Re: [PATCH v7 5/8] Acceptance tests: keep a stable reference to the QEMU build dir

[Wainer dos Santos Moschetta <wainersm@redhat.com>]

On 11/4/19 1:13 PM, Cleber Rosa wrote:
> This is related to the the differences in in-tree and out-of-tree
> builds in QEMU.  For simplification, <BLD> means my build directory.
>
> Currently, by running a `make check-acceptance` one gets (in
> tests/acceptance/avocado_qemu/__init__.py):
>
>     SRC_ROOT_DIR: <BLD>/tests/acceptance/avocado_qemu/../../..
>
> This in itself is problematic, because after the parent directories
> are applied, one may be left not with a pointer to the build directory
> as intended, but with the location of the source tree (assuming they
> differ). Built binaries, such as qemu-img, are of course not there and
> can't be found.
>
> Given that a Python '__file__' will contain the absolute path to the
> file backing the module, say:
>
>     __file__: <BLD>/tests/acceptance/avocado_qemu/__init__.py
>
>                    |  4  |     3    |      2     |     1     |
>
> A solution is to not "evaluate" the third parent dir (marked as 4
> here) because that ends up following the "tests" directory symlink to
> the source tree.  In fact, there's no need to keep or evaluate any of
> the parent directories, we can just drop the rightmost 4 components,
> and we'll keep a stable reference to the build directory (with no
> symlink being followed).  This works for either a dedicated build
> directory or also a combined source and build tree.
>
> Signed-off-by: Cleber Rosa <crosa@redhat.com>
> ---
>   tests/acceptance/avocado_qemu/__init__.py | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tests/acceptance/avocado_qemu/__init__.py b/tests/acceptance/avocado_qemu/__init__.py
> index 6618ea67c1..17ce583c87 100644
> --- a/tests/acceptance/avocado_qemu/__init__.py
> +++ b/tests/acceptance/avocado_qemu/__init__.py
> @@ -16,7 +16,7 @@ import tempfile
>   
>   import avocado
>   
> -SRC_ROOT_DIR = os.path.join(os.path.dirname(__file__), '..', '..', '..')
> +SRC_ROOT_DIR = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(__file__))))

In this case, wouldn't make sense to rename the constant from 
SRC_ROOT_DIR to BUILD_ROOT_DIR?

This patch looks good to me besides that.

- Wainer

>   sys.path.append(os.path.join(SRC_ROOT_DIR, 'python'))
>   
>   from qemu.machine import QEMUMachine