python-testing

A set of Python and JavaScript testing rules that require new code to include unit tests. Unit tests check small parts of a program automatically, while code coverage measures how much code the tests exercise.

In plain words
What is it for?
Use it to organize pytest tests for Python, Vitest tests for JavaScript or TypeScript, run all or selected tests, and generate coverage reports.
Why use it?
It makes testing a required part of development and checks that tests pass before changes are committed. The rules also set a 90% minimum coverage target.

Cursor rule for Cursor

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 rules/quinnjr/fruityloops-mcp/python-testing
Clone the repo
git clone --depth 1 https://github.com/quinnjr/fruityloops-mcp

Made for: Cursor.

Per session 1,154 This file is loaded in full into every session.
When invoked 1,154 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
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 $0.01154 $0.01154
Opus 5 $0.00577 $0.00577
Sonnet 5 $0.00231 $0.00231
Haiku 4.5 $0.00115 $0.00115

Measured yesterday against content hash 12adf9cf9bd8, 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 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.

.cursor/rules/python-testing.mdc · 238 lines

How it starts

The opening of the file, as written. The whole thing — 238 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Python and Testing Rules

Testing Requirements

Unit Tests are Mandatory

All new code must include unit tests.

  • Minimum 90% code coverage
  • Tests must pass before committing
  • Use Vitest for TypeScript/JavaScript, pytest for Python

Running Tests

# Run all tests
uv run pytest

# Run with coverage
uv run pytest --cov=src/fruityloops_mcp --cov-report=term-missing

# Run specific test file
uv run pytest tests/test_server.py

# Run specific test
uv run pytest tests/test_server.py::TestFLStudioMCPServer::test_initialization

Writing Tests

Follow pytest conventions:

# File: tests/test_feature.py
import pytest
from fruityloops_mcp.module import Feature

class TestFeature:
    """Test suite for Feature class."""
    
    def test_basic_functionality(self):
        """Test basic functionality."""
        feature = Feature()
        result = feature.do_something()
        assert result is not None
    
    @pytest.mark.asyncio
    async def test_async_functionality(self):
        """Test async functionality."""
        feature = Feature()
        result = await feature.do_async()
        assert result == expected_value

Test Organization

tests/
├── __init__.py
├── test_server.py          # Server tests
├── test_midi.py            # MIDI interface tests
├── test_integration.py     # Integration tests
├── test_edge_cases.py      # Edge case tests
└── conftest.py             # Shared fixtures

Python Code Standards

Package Manager

Always use uv instead of npm, pip, or ts-node.

# ✅ Correct
uv run pytest
uv run python script.py
uv add package-name
uv sync

# ❌ Wrong
pip install package-name
python script.py
npm install

Code Quality Tools

Ruff for linting and formatting:

# Check code
uv run ruff check .

# Fix issues automatically
uv run ruff check --fix .

# Format code
uv run ruff format .

# Check formatting without changes
uv run ruff format --check .

Type Hints

Read the full file on GitHub · 238 lines

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 · 238 lines · 1,154 tokens per session scan A 12adf9cf9bd8

Subscribe to this mod's changes

python-testing is a cursor rule published in the GitHub repository quinnjr/fruityloops-mcp (5 stars, last pushed 8mo ago), licensed MIT. It adds 1,154 tokens to every session, about $0.0058 per session on Opus 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 2026-08-31.