Re: [RFC PATCH 9/9] iotests: use tests/venv for running tests

[Paolo Bonzini <pbonzini@redhat.com>]

On 5/13/22 02:06, John Snow wrote:
> Essentially, this:
> 
> (A) adjusts the python binary to be the one found in the venv (which is
> a symlink to the python binary chosen at configure time)
> 
> (B) adds a new VIRTUAL_ENV export variable
> 
> (C) changes PATH to front-load the venv binary directory.
> 
> If the venv directory isn't found, raise a friendly exception that tries
> to give the human operator a friendly clue as to what's gone wrong. In
> the very near future, I'd like to teach iotests how to fix this problem
> entirely of its own volition, but that's a trick for a little later.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>   tests/qemu-iotests/testenv.py | 24 +++++++++++++++++-------
>   1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/tests/qemu-iotests/testenv.py b/tests/qemu-iotests/testenv.py
> index 0007da3f06c..fd3720ed7e7 100644
> --- a/tests/qemu-iotests/testenv.py
> +++ b/tests/qemu-iotests/testenv.py
> @@ -65,8 +65,9 @@ class TestEnv(ContextManager['TestEnv']):
>       # lot of them. Silence pylint:
>       # pylint: disable=too-many-instance-attributes
>   
> -    env_variables = ['PYTHONPATH', 'TEST_DIR', 'SOCK_DIR', 'SAMPLE_IMG_DIR',
> -                     'PYTHON', 'QEMU_PROG', 'QEMU_IMG_PROG',
> +    env_variables = ['PYTHONPATH', 'VIRTUAL_ENV', 'PYTHON',
> +                     'TEST_DIR', 'SOCK_DIR', 'SAMPLE_IMG_DIR',
> +                     'QEMU_PROG', 'QEMU_IMG_PROG',
>                        'QEMU_IO_PROG', 'QEMU_NBD_PROG', 'QSD_PROG',
>                        'QEMU_OPTIONS', 'QEMU_IMG_OPTIONS',
>                        'QEMU_IO_OPTIONS', 'QEMU_IO_OPTIONS_NO_FMT',
> @@ -98,6 +99,10 @@ def get_env(self) -> Dict[str, str]:
>               if val is not None:
>                   env[v] = val
>   
> +        env['PATH'] = os.pathsep.join((
> +            os.path.join(self.virtual_env, 'bin'),
> +            os.environ['PATH']
> +        ))
>           return env
>   
>       def init_directories(self) -> None:
> @@ -107,13 +112,17 @@ def init_directories(self) -> None:
>                SOCK_DIR
>                SAMPLE_IMG_DIR
>           """
> -
> -        # Path where qemu goodies live in this source tree.
> -        qemu_srctree_path = Path(__file__, '../../../python').resolve()
> +        venv_path = Path(self.build_root, 'tests/venv/')
> +        if not venv_path.exists():
> +            raise FileNotFoundError(
> +                f"Virtual environment \"{venv_path!s}\" isn't found."
> +                " (Maybe you need to run 'make check-venv'"
> +                " from the build dir?)"
> +            )
> +        self.virtual_env: str = str(venv_path)
>   
>           self.pythonpath = os.pathsep.join(filter(None, (
>               self.source_iotests,
> -            str(qemu_srctree_path),
>               os.getenv('PYTHONPATH'),
>           )))
>   
> @@ -138,7 +147,7 @@ def init_binaries(self) -> None:
>                PYTHON (for bash tests)
>                QEMU_PROG, QEMU_IMG_PROG, QEMU_IO_PROG, QEMU_NBD_PROG, QSD_PROG
>           """
> -        self.python = sys.executable
> +        self.python: str = os.path.join(self.virtual_env, 'bin', 'python3')

Is this guaranteed even if, say, only a /usr/bin/python3.9 exists? 
os.path.basename(sys.executable) might be more weirdness-proof than 
'python3'.

Paolo