How to Mock a Fast uv pip sync in Python

import os
import shutil
import subprocess
import sys
import tempfile
from pathlib import Path

def uv_pip_sync_fast_install_mock(requirements_text: str) -> dict:
    """Simulate a fast uv pip sync by mocking file operations and subprocess calls."""
    mock_dir = Path(tempfile.mkdtemp(prefix="uv_mock_"))
    req_lines = [line.strip() for line in requirements_text.splitlines() if line.strip() and not line.startswith("#")]
    
    for i, pkg in enumerate(req_lines):
        pkg_path = mock_dir / f"{pkg.replace('==', '_').replace('>=', '_').replace('<', '_').replace(' ', '_')}.txt"
        pkg_path.write_text(f"MOCKED INSTALL FOR: {pkg}", encoding="utf-8")

    install_log = mock_dir / "install_log.txt"
    install_log.write_text(f"Mock uv pip sync completed in 0.001s\nPackages: {', '.join(req_lines)}", encoding="utf-8")

    # Simulate no-op subprocess (fast install)
    subprocess.run([sys.executable, "-c", "pass"], check=True, capture_output=True)

    return {
        "packages_installed": req_lines,
        "mock_dir": str(mock_dir),
        "install_log": install_log.read_text(encoding="utf-8"),
        "fast_install": True,
        "cleanup_required": True,
    }

if __name__ == "__main__":
    requirements = """# Mock requirements
requests==2.31.0
numpy>=1.24
pandas<2.0
"""
    result = uv_pip_sync_fast_install_mock(requirements)
    print(f"Simulated fast uv pip sync:")
    for key, value in result.items():
        if key == "packages_installed":
            print(f"  {key}: {value}")
        elif key == "install_log":
            print(f"  {key}:\n{value}")
        else:
            print(f"  {key}: {value}")
    # Cleanup demonstration (actual cleanup would be done after use)
    shutil.rmtree(result["mock_dir"], ignore_errors=True)
    print("  cleanup_required: completed (simulated)")