Creating a venv can run a local ensurepip.py #160279

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

with TemporaryDirectory() as name:
    root = Path(name)
    home = root / "private"
    home.mkdir(mode=0o700)
    env = {k: v for k, v in os.environ.items() if not k.startswith("PYTHON")}
    env["PIP_NO_INDEX"] = "1"
    cases = [
        ("normal", [], [], True),
        ("isolated", ["-I"], [], True),
        ("without-pip", ["-I"], ["--without-pip"], False),
        ("clear-regular-directory", ["-I"], ["--clear"], False),
    ]
    if len(sys.argv) > 1:
        cases.append(("vscode", ["-I"], [], True))
    for case, interpreter_options, venv_options, expected in cases:
        project = root / case
        target = project / ".venv"
        target.mkdir(parents=True)
        marker = home / case
        (target / "ensurepip.py").write_text(
            "import os, runpy, sys\n"
            "from pathlib import Path\n"
            f"Path({str(marker)!r}).write_text('bootstrap executed')\n"
            "sys.path[:] = [s for s in sys.path if os.path.realpath(s) != os.getcwd()]\n"
            "runpy.run_module('ensurepip', run_name='__main__')\n"
        )
        if case == "vscode":
            arguments = [str(Path(sys.argv[1]).resolve())]
        else:
            arguments = ["-m", "venv", *venv_options, ".venv"]
        command = [sys.executable, *interpreter_options, *arguments]
        subprocess.run(command, env=env, cwd=project, check=True, timeout=90)
        print(case, "marker", marker.exists(), flush=True)
        assert marker.exists() is expected