[RFC PATCH v2 7/7] iotests: self-bootstrap testing venv

[John Snow <jsnow@redhat.com>]

When iotests are invoked manually from
e.g. $build/tests/qemu-iotests/check, it is not necessarily guaranteed
that we'll have run 'check-venv' yet.

With this patch, teach testenv.py how to create its own environment.

Note: this self-bootstrapping is fairly rudimentary and will miss
certain triggers to refresh the venv. It will miss when new dependencies
are added to either python/setup.cfg or tests/setup.cfg. It can be
coaxed into updating by running 'make check', 'make check-block', 'make
check-venv', etc.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 tests/qemu-iotests/testenv.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tests/qemu-iotests/testenv.py b/tests/qemu-iotests/testenv.py
index 29404ac94be..e985eaf3e97 100644
--- a/tests/qemu-iotests/testenv.py
+++ b/tests/qemu-iotests/testenv.py
@@ -112,10 +112,10 @@ def init_directories(self) -> None:
         """
         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?)"
+            mkvenv = Path(self.source_iotests, '../mkvenv.py')
+            subprocess.run(
+                (sys.executable, str(mkvenv), str(venv_path)),
+                check=True,
             )
         self.virtual_env: str = str(venv_path)
 
-- 
2.34.3