testwheel.py: Fix up the error handling

When no PySide was present, the too would error out:

testwheel.py", line 520, in <module>
   VERSION[0] = path_version
   TypeError: 'tuple' object does not support item assignment

This apparently resulted from some old code trying to determine
the version from the path.
Split out the code trying to find the root into a helper
function and reorder the code for clarity. Print out errors
to stderr.

Change-Id: I3f4e878cf3e3d09466180c65e92da98946ee6826
Reviewed-by: Shyamnath Premnadh <[email protected]>

Author: FriedemannKleint

scripts/packagetesting/testwheel.py

@@ -57,14 +57,26 @@ def get_pyside_version_from_import():
             from PySide2.QtCore import qVersion
             qversion_string = qVersion()
         except ImportError:
-            print('Unable to determine PySide version; could not import any version',
-                  file=sys.stderr)
+            pass
     if qversion_string:
         major, minor, patch = qVersion().split('.')
         return int(major), int(minor), int(patch)
     return 0, 0, 0
 
 
+def find_pyside_root():
+    for p in map(Path, sys.path):
+        if p.name == 'site-packages':
+            root = p / 'PySide6'
+            if root.is_dir():
+                return root
+            root = p / 'PySide2'
+            if root.is_dir():
+                return root
+            break
+    return None
+
+
 def list_modules():
     """List the installed Qt modules."""
     if VERSION[0] > 5:
@@ -500,35 +512,26 @@ def install_wheels(wheel_dir):
             install_wheels(tmpdir)
 
     VERSION = get_pyside_version_from_import()
+    if VERSION[0] == 0:
+        print('Unable to determine PySide version; could not import any version',
+              file=sys.stderr)
+        sys.exit(1)
     if do_pyinst and sys.version_info[0] < 3:  # Note: PyInstaller no longer supports Python 2
         print('PyInstaller requires Python 3, test disabled')
         do_pyinst = False
-    root = None
-    path_version = 0
-    for p in map(Path, sys.path):
-        if p.name == 'site-packages':
-            root = p / 'PySide6'
-            if root.is_dir():
-                path_version = 6
-            else:
-                root = p / 'PySide2'
-                path_version = 2
-            if not root_ex:
-                root_ex = root / 'examples'
-            break
-    if VERSION[0] == 0:
-        VERSION[0] = path_version
-    print('Detected Qt version ', VERSION)
-    if not root or not root.is_dir():
-        print('Could not locate any PySide module.')
+    root = find_pyside_root()
+    if not root:
+        print('Could not locate any PySide module.', file=sys.stderr)
         sys.exit(1)
+    if not root_ex:
+        root_ex = root / 'examples'
     if not root_ex.is_dir():
         m = f"PySide{VERSION} module found without examples. "
         m += ("Specify --examples <dir>." if VERSION >= (6, 5, 0)
               else "Did you forget to install wheels?")
-        print(m)
+        print(m, file=sys.stderr)
         sys.exit(1)
-    print(f'Detected PySide{VERSION} at {root}.')
+    print(f'Detected PySide {VERSION[0]}.{VERSION[1]}.{VERSION[2]} at {root}.')
 
     list_modules()