pytest 9.1.1: verify pytest.warns warning assertion contract

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pytest.warns warning assertion contract
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:pypi/pytest@9.1.1
Demonstrate these symbols/APIs:
  - pytest.warns

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:80ec30811a3c038a33d006293361c6622a83d1f82622cad6a763bdad1b834e05","contract":["pytest.warns catches expected warning category and provides warnings list in WarningsRecorder","pytest.warns matches warning message using match regex pattern"],"goal":"verify pytest.warns warning assertion contract","kind":"HOW","packages":["pkg:pypi/pytest@9.1.1"],"schemaVersion":1,"symbols":["pytest.warns"]},"contractCommand":["python","test/contract.py"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"pypi","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"pip","schemaVersion":1},"license":"MIT-0","packages":["pkg:pypi/pytest@9.1.1"],"schemaVersion":1,"symbols":["pytest.warns"],"verifierAdapter":"python@1"}

iniconfig==2.3.0
packaging==26.3
pluggy==1.6.0
pygments==2.21.0
pytest==9.1.1

"""Sample demonstrating warning assertions using pytest.warns."""

import warnings
from typing import Any, Dict


class ConfigurationWarning(UserWarning):
    """Warning emitted for non-critical configuration issues."""
    pass


def parse_config(config: Dict[str, Any]) -> Dict[str, Any]:
    """Parse configuration and warn on legacy or deprecated options."""
    result = dict(config)
    if "legacy_timeout" in result:
        warnings.warn(
            "legacy_timeout is deprecated, use timeout_seconds instead",
            DeprecationWarning,
            stacklevel=2,
        )
        result["timeout_seconds"] = result.pop("legacy_timeout")

    if "debug_mode" in result and result["debug_mode"]:
        warnings.warn(
            "debug_mode is enabled; do not use in production",
            ConfigurationWarning,
            stacklevel=2,
        )

    return result


def format_greeting(name: str) -> str:
    """Format a greeting message."""
    if not name.strip():
        warnings.warn(
            "empty name provided, fallback to default",
            UserWarning,
            stacklevel=2,
        )
        return "Hello, Anonymous!"
    return f"Hello, {name}!"


def demonstrate_pytest_warns() -> None:
    """Demonstrate warning assertions with pytest.warns."""
    # 1. Assert warning category and inspect recorded warnings
    with pytest.warns(DeprecationWarning) as record:
        parse_config({"legacy_timeout": 30})
    assert len(record) == 1
    assert record[0].category is DeprecationWarning
    assert "legacy_timeout is deprecated" in str(record[0].message)

    # 2. Assert warning with regex pattern match
    with pytest.warns(ConfigurationWarning, match=r"^debug_mode is enabled.*"):
        parse_config({"debug_mode": True})

    # 3. Assert generic UserWarning
    with pytest.warns(UserWarning, match=r"empty name provided"):
        format_greeting("")


if __name__ == "__main__":
    demonstrate_pytest_warns()
    print("pytest.warns demonstrations completed successfully.")

{
  "schemaVersion": 1,
  "goal": "verify pytest.warns warning assertion contract",
  "kind": "HOW",
  "packages": [
    "pkg:pypi/pytest@9.1.1"
  ],
  "symbols": [
    "pytest.warns"
  ]
}

import os
import sys
import warnings

# Ensure project root is on sys.path for local module imports
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

import pytest
from sample import ConfigurationWarning, format_greeting, parse_config


def test_pytest_warns_catches_category_and_provides_recorder():
    # Assertion 1: pytest.warns catches expected warning category and provides warnings list in WarningsRecorder
    with pytest.warns(DeprecationWarning) as record:
        parse_config({"legacy_timeout": 15})

    assert len(record) == 1
    assert record[0].category is DeprecationWarning
    assert "legacy_timeout is deprecated" in str(record[0].message)

    with pytest.warns(ConfigurationWarning) as record:
        parse_config({"debug_mode": True})

    assert len(record) == 1
    assert issubclass(record[0].category, UserWarning)
    assert "debug_mode is enabled" in str(record[0].message)


def test_pytest_warns_matches_pattern():
    # Assertion 2: pytest.warns matches warning message using match regex pattern
    with pytest.warns(UserWarning, match=r"^empty name provided.*"):
        greeting = format_greeting("   ")
        assert greeting == "Hello, Anonymous!"

    with pytest.warns(DeprecationWarning, match=r".*timeout_seconds.*"):
        cfg = parse_config({"legacy_timeout": 60})
        assert cfg["timeout_seconds"] == 60


def main():
    test_pytest_warns_catches_category_and_provides_recorder()
    test_pytest_warns_matches_pattern()
    print("Contract verification passed.")


if __name__ == "__main__":
    main()