Allow simulating unimportable backends

I have both backends available in my test environment and use
QUTE_TESTS_BACKEND to pick a backend.

Since moving to qutebrowser/qt.py as a file instead of modules some
error cases show up as AttributeErrors at import time instead of ImportErrors.
In particular when you import a qutebrowser module like
webenginequtescheme and the webengine stuff in qt.py is None we get
errors like

    AttributeError: 'NoneType' object has no attribute 'QWebEngineUrlSchemeHandler'

when we import the qutebrowser module.

This is a way for me to make sure those errors show up for me even when
I have both backends available.

1 files changed, 5 insertions, 0 deletions

diff --git a/qutebrowser/qt.py b/qutebrowser/qt.py
index 445d5f860..3934ced0f 100644
--- a/qutebrowser/qt.py
+++ b/qutebrowser/qt.py
@@ -20,6 +20,7 @@
 """Wrappers around Qt/PyQt code."""
 
 # pylint: disable=unused-import
+import os
 from dataclasses import dataclass
 
 
@@ -87,6 +88,8 @@ elif PyQt6:
     from PyQt6 import QtOpenGL as opengl  # type: ignore[no-redef]
 
 try:
+    if os.environ.get("SKIP_WEBENGINE_IMPORT"):
+        raise ImportError
     if PyQt5:
         from PyQt5 import QtWebEngineCore as webenginecore  # type: ignore[no-redef]
         from PyQt5 import QtWebEngineWidgets as webenginewidgets  # type: ignore[no-redef]
@@ -126,6 +129,8 @@ except ImportError:
     webenginewidgets = None  # type: ignore[assignment]
 
 try:
+    if os.environ.get("SKIP_WEBKIT_IMPORT"):
+        raise ImportError
     if PyQt5:
         from PyQt5 import QtWebKit as webkit  # type: ignore[no-redef]
         from PyQt5 import QtWebKitWidgets as webkitwidgets  # type: ignore[no-redef]