python-testing-patterns

python-testing-patterns is a skill for Claude Code, Codex from beel-collab/presets.dev. It costs 33 tokens per session (346 once invoked), scanned A, a copy of python-testing-patterns, MIT.

A guide to testing Python programs with pytest, a Python testing tool. It covers unit tests, fixtures, mocks, parameterized cases, integration tests, async code, databases, and test-driven development (TDD), where tests are written before implementation.

In plain words
What is it for?
Use it to build Python test suites, test APIs and database code, mock dependencies, test concurrent code, apply TDD, or run tests in CI/CD.
Why use it?
It helps create repeatable tests, isolate external services, catch regressions, and investigate failing tests. It also supports running tests automatically in CI/CD.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/beel-collab/presets.dev/python-testing-patterns
Any agent
npx skills add beel-collab/presets.dev --skill python-testing-patterns
Clone the repo
git clone --depth 1 https://github.com/beel-collab/presets.dev

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for python-testing-patterns

README.md
[![agentmods](https://agentmods.dev/badge/skills/beel-collab/presets.dev/python-testing-patterns.svg)](https://agentmods.dev/skills/beel-collab/presets.dev/python-testing-patterns)
Your own site
<a href="https://agentmods.dev/skills/beel-collab/presets.dev/python-testing-patterns"><img src="https://agentmods.dev/badge/skills/beel-collab/presets.dev/python-testing-patterns.svg" alt="Measured on agentmods" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 346 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 92% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00033 $0.00346
Opus 5 $0.00016 $0.00173
Sonnet 5 $0.00007 $0.00069
Haiku 4.5 $0.00003 $0.00035

Measured yesterday against content hash 2f57dd627692, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

python-testing-patterns scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

92% identical to python-testing-patterns — 15 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

claude/skills/development/python-testing-patterns/SKILL.md · 47 lines

What it actually says

Python Testing Patterns

Comprehensive guide to implementing robust testing strategies in Python using pytest, fixtures, mocking, parameterization, and test-driven development practices.

Use this skill when

  • Writing unit tests for Python code
  • Setting up test suites and test infrastructure
  • Implementing test-driven development (TDD)
  • Creating integration tests for APIs and services
  • Mocking external dependencies and services
  • Testing async code and concurrent operations
  • Setting up continuous testing in CI/CD
  • Implementing property-based testing
  • Testing database operations
  • Debugging failing tests

Do not use this skill when

  • The task is unrelated to python testing patterns
  • You need a different domain or tool outside this scope

Instructions

  • Clarify goals, constraints, and required inputs.
  • Apply relevant best practices and validate outcomes.
  • Provide actionable steps and verification.
  • If detailed examples are required, open resources/implementation-playbook.md.

Resources

  • resources/implementation-playbook.md for detailed patterns and examples.

Limitations

  • Use this skill only when the task clearly matches the scope described above.
  • Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
  • Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 47 lines · 33 tokens per session scan A 2f57dd627692

Subscribe to this mod's changes

python-testing-patterns is a skill published in the GitHub repository beel-collab/presets.dev (2 stars, last pushed 4mo ago), licensed MIT. It adds 33 tokens to every session and 346 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to python-testing-patterns, differing in 15 lines, and is treated as a copy.