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

[Cleber Rosa <crosa@redhat.com>]

On Thu, Nov 07, 2019 at 05:22:24PM -0200, Wainer dos Santos Moschetta wrote:
> 
> 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
>

So, based on your review, I went back and forward with this.  I'm
going to propose something different on v8, basically distinguishing
between source and build directories.  I'm keeping this patch as is on
v8 though, just for the sake of making the indivdual changes easier to
track.

Thanks,
- Cleber.

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