testing-python-libraries

testing-python-libraries is a skill for Claude Code, Codex from CHENyiru3/AI-Skills-Collections. It costs 68 tokens per session (893 once invoked), scanned A, original, MIT.

A guide to testing Python libraries with pytest, a tool for running automated checks. It covers fixtures for shared test data, parameterized cases, mocks, coverage, property-based testing, and running tests in continuous integration.

In plain words
What is it for?
Use it to organise a tests directory, test functions and edge cases, reuse setup with fixtures, measure coverage, and run library tests in CI.
Why use it?
Automated tests reveal when a change breaks existing behaviour and make refactoring safer. Coverage and varied test inputs help expose paths that a few hand-checked examples may miss.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to organise a tests directory, test functions and edge cases, reuse setup with fixtures, measure coverage, and run library tests in CI.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/chenyiru3/ai-skills-collections/testing-strategy
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.

Any agent
npx skills add CHENyiru3/AI-Skills-Collections --skill testing-strategy
Clone the repo
git clone --depth 1 https://github.com/CHENyiru3/AI-Skills-Collections

Made for: Claude Code, Codex.

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README.md
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<a href="https://agentmods.dev/skills/chenyiru3/ai-skills-collections/testing-strategy"><img src="https://agentmods.dev/badge/skills/chenyiru3/ai-skills-collections/testing-strategy.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 68 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 893 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found 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 5.1 $0.00068 $0.00893
Opus 5.5 $0.00027 $0.00357
Sonnet 5.5 $0.00014 $0.00179
Haiku 4.5 $0.00007 $0.00089

Measured 6d ago against content hash 023f8e373cc1, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

testing-python-libraries 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 6d ago.

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.

skills-market/programming/python/testing-strategy/SKILL.md · 119 lines

How it starts

The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Python Library Testing

Quick Start

pytest                              # Run tests
pytest --cov=my_library             # With coverage
pytest -x                           # Stop on first failure
pytest -k "test_encode"             # Run matching tests

Pytest Configuration

# pyproject.toml
[tool.pytest.ini_options]
testpaths = ["tests"]
addopts = "-ra -q --cov=my_library --cov-fail-under=85"

[tool.coverage.run]
branch = true
source = ["src/my_library"]

Test Structure

tests/
├── conftest.py           # Shared fixtures
├── test_encoding.py
└── test_decoding.py

Essential Patterns

Basic test:

def test_encode_valid_input():
    result = encode(37.7749, -122.4194)
    assert isinstance(result, str)
    assert len(result) == 12

Parametrization:

@pytest.mark.parametrize("lat,lon,expected", [
    (37.7749, -122.4194, "9q8yy"),
    (40.7128, -74.0060, "dr5ru"),
])
def test_known_values(lat, lon, expected):
    assert encode(lat, lon, precision=5) == expected

Fixtures:

@pytest.fixture
def sample_data():
    return [(37.7749, -122.4194), (40.7128, -74.0060)]

def test_batch(sample_data):
    results = batch_encode(sample_data)
    assert len(results) == 2

Mocking:

def test_api_call(mocker):
    mocker.patch("my_lib.client.fetch", return_value={"data": []})
    result = my_lib.get_data()
    assert result == []

Exception testing:

def test_invalid_raises():
    with pytest.raises(ValueError, match="latitude"):
        encode(91.0, 0.0)

For detailed patterns, see:

Test Principles

Principle Meaning
Independent No shared state between tests
Deterministic Same result every run
Fast Unit tests < 100ms each
Focused Test behavior, not implementation

Read the full file on GitHub · 119 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 6d ago First seen · 119 lines · 68 tokens per session scan A 023f8e373cc1

Subscribe to this mod's changes

testing-python-libraries is a skill published in the GitHub repository CHENyiru3/AI-Skills-Collections (1 stars, last pushed 7d ago), licensed MIT. It adds 68 tokens to every session and 893 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-02.

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