dev_tools/bash_scripts_test.py does not guard against interference from user's ~/.gitconfig

[mhucka]

Description of the issue

When running pytest in the Cirq repo (or check/pytest), the tests in dev_tools/bash_scripts_test.py run a series of git commands and compares the output against expected values. A few of the tests will fail with very confusing errors if the user has configured init.templateDir in their global ~/.gitconfig file. The reason is that the command

git init --quiet --initial-branch master

will generate a "warning: re-init ignored" message, and that in turn causes the tests in bash_scripts_test.py to fail because the tests rely on matching exactly the stdout/stderr from the commands.

How to reproduce the issue

1. Set init.templateDir, either using a git config command or by creating a ~/.gitconfig file manually and putting something like this in it:

   [init]
       templateDir = ~/.config/git/template
   

2. Run the following command in a shell from the Cirq repo top level:

   check/pytest -vvv dev_tools/bash_scripts_test.py::test_pytest_changed_files_file_selection
   

The result will be a bunch of output ending in a failure. The full output is below.

> check/pytest -vvv dev_tools/bash_scripts_test.py::test_pytest_changed_files_file_selection                                                                                    quantum/repos/Cirq
=========================================================================================== test session starts ============================================================================================
platform darwin -- Python 3.9.13, pytest-7.1.2, pluggy-1.0.0 -- /Users/mhucka/project-files/quantum/repos/Cirq/env/bin/python3
cachedir: .pytest_cache
rootdir: /Users/mhucka/project-files/quantum/repos/Cirq
plugins: asyncio-0.18.3, forked-1.4.0, xdist-2.2.1, cov-3.0.0
asyncio: mode=legacy
[gw0] darwin Python 3.9.13 cwd: /Users/mhucka/project-files/quantum/repos/Cirq
[gw1] darwin Python 3.9.13 cwd: /Users/mhucka/project-files/quantum/repos/Cirq
[gw2] darwin Python 3.9.13 cwd: /Users/mhucka/project-files/quantum/repos/Cirq
[gw3] darwin Python 3.9.13 cwd: /Users/mhucka/project-files/quantum/repos/Cirq
[gw0] Python 3.9.13 (main, May 24 2022, 21:28:12)  -- [Clang 12.0.0 (clang-1200.0.32.29)]
[gw1] Python 3.9.13 (main, May 24 2022, 21:28:12)  -- [Clang 12.0.0 (clang-1200.0.32.29)]
[gw2] Python 3.9.13 (main, May 24 2022, 21:28:12)  -- [Clang 12.0.0 (clang-1200.0.32.29)]
[gw3] Python 3.9.13 (main, May 24 2022, 21:28:12)  -- [Clang 12.0.0 (clang-1200.0.32.29)]
gw0 [1] / gw1 [1] / gw2 [1] / gw3 [1]
scheduling tests via LoadScheduling

dev_tools/bash_scripts_test.py::test_pytest_changed_files_file_selection
[gw0] [100%] FAILED dev_tools/bash_scripts_test.py::test_pytest_changed_files_file_selection sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=0 mode='r' encoding='UTF-8'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=1 mode='w' encoding='UTF-8'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=0 mode='r' encoding='UTF-8'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=1 mode='w' encoding='UTF-8'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=0 mode='r' encoding='UTF-8'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=1 mode='w' encoding='UTF-8'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=0 mode='r' encoding='UTF-8'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=1 mode='w' encoding='UTF-8'>


================================================================================================= FAILURES =================================================================================================
_________________________________________________________________________________ test_pytest_changed_files_file_selection _________________________________________________________________________________
[gw0] darwin -- Python 3.9.13 /Users/mhucka/project-files/quantum/repos/Cirq/env/bin/python3

tmpdir_factory = TempdirFactory(_tmppath_factory=TempPathFactory(_given_basetemp=PosixPath('/private/var/folders/m1/fxfnb93j1vv_nlxq8nd... _basetemp=PosixPath('/private/var/folders/m1/fxfnb93j1vv_nlxq8nd9brkr0000gz/T/pytest-of-mhucka/pytest-35/popen-gw0')))

    @only_on_posix
    def test_pytest_changed_files_file_selection(tmpdir_factory):

        result = run(
            script_file='check/pytest-changed-files',
            tmpdir_factory=tmpdir_factory,
            arg='HEAD~1',
            setup='touch file.py\ngit add -A\ngit commit -m test --quiet --no-gpg-sign\n',
        )
        assert result.returncode == 0
        assert result.stdout == ''
>       assert (
            result.stderr.split()
            == (
                "Comparing against revision 'HEAD~1'.\nFound 0 test files associated with changes.\n"
            ).split()
        )
E       assert ['warning:',\n 're-init:',\n 'ignored',\n '--initial-branch=master',\n 'Comparing',\n 'against',\n 'revision',\n "'HEAD~1'.",\n 'Found',\n '0',\n 'test',\n 'files',\n 'associated',\n 'with',\n 'changes.'] == ['Comparing',\n 'against',\n 'revision',\n "'HEAD~1'.",\n 'Found',\n '0',\n 'test',\n 'files',\n 'associated',\n 'with',\n 'changes.']
E         At index 0 diff: 'warning:' != 'Comparing'
E         Left contains 4 more items, first extra item: 'files'
E         Full diff:
E           [
E         +  'warning:',
E         +  're-init:',
E         +  'ignored',
E         +  '--initial-branch=master',
E            'Comparing',
E            'against',
E            'revision',
E            "'HEAD~1'.",
E            'Found',
E            '0',
E            'test',
E            'files',
E            'associated',
E            'with',
E            'changes.',
E           ]

dev_tools/bash_scripts_test.py:90: AssertionError
============================================================================================= warnings summary =============================================================================================
env/lib/python3.9/site-packages/pytest_asyncio/plugin.py:191
env/lib/python3.9/site-packages/pytest_asyncio/plugin.py:191
env/lib/python3.9/site-packages/pytest_asyncio/plugin.py:191
env/lib/python3.9/site-packages/pytest_asyncio/plugin.py:191
env/lib/python3.9/site-packages/pytest_asyncio/plugin.py:191
  /Users/mhucka/project-files/quantum/repos/Cirq/env/lib/python3.9/site-packages/pytest_asyncio/plugin.py:191: DeprecationWarning: The 'asyncio_mode' default value will change to 'strict' in future, please explicitly use 'asyncio_mode=strict' or 'asyncio_mode=auto' in pytest configuration file.
    config.issue_config_time_warning(LEGACY_MODE, stacklevel=2)

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
========================================================================================= short test summary info ==========================================================================================
FAILED dev_tools/bash_scripts_test.py::test_pytest_changed_files_file_selection - assert ['warning:',\n 're-init:',\n 'ignored',\n '--initial-branch=master',\n 'Comparing',\n 'against',\n 'revision',\n...
====================================================================================== 1 failed, 5 warnings in 1.22s =======================================================================================

Cirq version

0.16.0.dev