spylang - Enforces strict coding conventions with comprehensive testing guidelines, multiple code compilation options, and backend-specific test decorators for targeted filtering.

How to install Spy

This entry records only its repository, not the path inside it, so there is no exact command to give. Open spylang/spy and copy the folder into ~/.claude/skills/, or the file into ~/.claude/agents/.

What Spy does

TL;DR: SPy is a variant of Python specifically designed to be statically compilable **while** retaining a lot of the "useful" dynamic parts of Python.

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README

SPy

**Discord server** [](https://discord.gg/wRb29FGZpP)

**Community calls**: Monthly on the first Wednesday of the month at 17:30 CET (Europe time). [Google calendar](https://calendar.app.google/5qMsCibGVH8kAkcs7) and [Discord Event](https://discord.com/events/1378402660914429992/1433058515311919245)

What is SPy?

TL;DR: SPy is a variant of Python specifically designed to be statically compilable **while** retaining a lot of the "useful" dynamic parts of Python.

It consists of:

an interpreter (so that you can have the usual nice "development experience" that you have in Python)
a compiler (for speed)

The documentation is very scarce at the moment, but the best source to understand the ideas behind SPy are:

blog post [Inside SPy, part 1: Motivations and Goals](https://antocuni.eu/2025/10/29/inside-spy-part-1-motivations-and-goals/)
PyCon Italy 2025 talk: [slides](https://antocuni.eu/talk/2025/05/spy-pycon-italy/) and [recording](https://youtu.be/W-8tgZDgYmw).
PyCon US 2024 talk: [slides](https://antocuni.pyscriptapps.com/spy-pycon-2024/latest/) and [recording](https://www.youtube.com/watch?v=hnQ0oJ_yXlw&ab_channel=PyConUS).

Additional info can be found on:

Antonio Cuni's blog
A peek into a possible future of Python in the browser by Łukasz Langa.

The [roadmap](./ROADMAP.md).

Try it in your browser

Explore SPy without installing it by exploring the [playground](https://spylang.github.io/spy).

Local development setup

At the moment, the only supported installation method for SPy is by doing an "editable install" of the Git repo checkout.

The most up-to-date version of the requirements and the installation steps is the [GitHub action workflow](https://github.com/spylang/spy/blob/main/.github/workflows/tests.yml).

Prerequisites: