How to Mock Commitizen Version Bump in Python

import subprocess
from unittest.mock import patch, MagicMock


def bump_version(current_version: str, increment: str = "patch") -> str:
    """Simulate commitizen's version bump logic."""
    major, minor, patch = map(int, current_version.split("."))
    if increment == "major":
        major += 1
        minor = 0
        patch = 0
    elif increment == "minor":
        minor += 1
        patch = 0
    elif increment == "patch":
        patch += 1
    else:
        raise ValueError(f"Unknown increment: {increment}")
    return f"{major}.{minor}.{patch}"


def run_commitizen_bump() -> str:
    """Mock the subprocess call to commitizen to avoid real execution."""
    with patch("subprocess.run") as mock_run:
        mock_run.return_value = MagicMock(
            returncode=0,
            stdout=b"bump: version 1.2.3 -> 1.2.4\n",
            stderr=b""
        )
        result = subprocess.run(
            ["cz", "bump", "--yes"],
            capture_output=True,
            check=True
        )
        return result.stdout.decode().strip()


if __name__ == "__main__":
    print(f"Direct logic: {bump_version('1.2.3')}")
    print(f"Mocked external call: {run_commitizen_bump()}")