vcsdd-language-python

name	vcsdd-language-python
description	Use this skill when applying VCSDD to Python projects. Provides hypothesis property testing patterns, mutmut mutation testing, and pytest integration for the VCSDD pipeline.
origin	VCSDD

VCSDD Language Profile: Python

Verification Toolset

Tier	Tool	Install	Use Case
1	hypothesis	pip install hypothesis	Property-based testing
1	mutmut	pip install mutmut	Mutation testing
1	pytest-cov	pip install pytest-cov	Coverage reporting

Hypothesis Pattern

from hypothesis import given, settings, strategies as st
from hypothesis import HealthCheck

@given(st.text(min_size=0, max_size=1000))
@settings(max_examples=500, suppress_health_check=[HealthCheck.too_slow])
def test_parse_never_raises_on_arbitrary_input(s: str):
    """Parse should never panic - it should return a Result."""
    try:
        result = parse(s)
        # If successful, roundtrip should hold
        if result is not None:
            assert serialize(result) == s
    except ParseError:
        pass  # Expected error types are ok

@given(st.from_regex(r'[a-z]{1,20}'))
def test_parse_valid_input(s: str):
    result = parse(s)
    assert result is not None
    assert serialize(result) == s

mutmut Setup

# Run mutation testing
mutmut run --paths-to-mutate src/

# Check results
mutmut results
mutmut show <mutation_id>  # See specific mutations

# Generate HTML report
mutmut html

Red Phase Evidence

# Run tests and capture output
pytest tests/ -v 2>&1 | tee .vcsdd/features/<name>/evidence/sprint-1-red-phase.log
# Verify failure
grep -q "FAILED" .vcsdd/features/<name>/evidence/sprint-1-red-phase.log