How to Mock subprocess Calls in Python with unittest.mock

import subprocess
from unittest.mock import patch, Mock


def run_vagrant(action: str) -> str:
    result = subprocess.run(
        ["vagrant", action],
        capture_output=True,
        text=True,
        check=False,
    )
    return result.stdout.strip()


def vagrant_wrapper(action: str) -> str:
    if action not in ("up", "destroy"):
        raise ValueError(f"Unsupported action: {action}")
    output = run_vagrant(action)
    return f"Vagrant {action} done: {output or 'no output'}"


if __name__ == "__main__":
    fake_output = "==> default: VM created"
    with patch("__main__.run_vagrant", return_value=fake_output) as mock_run:
        result = vagrant_wrapper("up")
        mock_run.assert_called_once_with("up")
        print(result)

    with patch("__main__.run_vagrant", return_value="") as mock_run:
        result = vagrant_wrapper("destroy")
        mock_run.assert_called_once_with("destroy")
        print(result)

    with patch("__main__.run_vagrant", side_effect=ValueError("Invalid command")):
        try:
            vagrant_wrapper("invalid")
        except ValueError as error:
            print(f"Error caught: {error}")