[PATCH 2/6] iotests: add warning for rogue 'qemu' packages

[John Snow]

Add a warning for when 'iotests' runs against a qemu namespace that
isn't the one in the source tree. This might occur if you have
(accidentally) installed the Python namespace package to your local
packages.

(I'm not going to say that this is because I bit myself with this,
but. You can fill in the blanks.)

Signed-off-by: John Snow <jsnow@redhat.com>
---
 tests/qemu-iotests/testenv.py | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/tests/qemu-iotests/testenv.py b/tests/qemu-iotests/testenv.py
index 88104dace90..8a43b193af5 100644
--- a/tests/qemu-iotests/testenv.py
+++ b/tests/qemu-iotests/testenv.py
@@ -16,6 +16,8 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
+import importlib.util
+import logging
 import os
 import sys
 import tempfile
@@ -25,7 +27,7 @@
 import random
 import subprocess
 import glob
-from typing import List, Dict, Any, Optional, ContextManager
+from typing import List, Dict, Any, Optional, ContextManager, cast
 
 DEF_GDB_OPTIONS = 'localhost:12345'
 
@@ -112,6 +114,22 @@ def init_directories(self) -> None:
         # Path where qemu goodies live in this source tree.
         qemu_srctree_path = Path(__file__, '../../../python').resolve()
 
+        # warn if we happen to be able to find 'qemu' packages from an
+        # unexpected location (i.e. the package is already installed in
+        # the user's environment)
+        qemu_spec = importlib.util.find_spec('qemu.qmp')
+        if qemu_spec:
+            spec_path = Path(cast(str, qemu_spec.origin))
+            try:
+                _ = spec_path.relative_to(qemu_srctree_path)
+            except ValueError:
+                self._logger.warning(
+                    "WARNING: 'qemu' package will be imported from outside "
+                    "the source tree!")
+                self._logger.warning(
+                    "Importing from: '%s'",
+                    spec_path.parents[1])
+
         self.pythonpath = os.getenv('PYTHONPATH')
         self.pythonpath = os.pathsep.join(filter(None, (
             self.source_iotests,
@@ -231,6 +249,7 @@ def __init__(self, imgfmt: str, imgproto: str, aiomode: str,
 
         self.build_root = os.path.join(self.build_iotests, '..', '..')
 
+        self._logger = logging.getLogger('qemu.iotests')
         self.init_directories()
         self.init_binaries()
 
-- 
2.31.1