test_mach_commands_spawn.py

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# This Source Code Form is subject to the terms of the Mozilla Public

# License, v. 2.0. If a copy of the MPL was not distributed with this

# file, You can obtain one at http://mozilla.org/MPL/2.0/.

"""Regression tests for Bug 2019789.

The newtab mach subcommands spawn a child mach process. Passing a bare,

relative, extension-less "./mach" as argv[0] crashes on Windows with

WinError 193 (CreateProcess cannot run a shebang script as a Win32 process)

and assumes CWD == topsrcdir. The fix launches via the running interpreter

(sys.executable) with an absolute path to mach. These tests pin that argv

shape so a relative "./mach" cannot creep back in.

"""

import importlib.util

import os

import sys

from os import path

from unittest import mock

import mozunit

from mach.registrar import Registrar

NEWTAB_DIR = path.abspath(path.join(path.dirname(__file__), path.pardir, path.pardir))

# Third-party and generated modules that mach_commands imports at module level.

# We only need them to satisfy the import; none are used by the code paths under

# test. mach.decorators is deliberately NOT stubbed: the @Command/@SubCommand

# decorators must run for real so the command functions register and remain

# callable.

_STUBBED_IMPORTS = (

    "requests",

    "yaml",

    "colorama",

    "taskcluster",

    "glean_utils",

    "run_glean_parser",

def _load_mach_commands():

    # Importing mach_commands runs the @Command/@SubCommand decorators, which

    # register into the global mach Registrar. In a bare pytest process no

    # categories are registered, so pre-register the "misc" category that the

    # newtab command declares; otherwise registration raises MachError.

    if "misc" not in Registrar.categories:

        Registrar.register_category("misc", "Misc", "Miscellaneous commands.")

    # Install the stubs only for the duration of the import, then restore

    # sys.modules. Some of these (yaml, colorama) are real modules that pytest

    # plugins import later; leaving fakes in sys.modules would break plugin

    # bootstrap during pytest.main().

    saved = {name: sys.modules.get(name) for name in _STUBBED_IMPORTS}

    for name in _STUBBED_IMPORTS:

        sys.modules[name] = mock.MagicMock()

    try:

        spec = importlib.util.spec_from_file_location(

            "newtab_mach_commands", path.join(NEWTAB_DIR, "mach_commands.py")

        module = importlib.util.module_from_spec(spec)

        spec.loader.exec_module(module)

    finally:

        for name, original in saved.items():

            if original is None:

                sys.modules.pop(name, None)

            else:

                sys.modules[name] = original

    return module

mach_commands = _load_mach_commands()

def _command_context():

    ctx = mock.MagicMock()

    ctx.topsrcdir = os.path.join("/fake", "topsrcdir")

    return ctx

def _assert_portable_mach_argv(argv):

    # The exact defect from Bug 2019789: a bare relative shebang path.

    assert argv[0] != "./mach"

    # Launch via the running interpreter, not by relying on the OS honoring

    # the mach shebang.

    assert argv[0] == sys.executable

    # Absolute mach path, so the spawn does not assume CWD == topsrcdir.

    assert os.path.isabs(argv[1])

    assert os.path.basename(argv[1]) == "mach"

def test_mach_argv_uses_interpreter_and_absolute_path():

    ctx = _command_context()

    assert mach_commands.mach_argv(ctx) == [

        sys.executable,

        os.path.join(ctx.topsrcdir, "mach"),

def test_install_spawns_via_interpreter_not_relative_mach():

    ctx = _command_context()

    with mock.patch.object(mach_commands.subprocess, "Popen") as popen:

        popen.return_value.returncode = 0

        popen.return_value.wait.return_value = 0

        mach_commands.install(ctx)

    popen.assert_called_once()

    _assert_portable_mach_argv(popen.call_args.args[0])

def test_bundle_spawns_via_interpreter_not_relative_mach():

    ctx = _command_context()

    with mock.patch.object(mach_commands.subprocess, "Popen") as popen:

        popen.return_value.returncode = 0

        popen.return_value.wait.return_value = 0

        mach_commands.bundle(ctx)

    popen.assert_called_once()

    _assert_portable_mach_argv(popen.call_args.args[0])

def test_watch_spawns_both_children_via_interpreter():

    ctx = _command_context()

    with mock.patch.object(

        mach_commands.subprocess, "Popen"

    ) as popen, mock.patch.object(

        mach_commands.time, "sleep", side_effect=KeyboardInterrupt

    ), mock.patch.object(mach_commands, "run_mach"):

        mach_commands.watch(ctx)

    assert popen.call_count == 2

    for call in popen.call_args_list:

        _assert_portable_mach_argv(call.args[0])

if __name__ == "__main__":

    mozunit.main()